Fig 2. Enhancement of heat killing of Clostridium difficile spores exposed to alcoholic chlorhexidine gluconate (CHG) solutions.

The mean log₁₀colony-forming unit (CFU) reduction of C. difficile spores exposed to 4% w/v CHG solution prepared in water or 70% ethanol. No killing of spores was observed in aqueous or alcoholic chlorhexidine solutions at 20°C. At 37°C, the presence of alcohol reduced the incubation time required to achieve an ~1 log₁₀CFU reduction from 3 hours to 1 hour. At 55°C, alcohol boosted spore reductions from 1.5 log₁₀CFU (aqueous) to 3log₁₀CFU (alcoholic), and 3log₁₀CFU (aqueous) to 5log₁₀CFU (alcoholic) after 1 and 2 hours respectively. The means of the data from experiments conducted in triplicate are presented. Error bars indicate standard error.