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A Comparative Study of Domestic and Hospital
Environmental Microbial Populations in Al-Ain
(UAE)
Amna Ali Jaffal
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Theses. 559.
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A COMPARATIVE STUDY OF DOMESTIC AND
HOSPITAL ENVIRONMENTAL MICROBIAL
POPULATIONS IN AL-AIN (UAE)
By
AMNA ALI JAFFAL
A Th esis Submitted to th e F ac ul ty of Sc ienc e of th e
unitedArab Emirate U niversity in partial f ul f il ment
of th e requirements f or th e deg ree of Master of
Environmental Sc ience
F ac ul ty of Scienc e UAE U niversity
D ec ember 1 994
The
Thesis
of
Amna
All
Jaffal
for
the degree
of
Master
Evironmental sciences is approved
\
Chair of Committee'
O--+-!�>�-
Ibrahim M. Banat, Ph D
Examining Committee Member: Herbert Nasanze, Ph D.
Examining Committee Member: AbdulmaJeed S Ameen, Ph. D
Examining Committee Member: Abdullah Abu-Ruwaida, Ph D.
Dean of the Faculty of Science: Salah EI-Nahawy
United Arab Emirates University
of
SCience
In
ABSTRACT
This is the first attempt to estimate b i olog ical i ndoor pol lution
i n the environment of AI-Ain city. The numbers and types of bacteria
and fun g i in the air and on the surfaces were measured in AI-Ain
hospital and three d ifferent types of d omestic environments.
F ive d ifferent types of wards at AI-Ai n hospita l , med ica l ,
surg ica l , ped iatrics, operati ng theater, a n d i ntensive care unit were
stud i e d . Their estimated indoor bioaerosols were compared to i ndoor
b i oaerosols in three types of dwe l l ing houses, very g ood , average,
and poor q u a l ity houses i n AI-Ain city . A bacteri o l og ical mechanical
a i r sampler, M K2 (Case l l a London) was used i n this stu d y .
T h e result o f this study showed that the s a m e g roups of
bacteria and fun g i isolated from the hospital environment were also
found i n domestic a i r samples. The hig hest number of bacteria in the
hospital was found in the ped iatric and female medica l wards while
the l owest were i n the operating theater. The number of bacteria in
the domestic environment was related to the type of housing ; the
h i g he r the q ual ity of house the l ower the number of m icro-organisms.
111
Pathogenic and human related micro-org anisms were found to be
more prevalent in a hospital environment than i n the domestic
environment.
In general the hospital a i r m i cro b i a l counts were
compara b l e to very good qual ity houses. The commonest species of
fun g i found i n both environments were Asperigil/us niger.
Surface
samples in hospital and homes showed that surface m icro-organisms
orig inated from air contaminants .
A com parison of hospital and domestic bacterial sensitivity was
carried out u s i ng coag ulase negative Staphylococci ( e N S) . These were
a lso compared to the patients'n e N S .
The sensitivity pattern of e N S
i n d icated that the "environment" or t h e source o f t h e m i crobes had some
effect u pon the micro-organisms.
Domestic a irborne eNS were very
sensitive to nearly a l l the anti biotics tested while patients harbored the
m ost res i stant e N S with hospital airborne e N S fal l ing in between.
Hospital a i rborne agents wou ld seem to be a m i xture of patients' strains
and the environmental strains possibly bro u g ht i n by visitors to the
hospita l .
iv
TABLE OF C ONTENTS
Title page
ii
Abstract
iii
Table of contents
iiii
List of tables
viii
List of figures
x
Acknowledgments
xii
CHAPTER I.
Introduc tion
1
Th e Objec tive of Th e Study
5
CHAPTER II
7
Review of l iterature
1 .1
H i story of I ndoor Air Pol l ution
7
1 .2
The Pollutants
9
1 .2 . 1 Dust
10
Sources of I ndoor Airborne M i crobes
11
1 .3 . 1 Outdoor Environment
11
1.3
v
TABLE OF C ONTENTS
1.3
Sources of I ndoor Airborne M i crobes
11
1 .3. 2 I ndoor Contam ination
12
Factors I nfluencing I ndoor M icrobial Levels
14
1 .4. 1 Air Currents
15
1 .4. 2 Other factors
16
1.5
Types of Environmental Bacteria
17
1 .6
Types of Environmental F u n g i
18
1 .6. 1 N i che o f Fung i in I ndoor Environment
18
1 .7
Hospital Environment
20
1 .8
Source of I ndoor Contamination i n H ospital Environment
22
1 .9
Hospital Bacteria Associated With I nfections
23
1.10
Domestic Environment M icrobes
25
1.1 1
Sick Building Syndrome
27
1 .4
CHAPTER III
MATERIALS AND METHODS
28
2. 1
Sources of Materials For Study
28
2. 1 . 1 Hospital Environment Study
28
vi
TABLE OF C ONTENTS
2. 1
2. 2
Sources of Materi a l s For Study
28
2. 1. 2 Domestic Environment Study
32
Sampling Techniques
42
2.2. 1 Air Samples
42
a
P l ate Exposure M ethod
42
b
Determ i n ation of Opti mum Plate Exposure Time
42
c
Mechan ical Bacterial Air Sampler M K2
43
d
Determ i nation of Opti mum Time Requ ired For
Mech a n i ca l a i r Sampler
48
2. 2. 2 Surface S a m p l i n g
52
2.3
C u lture Media
52
2.4
Identification Techn ique
53
2.4. 1 Bacteria l I d e ntification
53
2.4. 2 Fungal Identificatio n
56
2. 5
Sensitivity Test
56
2.6
Data Processing Statistical M ethods and Analysis
57
vii
TABLE OF CONTENTS
CHAPTER IV
RESULTS
63
CHAPTER V
DISCUSSION
93
CHAPTER VI
CONCLUSION
111
CHAPTER VII
BIBLIOG RAPHY
1 14
viii
LIST OF TABLES
P ag e
Tabl e 1
The total num ber of C F U on blood Agar at d ifferent
time using plate a i r exposure method
Tabl e 2
The total number of C F U on blood Agar at different
time using mach i n e air sampler method
Tabl e 3
65
Domestic a i r m icro-organisms isolated from three
68
types ofhouses
Tabl e 6
D o mestic air m icro-org a nisms isolated from three
types of houses comparing Living rooms to bedrooms
Tabl e 7
51
Hospital air m icro-organ isms isolated from five
ward u s i n g a i r samples
Tabl e 5
50
M icro-organisms isolated by exposure method
com paredwith i solates by air sampler
Tabl e 4
46
71
M i cro-org a n i s m s i solated from the hospital environment
compared to m icro-organisms from the house
environment col lected using the air samples
ix
73
LIST OF TABLES
Ta b l e 8
Surface m icro-organisms isolated from d ifferent wards
at AI-Ain Hospita l
Ta b l e 9
77
M icro-org a n isms isolated from surfaces i n d ifferent
house types
Ta b l e 10
79
M icro-organisms isolated from hospital surfaces
compared with those from different house types
Ta b l e 11
I ntensive Care U nit and Operating Theater microorganism s isolated from air and surface samples
Ta b l e 12
84
Total num bers of air and surface m icro-organisms
isolated from hospital and the three types of houses
T a b l e 13
80
85
The most d o m i nant fun g i in hospital air isolated from
five wardusing a i r sampler
87
Ta b l e 14
A i r- borne fun g i i so l ated from three types of houses
88
Ta b l e 15
Air fun g i i solated from hospital and three types
91
of house
Ta b l e 16
Sensitivity pattern of coag ulase negative staphylococci
iso l ated from deferent areas a n d patients' bodies
x
92
LIST OF FIGURES
Pages
F ig ure 1
A M a p of AI-Ain C ity.
F ig ure 2
M a p of AI-Ain city showing the l ocation of AI-Ai n
30
Hospital a n d homes stud ied.
31
F ig ure 3
Photograph of AI-Ai n hospital .
34
F ig ure 4
Photog raph representing a ward-room inside
the hospita l .
35
F ig ure 5
O utside views of a very good house (type 1 ) .
36
F ig ure 6
I nside views of a very good house (type 1 ).
37
F ig ure 7
Outside views of a medium qual ity house (type 2 ) .
38
F ig ure 8
I nside views of a med ium q u a l ity house (type 2 )
39
F ig ure 9
O utside views of a poor qual ity house (type 3 ) .
40
F ig ure 1 0
i n s i d e views of a poor quality house (type 3 ) .
41
Xl
LIST OF FIGURES
Fig u re 11
Plate exposure culture method
Fig u re 12
M echanical air sampler (Case l l a Bacterial Air Sampler
M K2)
Fig u re 1 3
45
47
C u lture plate after 48 hours incubation time showing
growth of bacteria and fungi using plate exposure
method for 30 min exposur tim e .
59
Fig u re 14
Fungal identification on g ross colonial appearance .
60
Fig u re 1 5
Fungal identification technique m icroscopic examination
( s l i d e culture) .
61
Fig u re 1 6
Picture of various unidentified bacteria .
62
Fig u re 1 7
C hart comparing H ospital a i r m i croorganisms isolated
from five wards using a i r sampler.
Fig u re 18
Chart comparing microorganisms isolated from hospital
air with three types of house
Fig u re 19
66
74
Chart comparing m icroorganisms isolated from hospital
surfaces with those from d ifferent house surfaces
Xll
81
ACKNOWLEDG MENT
It g ives me great honour and pleasure to take this opportunity
to thank my supervisors , Dr. l bra h i m Banat and Dr. Herbert Nsanze,
for their great cooperation , their valuable advice, g u idance and
patience throughout my study.
I also greatly a ppreciate the help
g iven by Dr. Abdou A. E I Mog heth.
My deep appreciation and g ratitud e to the U .A . E . University,
represented by its Chance l l or, H i s H ig h ness S h e i kh Nahyan Bin
M u barak AI Nahyan, for g iving m e the opportunity to obtain a higher
d eg ree.
I am indebted and thankfu l to those working i n the ministry of
health, headed by H i s . E m i nence. the M in i ster of Health , Ahmed
Saeed AI Bad i for cooperation and assistance
I would l i ke also to thank a l l those who assisted me during my
work on this thesis especia l l y Dr. Abd u l Bari and M r. Mohammed
xiii
Yonis from the Department of C ommunity Med icine at the Facu lty of
Medical Science . and H ealth at U .A . E . University, for their help in the
statistical analysis of my data, a lso M r. , Ahmed Salem the chief
technician of AI-Ai n hospital laboratori e s , and a l l the staff members
in the Microbiology Department.
F i n a l ly I would l i ke to express my deep thanks and gratitude to
my parents, for their sacrifice and patience through all the stages of
my study. I also wish to thank a l l my friends especially Ms Amna
Hamad AI- Dhaheri , who hel ped me and stood by me during the
period of my study.
xiv
CHAPTER I
....................
��
�����......
-------------
INTRODUCTION
P o l l ution is one of the most pressing problems of our age.
Pol l ution of the atmosphere has n ow reached a level that poses a
potential threat not only to the health and wel l-being of popu lations of
the g l obe but to the survival of e ntire life (Samet and S peng ler,
1 991 )
.
This study focuses o n indoor air, because indoor air is the
med ium through wh ich peo p l e , buildings, and climate interact.
Human health and their wel l-being are determined by physica l ,
chemica l , a n d biologica l properties o f their indoor air; a n d indoor air
qua lity can be readily d efined and rationally control led .
The contam ination of the indoor environment by microbial
popu lation and other p o l l utants i s a major health problem (Langmuir,
1 980). The concentration of indoor pol l utants varies with the strength
of the pol l ution sources , the vol u m e of the pol l uted space, the rate of
air exchange between indoor and outdoor air, and other factors that
affect removal of p o l l utants. H e a lth risks from indoor pol l ution
1
depend on indoor pol l utants concentration , patterns of human activity
and type of indoor source of air pol l ution used such as com bustion
source ,
which,
along
with
indoor concentration
of pollutants,
determine personal exposures (Samet and S peng ler, 1 99 1 )
I ndoor biolog ica l pol l ution, whi l e of serious concern to a l l
who inhabit i nteriors , h a s o n l y recently began t o receive the
attention afforded outdoor or even indoor chemica l pol l ution
(Yunginer et al. , 1 976) . This a pparent lack of interest is tied to the
d ifficulties of sampling biolog ical aerosols and their variable
health effects.
The a i rborne bioflora i s i nherently com p l ex and
variable to a point that d efies q uantification. The air i n a single
room i n a "clean" house may contai n hundreds of d ifferent kinds of
biolog ica l particles and technology does not exist to quantify or
qual ify a l l of them .
A s many as fou r d i stinct sampling modal ities are required if
those
particles that are
measurable are to
be
accurately
assessed . H ea lth effects of biolog ical aerosol s are basica l l y
d i fferent from those o f thei r chemical counterparts. T h e maj ority of
2
bioaerosols are
non pathogenic and
cause disease only in
sensitized or g rossly immunocompromised peo p l e . F u rthermore ,
pathogenic environmental micro-organisms are usually a b l e to
infect
only
very
suscepti ble
hosts.
The
levels
of
e ither
saprophytes or pathog e n s req uired to cause d i sease d iffer with
each particle type and these levels are unknown for most
microbes.
It i s wel l documented that the hospital environment i s a source
of hospital acq u i red infections ( Bennett and Brachman 1 992) . Many
of the
m i crobes
which
cause
i nfectious
d i seases
such
as
tuberculosis, staphylococcal infections, brucel losis and most of
nosocomial pneumonias are transmitted by indoor air.
For this reason knowledge of the incidence of m i cro flora i n
t h e hospital and i n residential dwe l l i ng is very important for the
understanding of the poss i b l e types of infections and a l l erg ies
caused by them . Furthermore , contro l ling the microbes in the
hospital and
domestic environment could play a rol e in the
prevention of i nfectious d i seases.
3
The a i m of this study was to compare the numbers and types
of a irborne microbial popu lation in a hospital and i n three types of
d omestic environments in AI-Ain city. In d o i n g thi s we were trying to
find the rel ation between these two environments and the effect of
the enviro nment o n the types, numbers of m icro-org a ni sms.
4
THE OBJECTIVE OF THE STU D Y
The main purpose of the study was to compare the
numbers and types of envi ronmental micro-org a n i sms in AI Ain
hospital and those found in homes of d ifferent social strata i n Al­
Ain city.
It is wel l known that a hospital harbors a d iverse population
of
m icro-org an isms.
The
m icro-organisms
in
the
hospital
environment could be a source of hospital acq u i red i nfection .
has
been
d ocumented
that
micro-organisms
which
It
cause
i nfectious d iseases can be a i rborne or be transmitted by hand lers.
M any studies
have
been
carried
out to estimate
hospital
enviro nmental micro-org a n i sms in d ifferent areas of the worl d .
H owever, t o o u r knowledge no microbial stu d i es have been done
i n any of the AI-Ain hospitals or anywhere i n the UAE .
The micro-org a n isms i n the air environment or surfaces of
homes at AI-Ain city have a l so not been d ocumented. The
i nfluence of d omestic microbes to inhabitants can be related to
5
i nfection i n their own home.
Some of these agents are
transmitted by a i r, particul arly from infected persons occupying
the same room . A lthough most of these are viral upper and lower
res p i ratory tract
i nfections,
bacteria
can
also
be
s i m i larly
transmitte d , l ea d i n g to for example streptococcal pharyng itis and
d iphtheri a . It i s esse ntial to know the types of micro-org an i sm s i n
t h e h o m e environment and the extent o f pathogenic m icro­
org a n i s m s frequently encountered in the air or on surfaces i n the
home e nv ironment .
If s i m i lar pathogenic organisms are found i n t h e hospital
and homes then they wou l d be identified and their characteristics
compared to estimate possi b l e relationshi p and thei r m ovem e nts
between
the
two
environments .
The
micro-org anisms
of
i mportance to human h ealth would be subjected to a nti biotic
sensitivity tests to d etermi n e their resistance patterns variation in
both the hospital and home environments . The effect of the
enviro n m e nt o n
any
queried
anti biotics
d i scussed.
6
resistance
wi l l
be
CHAPTER II
--------------
----
1. REVIEW OF LITERATURE
1.1 History of Indoor Pol l ution
The problems of indoor poll ution began with the energy
conservation just before World War I I , but the energ y crisis of
1 973 exacerbated the problems. In order to minimize the use of
energy, several cou ntries began looking for ways to conserve
energy. The largest user of energy was found to be the building
sector which adopted two ways of energ y saving . F i rst, the
equipment used i n b u i l d i n g s were made more efficient; and
secondly, the bui ld in g s were better i nsulated to stop any air l eaks,
and used as l ittl e outsi d e a i r as poss i b l e . The result of this
process was l ess outsi d e a i r entering i nto these buildings to
sweep o ut pollutants that are generated within the b u i l ding .
Furthermore , occa s i o n a l l y pollutants brought i n from the out door
add to those a lready g e nerated inside. Thus indoor levels of a i r
pollution i s usual ly con s i dered worse than outdoor l evels ( M i l l er
and Kel ler, 1 99 1 ) . Although this practice saved great amounts of
energy, it was at an environmental cost.
7
Lucretius, a g reat p h i losopher, first suspected i ndoor a i r to
be a potential agent for transmitting i nfectious d i sease , nearly two
thousand years ago. H e saw d ust motes in a sun beam i n a dark
room and considered the poss i b i l ity that the motes might carry
pesti lences (Greg ory, 1 96 1 ) .
Since then , it has been wel l
documented that some d i seases are transmitted b y a i rborne
particles ( N ational Research Council 1 96 1 , 1 98 1 , Kundsin , 1 980) .
P u b l i c i nterest of the i ndoor a i r pol l ution has g rown considera bly
over the past few years . A large part of this i nterest began when
Leg ionnaire's D isease was d iscovered in 1 977 ( M i l ler and Kel ler
1 99 1 ) .
The i ndoor environment can potentially place human
occu pants at g reat risk, because enclosed spaces can confi ne
aerosols and
a l l ow them to
build
u p to infectious
levels
(Spen d love and F a n n i n , 1 98 3 ) . Ventilation systems can pick up
contaminated air and d i stri bute i nfectious m icro-organisms to
other parts of the b u i ld in g ( H u d d l eson and Munger, 1 940).
Components
of
vent i l ation
systems
can
actua l ly
become
contam inated and pathogenic micro-organi sms such as Legionella
pneumophila
are
su bseq uently transmitted to
occu pants (Gl ick, 1 978) .
8
the
buildings
1 .2
The Pol luta nts
The a i rborne p o l l utants that may be present i n the indoor
environment comprise a complicated mixture of l iving and
i nanimate materials of gases, vapors, fibers, dusts, and m icrobes.
Studies carried out by H e a lthy B u i ld ings I nternational ( B i nn i e ,
1 99 1 ) found that i n over one third o f more than 400 b u i l d i ng s
studied , the major p o l l utant was a l lergenic fung i . I n g reater than
two thi rd s , air supply systems were contaminated with dust, d i rt
a n d microbes. The micro b i olog i ca l contaminants o f i ndoor air
include viruses, bacteria , protozoa, algae, i nsect fragments,
a n imal dander, and fungal s pores.
The contaminants may be
viable organisms that multiply i n an i nfected host or they may l ive
in dust, soi l , water, o i l , org a n i c fi lms, food , vegetable debris, or
wherever the micro cl i mate provides the rig ht temperature ,
humidity and nutrie nts for g rowth (Samet and Speng ler, 1 99 1 ).
This
i nvestigation
excludes
v i ruses,
algae,
and
parasites.
Although these a re i m portant, they are outside the scope of our
study
9
1. 2.1 Dust
C lean ambient a i r at the breathing level ( 1 .5 metres above
the g round) contains 20-40 mg/m 3 of d ust in the form of sea
spray, soluble salts, organic m atter, and microbes.
M uch of
inhaled d ust is harmless ( H o lt, 1 980).
I ndoor d ust contains the sam e ingred ients as a m bient d ust,
but the com position is significantly d ifferent.
House d u st,
especially in bedrooms, frequently contains m ites, hairs and feces
of pets, insect frag ments, skin scal es of human and pets. House
d ust may a lso contain pollen carried by wind or by insects ( M eyer,
1 983) .
House d ust may also contain fungal spores, and bacteria
which can act as i n d i rect a l l ergens by sti m u l ating the release of
med iators from the host cel l ( Meyer, 1 983), and other components
such ash of cigarettes or incinerators, fi bers , fingernail fil ings,
food crumbs, g lue, o i l , soot, paint chips, p lant parts, soi l , wood
shavings and others ( H u n g , 1 994).
10
1 .3
Sources of Indoor Airborne Microbes
1 .3.1 Outdoor Environment:The majority of biolog ica l particles found i ndoor comes from
the
outdoor
environment.
The
m ajority
of
fungal
spores
encountered indoors are derived e ither d i rectly ( by penetration) or
i n d i rectly (by penetration and subsequent g rowth o n surfaces)
from outdoor a ir. Most fun g i are primary d ecay org a n isms and are
a bundant on dead or dying plant and a n i m a l m aterials. Many are
plant pathogens and can be present a bunda ntly in a i r wherever
their host plants are g rown. A few fun g i are human pathogens.
H owever, many fungal species are primari l y saprophytic decay
org a n i sm s that can o p portuni stica l ly cause human d i sease and
mainly exist i n outdoor environments such a s Cladosporium,
Alternaria, Pencillium and Aspergillus.
Us u ally outdoor fungal
s pore levels exceed those i n d oors , only in cases of serious
contam ination do i ndoor spore levels exceed outdoor l evels. A
wide variety of bacteri a , most of whi ch a re not human pathogens
such as Bacillus s pecies and Actinomycetes, are a bundant
outdoor.
These agents when provided with substrates after
penetration may possibly g row o n i nterior surfaces . Other bacteria
11
such as L egionel/a pneumophila which cause human d i sease
thrive i n outdoor reservoirs.
This organismt i s basica l ly soi l
born e , and i s probably i ntroduced i nto coo l i n g towers and other
e n richmed environment d uring excavations for roads or buildings
o r through sand storms ( Burg e and Fealey, 1 99 1 ) .
1.3. 2 Indoor Contamination:-
M i cro-organisms found i n the environment are associated
with human d roplets, d u st particles or on s ki n squames. Dro p l et
nuclei are the smallest particles of bacterial or vira l residues from
the evaporation of l arger particles expel led by cough i n g , sneezing
or talking . They may remain suspended in air for long period s and
a re carried by air current until inhaled or vented (Kund s i n , 1 985).
D u st particles that have settled on surfaces may become
resuspended by physical action and may remain a i rborne for a
prolonged period. Airborne particles may remain suspended for
hours or possi bly d ays, depend i ng on enviro nmental factors . S kin
squames may become airborne and provide a mechan i s m for the
a irborne transmission of org anisms
( Bennett and Brachman,. 1 992) .
12
such
as
Staphylococci
I nd oor buildup of bioaerasols results from two general
p rocesses:- materia l being shed by residents and accumulating
i nd oors, and actual g rowth on i nterior substrates . Shed m aterials
i nclude, particu l ates such as human and animal skin scales
(dande r), bacteria , and dermatophytes. Human (or a n i m a l ) skin
s ca l e s , for exa m p l e , support not only a l ively m ite popu l ation, but
mesop h i l i c bacteria and fun g i such as Aspergillus a mste/odami
and Wallemia sebi, both of which can stand relative d ryness. S k i n
sca l e s as wel l as m a n y fabrics , leather and wood m aterials,
a bsorb sufficient water from the a i r to support fun g a l g rowth .
Bacterial endotoxins and (theoretical ly) fun g a l mycotoxins
can accumulate i n d oors from m icro-organisms g rowin g o n i nterior
surfaces . Adverse health effects from endotoxin in com mercial
environments have been reported (Aas, 1 980). M ycotoxins have
not been measured in a i r, but have been i m p l icated in cases of
l eukemia fol l owing exposure to Asperigil/us speci e s . M ost severe
i ndoor biologica l pol l ution problems result from m icro b i a l g rowth
on surface withi n structures. Any substrate that i ncludes carbon
source and water wi l l support the g rowth of some m i cro-org anis m .
13
An absolute requirement for a l l kinds of i nterior contam ination is a
constant source of moisture, moreover a very small leak i n a roof
or water p i pe i s sufficient to support a bunda nt fun g a l g rowth.
Modern appli ances such as h u m i d ifiers, vaporizers, water
s prays,
cond itioners,
evaporative
coole rs ,
self-defrosti ng
refrig e rators and flush toi l ets, provide stan d i n g water reservoirs
which, when not absolutely clean, can provide ideal enri chment
s ituation for the g rowth of m icro-org a n i s m s . I n these appl iances
water (usually contam inated) is in contact with a moving a i r
strea m which can p i c k u p sma l l particu l ates ( bacteria a n d
a ntigens) and spray them i n t o room a i r ( Burg e , 1 98 5 ) .
1.4
Factors Inf l uencing I ndoor Microbial Level s:I nd oor surface contaminatio n by bacteria , fun g i or other
biolog i ca l particles is only dangerous when the particles become
a i rborne and inhaled .
There are several factors that can cause
aerosol ization of surface micro-organisms as l i sted below:
14
1.4.1 Air Currents
Air i s almost never sti l l , and even the most d e l icate of air
currents can cause fungal spores such as those of Aspergill us and
Penicillium
to
become
airborne.
Air
current
produced
by
convection from rad iant heat, and by air mechanica l ly circulated
by forced a i r systems are more than adequate to s pread d ust
including entrapped biolog ica l particles, as wel l a s mobil izing
surface g rowth .
P ractica l l y any human or pet activity can increase airborne
microbial l oads.
Such activities incl u d e , vacuming , sweeping
d ustin g , scrubbing contaminated surfaces and bed making . I ndoor
concentrations
vary ,
not
only
with
the
strength
and
the
concentration of the pollution sources, but with the volume of the
p o l l uted s pace ; and the rate of air exchange betwee n i ndoor and
outdoor air.
15
1.4. 2 Oth er Factors
The s ize and d ensity of the airborne particles can i nfluence
the d i stance it moves. Wil liams et at. ( 1 956) d i scusses the
m u ltitude of factors i nfluencing the bacterial cou nt in the a i r of
occup ied school rooms. They l ist the fol lowing as i m portant
factors :
- Room a i r temperature versus the temperature outsi d e the
class room
- Rel ative humid ity outside versus the relative h u m i d ity
i ns i d e .
- Rai nfa l l on t h e day of t h e visit a n d over t h e previous 7
d ays.
- Solar rad i ation on the d ay of the visit and on the previous
7 days.
- External wind velocity and the degree of wi ndow o pen i ng .
- Venti l ation rate and the number of chi l d ren i n the room
- Amount of tal ki n g and the amount of activity of the
chi ld re n .
16
Wind
predictors
d i rection
of
and
m i cro
relative
humidity were
biolog ical
air
the
concentratio n .
best
The
concentrations of bacteria and fungi were negatively associated
with temperature ( except for Actinomycetes and the indoor
concentration of moni l i aceous molds) and wind speed (except for
Basidiomycetes) b ut were positively associated with rel ative
humid ity ( M acher and H uang , 1 99 1 ) .
1.5
Type of Environmental Bacteria
Bacteria occur i n a lmost every environment particularly i n
d usty, d i rty places inhabited b y humans or animals. Most o f the
species of bacteria isolated from buildings are harm less and
frequently include members of the genera , Bacillus species,
Micrococcus s pecies and Corynebacterium species.
However,
the species that have been associated with diseases incl ude
Pseudomonas species especially P. aeruginosa, Fla vobacterium
species,
Staphylococcus
aureus,
Serratia
Legionella penumophila ( B i nn i e , 1 99 1 ) .
17
marcescens
and
1. 6
Type of Environmental F ung i
Fung i are u b i q u itous i n nature and i nevitably enter b u i l d i n g s
from t h e outdoors t o set u p coloni es wherever conditions for
growth are favorable. They a re very resistant, and once they have
estab l ished themselves in a n iche in a b u i ld i ng , they a re very
d ifficult to comp l etely era d i cate. Studies carried out by Healthy
Building I nternational ( B i n ni e, 1 99 1 ) found that in more than one
thi rd of the b u i l d i n g s studied , one of the major pol l utants was
fun g i. Some of these fun g i are known to be pathogenic.
F u ng i
isolated from heating, vent i l ating , a i r con d itioning systems and
other parts of bui ld i n g s can cause problems i n susceptible people
either by causing d i rect i nfection or by causing an al l ergy reaction
( M i l ler and Kel ler, 1 99 1 )
1. 6. 1 Nich e of F ung i in Indoor Environment
Some
fung i ,
particularly
some
members
of
the
Hyphomycetes, g row very wel l in an i ndoor environment. Species
of Penicillium, Aspergillus, Cladosporium, Phoma, Rhodotorula,
Ulocladium, Stachybotrys, etc. have been isolated from materials
used i n i ndoor enviro nments.
Chaetomium of the Ascomycotina
18
and some Basidiomycetes have a l so been i solated from wood
structures of b u i l d i n g s . These fun g i cause decays in wood . Many
other fun g i have a lso been i so l ated from or observed on plants
and potting soils and on paper, plaster, carpet, g l ass, plastics,
and many other item s . M any fungal spores can a lso come from
vegetation near b u i l d i ng s . These s pores may be carried i nto a
b u i l d i ng through doors , windows or outside a i r i ntakes ( H u n g ,
1 994) .
I n over 2 0 0 s u rveys o f a irborne spores, carried out i n
various parts o f t h e worl d , four g enera ; Cladosporium, Alternaria ,
Pencillium a n d Aspergillus accounted for the highest mean
percentage .
These four genera also constituted the most
prevalent i n a l l erg ic resp i ratory d isease (Col and Samson, 1 984) .
Aspergillus s pecies are known to cause i nfections, especially A.
niger and A. fumigatus ( B i nn i e , 1 99 1 ) .
19
1.7
Hos pita l Environ me n t
The purpose of estimatin g t h e types a n d numbers of
bacteria in hospital air is a s rel evant as for other indoor m icrobial
population.
The m icrobial q uantities and types are d i rectly and
indirectly rel ated to patients as a source or as reci pients. The rol e
the hospital environment plays i n n osocomial i nfections can
occasionally
be
scie ntifica l l y
d eterm ined .
Although' hospital
hyg iene i s g enera l ly h i g h , it is i m poss i b l e to exclude m i crobes
from the enviro nment; but the q ua ntity can be contro l l e d .
Each
hospital has d i fferent standard of cleanl iness; this may i nfluence
patient care. There are n o establ ished standards for viable or non
viable particu l ate counts in the operating room or in any other
hospital areas. H owever the accum u l ation of micro-organisms on
surfaces can be used to evaluate housekeep i ng procedures as
wel l as m i cro-org a nisms shed by patients and personnel .
The
micro-organisms of the hospital enviro nment and the microbiology
of hospital acquired i nfections are i nsepara b l e . Health personnel
have been rel uctant to accept this fact, but finding a solution
depends on acceptance of the pro b l e m ( Ku nd s i n , 1 985) .
20
Some knowledge of e nvironmental m i crobes could serve as
a tool for:- Identifying institutional l y rel ated i nfectious d i sease .
- Tracing movements of a i rborne bacteri a .
- Detecting persons, o bjects, activities, or items of
e q u i pment that generate a irborne contam ination.
- Evaluating the efficiency of air cleani n g d evices or
systems.
- Assessi ng the hazard s of hospital venti l ation systems .
S ayer et al (1972) i n a study of hospital a irborne bacteria ,
categorized the hospital bacteria i nto two g roups : -
( a)
The usually i nconsequent a i rborne bacte ri a l flora g ro u p
whi ch included t h e colonies of Gram positive rods ,
Micrococcaceae, Diphtheroids, S. epidermidis a n d a l pha o r
gamma haemolytic Streptococci.
( b)
The potentially pathogenic a i rborne bacterial flora g ro u p ,
which I ncluded: Streptomyces, Fla vobacterium, Mimae tibe
e . g . Mima l i ke or Herellea l i ke , Klebsiella, Staphylococcus
21
aureus, Achromobacter g roup, Pseudomonas species,
Psudomonas aeruginosa and poss i b l ly Erwinia.
1 .8
Source of Indoor Contamination in Hospital
Environment
I ndoor hospital microbes can accumulate l i ke any other
occupied buildings as descri bed already for d omestic b u i l d i n g s .
Addition t o these there are special considerations for t h e hospital
sources:
1
Staff members can be a source of environmental m icro­
org a nisms because of the inhalation of ambient
microorganisms, therefore, personnel who work i n the
cleanest hospital area such as operati n g room, have the
l owest rate of colonization with Staphylococcus a ureus
and personnel who work i n open ward s have the hig hest
rate of colon ization ( Kundsin 1 985)
2
Patients and health care personnel can be victims as well
as sources of environmental microorganisms. They are
22
victims when i nfected or colonized by hospital flora and
sources when they shed these microorg a nisms.
3
M ed i ca l equipment and fluids when its contaminated .
4
Appl iances such as humidifiers, cool-mist vaporizers, a i r
conditioners a n d ventil ation contribute t o aerosols.
5
Visitors and whatever materials they bring with them s uch
as food and flowers .
6
Although there is (as yet) no evidence that the presence of
carpets i n hospitals create an infection hazard , a l arge
a mount of dust is deposited i n carpets , and these d u st
particles are com bined with large number of airborne
potentially pathogenic microorganism s ( Maurer, 1 985) .
1.9
Hospital Bacteria Associated with Inf ections
Transmission of tuberculosis and staphylococcal i nfections
in hospital environment are examples of airborne spread by
means of d ro p l et nucl e i .
Staphylococci are shed i n g reat
numbers attached to tiny skin scales. Staphylococcus a ureus may
cause i nfections of the respiratory system when i nhaled , food
pOiso n i n g when swa l lowed and wound sepsis when a l l owed to
23
enter
an
open
wound
(Maurer,
1985).
Although
most
staphylococcal wound sepsis is a result of hand transmission, i n
one report, several post operative wound i nfections were said to
have res u lted from the a irborne spread of Staphylococci from a
staff member who remained at the peri phery of the operating
room thro u ghout the surg ical procedure.
The only route for
transmission of the org a nisms was through the air (Bennett et al.,
1992) .
Esherichia coli is one of the common causes of i nfections of
the urin a ry bladder.
Some types of E.coli (Enteropathogenic
E. coli EPEC) may be responsible for outbreaks of g a stroenteritis
among neonatal unit. Other bacteria responsi ble for hospital
i nfections a re Klibsiella, Proteus and Pseudomonas, and spore
form i n g bacteria such as Clostridium tetani which i s commonly
found i n the soil and enters the hospital i n d u st (Maurer, 1985) .
Legionella pneumophila, an agent o f serious pulmona ry
d i sease, e nters the indoor environment from b u i l d i ng vents
located close to coo l i n g towers , and also from b u i l d i ng hot water
24
services
( More l y,
1 985).
Formation
of
aerosols
from
contaminated water i s a major mode of spread of Legi o n e l l a ( Hart
and M a k i n , 1 99 1 ), humans probably acquire the organism by
inhaling aerosol s generated from these environmental sources as
there i s evidence to s uggest that inhalation is a l so a mode of
entry.
1 .1 0
Domestic Environmental Microbes:I n previous stu d i es ( Kodama and McGee 1 98 6 ; Raza et al.,
1 989; Macher and H uang, 1 99 1 ) d omestic environmental m icro­
organisms were genera l ly categorized into bacterial and fungal
groups .
A]
B a cteria were conveniently d ivided i nto 5 groups a s fol l ows:
i)
G ram positive cocci .
ii)
G ram positive baci l l i .
iii)
Gra m n egative cocci .
iv)
Gra m negative baci l l i .
v)
Gra m negative d i pl ococci .
25
8]
Fungal s pecies of domestic ind oor a i r have been identified
as:-
Aspergillus,
Alternaria,
Cladosporium,
Penicillium,
Curva la ria, Mucor and Helminthosporium.
The benefits of estimating the types and numbers of
microorgan i sms i n Domestic enviro nment includes;
[a ]
Estab li s h i ng the types of m icroorganisms i n homes
environment .
[ b]
I d e ntifyi ng the pathogen i c and a l lergen i c organism which
occupies the home environment.
[c]
Evaluating the sanitation of homes.
[d ]
Estimation the environmental factors affecting the presence
of
microorganisms i n homes
[e ]
D etermi n i ng the rel ationship between the home social
strata and the m icro-organisms present .
26
1.1 1
Sick Buil ding Syndrome (SBS)
I n 1 982 the World H ea lth Organization recognized the "sick
build ing syndrome" a s a m a l ady affecti ng a proportion of people in
certa i n problem bui l d i ngs. The indicators that a bui l d i ng may be
sick usual ly are increased staff complaints of minor health
symptoms, stuffy a i r, i nterm ittent odors, and visi ble i ncreases i n
d u st l evels. Othe r factors m a y be uneven temperature zones,
noticeab l e smoke accu m u l ation, and d i rt coming out of air supply
d iffusers.
M anagement may be aware of increased staff
a bsenteeism and red u ced productivity.
The symptoms that
affected people are usual l y groups of al most trivial problems such
as eye , nose and throat, i rritation; headache, rhi n itis and sinusitis
with skin irritation; cough , shortness of breath, and general
lassitude; and d izzi ness, n ausea and mental confusion. The study
of sick b u i l d i ng synd rome i s o n goi ng, and as method s conti nue to
be d eveloped, more wi l l be learned about the true role of
microbes and their products in the problem (Binnie, 1 99 1 ) .
27
2 MATERIALS AND METHOD
This project was carried out at AI-Ain city.
AI-Ain city is
l ocated i n the eastern province of Abu-D h a bi Emirate, in the UAE.
The population consists of nationals and a heterogeneous
expatriate population from d ifferent parts of the worl d . The most
recent estimated population of AI-A i n , accord i ng to the M i nistry of
Health Annual Report, ( 1 992) i s 270. 800 (male
female
=
=
1 62 . 900 and
1 07.900) .
2.1 Sources of Material f or Study
2.1 .1 Hospital Environmental Study:
AI Ain has three hospita ls serving the above population.
The hospital environmental study was conducted at AI-Ain
Hospital which i s the largest ( 5 1 1 bed) institution with 2 3 wards
that cover all standard i npatient and several out-patient faci lities.
It is 1 4 years old and serves both the national and expatriate
resident population of AI-Ain M ed ical D i strict and is l ocated at the
center of AI-Ain city.
28
The study samples were col lected
from the fol lowing
hospita l
units:
Male surgical ward
Female surgical ward
M a l e med i cal ward
Female medi cal ward
Ped iatrics ward
O perating theater
I ntensive care unit
29
�I
j=
Ii:]I "J,'II
'\,�
1- II
I,!
n
--
--
-1
-----
1--
\\
Figure 1-
A Map of AI-Ain City
30
I
Ir:
4
1
"
A= T)pe I houses
B=-
TlI)C II houses
C=T)pc III houses
11= lIosl,ital
/
Figure 2
Map of AI-Ain city showing tha location of AI-Ain
Hospital and location of homes studed
31
M icrobiological sample were taken from a l l of these areas
as descri bed later. Each ward was represented by five rooms.
The rooms are usually d ivided i nto four partitions separated by
curta ins. Each room has a capacity of four patients .
During the
sampl i ng procedure all the curtai n s were o pened so that the
whole room cou ld be sam pled as a unit. The i ntensive care unit
con s i sted of three rooms, with three patients capacity. Sampl i ng
was aga in carried out i n a l l the three room s .
The operating
theater consisted of three operation rooms and two pre and post
operative preparation and recovery room s . S a m p l ing was done i n
a l l rooms when no surgica l activity was ta ki ng place .
2. 1 . 2 D omestic environmental study:
Three types of dwe l l ing houses i n AI-Ai n city were selected.
They were graded on basis of differences in social econom ic
status of the occupants; the area where the houses were located,
thei r architectural design, and thei r sanitary con d itions.
32
Houses were classified as fol lows:
Type 1
=
Very good quality houses
Type 2
=
Average quality houses
Type 3
=
Poor q u a l ity houses
Type 1 Consisted of very spacious newly built and wel l d esigned
villas.
They were located in the up market area of the city . A l l
residents h a d h igh i ncome a n d social strata ( accord ing t o local
gra d i ng) .
Type 2 were homes b u i lt accord i ng to the traditional loca l design,
they were b u i lt by the government for nationals of med ium
i ncom e . These residances are in groups which are very close to
each other and are trad itional fol k areas.
Type 3 represent poor houses bordering on slums.
Each was a
s i ngle room or more but d id not exceed three rooms a l l which
were b u i lt at ran d o m . These shelters are inhabited by the poor low
i ncome expatriate population usually at more than three i n d ividals
per roo m .
33
F i g ure 3
Photograph of AI-Ain Hospital
F igure 4
Photograp h representing a ward-room inside the
hospital
35
Figure 5
Outside views of a very g ood house (lype 1 )
36
F igure 6
I nside views of a very good house (type 1 )
37
Figure 7
Outside views of a medium quality house (type 2)
38
Figure 8
Inside views of a medium quality house (type 2)
39
Figure 9
Outside views of a poor quality house (type 3)
L
.J
Figure 10
Inside views of a poor quality house (type 3)
2. 2 SAMPLING TECHNIQUES
2. 2.1
Air Sampl es
Two air sampling techniques were com pared for use in th is
study.
These were d irect open agar plate exposure
technique and
bacteria
mechanical
air sampler,
M K2
(Casella Londo n ) .
a
This
Pl ate Exposure Technique
method
a l l ows
airborne
m icro-org anisms
to
be
deposited on to blood agar plates exposed to room air for
defi nite periods of t i m e . Plates were located in the m i d d l e of
the room away from opened windows or d oors , and about 1
meter above the floor.
After that the covers are re placed
and plates were then incubated at 370C for 48 hours after
which the colony form ing units ( C F U ) were counted .
b
D etermination of optimum plate exposure time
Three blood agar p l ates were exposed i n the center of the
room, open and faci ng upward s .
The first plate was
exposed for 5 m i n utes and closed , the second plate running
42
a long with the first was exposed for 30 minutes and the third
plate was exposed for as long as 60 minutes.
proced ure was repeated i n five d ifferent rooms .
This
A l l the
plates were incubated aerobica l ly at 370C for 48 hours and
CFU were counted and identified .
Tabl e 1 shows that the mean count of C F U per room
increases with time of exposure . At 30 minutes exposure the
number of C F U was 6 folds higher than at 5 mi nutes. This
was
proportional
to
the
time
of exposure
i n d i cating
approximately 2 C FU/min. Longer exposures u p to 60
mi nutes d id not produce s i g n ificant d ifference . Therefore 30
mi n utes exposure time was selected for further stu d i e s .
c
Mec h anical Bac terial Air Sampl er MK2
The orig inal
i nstrument used was developed
by
D rs .
Bourd i l lon Lidwe l l and Thomas of the Medical Research
Council ( I nstruction l eaflet 3 1 09/79 bacteria sampler 2 ) .
43
The air being sampled is d rawn at high speed through a
narrow s l it at a control led rate ; the plate i s 0.2 cm below the
slit.
The surface of the agar plate col lects the airborne
bacteria and fungi which , because of the high velocity, are
caught on the moi st agar surface .
During sampl ing , the
plate is rotated under the s l it to evenly d i stri bute the
colonies. The blood agar plate had an inside d iameter of 8.5
cm and outside d i ameter 9 cm.
The machine can be set for three d ifferent times: 30 seconds
which re presents 15 l itres of a i r, 2 minutes representing 60
l itres of air, and 5 minutes representing 150 l itres of a i r. To
determine the
optimum time
for the
a i r samples,
a
comparison of the total number of C F U col lected at these
three different times in the same room was recorded . It was
repeated in five d ifferent rooms in the hospital.
For each
sample the mach i ne was located in the center of the room
away from opened windows and doors , and sampling
position was 1 metre from the floor.
44
Figure 11
P late exposure culture method .
45
I
3
46
I
17
I
23
1
Room 5
I
33
13
2
Room 4
Mean
14
29
6
Room 3
22
39
9
7
1
Room 2
15
13
l
cfu/60 m i n
5
cfu/30 m in
Room 1
cfu/5 m i n
Total n u m ber of cfu
time u s ing p late A ir Exposure method
The t otal number o f cfu o n Blood Ager at D ifferent
R O O M NU M B E R
Table 1
':
Figure 12
••
.,
'
• #'
�
.'
' .. -.
-.
Mechanical air sampler (Casella Bacterial Air
Sampler MK2)
�7
. \
.,
,
d
D eter mination of Optimum Time Requir ed f or
Mech anical Air Sampl er
Tabl e 2 shows the result of d ifferent samp l i n g time using
the machine air sampler for d ifferent rooms. It shows that 15 l itres
of a i r produced a mea n of 89 C F U , 60 I itres produced a mean of
359 C F U , and 1 50 I itres had a mean count of 755 C F U .
The
types of C F U col lected increased with the rise of amount of a i r
sucked .
F o r exampl e , when 15 l itres o f air were sampled only
one or two types of bacteria g roups were isolated but when 60
l itres were samp l e d , five to six types were isolated , and when 150
l itres were taken, e i g ht types of bacterial g roups were isolated .
Therefore 150 l itres or 5 minute sampling was chosen as it g ave
the h i g hest cou ntable numbers and larger selection of microbial
isolates.
Tabl e 3 shows a comparison between the p l ate exposure
method and the mechanical bacteria air sampler. It shows that the
d ifferences between the two methods is only in the n umber of
colonies col lected by each method and not i n the types of micro­
organisms identifi e d . P l ate exposure method col lected a mean of
48
50 colonies per 5 minutes, whi l e the machine col lected a mean of
475 1 colonies per 0. 15 m3 / five minutes, equivalent to 1000 C F U
per m 3 i n five m i n utes , in the hospital environment. That reflects
the efficiency of the machine which col lected amount of colonies
easily converted to s pace and time and taking less time compared
with p l ate exposure method .
49
I
50
89
I
40
Room S
I
1 07
13
Room 4
M ea n
60
1 73
Room 3
359
987
293
60
Room 2
347
1 60
Room 1
I
755
273
1 93
1 707
840
760
( ::::: 60L A ir) (::::: 1 50L A ir)
(::::: 1 5 L A i r)
c fu/5 m i n
c fu/2 m i n
c fu/3 0 s e c
t ime u s i ng Machanical bacterial air sampler
The total num ber o f c fu o n Blood Age r at D ifferen t
R O O M NU M B E R
Table 2
I
,
1384
329
15
240
823
96
18 17
475 1
21
4
1
3
5
1
14
50
Staphylococcus (eNS)
Micrococcus species
Streptococci (alpha haemolytic)
D iphtheroid bacilli
Bacillus species
Streptomyces species
Unide n t i fied bacteria
TOTA L
51
47
1
<
Total No. o f
cfu/one M 3 u s ing
A ir sampler
Staphylococcus au reus
ORGANISMS
Total No. of
c fu/30 m in exposure
( M ea n cou n t s p e r h os p i t a l wa r d )
M icro-organisms isolated by exposure method compared
with micro-organ isms i s olated by A i r sampler
TYPES OF
Ta b l e 3
I
2 . 2 . 2 Surf ac e Sampl ing
I n each room a test area was selected for surface samples.
Scm 2 were selected from large flat nonabsorbent surfaces
such as tables or cabinets; two samples were ccollected
from each room. A swa b was moistered with steri le distilled
water and used to swab the selected surface. The swabs
were streaked on b l ood agar plate and incubated for 48
hours at 37 o C. The total number of CFU were counted and
the types of bacteria were identified (Macher and Huang,
1991 ) .
2.3
Cul ture Media
The followi ng bacteriolog i cal and mycolog ical med ia were
used for isolation and identification of bacterial and fungal
m i cro-org anisms:
Try pticase soy agar base ( B B L microbiology system) and
sheep blood sup p lement for bacteriological isolation.
Sabouraud Dextrose agar (BBL microbiology system) for
iso l ation of moulds and yeasts.
Sucrose mineral agar (Czpel-DOX) for moulds identification.
52
Mannitol salt agar ( Oxoid C M 85) selective med ium for the
identification of presumptive pathogenic staphylococci.
M acconkey agar without salt-(MAST d iagnostics) selective
med ium for d ifferentiation of g ram negative Bacilli.
Mueller H inton Agar for sensitivity test.
The cultures were incubated for 48 hours at 370C for
bacteria and for 7 d ays at 250C for fun g i . The C F U were
enumerated using Gallen Kamp colony counter and numbers
were converted to m icro-organisms per cubic meter of air.
2.4
Identif ication T ech niques
2.4.1
Bacterial Identif ication
Bacterial colonies were i n itially characterized by colon i al
morphology and m icroscopic exam ination of Grams stai ned
smear.
Further identification using oxidase,
catalase,
coagulase, A P I 2 0 S , A P I 20 E for E ntenobacteriaceae, and
API 20 NE for non fermenting Gram negative Bacilli.
Some bacteria were identified accord ing to Cowan and
Steel's ( 1 974) manual for the identification of med ical
53
bacteria ,
and
Identification
methods
in
applied
and
environmental microbiolog y ( 1 992) , Accord ing to a l l above
methods, organisms were classified i nto n i ne g roups as
follows:
1
Staphylococcus a ureus; for all Gram positive cocci , that
were catalase positive and coagulase positive.
2
Coag ulase Negative Staph yl ococci ( e NS) ; for all catalase
positive, coagulase negative g ra m positive cocci in clusters .
3
Micr ococcus species; for all strictly aerobic, catalase
positive large Gram positive cocci .
4
Str eptococcus species (al pha h aemolytic) ; for all alpha
haemolytic, catalase negative g ram positive cocci in chai n s .
5
D ipth er oid bacil l i;
negative,
non-spore
for
all
forming
basica l ly irregular formation.
54
catalase
g ram
positive ,
positive
oxidase
rods
with
6
G ram neg ati ve b ac i l l i :
This g roup included a l l Gram
negative rods which were either Enterobacteriaca and
identified by A P I 20E, and non fermenting g ro u p which were
identified by A P I 20 N E .
7
Bac i l l us speci es: This g roups included all the large spore
forming Gram positive rods with several d ifferent colony
m orpholog ical characters (roug h , smooth , muco i d ) .
8
Streptomyc es spec i es were all the slow g rowin g , roug h ,
toug h colonies adherent t o the med ium with earthy odour.
Gram stai n showed g ram positive filaments bacteria .
9
U ni dentifi ed b acteri a: This covers all other org a n isms, not
i ncluded i n any of the group above. These were generally
sma l l colonies that were not characteristic of known human
associated organisms.
The majority were large Gram
negative cocci, some gram positive rod s and g ram negative
rods. All these were negative to all identification tests used
to screen the other organisms.
55
2.4. 2 F ungal identif ication
Fung al colon ies were identified by colony a ppearance and
m i croscopic
examination
of
the
spore
and
hypha I
characteristics on lactophenol cotton blue, scotch tape
mounts or slide culture where the tape mounts were
inconclusive.
These were identified accord ing to the
manual of soil fung i (Gillman, 1 957), and Soil fun g i in qatar
and other arab countries ( M oubasher, 1 993).
2.5 Sensitivity T est
The D i s k-plate technique was used .
I n this method a
bacterial colony was d i s persed i n five millil iters of sterile
broth , then a sterile cotton swab was used to i noculate the
surface of M ueller H i nton Agar P l ate.
After that the
a nti biotics were added . The plate was incubated at 37 DC
for 24 hours .
Sensitivity test were performed usi n g sixty Coagulase
negative
staphylococci
o btai ned
from
three
d ifferent
sources (hospital environment, d omestic environment and
56
patient's ) . Patient stra i ns were isolated from s ki n swabs of
hospital patient.
commonly
All strains were tasted against seven
used
Anti biotics
(Penicillin ,
Ampicillin ,
Aug mentin, Cephalothi n , Erythromycin , Tetracyclin and
Gentamicin).
2.6
Data processing , Statistical meth ods and anal ysis
The variables were coded , and all the d ata entered and
pro cessed i n the Department of Community Med icine,
Faculty of Med i cine and Health Science at the UAE
U n i versity .
Data entry was done by using DOS-5 ed itor.
The statistical software packages S P S S (Norusis , 1992)
and
B M DP (B M D P ,
stati stical analysi s .
1 992) were used for performing
Harvard
Graphics
(H G
VER
3 . 0)
package was used for graph i n g .
Basic statistics, frequency table, one way and two way
tabulations were obtai ned . Tests of s i g n ificance were
performed using the chi-square test for two or more
categorical variables . I n 2 x 2 tables , the F isher exact test
57
sample size was small. The significance of d ifference
between two continuous variables were determined by
students t-test. Also, the two ways Anova model was
performed to explore the joint effects of variables .
Means
P-Iess or equal to 0 . 05 were considered as the cut-off value
for s i g nifi cance.
58
Figure 13
Culture plate after 48 hours incubation time showing
bacteria and fungi using plate exposure method for
30 min exposur time.
59
F igure 1 4
Fung al identification using g ross colonial ap pearance
1.
2.
Aspergillus niger
Aspergillus fumigatus
60
Figure 15
Fungal identification, microscopic examination .
12-
Alternaria species
A spergillus niger
61
-(
•
"
,
F i g ure 1 6
Various unidentified bacteria
62
CHAPTER III
...........
.... ... ..............
..
..-----
RESULTS
The main results of the study for the bacterial and fung a l counts
for both hospital and d i fferent homes are shown in tables 4-1 6
These ta bles a lso contai n data for surface samples counts.
Tabl e 4 and f ig ure 1 7 shows hospital micro-org anisms
isolated from five d ifferent wards in AI Ain hospita l . The results
reflect the mean of five rooms in each ward .
There were n ine
groups of bacteri a l in addition to the fungi isolates .
These n i ne
g roups were d ivided i n to two g roups ; the human related micro­
organisms
represented
by
the
first
six
g roups
and
the
enviro nmenta l and soi l micro-org a nisms represented by three
rem a i n i ng g roups .
The most l a rgest quantities of micro-organisms were the
unidentified bacteria .
This g roup i ncluded different types of
bacteria which are not known to be related to med ical m i crobes ,
difficult to identify, and were possibly soil and ai rborne bacteria .
The second commonest org anism occurri ng i n a l l ward u n its was
63
and
Micrococcus
species.
All
other micro-organisms
were
detected in small numbers .
It was generally observed that ped iatric and female medical
wards had the h i ghest bacterial count while the surg ical wards
had the lowest. The fungal colony counts were close i n all ward s .
I n general male ward s had less bacterial count compared with
female ward s .
The classical pathogen ic Staphylococcus aureus a n d the
E nterobacteriacae g roup were rarely isolated . S aureus was more
common in ped i atrics and female surg ical wards compared to
other ward s . The g ram neg ative rod s which were isolated from
ped iatric, male med ical and female surgical wards included
several genera and s pecies such as Pseudomonas species,
Enterobacter species,
vu/neris.
pathogens.
A eromonas
species,
and
Esherichia
Some of these are known to be occasional human
The total fun g al isolates are included to g ive a
com plete picture but will be presented separately later.
64
I
I
13
153
13
100
0
53
33
87
13
Micrococcus species
Streptococci (alpha haemolytic)
D iphtheroid bacilli
Gram negat ive bac i ll i
Key:
FSW
MMW
=
Female surgical ward,
B AED
MSW
=
6S
Pediauic ward.
Male surgical ward,
FMW
=
701 3
2 20 5
3479
Male medical ward,
180
13 3
15 3
Fungi
=
2887
873
1673
Unidentified bacte ria
TOTAL
73
220
53
0
Streptomyces species
7 1 93
73
2200
13 3
24696
706
9086
479
4 1 13
86
60
1440
1200
73
1959
692 1
73
TOTA L
347
27
927
195 3
33
PA E D
Female medical ward,
4806
167
145 3
10 13
1040
0
393
0
373
1307
25 3
453
1947
27
F.S . W.
M3 )
367
=
273
627
1087
Staphylococci (eNS)
Bacillus species
0
0
13
Staphylococcus aures
0
M.S.W.
F. M . W.
(No. o f c fu/one
( F i g u res a re mea n s of 5 roo ms / wa rd)
using a i r sam pler
H ospital A ir m i cro-organ isms isolated from five ward
M.M.W
O R G A N IS M S
T Y PE S O F
Table 4
Z
::J
E
QI
.0
'-
0
�
lL
()
.....
o
500
1 000
1 5 00
2000
2500
3000
=
Sta p h . (CNS)
=
U n id e n t i fied bacteri a
Colonis F o rm i n g U n i t s
U . bact e ri a
CFU
U . b a ct e ri a
I
I
I
I
I
I
I
I
I..
I
I
I
Bacillus spp
66
/
/
/
/
M icrococcus s p p
/
/
/
D i p h t h eroid baci l l i
/
F i g ( 1 7) C o m pa r i n g H o s p i t a l a i r m i c ro-o rg a n i s m s i s o l ated fro m f i ve w a rd s u s i n g a i r sa m p l e r
D PA E D
ml F . S . W .
IIII F . M . W .
D M . S W.
OO M . M . W.
Ta b l e
5
shows
m icro-org an isms
i so l ated
from
three
different types of houses. Except for S. aureus, wh ich was not
iso l ated , the same groups of bacteria l and fungi isolated from
hospital environment were found a lso i n d omestic air samples.
The most common
m icro-organism was
again,
un identified
bacteria fol l owed by Bacillus species. In third position in a l l house
types was the coag ulase negative staphylococci. The types of
Gram negative rods isolated from d ifferent house types included
Pseudomonas vesicularis and other Pseudomonas species, not
known as human pathogens.
The
most
i mportant
observation
was
the
sign ificant
d ifferences between the three types of houses, in other word s , the
l ower the type of houses the higher the number of bacterial counts
were ( p<O.04S).
67
3050
2470
0
1 20
4
3733
893
4909
273
1 5452
2 1 07
987
74
12
230
21 17
5 37
3 807
260
10131
734
1 89
7
17
1 84
1 95 0
390
2000
217
5688
Staphylococci (eNS)
Micrococcus species
Strep tococci (alpha haemolyt ic)
Gram negative bac illi
D iphtheroid bacilli
Bacillus species
Streptomyces species
Unidentified bacteria
Fungi
TOTAL
68
T Y PE 3
T P Y E O F H O US E S
TYPE 2
O RG A N I S M S
T Y P ES O F
( F i gu res a re mea n o r 5 h o u ses ro r ea c h type, v a l u es rep resen t c ru/m 3 )
Domestic A i r m ic ro-organisms iso lated from three types o f houses
TYPE 1
Tabl e 5
T a b l e 6 shows the counts and the d i stri bution of micro­
organisms i n l iving rooms and bedrooms in the three d ifferent
types of houses. I n the best q u a l ity houses ( type 1 ) , there were
more m icro-organisms in bedrooms than in l iving rooms for three
out of four human associated bacteri a l agents, the opposite was
noted for the non human m icro-organisms.
In type 2 (middle
class) houses and type 3 ( poor class) coag ul ase negative
Staphylococci counts were h ig her i n bed rooms than l iving rooms
whi l e the counts of M i crococci, Oiphtheroid bacilli
and Gram
negative baci l l i were h i gher i n l iving rooms than bedrooms.
However there was no s i g n ificant d ifferences between l iving
rooms and bedrooms for any of the organi sms isolated. I n a l l
types o f houses a l l the e nvironmenta l (non human related)
bacterial counts were h i g her i n l iving rooms than the bedrooms
and the d ifferences between these houses were not significant.
In concl usion the total count of micro-organisms i solated
from l iving rooms were h i g her than that isolated from bedrooms
for all
types of org a n i sms
except for coag ul ase
negative
Staphylococci and al pha hemolytic streptococci , which were
69
hig her i n bedrooms i n a l l types of houses . There were significant
differences between human micro-organisms and environmental
micro-organisms in each room in the three d ifferent types of
houses ( p<O.005).
70
- "
......
.
,
. ....
·.···.·u·
,
-
......................
' ...........
. .. .
LR
=
L i v i n g Room
Unidentified bacteria
BR
=
, ..
......
BR
LR
.... .. ..............
BR
LR
BR
LR
BR
LR
BR
LR
.
87
280
33
0
13
0
237
1 40
.,
"
1 440
2460
............. .. . . . . . . . . .. . . . . . . . ... ... . ...
. .....
800
667
T Y PE 1
.
1 13
327
1 367
2867
. .......... ........ . ......... ...........
... .
27
33
80
67
560
1413
2360
1 85 3
TYPE 2
360
420
447
627
BR
LR
71
1 987
20 1 3
3460
4 1 53
. . . . . . . . ............................ ..... .... .. . . . ................ ...................... . ......... . ... ..... .......... .. ............
BR
LR
........................... . . . . . . . . . ..... . . .......................... ................ . ............. . ........................ . ...
. . . . . . . . . . . ... .
,--. .
.. .
... . .
B e d Room
................................ . ............ ....................................... .......................... . .
Streptomyces species
............................................................ ....................................................
Bacillus species
o.
.......
0.
............
. . . . . ............................. . .......... . ............................... ........... ...................
D iphtheroid bacilli
.." ..............
Gram negative bac illi
. . ' . . . ..
.
. . . . . . . . . . . ....
Streptococci (alpha haemolytic)
Micrococcus species
. . . . . . .,. . . . . . . .,. . . . . . . . . . . .' , . . . ........................,
, ..
BR
LR
(eNS)
Staphylococci
SOURCE
0
7
1 13
4 1 27
0
0
2 35 3
2587
3906
2 1 93
T Y PE 3
4380
5437
.................................... ..... .
753
1033
.. ................. , ........... ' ........
3560
3906
. ........................................
TPYE O F HOUSES
Domestic a i r m icro-organ isms iso lated from t hree types
of house comparing l i ving rooms to bedrooms
( F i gu res a re mean o f 5 hou s es fo r each type, va l u es r e p resen t c fu /M 3 )
ORGANISMS
Table 6
Tab l e 7 and figure 1 8 presents the numbers of six
commonly encountered bacterial and fungal isolates for hospital
air and the three d ifferent types of house.
The total bacterial
count of hospital air m icro-organisms was the lowest. It was
s i g nificantly lower than type 2 and type 3 houses ( p<O.05).
Coag u lase negative Staphylococci and Micrococcus species were
s i g n ificantly h i g her i n the hospita l environment compared to type 1
houses only.
For the environmenta l bacteria and fung i , the
hospital had consistently lower counts and the number increased
with the l owing of housing standard s . The greatest d i s parity
occurred for a l l m icro-org a n i sms between hospital and type 3
house. The hospital had the l ower counts of a l l types of m icro­
org a n i sms except for Diphtheroid bacilli. The most common group
of m icro-organisms were the u n i dentified bacteria .
I n conclusion
the hospital a i r m icrobial counts are com parable to house type 1
houses , representing very good qual ity houses.
72
390
2000
217
5664
96
1817
141
4893
Strep tomyces species
Unidentified bacteria
Fungi
TOTAL
7
3733
21 17
1 950
823
Bacillus species
273
1 5332
1 0 045
4909
260
3 807
893
4
230
1 84
240
D iphtheroid bacilli
537
2470
987
1 89
392
M icrococcus species
Staphylococci
3050
H OU S E TYPE 3
2 1 07
H O USE T Y P E 2
734
H O US E T Y PE 1
1 3 84
H O S PITA L
( F i g u r es a re mea n o f the n u m be r o f c fu/one M 3 )
M icro-organisms isolated from hospital env i ronment compared
to m ic ro -organ is ms from the house env ironment
collected us ing air samples
(eNS)
O R G ANISMS
Table 7
z
:J
E
(1)
.0
'-
.....
0
::::>
LL
()
0
500
1 00 0
1 50 0
2000
2500
3000
3500
4000
4500
5000
5500
6000
=
/
/
/
/
B a ci l l u s s p p
=
U n id e n t i fi ed bact e ria
C o l o n is Form i n g U n its
U. bact e ri a
CFU
U . bact e ri a
/
74
S t a p h . (CNS)
M i crococcus spp
� ------ ---�----��- -------�--
S H O U S E TYPE 3
. H O U S E TYPE 2
C H O U S E TYPE 1
m H O S P I TAL
F i g ( 1 8) Co m p a r i n g m i c ro -o rg a n i s m s i so l at ed fro m h o s p i t a l a i r w i t h t h ree t y p e s of h o u se s
Ta b l e 8 shows the s u rfaces micro-organisms isolated from
d ifferent wards in the hospita l .
There were seven bacterial
groups, (Gram negative bacteria not tabulate d ) .
Notably absent
were S. aureus and a l pha hemolytic streptococci.
Coag ulase
negative Staphylococci were the most frequent micro-organism
d etected on surfaces. This gro u p was the commonest in a l l
hospital ward surfaces fol l owed by Bacillus species.
It was observed that a smaller count of colonies was
obtained in comparison to that from the a i r samples.
However,
the size of areas and methods used d iffered completely and CFU
cou nts cannot be compare d .
The medical wards had a higher
total count for coagu lase negative Staphylococci and other human
related m icro-org anisms than the surg ical counterparts. On the
other hand the medica l wards had lower counts of environmental
org an isms than the surg ical wards.
Female wards had a hig her bacteri a l count compared with
male ward s . Gram negative rods (not shown on table) were
i solated from one female surg ical ward and one room in the male
75
med ical ward i n such a h i g h count that the particular site sampled
was considered recently contam i n ated .
These contaminations
included , types of known to cause human infections such as
Acinetobacter, Klebsiella pneumonia, Pseudomonas stutzeri and
Pseudomonas putida .
A very h i g h count of a l pha hemolytic
stre ptococcus was obtained i n one room only in male surg ical
ward .
The d ifferences between human micro-organisms and
environmental micro-organism s were s i g n ificant in female med ical
and female surg ical wards (p<O.OS), and not sig nificant in male
surg i ca l , male med ica l ward s , and ped i atrics wards .
76
4
13
3
80
Un identified bacteria
TOTAL
Key:
=
=
M MW
FSW
Female surgical ward,
Male medical ward,
B AED
=
0
1
0
Streptomyces species
MSW
6
3
7
Bacillus species
77
Pediatric ward.
Male surgical ward,
FMW
81
5
3
13
D iphtheroid bacilli
40
3
1
Staphylococcus
1
63
F.M.W.
Micrococcus species
M .S.W.
19
=
M.M.W
=
320
69
50
Female medical ward,
33
8
5
3
51
31
14
1 88
TOTAL
2
20
5
4
30
PAED
0
15
5
5
20
F.S.W.
( N o . of c fu/ I O c m 2 s u r face a r e a )
( F i gu res a re mean o f 5 rooms i n e a c h w a r d )
in Al A in Hospital
S u rface m icro-organ isms isol ated from d i fferent wards
56
(eNS)
ORGANISMS
T Y PES O F
Ta b l e 8
Ta b l e 9 shows the results of counts and types of s u riace
m i c ro -o rg a n i s m s isolated from d i fferent houses . The numbers of
micro-organisms increased with the decreasing status of house .
The commonest org a n i s m i n a l l house types were Bacillus
species
fol l owed
by
coag u l ase
negative
Staphylococcus;
Streptomyces and u n i d e ntified bacteria respectively.
All other
organisms were isolated in small q uantities.
Ta b l e 10 and fig u re 19 compare surface micro-organisms
isolated from the hospital and the three different types of houses.
The hospital had the h i g hest count of coagulase negative
Staphylococcus and Diphtheroid bacilli, and the lowest count of a l l
other types o f org anisms. Type 3 houses had the hig hest count of
environmental org anisms (Bacillus species, Streptomyces and
u n i d e ntified bacteria). Although overal l surface count of bacteria
in hos p ital is l ower, there is no s i g nificant d ifference with any type
of houses.
78
8
0
19
1
15
0
16
2
7
57
Strep tococci (alpha haemolytic)
Diphtheroid bacilli
Bacillus species
Strep tomyces species
Unidentified bacteria
TOTAL
79
27
8
2
Micrococcus species
61
8
6
17
14
Staphylococcus (eNS)
90
14
5
16
3
19
0
0
1
T Y PE 3
Staphylococcus aureus
TPYE O F HOUSES
2
( N o. o f cfu/cm )
T Y PE 2
ORGANISMS
TYPES O F
( F i g u res a re mea n o f 5 houses fo r e ach t y p e )
M ic ro-organ isms isolated from s u rfaces in di fferent house types
T Y PE 1
Table 9
16
4
Bacillus species
6
43
Unidentified bacteria
TOTAL
Streptomyces species
S6
7
2
0
2
Diphtheroid bacilli
1
15
1
Streptococci (alpha haemolytic)
<
2
1
Staphylococcus
Micrococcus species
80
H O US E T Y PE 1
14
H OS P I T A L
61
8
1
19
0
8
8
17
H O USE TYPE 2
( N o . of c fu / l O c m 2 s u r face a r ea)
M i c ro-organ i sms isolated from hospi t a l su rfaces compared
with those from di fferent house types
29
(eNS)
ORGANISMS
TYPES OF
Ta b le 1 0
1
90
14
5
27
<
16
3
19
H O US E T Y P E 3
I
Z
::J
E
Q)
..a
'-
0
'+-
�
LL
0
o
5
10
15
20
25
30
=
���
ta�
�;,�9..
=
�
J
:
I il,
':" : i"
.,:::::::,
U n i d e n tified b a ct e ri a
C o l o n i s F o rm i n g U n it s
U . b a cteria
CFU
��r� tm;j-
'�f
�'
�:
1 filii ••
��:
m�
;m;
r,,:�... .'..4','.1:'.'.
�;�:�:
f�J
81
StreptococCi
..' :::
·�t\· ·
::,
,
;�'
"I
'.
U . bact e r i a
•
�{t�
ITl H O U S E TYP E 3
IlII H O U S E TYP E 2
C H O U S E TY P E 1
rrE H O S P ITAL
F i g ( 1 9) C o m p a r i n g m i c ro-o rg a n i s m s i s o lated fro m h o s p it a l s u rfaces w i t h t h o se f ro m d i fferent h o u se s s u rfaces
Ta b l e 11 shows the result of the observation in the cleanest
area in the hospita l ; the I ntensive Care U nit and the O perating
Theater (OT) .
I n air samples ICU collected a mean of (687
C F U/M 3 ) per room, most of which were coagu lase negative
Staphylococci . In the OT a mean of (473 C F U/M 3 ) per room were
col lected , nearly half of which were Micrococcus species. I n both
areas, the human related organisms exceed ed environmental
org a n i s m s . For surface samples, significant d ifferences between
human
related
micro-organisms
and
e nvironm ental
micro­
org a n i sms i n OT (pv O . 05) I C U col lected a mean of 2 5 colonies
=
per roo m , 24 of which were coag ulase negative Staphylococcus,
wh i l e i n OT a mean of 4 colonies per room was col l ected . OT has
the l owest count of surface and air m icro-org a n i sms fol l owed by
I C U com pared with any hospital ward . In concl usion both the I C U
a n d O T had s i g nificantly more human related m icro-organisms in
a i r ( p < O . 005).
82
Ta b l e 1 2 shows a 2x2 comparison figures of air agai nst
surface micro-organisms i n hospital and the d ifferent types of
house s .
Although the surface organisms were much lower,
usually under 1 % of the a i rborne q uantity, they were generally
proportional to the quantity i n the air. This strongly suggests that
the surface organ isms ori g i n ate from the a i r rather han from other
sources .
83
I
=
687
TOTAL
OT
0
27
Fungi
Intensive Care Unit,
13
0
Unidentified bacteria
=
47
7
Strep tomyces species
rcu
93
53
Bacillus species
Key :
33
0
D iphtheroid bacilli
84
Operating Theater,
473
0
7
0
Strep tococci (alpha haemo lyt ic)
2S
0
0
0
0
1
0
200
80
Micrococcus species
24
80
leU
4
0
0
1
1
0
0
1
1
OT
1
OT
I
ICU
S U R FACE S A M PLES
No. of cfu/ l O cm 2
A I R S A M PLES
N o . of c fu/M 3
520
ORG ANISMS
TYPES OF
-
( F i g u res a re mea n of 5 rooms i n each a re a )
Intensive Care Unit and Ope rating Theater M icro-organ isms
isolated from a i r and su rface s am ples
Staphylococcus (CNS)
_
.
-
Table 1 1
I
The n wn be rs are the mean out of
Unident ified bacteria
Bacillus species
Micrococcus species
: Staphylococcus (eNS)
O R G A N IS M S
T Y P ES O F
Table 1 2
5
isolation in each case.
S urface
Air
S urface
Air
S urface
85
1 8 17
6
2000
7
1 950
16
392
1
Air
823
4
1 89
2
l 384
29
Air
S urface
734
14
H O S PI T A L
SOURCE
H O US E T Y P E
and the three types o f houses
1
2
)
3807
8
2 1 17
19
987
8
2 1 07
17
HOUSE TYPE 2
c fu/ l O c m
m i c ro -organisms isolated from hospital
Total n u mbe rs o f a i r (cfu!M 3 ) and su rface (
4909
14
3733
27
2470
3
3050
19
H OUSE TYPE
J
Ta b l e 13
shows the quantity of fungal spores found in
hospital a i r. It i s assumed that each fungal colony ori g inated from
a s i n g l e aeri a l fun g a l spore .
There were five genera of fungi
isolated with a predomi nance of A spergillus species.
Asperg i l l us species were isolated .
were the most d o m i n ant.
A. fumigatus and
Six
A. niger
There was no sign ificant d ifference in
the total number of isolates from d ifferent hospital units.
Ta b l e 14 g ives the fungal isolates from the d ifferent types
of homes. There were six g enera and seven species of Asperg i l l i
represent approximate l y 7 5 % of a l l isolates .
A . niger was the
most common than any other Asperg i l lus species depending on
there total counts as wel l as the number of there isolation
comparing to other g e nera .
There was an i ncrease of fungal
isolates with the l owerin g of housing standard s ; concerni ng A.
niger, Alternaria and chaetomi u m but not with other fungal
speci es, which were i rre g u larly isolated .
86
i
I
I
I
25
15
9
A . Jumigatus (Frese n i u s )
0
0
1
0
Penicillium species
Verticillum species
=
=
=
=
=
MMW
MSW
FMW
FSW
B AED
Pediatric ward.
Female surgical ward,
Female medical ward,
Male surgical ward,
Male medical ward,
11
11
Chaetomium species
38
4
0
A . versicolor (Tirabosh i )
31
9
0
4
A. terreus (Thorn & R ap per)
TOTAL
5
0
0
A. tamarii (Kite)
87
48
0
0
4
0
0
0
1
A. sparsus (Thorn & Rapper)
5
4
1
A . n iger ( V an Tieghem)
Key:
I
34
23
16
Aspergillus species
0
4
4
A lternaria species
F.M.W.
I
45
4
0
0
1
7
9
4
16
0
37
4
F.S.W.
I
( No . o f col o n i es/M 3 a i r )
M .S . W.
-
from five ward u s ing a i r samp ler
*
I
1 73
4
10
27
6
16
9
5
30
53
119
13
TOTAL
I
=
=
=
M
L
=
H
O.R
*25
of
I
Low Occurrence less than 5 .
Moderate Occ urrence 5-9,
L
L
M
M
M
L
L
H
H
-
M
O.R
H igh Occurrence more than 1 0,
Occurrence Remark,
2
4
7
7
8
1
2
10
17
-
8
out of
No.
isolation
25 is t h e n u m be r of isol a ts
12
0
0
1
1
0
0
0
4
4
9
1
PAED
The most dom inant fu ngi in hosp i t a l a i r isolated
M.M.W
O RGANISMS
- --
Table 1 3
I
,
0
548
0
1 53
0
0
0
0
53
0
1 13
0
0
366
33
80
33
33
46
0
20
0
0
47
13
305
A . flavus (Rapper & Fennel)
A . n iger (Van Tieghern)
A . sparsus (Thorn & Rapper)
A . tamarii (Kite)
A. versicolor (Tiraboshi)
Mucor species
Penicillium species
Trichoderma species
Verticillum species
TOTAL
Chaetomium species
88
53
0
0
A . fum igatus (Fre sen i u s )
A . terreus (Thorn & Rapper)
327
1 53
225
Aspergillus species
5
0
7
5
1
80
7
7
M
L
L
L
L
M
L
M
L
H
L
L
-
M
O.R
Key:
==
==
M
L
=
=
H
O.R
I
5-9,
Low Occurrence less than
Moderate OccWTence
5.
High Occurrence more than 1 0 ,
Occurre nce Remark.
* 1 5 i s t h e n u m be r o f isol a ts
1
6
1
27
0
2
1
0
15
1
2
3
-
6
out of * 1 5
isol ation
No. o f
240
0
1 27
47
0
A lternaria species
T Y PE 3
T P Y E O F H O U S ES
( N o . o f co ion ies/M 3 a i r )
T Y PE 2
ORGANISMS
TYPES O F
A ir-borne fun g i iso lated from three types o f houses
T Y PE 1
_
.
_
-
Ta b l e 1 4
Tab l e 1 5 com paring AI Ain hospital fungal isolates to those
of the 3 types of houses, l i ke bacterial isolates, the hospital had
l ower total fungal counts compared to the domestic environment.
Although there was no significant d ifference between hospital and
type 1 and 2 houses the d ifference was significant for type 3
house.
I n tota l there were seven genera of fun g i isolated i n the
i ndoor environment of hospital and homes.
Chaetomium were the most constantly found
A.
in
niger and
all
areas
i nvestigated .
Tab l e 1 6
shows
anti biotics
sensitivity test
for
sixty
coa g ul ase neg atives staphylococci ( e N S ) obtained from three
d ifferent sources. Twenty were from domestic areas, twenty from
hosp ital environment, and twenty from hospital patients.
They
were tested against seven commonly used anti m icro b i a l agents
l i sted in the table. The results are expressed as a percentage of
org a n i s m s sensitive to the dru g .
89
The domestic e N S were highly sensitive to the seven drugs
(mean sensitivity of 93%) and completely sensitive ( 1 00%) to five
of the d rug s .
The hospital environmental e N S were 1 00%
sensitive to gentamicin only and moderately sensitive to five
d ru g s but genera l ly resistant to erythromyci n .
I n contrast t o the e N S , isolates from patients' specimen were
eval u ated s i m u ltaneously. These strains were less sensitive than
even
the
hospital
environmental
e rythromyci n and tetracycl i n e .
organisms
except
for
There was a very s i g n ificant
d ifference between sensitivity of patients' strains and hospital
strains for penici l l i n and ampici l l i n but not for augmenti n . There
was a moderate d ifference with cephalothi n and g entamici n .
T h e overa l l analysis shows that t h e resistance o f hospita l
environmental strains were i n between the d o mestic and the
patients' strains.
90
-
-
1 13
0
0
0
46
7
33
46
20
0
0
53
9
16
5
7
7
4
A. jumigatus (Fresenius)
A . tamarit' (K ite)
A. terreus (Thorn & Rapper)
A . sparsus (Thorn & Rapper)
A . versicolor (Tiraboshi)
Chaetomium species
Penicillium species
305
2
1 73
Verticil/urn species
The n wnbers are the mean out of
isolation in each case.
l3
-
Trichoderma species
TOTAL
47
-
Mucor species
91
0
80
30
A . n iger (Van Tieghem)
5
0
225
1 19
Aspergillus species
366
0
53
0
0
0
153
1 53
47
0
H O US E T Y P E 2
( N o . of co i o n i es/M 3 a i r )
-
13
--
A lternaria species
-
n O US E T Y P E 1
ORG ANISMS
TYPES OF
�
A i r Fungi isolated from hospital and three types o f houses
H OS PIT A L
--
Table 1 5
548
0
0
7
7
80
27
0
0
7
53
240
327
1 27
H O US E T Y PE 3
II
I
K ey:
Amp
Ery
=
Erythromyc i n ,
Tet
=
=
Tetracyclice,
A mpici l l i n ,
Gen
Aug
=
=
92
Gentamici n.
A ugmemi n ,
89
74
65
M ean
Pen ic i l l in ,
82
42
20
Patients
=
85
80
75
Hospital
Pen
1 00
1 00
1 00
1 00
Domestic
Cep
=
92
82
95
Cep.
A u g.
Amp.
Pen.
A REAS AND PATIENTS
Ceph alothin,
46
50
35
55
E ry.
STAPHY LOCOCCI I SOLA TED FROM DIFFERENT
SENS ITIVITY P AITERN OF COAGULAS E NEGATIVE
S o u rce o f C N S
Table 1 6
72
60
60
95
Tel.
96
89
1 00
1 00
Gen.
76
60
75
93
Mean
I
CHAPTER IV
DISCUSSION
I ndoor air contai n s a large micro b i a l popul ation.
The
s i g nificance of these microbes is d e batable in some q uarters,
whereas e lsewhere it is considered s i g n ificant. The i mportance of
the estimation of the numbers and types of a i rborne m i cro­
organisms is that it m i g ht be used as an i nd ex for the cleanliness
of the environment (Wi l l iam et al. , 1 956).
Although work elsewhere has shown what is expected i n
hospita l s , there is very l ittl e i n the l iterature on d om estic microbial
flora . This study therefore is new as far as this area i s concerned ,
particularly so, i n the Gulf States.
In order to evaluate the qual ity of the a i r in the hospita l , and
to fi nd the relationsh i p between the bacterial count and the
enviro nmental cond ition, a compari son between the hospital and
the three types of houses were carried out.
93
A irborne i nfections particularly of the respiratory nature in
domestic areas
common.
and
in
crowded
con d itions
are
extremely
Airborne spread of nosocomial bacteria l or viral
i nfection i s known to occur, but is probably uncommon , therefore
a i r sampling should be carried out less freq uently.
P erhaps the
most common and recent indications for use of this technique
have i nvolved Legionella and Asperigil/us i nfections and
in
monitorin g o f o perating room infections.
Air samp l i ng may be performed with either sett l i n g plates or
by using more sophisticated equi pment. P l ate exposure method
is one of the s i mplest methods used for air exami natio n .
I t has
been recommended for the quantitative evaluation of airborne
bacteria , however, it col lects mainly those particles larg e enough
to be pul led by gravity or impacted by air turbu lence onto the
col lecting surface ( Herman and More l l i , 1 96 1 ; Wolf et a/. , 1 964) .
For these reasons airborne particles that are too s m a l l to settle
out q uickly may n ot be col lected . Add itiona l l y if the turbulence of
the a i r to be sampled varies from time to time, the y i e l d s of the
exposure plate wi l l a l so vary (Cole and Bernard , 1 96 2 ) . Although
94
this i s an i nexpensive way to evaluate airborne micro b i a l
conta m i n ation, q uantitative resu lts may correlate poorly with those
o btai ned with mechanica l volumetric air samplers .
B ecause of
variation i n particle size and unknown influences of air turbul e nce ,
nucle i of a pproximately three micro meter can remain suspended
indefin itely
and
can
only
be
col lected
with
h i g h-vel ocity,
volumetric a i r samp l ers .
Although Sayer et a/. ( 1 972) have reported that Gravity
S ett l i ng C ulture (GSC) P late should not be used for quantitative
estimation of hospital airborne bacteri al flora , plate exposure
method was used i n this study to evaluate the efficiency of the
bacterial a i r sampler which was being used for the first time i n the
AI-Ain study. The comparison between the two methods shown in
table three shows that plate exposure method for 30 m i nutes
col l ected a total of 50 CFU against 4750 col lected by the
mechanical a i r sampler in five mi nutes: this is just over one
percent efficiency as far as quantity is concerned . Furthermore
qual itatively the same types of micro-organisms were col lected by
the mach i n e in five m i n utes sampling time as by plate exposure
95
method i n 30 m i n utes. We can quantitate the micro-organisms of
the bacteri a l a i r sampler as 0. 1 5 m 3 per 5 m inutes whereas the
plate exposure method cannot be estimated i n terms of air
volume.
For this reason the superior mechanical air sampler
(Casella bacteria sampler MK2) was chosen. Although there a re
several types whi ch are more convenient, we used Case l l a
bacteria sampler M K2 which was avai lable t o u s .
Sayer et al. (1 972) reported that airborne Staphylococcus
aureus was d etected i n hospital by the Andersen sampler but not
by the accompanying GSC plate. In this study however, the plate
exposure method collected only 2 colonies of S aureus, and a
mean of 2 1 colonies of coagulase negative staphylococcus per
room . Thi s find i n g i s i n l i ne with H a l l ' s fi n d i n g s ( 1 962) , when he
considers the G S C p l ate, g e nera l l y adequate for col lection of
Staphylococci in suspected hospital rooms.
Walter ( 1 966 ) , has d ivided hospita l airborne bacteria i nto
three groups in d e scend i ng of the s ize of particulate :
1)
D ust borne bacteria i .e . passengers on rafts of d ebri s , s k i n
sca l e s .
96
2)
Droplet borne bacteria i . e . passengers within fl uid droplets.
3)
B acteria representing the d roplet nuclei from which most or
all of the
moi sture has evaporated .
The Andersen a i r sampler which was used by Sayer et al.
( 1 972) , relates the i s o l ated bacteria to the parent particle size,
making it pos s i b l e to pre d i ct the magnitude of inhalation risk. The
air sampler used in this study does not do that, therefore the
isolated m icro-org a n i s m s were d ivided i nto two groups.
1)
H uman associated org anisms which are normal l y found i n
or o n h u m a n b o d y a n d cloth i n g , cou l d b e generated from
human activities and were not isolated from outdoor a i r
samples.
These i nclude:
Staphylococcus,
S. aureus,
coag ulase negative
Micrococcus specie s ,
alpha hemolytic
Streptococci, G ra m negative rod s, and Diphthiroids species.
2)
Environmental organism s which come from other sources
such as a i r d ust, soi l , and water.
These were most
frequently isolated from outdoor a i r samples.
97
These
i ncluded
Bacillus species,
Streptomyces species,
and
unidentified bacteri a .
U n i dentified bacteria were the commonest g roup of bacteria
isolated from either hospital or domestic air samples. These were
m icro-organisms of no med ical i m portance.
They consisted of
aerobic g ram negative cocci , larger than Neisseria and Moraxella
speci e s . There was also a large presence of very small g ram
positive rod s and g ra m negative rod s . It was concl uded that this
group was mainly soil borne bacteria which have also been found
to be dominant i n the d u st of three types of dwel l i n g s in I n d i a
( Raza, 1 989) .
Q uantitative study of d ifferent hospital units showed that the
ped iatric ward and female medical wards had the hig hest total
count of bacteria .
This could be due to many factors , a s
d i scussed b y Woods , 1 986. These fin d i ng s could b e expla ined by
the fact that the n u m ber of v i sitors in ped iatric and female med ical
ward s exceed visitors i n other hospital areas . For example i n one
room i n ped iatric ward , there were seven chi ldren and three lad ies
98
at the same time during sampling process and i n one female
med ical ward room there were five fem a l e visitors i n only one
partition of the four partitions. At no time d id the visitors in the
male wards exceed three d uring sampling processing . It was a l so
o bserved that the amount of m aterials brought from outside, s uch
as carpets, flowers , fruits , were more common in ped iatric and
female ward s .
There may be other environmental and human
factors that cou ld have contri buted to these inconsistencies, which
were not observed .
I n comparison to other bacteria the numbers of pathogenic
micro-organisms i n the hospital a i r was found to be l ow.
Pathogens represented less than 1 % of the total count of bacteria
i solated .
Using an Andersen a i r sampler, Wi l l iam ( 1 956) found
that 3% of the total count of org anisms were pathog enic bacteria.
However,
he
included
Streptomyces
associated micro-org anisms.
species,
as
human
In this stud y streptomyces s pecies
was considered as a enviro nmental m icro-org anism. The reason
for this consideration that the types of streptomyces isolated were
u n l i ke those that cause actinomycetoma.
99
The low concentration of pathog e n i c organisms in hospital
a i r could possibly be due to the fact that there was not enough a i r
current t o d i stri bute t h e bacteria from t h e reservoi r (patient).
In
order t o evaluate this poss i b i l ity, a i r d rafts were created by
aerating and rearrang ing the patient bed sheets , curtains and
carpets if present. Air samples specimens were taken before and
after this practice .
Samples col lected after aerating showed
double the numbers of C F U total count as compared with samp l es
before aerating. Both samples showed the same types of m icro­
organisms which d i d not i nclude pathogenic ones.
Pathog enic org anisms of the type causing wound infections,
shou ld theoretical ly be i n high concentration in certai n hospital
areas but this is not the case as they d o not seem to be airborn e .
The mode of transmission o f these is l i ke l y t o b e v i a physical
contact of staff rather than by a i rborne means.
i nfections
such
as
throat
infections
the
In airborne
causative
agent
(pathogenic streptococcus) is usually isolated i n a small numbers
( i e . 1 0 to 20 colonies per swab); whereas one could find a 1 06
1 00
C FU/swa b of non pathogenic streptococcus such as S. viridans
i so l ated from same throat swab of the i nfected patient
It was interesting to compare the types of a irborne m icro­
org a n i sms found i n hospital to those at the home environment. As
this was the main purpose of this study, serious efforts were made
to understand the d ifferences, s i m i larities and the relati'onship of
the two environments .
Human pathogenic micro-organisms particularly S. aureus
and members of Entero bacteriacae were more prevalent in
hospitals than i n homes. S. aureus is n ot a very common skin or
res p i ratory flora . It would be expected that it come from bacterial
lesions or d ifferent types of infections i n patients. These patients
would , therefore , be hospital ized and thei r m icro-organisms
spread to some degre e . Enteric organisms are l i kely a l so to arise
from
wounds,
stools
and
uri ne
of
i nfected
patients .
Enterobacteriacae were more common i n hospital e nvironment,
both for a i r and surface samples, than i n domestic areas as it
would be expected .
101
Although there are no standard s for viable or nonvi a b l e
particu l ate in t h e operating room, or i n any other hospital area
(Kunds i n , 1 985) , the num ber of m icro-org a n i sms in operating
rooms and I ntensive care unit was very low. This was antici pated
d u e to the h i g h san itation level present in these areas, as
compared to other hospital areas.
The comparison of m icro-organisms found in homes and
the hospital showed that there were more m icro-organisms in
residenti al houses i n both air and surfaces than i n the AI Ain
hospita l . The m i cro b i a l counts found in the h i ghest status houses
compared favorably to that of the hospital and therefore , it coul d
be concluded that the these houses have hyg ienic standard close
to that found in the hospita l .
O n the other hand , there is a noticeable d ifference between
the hospital and types two and three res i dential m i crobes.
This
however reflects i n q uantity rather than i n the types of m i crobes.
The poor qual ity houses had the h i g her bacterial population .
1 02
Raza ( 1 989) has reported that the bacterial popu lation i n the
i ndoor d ust of s l u m dwe l l i ng s was h i g her than that in m i d d l e class
and u pper class dwe l l ings. The fact that the microbial flora of the
i ndoor air d epended on the number and types of people present
(Oug i d , 1 946), the qual ity of the household system ( F i n k et al. ,
1 97 1 ; F raser et a/, . 1 977; P ickeri ng et a/, . 1 976), and mechanica l
movem e nt with i n t h e enclosed space . Thi s fact can expl a i n these
find i n g s because in the poor houses there are too many people i n
a smal l s pace.
Therefore , whatever m i crobes are shed wou l d
lead t o a b u i ld u p o f numbers i n t h i s confined space.
I n contrast, i n the best type of house, there are fewer
res i d e nts per cubic meter (area) of house space occu pied and
therefore , shed m i crobes are spread out i n the space ava i l a b l e .
I n add ition, t h e better t h e house , the better the vent i l ation to
sweeps out microbes from indoor environment.
C l ea n i ng proced ures also vary between hospita l s and
domestic areas and between the d ifferent types of d omestic
environments.
It was observed that the best type of house had
103
many domestic cleaners, good housekeeping procedures and a
good a i r cond itio n i n g system that augur well for good indoor
standard s .
The s i m i larity i n t h e number o f micro-organisms i n the
hospital and in the very g ood quality homes is an i n d i cator that
both areas have a g ood hygienic standard .
i nternational
standard s
for
sanitation
I n AI-Ain Hospital
through
steri l ization,
d isinffection and clea n i n g are appl ied , therefore the hyg ie n i c
standard o f a i r a n d surfaces i s h i g h . The hospital a d m i n i stration
should be congratu lated for that.
It is however not surpri sing that the environmental micro­
organisms are fou n d i n much h i g her numbers as the housing
standards dro p .
The effect of desert storm s and spread of soil
bacteria would be i nteresting to study.
O n visiting home areas, one other s i g n ificant o bservation
made was the d ifference i n the numbers of human associated and
envi ronm ental m icro-org an isms between the l iving area and
1 04
sleeping q uarters .
It was particularly noticed that the number of
human and environmental microbes in l iving rooms and bedrooms
were found to be h i g her i n the lower status homes.
H uman
related microbes were found i n bedrooms more frequently than
l iving rooms.
The i m p l ication i s that more time is spent in
bedrooms than l iv i n g rooms.
On the other hand the soi l , water
and a i r m icro-org a n i sm s , were found more frequently" in l iv i ng
rooms than bedroom s .
Thi s i nd icates probably that bedrooms
have less exposure to d u st than other room s , regard less to the
status of the house.
Comparison of m i crobial num bers i n a i r samples and on
surface are not con s i dered here .
The two systems are n ot
su pposed to be com para b l e but B uttner and Stetzenbach ( 1 993)
sugg est that they are related in certain circumstances . However,
the types of micro b i a l g enera (or s pecies)and not the num bers of
microbes in these two systems were the same , therefore one
wou l d postulate a relationship between the deposit from a i r to
surface by gravity and from surface to air, by currents .
105
The study of fun g a l a i r spora is of g reat im portance and
i nterest i n order to understand the d i ssemi nation, spread , and
movement of the microbes, particularly the pathogeni c ones in the
atmosphere (Mostafa, 1 976).
I n this study three g enera of fun g i were frequently isolated
from hospital air and the three types of houses these were
A sperigil/us niger, a Chaetomium species, and an Alternaria
species. Another two Penicillium species and Asperigil/us tamarri,
were isolated less frequently.
S even A sperigil/us species were
isolated in this study. Kodama ( 1 986) reported that the air inside
aircond itioned homes was found to have fewer fung i , but had a
significantly
greater
number
of A sperigillus
species,
when
compared to the outdoor a i r. Raza ( 1 989) reported that A . f1avus
and , A. niger were dominant i n a l l the types of dwe l l i n g s in I nd i a .
Also h e observed a h i g h concentration of Asperigil/us in most
i ndoor environments .
It was also found that the most frequent
isolates of Asperigillus s pecies from outdoor a i r were A. f1avus, A .
niger, A. fumigatus a n d A . terreus i n Kuwait (Mustafa , 1 976) . Th is
1 06
can explain the h i g h
concentration
of Asperigillus species
compared with other fun g a l groups.
The study of a nt i biotic sensitivity pattern of patient's micro­
organi sms is of g reat cl i ni cal rel evance and value.
It is a lso
appreciated that the knowledge of anti-microbial sensitivity pattern
i s also of epidemiolog i ca l value. M i crobes from the same source
usua l l y exh i b it s i m i lar suscept i b i l ity to the same anti-microbial
agents .
When the source of a bacterial epidemic d i sease is
i nvestigated , domestic or hospital enviro nmental m icro-organisms
are compared with the patients' org a n isms.
One of the tools
used , among many sophisticated tech ni q ues avai l a b l e , is the
anti biotic sensitivity com parison.
In this study, this relationsh i p
has been evaluated u s i n g coa g u l ase negative Staphylococci
(CNS).
It was clearly observed that there was a d ifference in
sensitivity patterns for hospital-associated m icro-organisms and
those isolated from homes.
The resu lts also showed that
domestic ai rborne C N S were sensitive to nearly a l l the anti biotics
tested .
The source of d o mestic stra i n s was the establ ished
environment or from peop l e who had n ot recently used any anti-
1 07
m i crobial agents. A few of the d omestic stra i n s were resi stant to
some antibiotics such as tetracycline.
Thi s res i stance was
probably due to the fact that some bacteria are natura l ly res i stant
to a particular antibiotic even if they were never exposed to the
same d rug ( Pelczar et al. , 1 993).
When the environment is stab l e , the bacterial population
wi l l remain unchan g ed , but if any factors affecti ng the sta b i l aty
changed to hosti le environment, only certain individual microbes
bearing protective m utation can adapt and survive.
In this way,
the environment natura l ly selects certain m utant strains that will
reproduce , g ive ris e to su bsequant generations, and i n time, be
the dominant strai n in the populatio n . O n e o f t h e clearest models
for this sort of selection and adaptation
is acq u i red d rug
res i stance in bacteria (Talaro and Talaro , 1 993) .
When
development
i nfrequent.
anti biotics
of
were
first
u s ed
antibiotic-re s i stant
However,
as
anti biotics
in
chemotherapy,
m icroorganisms
was
became widely used ,
resistance became much more of a problem as susceptible
1 08
m icrobes were e l i m inated and the numbers of res i stant micro­
org an i s m s increased .
The i nitial a ppearance of a res istant
bacterium i n an otherwise suscepti ble popu lation i s often caused
by a m utation in a s i n g l e bacterial gene. The g ene for res istance
can be transmitted from a res i stant cel l to a s uscepti ble cel l by
conj ug atio n .
res i stance.
Thi s process is cal led transmissible antibiotic
It i s however not known whether the environment
where this process takes place has any s i g nificant effect ( Pelczar
et a l , . 1 993).
Patients stra i n s were the most resi stant ones compared to
d omestic and hospital stra i n s .
subjected
or
exposed
to
Patients stra i n s are usually
anti-micro b i a l
agents
used
by
hospital ized patients. The appearance of d rug-resi stant bacteria
is a reflection of the forces of natural selection because the drug­
res i stant vari ant from of pathogens has a u n i q ue fitness trait that
i s absent from the ori g inal species, it possesses physiological or
structural properties that a l low it to g row i n the presence of a
stress not tolerated by the orig inal popul ation ( Boyd , 1 98 8 ) .
In
ecolog ical terms the environmental factor ( i n t h i s case, the d rugs)
1 09
has put selection pressure on the population , thu s the fitter
m icrobe (the d rug-resistant one ) survived , and the population has
evolved to a cond ition of drug resistance .
N atural selection for
d rug-resistant forms is apparently a common phenomenon.
takes
place
most
frequently
in
various
natural
It
habitats,
l aboratories, and medical environments .
The hospital airborne micro-organisms seem to be a mixture
of patients ' , environmental and visitor' s stra i n s as their sensitivity
fa l l s between domestic and patient stra i n s .
l LO
CHAPTER V
C ON CLUSIONS
Human pathogenic m icro-organism s particularly S. 8ureus and
mem bers of Enterobacter iacae were very i nfrequent.
M i crob i a l flora of the i ndoor air depends on the number and types
of people present, thus the q ual ity of the household system and
mechanical movement withi n the enclosed space. I n poor houses
there are too many people i n a sma ll space . Therefore, whatever
m icrobes are shed would lead to a b u i l d up of numbers in t h i s
confined space.
I n the best type of house, there are fewer residents per cubic
meter (area) of house space occu pied and therefore , shed
microbes are spread out i n the space ava i l a b l e .
I n addition, the
better the house, the better the ventilation to sweeps out m icrobes
from indoor environment.
I I I
C l eaning proced u re s a l s o vary between hospitals and d omestic
areas and between the d ifferent types of domestic environments .
The best type of house had many domestic cleaners , g ood
housekeeping proced ures and a good air cond itioning system.
The s i m i larity i n the n u m ber of micro-organisms i n the hospital
and in the very g ood q u a l ity homes is an ind icator that both areas
have a good hyg ienic standard s .
The
source
of
dome stic
strains
of
coag ulase
negative
Staphylococci was the environment or from people who had n ot
recently used any anti-microbial agents .
Resistance to some
anti biotics was detected in some of these strains. This res i stance
was probably due to the fact that some bacteria are natura l l y
resistant to a particular antibiotic even i f they were never exposed
to it. However, patients strains are usually s u bjected or exposed
to anti-microbial ag ents used by hospital ized patients therefore ,
tend to develop resi stance through mutations and ad aptation for
survival
under
the
environmental
represented by chemotheraputic agents
1 12
conditions
which
are
The hospital airborne m i cro-org anisms seem to be a mixture of
patients', environme ntal and visitor's strains as their sensitivity
falls between domestic and patient stra i n s .
1 13
CHAPTER VI
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