RESEARCH ARTICLE Induced Sporicidal Activity of Chlorhexidine against Clostridium difficile Spores under Altered Physical and Chemical Conditions

Background Chlorhexidine is a broad-spectrum antimicrobial commonly used to disinfect the skin of pa-tients to reduce the risk of healthcare-associated infections. Because chlorhexidine is not sporicidal, it is not anticipated that it would have an impact on skin contamination with Clos-tridium difficile, the most important cause of healthcare-associated diarrhea. However, although chlorhexidine is not sporicidal as it is used in healthcare settings, it has been re-ported to kill spores of Bacillus species under altered physical and chemical conditions that disrupt the spore’s protective barriers (e.g., heat, ultrasonication, alcohol, or elevated pH). Here, we tested the hypothesis that similarly altered physical and chemical conditions result in enhanced sporicidal activity of chlorhexidine against C. difficile spores. Principal Findings C. difficile spores became susceptible to heat killing at 80°C within 15 minutes in the pres-ence of chlorhexidine, as opposed to spores suspended in water which remained viable. The extent to which the spores were reduced was directly proportional to the concentratio