Blog | Monday, March 18, 2013

Enamored with chlorhexidine, but is it justified?

Regular readers of our blog understand how smitten we are with chlorhexidine gluconate (CHG).

For use in lines, dressings and the oropharynx, we have controlled trial data. However, for CHG bathing (a.k.a. "source control"), the data have consisted of quasi (before-after) studies without concurrent control groups. So we take note this week of two multicenter, cluster-randomized crossover trials, one published in the New England Journal of Medicine (adult ICUs) and one published in Lancet (pediatric ICUs). Both studies were partially supported by Sage, the manufacturer of the no-rinse 2% CHG wipes used, and both had the same design: randomization to 6 months of daily CHG or nonantimicrobial bathing, followed by 6 months of the opposite. The adult (NEJM) study was interrupted by a several month recall of the CHG cloths, but the investigators handled that problem well (and analyzed the data with and without the interruption data included).

The adult ICU investigators examined the outcomes of health care-associated BSI and MRSA/VRE acquisition, finding significant reductions in both during CHG use. I'm most impressed with the CLABSI numbers: a 53% reduction during CHG use (1.6 vs. 3.3 per 1000 cath days). The Lancet (PICU) study is underwhelming by comparison, possibly due to the focus on longer-stay kids and the fact that written informed consent was required (which resulted in many subjects not being included; a waiver of informed consent was obtained from every center in the adult study, resulting in more complete enrollment).

The primary outcome in the pediatric study was any bloodstream infection (actually, any positive blood culture) and by intent-to-treat analysis, the reduction in "bacteremia" (in quotes because some of the positive blood cultures were likely contaminants) was not statistically significant, whereas by "per-protocol" analysis the 33% reduction was significant (3.3 vs. 4.9 per 1,000 patient days, P=0.04). CHG was safe in both studies, with no increase in skin reactions, no major adverse events.

A sample of MRSA and VRE were collected and subjected to CHG susceptibility testing in the NEJM study, and the results were what would be expected, but who knows how to interpret CHG MICs anyway?

Now for the caveat, the sobering note, the but, but, but, the impact of CHG was among the gram-positive organisms, almost entirely coagulase-negative staphylococci (the yeast (Candida) findings in the adult study are of interest, but the numbers are small). A published table combines the results of both studies by organism group. Not such an exciting story for the gram negative rods, or for S. aureus, which as we know are the more problematic, virulent bugs.

And to finish, a poorly constructed haiku about chlorhexidine:
Chlorhexidine can
reduce the infection risk
not for the bad bugs?

Daniel J. Diekema, MD, FACP, practices infectious diseases, clinical microbiology, and hospital epidemiology in Iowa City, Iowa, splitting time between seeing patients with infectious diseases, diagnosing infections in the microbiology laboratory, and trying to prevent infections in the hospital. This post originally appeared at the blog Controversies in Hospital Infection Prevention.