01 July 2008

Isolation: Doesn't work if healthcare workers contaminate themselves afterward

In the new Emerging Infectious Diseases, there is a small but very smart study that ought to get wider play. It was done by a PhD candidate at University of North Carolina, Chapel Hill named Lisa Casanova, with the help of faculty and the local health department.

Background: In certain highly infectious environments — including in-hospital isolation — healthcare workers wear what is usually known as "personal protective equipment" or PPE. PPE generally includes gloves, gown and an eye shield, goggles or face-splash guard (also called "barrier precautions") as well as a mask or a respirator ("respiratory protection"). PPE protects the healthcare worker while he or she is in the patient's presence, but it poses a problem when the worker leaves that environment, because the PPE is likely to be carrying the disease organism on its surface. If the worker doesn't doff the PPE very carefully, he or she might contaminate himself/herself and become infected or colonized, or spread the organism further in the healthcare environment.

This accidental contamination was a significant problem in the 2003 SARS epidemic — so after SARS was over, the Centers for Disease Control and Prevention came up with a recommended procedure for taking off PPE (on this page, half-way down). Casanova decided to test how well the protocol actually works.

Answer: Not so much. She had 10 volunteers (men and women, left- and right-handed) dress in PPE, contaminated the equipment in certain spots ("front shoulder of gown, back shoulder of gown, right side of N95 respirator, upper right front of goggles, and palm of dominant hand") with a benign virus, had the volunteers take off their PPE, and then tested them for the virus's presence. Results:
Transfer of virus to both hands, the initially uncontaminated glove on the nondominant hand, and the scrub shirt and pants worn underneath the PPE was observed in most volunteers.
Casanova recommends changes: additional PPE; different PPE and doffing protocols, such as are used in surgical suites; or PPE impregnated with antimicrobials. (#1 and #3 of course would be more costly; #2 would require procedural change but not necessarily additional garments).

She also raises a vital ongoing issue for MRSA infection control: that healthcare workers may not be punctilious about hand hygiene because they believe that gloves are adequate protection. Only, as this study demonstrates, they are not:
This study also indicates the need for continued emphasis on hand hygiene. A barrier to improving hand hygiene compliance rates is the belief that gloves make hand hygiene unnecessary (14). This is contradicted by our study and others showing that organisms can spread from gloves to hands after glove removal (15). Even if double gloving is incorporated into protocols for PPE use, it is not a substitute for proper hand hygiene.
The cite is: Casanova L, Alfano-Sobsey E, Rutala WA, Weber DJ, Sobsey M. Virus transfer from personal protective equipment to healthcare employees’ skin and clothing. Emerg Infect Dis. 2008 Aug; [Epub ahead of print]

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