Chlorhexidine: Also prevents general malaise and existential crises

We can now add Clostridium difficile to the long list of maladies that can be prevented by the zealous application of chlorhexidine (in this study, a 4% aqueous solution, first thrice-weekly and then daily, hospital-wide). Yes, I realize that this study (from our good friends in Nebraska) was quasi-experimental (lacking a concurrent control group), and I realize that it was funded by a manufacturer of chlorhexidine (a company whose name I cannot spell or pronounce).

Potential confounders include changes in diagnostic testing during the course of the study (but these changes should have made a decrease more difficult to detect, because they moved to increasingly sensitive assays), and the introduction of other C. difficile control measures (pre-emptive isolation and bleach disinfection were introduced a couple years before the start of this study, but could have had some delayed impact). Finally, there is the biological plausibility issue—if chlorhexidine isn’t sporicidal, how could it impact C. difficile rates? The authors suggest it could be due to physical removal of spores, and/or to killing of vegetative bacteria or prevention of spore germination. All seem plausible, but require further study.