Thursday, May 5, 2011

Pre-emptive contact precautions of intubated patients: effective??

One of the odd things about contact precautions is that they are typically used to isolate patients colonized or infected with MDROs like MRSA. What this does is protect the healthcare worker from being contaminated with the MDRO but does little to protect the uncolonized patients.  The contact "event" we should MOST care about is contact between the contaminated or colonized healthcare worker and the uncolonized patient. So, current active detection and isolation programs have it all wrong. Please read that paragraph again.

Thus, I read with interest a paper just e-published in the JHI by Matsushima et al.  The authors noticed, using surveillance data, that ventilated patients in their ICU were 8 times as likely to acquire MRSA compared to non-ventilated patients.  Based on this finding they decided to place all ventilated patients on contact precautions throughout their stay to see if it reduced MRSA acquisition.  This intervention is close to a universal contact precautions intervention (or close to the STAR*ICU study that was a study of barrier precautions - gloves or gowns/gloves).

The study was completed in a 19-bed ICU in Osaka, Japan.  A unique (for the US at least) characteristic of this ICU was that only 2 rooms were single-bed rooms while the remaining 17 beds were in a single open ward. There were 2 study periods.  Period 1 occurred during 2004 and period 2 was a 3-year period from 2005-2007. During period 1, contact precautions were only used if the patients was found to be colonized with an MDRO. Surveillance cultures were obtained on all admissions and weekly using sputum, nasal and urine sources. During period 2, the same practices existed as period 1, but all patients who were intubated were placed on contact precautions for their entire stay.  MRSA acquisition occurred when a patient negative for MRSA on admission culture became positive on a subsequent surveillance or clinical culture.  They actually completed segmented Poisson regression looking for changes in slope/intercept of HA-MRSA rates. Woo woo!

The main difference between period 1 and period 2 was that many more people were placed on contact precautions during period 2. In period 1, 2.9% of patients were MRSA+ on admission and isolated while in period 2, 6.1% of patients were MRSA+ on admission, but fully 43% of patients were placed on contact precautions. Importantly, the colonization pressure was 2x greater in period 2.  Keep that in mind...

Interestingly, HA-MRSA infection in all patients declined from 3.6 to 2.3 per 1000 patient-days, p<0.05. The incidence of HA-MRSA in the intubated patients greatly decreased from 12.2% to 1.1%. I have pasted the key figure -->.  What it shows is that while HA-MRSA colonization and infection declined in intubated patients it actually slightly increased in non-intubated patients (who could be considered a non-equivalent control group).  Very cool.

Usual caveats: single center with somewhat unique bed arrangement in the ICU, and of course the control group wasn't random.  However, this is a fairly strong quasi-experimental study with good epi and statistical methods. And it points out that isolating patients actually PROTECTS them, so if there are downsides associated with contact precautions, like fewer visits from healthcare workers, at least the patients isolated directly benefit from the isolation.  This sort of study could actually help flip how we think about contact precautions. Isolate the uncolonized!


  1. So does this suggest the contact precautions outside of ICUs, as in MRSA prevention programs, might be part of the reason why they are effective?

  2. It is possible if there is a period of isolation prior to knowledge of MRSA results so that uncolonized patients are isolated. With rapid PCR tests this would be less likely.