How Pathogens Spread in the
Healthcare Setting:
Understanding the Basics
Healthcare-Associated Infections:
A Practice-Oriented Update
Tom Talbot, MD MPH
Assistant Professor of Medicine
and Preventive Medicine
Chief Hospital Epidemiologist
Vanderbilt University School of Medicine
April 21, 2010
Objectives
• Review how pathogens are spread to
patients and healthcare workers in the
healthcare setting
• Understand which modes of spread are
more important than others
True or False:
Contaminated Products are the
Most Common Source of Pathogens
that Cause Healthcare-Associated
Infections.
A. True
B. False
Sources of Pathogens
• Patient’s normal flora
• Healthcare worker’s flora
• Infected person
– Open wound
– Uncontrolled “secretions”
• Contaminated products
Who is the Person Circled?
A. Louis Pasteur
B. Alexander Fleming
C. Ignaz Semmelweis
D. William Osler
Transmission of Pathogens in
the Healthcare Setting:
Healthcare
Worker’s Hands
Ignaz Semmelweis
• Vienna, 1847
• Deaths from puerperal fever:
–  on ward attended by MDs/students
• Required washing of hands in antiseptic
chlorinated lime solution before
attending to laboring patients
• Mortality rates: 12.2%  2.3%
After Hand Hygiene
True or False:
Hand Hygiene Should be Performed
After You Remove Gloves Following
Patient Care.
A. True
B. False
What About Gloves?
• Gloves can have microperforations that
allow bacteria to pass
• May contaminate hands during removal
Transmission of Pathogens in
the Healthcare Setting:
The Environment
• Some pathogens survive for some
time on surfaces – MRSA, VRE, C.
difficile, hepatitis B
Environmental Contamination
VRE (n = 17)
C. diff (n = 9)
Eckstein BC et al BMC Infect Dis 2007,7:61+
Call button after
cleaning
X
X
X
X
X
X
X
X
C. difficile recovered from 83% of “dirty surfaces
C. difficile recovered from 67% of “clean” surfaces
Dubberke ER et al Am J Infect Control
2007;35:315+
What About . . .
Transmission of Pathogens in
the Healthcare Setting:
Respiratory
Droplets
Spread of Respiratory Pathogens
• Some pathogens can be spread by various sizes
of particles that travel in the air
– Larger droplets
• Pertussis (whooping cough)
• Influenza
– Smaller aerosols
• M. tuberculosis
Transmission of Pathogens in
the Healthcare Setting:
Improper Aseptic
and Sterile
Practices
Clean vs. Dirty
Crnich CJ, Maki DG CID 2002;34:1232+
Brief Factual Description:
Attending physician for ICU failed to maintain sterile technique for insertion of an arterial line. MD
came from another patient's room, did not wash hands, did not place sterile gloves on and inserted
arterial line in this patient. RN asked MD to put gloves on and mind the sterile field and MD refused.
Transmission of Pathogens in
the Healthcare Setting:
Sharps and
Needlestick
Injuries
Sharps Injuries
• Can result in spread of infection to
healthcare workers
– Bloodborne viruses:
• HIV
• Hepatitis B
• Hepatitis C
Sharma GK et al Acad Med 2009;84:1815+
HCWs with documented and possible occupationally acquired
AIDS/HIV infection, by occupation, as of December 2002.
Documented
Possible
Nurse
Occupation
24
35
Laboratory worker, clinical
16
17
Physician, nonsurgical
6
12
Laboratory technician, nonclinical
3
-
Housekeeper/maintenance worker
2
13
Technician, surgical
2
Embalmer/morgue technician
1
2
Health aide/attendant
1
15
2
Respiratory therapist
1
2
Technician, dialysis
1
3
Dental worker, including dentist
-
6
Emergency medical technician/paramedic
-
12
Physician, surgical
-
6
Other technician/therapist
-
9
Other healthcare occupation
-
5
57
139
Total
HCV: Occupational Transmission
Sulkowski MS et al. JAMA 2002;287:2406
HCV: Occupational Transmission
425
17 (4%)
Sulkowski MS et al. JAMA 2002;287:2406
Cases Transmitted to
Patients from Infected
Providers
Hepatitis B
375 reported cases
Hepatitis C
15 reported cases
HIV
9 reported cases
For Medication Administration, You
May Reuse the Syringe As Long As
You Use a Different Needle.
A. True
B. False
Transmission of Pathogens in
the Healthcare Setting:
Unsafe Injection
Practices
Nevada 2008
• Jan: Cluster of HCV infections
– All underwent endoscopy at same site
•
•
•
•
Investigation ensued
39,562 potentially exposed patients
6 cases of hepatitis C identified
Patients who had procedure at Endoscopy
Center “A” 28 million times  risk of
HCV
• Single-use equipment reused 3x if possible
Nursing Home Outbreak:
Mississippi 2003
• 2 deaths from acute Hep B
• 15/158 residents (9%) with acute Hep B
• Among those w/ routine glucose monitoring:
37% vs. 1% (RR 39.0)
• Glucometer not cleaned between pts
• Multi-dose insulin vials not labeled
• Staff reported seeing reuse of lancets &
needles
Webb R et al MMWR Weekly Rep 2005;54:9+
Transmission of Pathogens in
the Healthcare Setting:
News of the
Weird