Maryn McKenna

Journalist and Author

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File under Unintended Consequences, 1

December 15, 2008 By Maryn Leave a Comment

My friend and colleague Helen Branswell of the Canadian Press reports (via the Toronto Sun) on the cruel and accidental irony behind an outbreak of healthcare-associated infections at Toronto General Hospital between Dec. 2004 and Mar. 2006. Based on a new paper in Infection Control and Hospital Epidemiology, it’s a fascinating and bizarre tale of the unpredictable hurdles that a hospital can face in attempting to eradicate HAIs.

It seems the hospital, in an attempt to reduce HAIs, installed hand hygiene stations in each room in its medical-surgical intensive care unit, in between the patient’s bed and a countertop that held patient-care materials. This would seem like good design: The sink was right in the middle of the “zone of action” in the room, so health care workers would be reminded to use it (unlike, for instance, retrofitted rooms I have seen where the sink is away from the bed or out of the path between the bed and the door, and where health care workers have to consciously think about using it rather than having it be automatic). And the sinks were of a particular design meant to reduce accidental contamination of health care workers’ hands: When the water was turned on, it flowed from a high gooseneck faucet straight down into the sink drain, without washing around the sink’s side.

But it turns out that design and location both had unanticipated flaws. Water flowing straight into the drain was more likely to splash from the drain back out of the bowl; when investigators marked the sinks with fluorescent dye, they found splashes up to a yard away. Because the sinks were so close to the patient beds, the water was able to contaminate the patients, and the countertops on the other side as well. And because the water was falling directly into the sink drains, without the reduction in velocity caused by allowing it to wash around the sides of the sink, it was able to dislodge biofilm colonies of drug-resistant Pseudomonas aeruginosa, a moisture-loving organism that was growing in the sink pipes — which then splashed out of the sinks in the water bouncing back from the drain.

When the investigators found that, they had an explanation for why 36 transplant patients in that ICU had become colonized with MDR pseudomonas over 18 months. Twenty-four of the patients developed invasive infections, and 17 died; 12 of those deaths were either caused or closely related to pseudomonas infection.

The investigators tried multiple times to decontaminate the sink drains; in a few cases, they were successful, but the drains became recolonized and grew fresh biofilms. It was not practical to relocate the sinks. Nevertheless, they shut down the outbreak: They swapped out the faucets, decreased the water pressure, put a splash barrier on the sides of the sink, and moved patient care materials on the counter next to the sink elsewhere in the ICU rooms. Once those rearrangements were complete, the outbreak stopped.

This outbreak obviously was not MRSA, and in the strictest sense it is not relevant to MRSA, which is not an organism that lives in sink drains. But in a broader sense — as an illustration of the completely unpredictable hurdles that can stand in the way of excellent infection control — it is a useful and tragic cautionary tale.

The abstract is here. The cite is: Susy Hota, MD; Zahir Hirji, MHSc; Karen Stockton, MHSc; et al. Outbreak of Multidrug-Resistant Pseudomonas aeruginosa Colonization and Infection Secondary to Imperfect Intensive Care Unit Room Design. Infection Control and Hospital Epidemiology 2009 30:1, 25-3.

Filed Under: Canada, disinfection, fomites, hospitals, infection control

Final report from ICAAC-IDSA 08 (news from ICAAC, 3)

November 4, 2008 By Maryn Leave a Comment

The ICAAC-IDSA (48th Interscience Conference on Antimicrobial Agents and Chemotherapy and 46th annual meeting of the Infectious Diseases Society of America) meeting ended a week ago, and I’m still thrashing my way through the thousands of abstracts.

Here’s my final, highly unscientific selection of papers that caught my eye:

* Evidence that the community-strain clone USA300 is a formidable pathogen: It first appeared in the San Francisco jail in 2001. By last year, it had become the sole MRSA strain found in the jail — it crowded out all others. (P. Tattevin, abstract C2-225)
* Another paper from the same UCSF research group finds that the emergence of USA300 has caused a dramatic increase in bloodstream infections, most of which are diagnosed in the ER, not after patients are admitted to the hospital. (B. Diep, abstract C2-226)
* And the CDC finds that USA300 is picking up additional resistance factors, to clindamycin, tetracycline and mupirocin, the active ingredient in the decolonization ointment Bactroban. (L. McDougal, abstract C1-166)
* An example of the complexity of “search and destroy,” the active surveillance and testing program that seeks to identify colonized patients before they transmit the bug to others in a health care institution: Patients spread the bug within hours, often before test results judging them positive have been returned from the lab. (S. Chang, abstract K-3379b)
* In addition to the report from Spain I posted on during the meeting, there is a report of emerging linezolid resistance in France. (F. Doucet-Populaire, abstract C1-188)
* And in addition to the abundant new news about MRSA in pork, and “pork-MRSA” or ST 398, in humans, over the past few days, there were reports of MRSA in milk in Brazil (W. Gebreyes, abstract C2-1829) and Turkey (S. Turkyilmaz, abstract C2-1832), and beef and chicken in Korea (YJ Kim, abstract C2-1831), as well as ST 398 itself acquiring resistance to additional drugs. (Kehrenberg, abstract C1-171)
* Echoing many earlier findings that MRSA seems most common among the poor, the poorly housed and the incarcerated, BR Makos of the University of Texas found that children are more likely to be diagnosed with the bug if they are indigent, or from the South (which I imagine is a proxy for lower socio-economic status, since the South is a more rural, more poor region). (abstract G2-1314)
* And finally, to the long list of objects (ER curtains, stethoscopes) that harbor MRSA, here are more: The ultrasound probes in emergency rooms (B. Wessman, abstract K-3377). Also: Dentures. (Ick.) (D. Ready, abstract K-3354)

Filed Under: animals, fomites, ICAAC, IDSA, infection control, jail, linezolid, pigs, poor, resistance, ST 398, USA 300, zoonotic

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

July 1, 2008 By Maryn Leave a Comment

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]

Filed Under: antibacterial, colonization, cost, fomites, hospitals, nosocomial

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