Wednesday, May 18, 2011

Cleanliness is next to godliness

At the Red Queen blog of the Brazilian scienceblogs there's an ongoing discussion on a post about the use of the white coat - by clinicians, but not only - outside of the clinical premises. There's even a picture where we can see almost everybody gowned up at the cafeteria of the medical school...

I remember working in such a setting, and I always felt uneasy seating beside someone with a lab coat saying "hematology" or "parasitology" and sharing the jar of orange juice. Besides the garment, we already had our badges and other displays of hierarchy. But I had some friends who told me that it's common to have two coats, one for "inside" (=working) and another one for "outside" (=showing), specially in high profile hospitals. BTW I didn't use one at this time, and in my lab activities from high school and undergrad days I had a blue collar coat used by lathe operators.

Anyway, I was curious about the real, established risks of parading with a lab coat inside and around a hospital, and so as usual I started digging for references. Here are some articles that analyzed hospital uniforms for the presence of pathogens - the list is very incomplete, so additions are welcome!

Bacterial flora on the white coats of medical students (Journal of Hospital Infection (2000) 45(1): 65-68):
This study has demonstrated that the white coats of medical students are more likely to be bacteriologically contaminated at points of frequent contact, such as the sleeve and pocket. The organisms identified were principally skin commensals including Staphylococcus aureus. The cleanliness of the coat as perceived by the student was correlated with bacteriological contamination, yet despite this, a significant proportion of students only laundered their coats occassionally. This study supports the view that the students' white coat is a potential source of cross infection on the ward and its design should be modified in order to facilitate hand washing. Hospitals training medical students should consider taking on the burden of providing freshly laundered white coats for the students.
The Endangered White Coat (Clin Infect Dis. (2010) 50 (7): 1073-1074):
Although little clinical evidence exists regarding the impact of these potential fomites on NI, some data seem to give credence to the thought that clothing may play a role in transferring pathogens. Several studies have shown that physicians' white coat sleeves and pockets are frequently colonized with bacteria associated with NI[1215]. Mackintosh et al [16] also showed that several pathogens transferred well from fabrics to hands. Scott et al [17] showed that several types of pathogens can be transferred from contaminated soiled cloth and surfaces to fingertips in detectable numbers. In a costbenefit analysis, Puzniak et al [18] showed that gown and glove use together lowered the incidence of vancomycin-resistant enterococci infection in a medical intensive care unit, which would seem to support the claim that clothes are a potential fomite for NI.
Bacterial contamination of health care workers' white coats (AJIC: American Journal of Infection Control (2009) 37 (2): 101-105):
Among the 149 grand rounds attendees' white coats, 34 (23%) were contaminated with S aureus, of which 6 (18%) were MRSA. None of the coats was contaminated with VRE. S aureus contamination was more prevalent in residents, those working in inpatient settings, and those who saw an inpatient that day. This study suggests that a large proportion of health care workers' white coats may be contaminated with S aureus, including MRSA. White coats may be an important vector for patient-to-patient transmission of S aureus.
The health professional's role in preventing nosocomial infections (Postgraduate Medical Journal (2000) 77 (903): 16-19):
Gloves, gowns, and masks have a role in preventing infections, but are often used inappropriately, increasing service costs unnecessarily. While virulent microorganisms can be cultured from stethoscopes and white coats, their role in disease transmission remains undefined. There is greater consensus about sterile insertion techniques for intravascular catheters—a common source of infections—and their care. By following a few simple rules identified in this review, health professionals may prevent much unnecessary medical and financial distress to their patients.
Survival of Enterococci and Staphylococci on Hospital Fabrics and Plastic (Journal of Clinical Microbiology (2000) 38 (2): 724-726):
The transfer of gram-positive bacteria, particularly multiresistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE), among patients is a growing concern. One critical aspect of bacterial transfer is the ability of the microorganism to survive on various common hospital surfaces. (...) Antibiotic sensitivity had no consistent effect on survival. The long survival of these bacteria, including MRSA and VRE, on commonly used hospital fabrics, such as scrub suits, lab coats, and hospital privacy drapes, underscores the need for meticulous contact control procedures and careful disinfection to limit the spread of these bacteria.
How Important Is the Environment in the Emergence of Nosocomial Antimicrobial-Resistant Bacteria? (Clin Infect Dis. (2008) 46 (5): 686-688):
Numerous studies have demonstrated that the environment of a patient's room can become colonized with bacteria, such as Acinetobacter species, VRE, Clostridium difficile, and methicillin-resistant S. aureus, as well as with viruses, such as influenza virus and norovirus [8]. But the importance of this colonization in leading to patient-to-patient transmission has not been shown with a high level of scientific evidence.
Survival of Nosocomial Bacteria and Spores on Surfaces and Inactivation by Hydrogen Peroxide Vapor (Journal of Clinical Microbiology (2009) 47 (1): 205-207):
In summary, we found that dried inocula of a range of nosocomial pathogens survived on surfaces for several weeks but were rapidly inactivated by HPV in a 100-m3 room. HPV has a potential role in decontaminating surfaces and equipment contaminated with such organisms.
Antibacterial and Laundering Properties of AMS and PHMB as Finishing Agents on Fabric for Health Care Workers' Uniforms (Clothing and Textiles Research Journal (2007) 25 (3): 258-272):
This study examined whether antibacterial finishes can effectively reduce the presence of bacteria on fabric used for health care workers' uniforms (HCWUs). (...) PHMB-treated specimens had a significantly larger reduction against both Staphylococcus aureus and Klebsiella pneumoniae bacteria before laundering and after 5, 10, and 25 laundering cycles than did AMS-treated specimens and no-treatment specimens.
Survival of Some Medically Important Fungi on Hospital Fabrics and Plastics (Journal of Clinical Microbiology (2001) 39 (9): 3360-3361):
These data indicate that many of the fungi (Candida, Aspergillus, Mucor, and Fusarium) which are associated with nosocomial infections in patients survived for at least a day and often longer on fabrics and plastics routinely used in hospitals. (...) While similar data do not exist for other fungi,the findings that other fungi can exist for extended periods on common hospital fabrics and plastics suggest that similar transfers from contaminated materials to hands, and vice versa, are likely. These survival data indicate that in this age of increasing antifungal resistance, when treatments for patients are becoming more limited, appropriate disinfection of the environment and conscientious contact control procedures are essential for optimal control of infections in hospitals.
Laboratory instrument contamination with dermatophytes – a risk for dermatophytosis (Letters in Applied Microbiology (2007) 44 (1): 112-113):
Nocardia asteroides and S. schenckii were also isolated from a shelf and a lab coat. Dermatophytes are a group of pathogenic fungi that invade keratinized tissues. Thus, the presence of dermatophytes on laboratory equipment is a risk for dermatophytosis. Dermatophytoses are common fungal infection of humans, and are considered to be one of the major public health problems in the world. User interfaces of laboratory instruments in medical mycology laboratories, such as microscopes, centrifuges, balances, flame and so on, may serve as potential reservoirs for the transmission of fungi.
Study Finds Lab Coat to Skin MRSA Transmission - Skin & Allergy News:
Researchers at Virginia Commonwealth University in Richmond used pigskin as an in vitro model to demonstrate that large inoculums of methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE), and pan-resistant Acinetobacter (PRA) bacteria could be transferred from a white cotton lab coat to pigskin 1 minute, 5 minutes, and 30 minutes after inoculation.
Bacterial contamination of uniforms (Journal of Hospital Infection (2001) 48 (3): 238-241):
Microbiological sampling of nurses' uniforms was undertaken using a Casella slit sampler. Staphylococcus aureus, Clostridium difficile and vancomycin-resistant enterococci were detected on uniforms both before and after a span of duty. Recommendations for provision and changing of nurses' uniforms are made.
Survival of nosocomial bacteria on hospital fabrics (Indian J Med Microbiol (2003) 21 (4): 291):
The results indicate that nosocomial bacteria can survive for many days on fabrics. The survival time observed by us is longer than that reported in a previous study.[4] This could be due to higher inoculum used by us. The effect of inoculum concentration on cell viability is dependent on the concept of cryptic growth in which bacteria in a nutrient limiting condition can live on nutrients from dying cells.[5] Further, gram negative bacilli were not included in the previous study.


  1. And some people (mostly MDs) insist there isn't scientific meaning.

  2. This post by J. Eisen is relevant:

    (more links at the end)


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