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Are surfaces and fomites a source of HAI?

Jen KokJen KokCentre for Infectious Diseases and Microbiology

Laboratory ServicesICPMR

Westmead Hospital

icpmrCentre for Infectious Diseases and Microbiology, Westmead Hospital

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Definition of fomite

• fomites: inanimate object or surface which may be

colonized with pathogens, facilitating transfer of

pathogens

• fomite factors that affect contamination rates


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• porous vs. non-porous

Rusin J Appl Microbiol 2002,

Appl Environ Microbiol 2008

Scanning electron microscopy


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Porous fomite Non-porous fomite

Definition of fomite

• fomites: inanimate object or surface which may be

colonized with pathogens, facilitating transfer of

pathogens



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• porous vs. non-porous

• presence of moisture

• frequency of use

• general cleanliness

Rusin J Appl Microbiol 2002,

Appl Environ Microbiol 2008

Assessing methodology and the quality of evidence in studies of fomites

• contamination rate ≠ transmission rate

• degree of contamination by specific pathogens

• colonizers vs pathogenic organisms

• temporal relationships


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• temporal relationships

• study “before and after” contamination rates

• addressing confounders

• hand-hygiene

• quality of disinfection procedures or other

interventions

Hota Clin Infect Dis 2004

Skin and environmental contamination by patients with MRSA prior to screening results

• rate of environmental contamination of patients not

known to be colonized with MRSA (n=83)

• MRSA surveillance swabs

• 18% patients contaminated environment within

25 hrs and 35% within 33 hrs


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25 hrs and 35% within 33 hrs

• caveats

• no baseline screening of room

• some isolates from nares, skin and environment

subject to typing were identical and not all typed

• surveillance swabs were not performed on room mates

of index cases where rooms were shared

Chang Infect Control Hosp Epidemiol 2010

Patient and environment factors affecting fomite contamination rates

• frequency of contamination dependent on:-

• patient’s infected body site

• 36 – 59% of surfaces positive if MRSA in wounds, stools

or urine vs. 6% if MRSA at other body sites

• 46% of environmental cultures in rooms of patients

with diarrhoea vs. 15% without diarrhoea for VRE


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with diarrhoea vs. 15% without diarrhoea for VRE

• environmental contamination of burns units

• MRSA up to 64% in burns vs. 1 – 18% non-burns units

• nature and frequency of contact, personal habits,

type of activity, personal mobility and general

level of cleanliness in the surroundings

Boyce J Hosp Infect 2007, Boone Appl Environ Microbiol 2007

Commonly colonized fomites

• bedside rails and tables, remote controls, IV pumps,

BP cuffs, torniquets; keyboards and mice

vs.

• mobile phones

• observational study (n=145 patients)


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• observational study (n=145 patients)

• 102/145 brought mobile phone into hospital

• only 1 patient’s phone had MRSA

• transmission not an issue as no patient shared

their phone with anyone during their stay

Boyce J Hosp Infect 2007, Elhassan Postgrad Med J 2011, Boone Appl Environ Microbiol

2007, Brady Clin Microbiol Infect 2011, Wilson J Hosp Infect 2006

Pathogen Types of

environmental

contamination

Length of survival Evidence of

transmission

MRSA Extensive

environmental

contamination

48 h on plastic

laminate surfaces, ≤ 9

wks cotton blanket

Environment to HCW

spread

VRE Extensive

environmental

contamination

≤ 58 days on

countertops

Environment to HCW

spread

C difficile Extensive

environmental

contamination

5 months on floors Correlation between

environmental and

HCW hand


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contamination HCW hand

contamination

Influenza virus Aerosolization,

survives on fomites

24 – 48 h Fomite to hands of

HCW

Parainfluenza virus Survives on clothing

and nonporous

surfaces

6 h on clothing, 10 h

on nonporous surfaces

Not proven, indirect

evidence

Norovirus Extensive

environmental

contamination

≤ 12 days on carpets, ≤

14 days in stools

Not proven

Candida spp Fomites 3 – 14 days depending

on spp

Possible

adapted from Hota Clin Infect Dis 2004

Respiratory and enteric virus transmission via fomites

• fomites can serve as viral reservoirs

• aerosolization

• sneezing/coughing (107 virions/mL

nasal fluid)

• aerosolized vomit (30 million virions per vomit)


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• direct transfer from hands to fomite surface

• respiratory viruses spread from hands to fomites

• foodborne outbreaks of enteric viruses

• under experimental conditions, respiratory viruses can

survive up to 72 hours and enteric viruses can survive >60

days Pancic J Clin Microbiol 1980, Boone Appl Environ

Microbiol 2007

Candida spp

• discrepant results in published literature• 25/39 patients carried one genotype in an outbreak of C. krusei

• environmental, food, dental and medical paraphernalia cultures

all negative

• outbreak controlled with improved infection control (screening,


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cohorting positive patients, hand-hygiene, amphotericin

prophylaxis)

VS.

• 24/98 patients positive for C. glabrata on screening

• 3/50 environmental surfaces contaminated

• isolates belonged to 28 different strain types

Vos J Clin Microbiol 2006,

Vazquez J Clin Microbiol 1998

Interrupting fomite colonization reduces MRO

• successful termination of a MRSA outbreak (in addition

to enhanced surveillance and cohorting)

• beds sequentially closed on wards for cleaning and

disinfection

• non-clinical areas also cleaned

• ventilation ducts cleaned and airflow tested


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• ventilation ducts cleaned and airflow tested

• increased cleaning time from 66.5 to 123.5 hr/week

• individual component, or the sum of all interventions as

a bundle?

• as environmental contamination increases, prevalence of

C. difficile hand carriage increased

Rampling J Hosp Infect 2001,

Gerding Clin Infect Dis 2008

Stethoscopes as vectors for C difficile and MRSA


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Direct: innoculate onto diaphragms, imprint onto agar

Indirect: innoculate onto skin, allowed to dry, then diaphragm pressed

onto skin prior to imprint onto agarVajravelu Infect Control

Hosp Epidemiol 2012

4 3 2 1

Frequency of stethoscopes cleaning amongst medical students (n=17)


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Burrie Aust Med Student J 2011

82% of students reported that senior colleagues affected their

attitude about stethoscope cleaning


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Aerosolization of C difficile with open and closed toilet lids


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Best J Hosp Infect 2012

Air sampling and settle plates following toilet flushing with inoculation

of C difficile spore suspension in feces (107 CFU/mL)

Aerosolization following toilet flush


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Best J Hosp Infect 2012

Standard wash-down toilet Rimless toilet

What is different yet similar between these two toilets?


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Touch no evil, breathe no evil and taste no evil


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