DECONTAMINATION
Calls to tackle
protein risk
considered the problematic
challenge of detecting and
removing residual protein.
Opening the discussion was a
presentation on ‘limitations on
residual protein contamination on
instruments’, by Nigel Tomlinson,
who previously advised the
Department of Health (DH)
on decontamination issues in
his role as principal scientific adviser.
(He has now retired.)
He explained that residual protein is
defined as ‘a mass of protein that remains
on an instrument after it has been washed
and disinfected, usually in a mechanised
way, within a sterile service department’.
This potentially poses a risk of protein
based infection (such as vCJD), and can
affect the acceptability of the instrument
for surgical use.
While working for the DH, Nigel
Tomlinson received complaints about the
functionality of some instruments: “There
is a relationship between instrument
design and levels of contamination, and
the effectiveness of the washing process,”
he pointed out.
He acknowledged that the
decontamination community would like to
see a lower level of bio-molecular protein
contamination of instruments at the end
of the process and, in an effort to tackle
the problem, the DH has adopted a riskbased strategy involving a number of key
steps including the investigation of
detection and quantification methods, the
optimisation of washing and disinfection,
and the development of new
decontamination techniques.
The first step has included the funding
of research into improving protein
detection and quantification. There have
been a number of pilot studies established
to investigate various approaches, with the
aim of suppressing vCJD-related risks,
within the hospital decontamination
setting. The emphasis has been on
examining these approaches in practice,
rather than simply using a scientific team.
New techniques in protein detection make it possible to set limits on
protein contamination on surgical instruments. In the future, there
may be national or local targets on permissible protein residues, but
just how much improvement can be reasonably achieved in reducing
protein-related infection risk? LOUISE FRAMPTON reports.
Following the publication of research,
which estimated that around one in 2,000
people in the UK may carry variant
Creutzfeldt-Jakob Disease (vCJD)
protein,1 the Science and Technology
Committee recently presented evidence on
vCJD and the ongoing risk it poses to the
UK.
Ordered by the House of Commons,
the meeting took place on 27 November
2013 and heard evidence from a number
of experts including Professor Collinge,
director of the Medical Research Council
(MRC) Prion Unit, UCL Institute of
Neurology.
He highlighted the fact that, in
addition to the 20,000 or 30,000 people
that are predicted to be infected and are
carriers in the population at the moment,
there are around 6,000 people in the UK
who have been notified that they are at
increased risk of developing the disease as
a result of receiving either blood from a
person who went on to develop vCJD or
blood products that are implicated, or
who have been exposed to contaminated
surgical instruments.2
Andrew Miller MP, chair of the science
and technology committee, said: “More
than twenty years on from the BSE crisis,
studies have suggested that thousands of
people may still carry the infectious agent
thought to cause vCJD – the human form
of ‘mad cow disease’.
“Although these people may never go
on to develop symptoms of vCJD,
important questions remain to be asked
about the potential risk posed by this
terrible condition and what the
Government should be doing to reduce
the spread of infection.”3
Protein removal:
surgical instruments
Against a backdrop of heightened
awareness, the issue of transmission risk
through contaminated surgical
instruments was high on the agenda at the
Institute of Decontamination Sciences’
(IDSc) annual conference, as experts
‘Important questions remain to be asked about the potential
risk posed by this terrible condition and what the Government
should be doing to reduce the spread of infection.’
JANUARY 2014
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DECONTAMINATION
Sensitive protein detection test
Dr Nanda Nayuni, William Harvey
Research Institute, Bart’s & The London
school of Medicine and Dentistry, Queen
Mary University of London, pointed out
that visual inspection and swabbing
methods for protein detection are
inadequate. He provided an insight into
a sensitive protein detection test
(ProReveal), which combines a compact
fluorescence imaging system and
OPA/NAC (o-phthaldialdehyde/N-acetyl
cysteine) reagent spray.
The process, which takes around five
minutes, produces an image of
contaminating proteins on an
instrument, measures the amount of
residual proteins, then indicates a ‘pass’
or ‘fail’ of the decontamination process
with an on-screen green tick or red
cross. To date, results show that the
technology can detect less than 50ng of
residual protein on a reprocessed
surgical instrument, making this a very
sensitive detection method.
The system can be used to optimise
decontamination processes and
chemistries, within SSDs, as well as by
manufacturers in the design of
instruments. Most recently, it was
announced that detergent manufacturer
and supplier, Serchem, is using the test
“Practicality matters – a good idea has
no value if it cannot be implemented,”
Nigel Tomlinson pointed out.
The pilot studies have included:
• Protein quantification using OPA/NAC
fluorescence – a collaboration between
Great Ormond Street Hospital
(GOSH) and University College
London Hospitals (UCLH) and Bart’s
& The London school of Medicine and
Dentistry, Queen Mary University of
London.
• Protein quantification using
epifluorescence scanning – University
of Edinburgh/Royal Infirmary of
Edinburgh.
• Protein quantification using
EDIC/epifluorescence microscopy –
University of Southampton).
Nigel Tomlinson described the technology
using OPA/ NAC fluorescence as the
‘most simple’, yet ‘most graphic’ of the
new techniques. He explained that the
approach uses an imaging camera and a
simple spray technique, which is very
tolerant of ‘operational variables’, (such
as the quantity of spray used and length
of time before image capture), which
makes it ‘very robust’.
In addition, the technique studied at
the University of Southampton has the
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THE CLINICAL SERVICES JOURNAL
to accurately diagnose the efficacy and
optimise the chemistry of its detergents
for protein removal.
The test’s ability to detect nanogram
levels of protein on surgical instruments
is being used by the company’s R&D
department in Telford, to test the efficacy
of its alkaline, neutral and enzymatic
cleaning ranges to remove proteins from
specifically calibrated protein soil test
standards. Since ProReveal provides
quantitative data on residual protein, using
the results of these experiments,
Serchem’s formulation scientists can
assess how effective current detergent
ranges are. Using the detection test will
also allow them to determine how
manipulating components of the
detergent’s formulation directly impacts
how much protein can be removed, thus
making designing an optimum formula for
maximum protein removal a quicker and
more accurate task.
Paul Arnold, sales director at Serchem,
commented: “We supply detergents to
over 240 sterile service and endoscopy
decontamination sites in the UK alone so
we are all too aware of how challenging
removing residual protein from surgical
instruments can be. Financial constraints
are being placed on many hospital sites,
some with older less efficient equipment
and less than ideal water conditions
where investment for new washers and
water treatment may not be possible and
this is proving to be a challenge.
“Then there is the issue of the
instrument manufacturers’ cleaning
instructions that complicates the
decision making process even further.
Therefore, it is up to detergent
manufacturers to intelligently design their
products to deliver maximum cleaning
efficacy, even when washing processes
are sub-optimal. We believe that
ProReveal can play a vital part in that
process and is a technology not to fear
but to embrace.”
• ProReveal is manufactured by
Synoptics Health and is commercially
available in the UK through Peskett
Solutions.
ability to not only quantify
protein, but also detect and
quantify amyloids – the major
component of plaque, which is
associated with degenerative
brain disease.
“I do not know which of
these technologies will prove to
be the most suitable in the
fullness of time and there is
also alternative technology
from Porton Down,” Nigel
Tomlinson commented.
Failures in decontamination led to congealed blood
However, he highlighted the accumulating inside the shaft of this laparoscopic
instrument.
need for protein detection
he asserted, adding that there also needs
technologies with very high levels of
to be an establishment of ‘a convention on
sensitivity: “We need to be getting down
to attomole levels to make a big impact on calibration’.
As part of this work, there needs to be
the risk of vCJD transmission.” It is also
agreement and standardisation on ‘units’
important to be able to ascertain how
– are we talking about protein mass per
much protein is present on an instrument
unit area or per instrument? In addition,
– not simply to determine ‘pass’ or ‘fail’,
are we interested in the whole instrument
or just the active surfaces – such as
blades, which are in contact with the
‘A lot of improvement
patient? There also needs to be discussion
on whether a protein contamination limit
does not require great
could be established nationally or locally.
He pointed out that the DH is more likely
cost – just additional
to take direction from organisations such
as the IDSc on such matters and it is
work and care.’
unlikely that decisions will be imposed by
JANUARY 2014
DECONTAMINATION
the Government, as they have been in the
past.
Prevalence and risk
Keeping instruments moist
The importance of keeping instruments
Prevalence studies on vCJD have been
moist prior to decontamination has
been acknowledged by a number of
performed on pathological specimens for
decontamination guidelines, such as
around nine years and have shown that
NICE Interventional Procedure
the infectious agent remains in the human
Guidance 196 and CFPP 01-01 –
population.
Management and Decontamination of
“The new protein tests are potentially
Surgical Instruments (Medical Devices)
‘game changing’, because they are
Used in Acute Care.
sensitive enough to allow you to refine
CFPP 01-01 states: “Keeping the
your techniques and remove protein down
environment around soiled instruments
to a level where you can make some
at, or near, saturation humidity (moist)
difference to the risk of CJD being
prevents full attachment of hydrophobic
transmitted to patients,” Nigel Tomlinson
proteins such that they are more
commented.
efficiently removed by cleaning.”
“The prevalence figure of ‘one in 2,000
A new pre-clean gel, designed to
people’ with the vCJD protein is not a
address this issue, was highlighted at
definitive estimate,” Nigel Tomlinson
commented, pointing out that there are a
number of risk estimates in circulation.
There has been one new clinical case in
‘Practicality matters
the UK, in the last two years, and three
suspected – but unconfirmed – new cases
– a good idea has no
overseas. The total number of cases in the
UK, to date, is 177. Figures for sporadic
value if it cannot be
CJD appear to be showing a slow increase
(there are over 80 recorded deaths per
implemented.’
year) and this is believed to be highly
transmissible, Nigel Tomlinson pointed
out.
to proceed towards lower contamination
Better protein detection, combined
levels. I would challenge you as to why
with improved washing can make a big
this is not a desirable aim, as there
difference to the risk of transmission, he
appears to be no cost implications – it is
commented; however, there is currently
simply a matter of some thoroughness in
no data on typical levels of contamination
the way we do our work and requires
on a wide range of instrument types and
collaboration with national or local
the question remains of just how much
scientists to ensure the optimisation of the
improvement can reasonably be achieved.
“A lot of improvement does not require washer disinfector and its chemistry.”
In terms of a possible ‘traffic light’
great cost – just additional work and
approach to risk, he suggested that 200
care,” he asserted. He went on to explain
micrograms per instrument could be
that contamination levels are dependent
defined as ‘red’; 50-200 micrograms
on instrument design, but improvements
would be ‘amber’ and below 50
in protein removal can be achieved
through the optimisation of washer
Contaminated instruments pose a risk
disinfector settings, choice of
detergent, alkalinity (which is known to of protein-related infection.
be helpful in destroying CJD
infectivity), as well as enzyme activity.
Although the latter is known to be
helpful, there are some parts of the
CJD molecule which are resistant to
enzyme action. In addition, particular
care should be taken in protein
detection and washer disinfection when
reprocessing instruments used on high
risk tissues (e.g. brain surgery and
posterior eye surgery).
The future: setting limits
In the future, protein limits will be set,
either nationally or locally, Nigel
Tomlinson concluded: “Most people I
have spoken to say they want a hard
target...It is, in my opinion, feasible to
use the new protein detection methods
JANUARY 2014
IDSc. Trials and independent
laboratory tests have shown that
Azo Gel (Synergy Health) is
effective in removing dried organic
debris bound to medical
instruments. The gel also provides
an optimal coating on stainless
steel medical instruments which
can reduce spills and splashes,
minimising risk of infection
exposure for personnel handling
contaminated instruments. A product
trial at the London Clinic demonstrated
improved productivity in a local CSSD
site – delivering a 21% increase in
instruments processed per hour and a
36% reduction in re-washes.
micrograms would be ‘green’.
“Most departments could achieve this
quite quickly,” he commented. However,
he added that research at GOSH and
St Bart’s suggests that it would not be
difficult to achieve even lower levels – a
‘green’ limit of 5 micrograms per
instrument may be defined in the future,
therefore.
“At this point, the threshold is crossed
where there is virtually no risk of vCJD
transmission for surgery, involving low
and medium risk tissues, as the risk is
being dealt with by the decontamination
unit. In this case, you will be doing
society a very big favour in dealing with a
disease that we understand very poorly.
This is a readily achievable objective,”
Nigel Tomlinson continued. “I cannot tell
you if this will become policy, but
professional and learned bodies can
influence the derivation of targets and I
would ask you to think hard about doing
this.”
The IDSc conference and exhibition
took place at the Hilton, Blackpool,
2-4 December 2013.
References
1 BMJ press release. http://www.bmj.com/
press-releases/2013/ 10/14/researchersestimate-one-2000-people-uk-carry-variantcjd-proteins Accessed on 14 October 2013.
2 Science and Technology Committee, oral
evidence: variant Creutzfeldt-Jakob Disease
(vCJD). http://data.parliament.uk/
writtenevidence/WrittenEvidence.svc/
EvidenceHtml/3969
Accessed on 27 November 2013.
3 Commons Select Committee. MPs take
evidence on variant Creutzfeldt-Jakob
Disease (vCJD). http://www.parliament.uk/
business/committees/committees-a-z/
commons-select/science-and-technologycommittee/news/131121-vcjd-ev
Accessed on 27 November 2013.
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