Only when chlorhexidine is mixed with alcohol is it truly an effective pre-op skin prepping agent, says a recent report in the Journal of Antimicrobial Chemotherapy, which stresses that alcohol is a highly potent antiseptic, not simply a solvent for chlorhexidine. Researchers also say they've found no evidence of chlorhexidine's effectiveness in preventing surgical site infections when the agent is used alone.
The researchers took a closer look at chlorhexidine's efficacy after landmark studies reported chlorhexidine outperformed povidone-iodine when the chlorhexidine was actually tested in combination with alcohol. They note that alcohol possesses strong immediate antimicrobial activity, but does not have residual activity on the skin, which is a primary benefit of povidone-iodine and, in particular, chlorhexidine.
Their systematic review of studies involving skin antisepsis before blood culture collection, vascular catheter insertion and surgery reveals chlorhexidine-alcohol showed superior performance over povidone-iodine in all 3 applications, but that superiority was not found in comparisons to competing applications that also included alcohol.
According to the study, between 29% and 43% of clinical trials involving the 3 applications attribute chlorhexidine-alcohol's combined efficacy to chlorhexidine alone. In addition, say the researchers, only 35% of studies list the actual agents involved in the research and correctly attribute their efficacies.
Several clinical practice and formal evidence-based guidelines "appeared to have propagated this misinterpretation," say the authors. "Our findings indicate that a widespread perception of chlorhexidine's efficacy had arisen that was in significant parts actually based on evidence for the chlorhexidine-alcohol combination," they write.
The researchers express concern that the omission of alcohol's role in chlorhexidine's effectiveness could cause caregivers to use chlorhexidine alone, which may expose patients to increased risk of infection. They believe the continued misunderstanding of the importance of using the chlorhexidine-alcohol combination is based on beliefs that alcohol is simply a solvent for chlorhexidine, when it is in fact a highly potent antiseptic.