Fig 4. The Impact of pH on heat killing of Clostridium difficile spores exposed to chlorhexidine gluconate (CHG).

The mean log₁₀colony-forming unit (CFU) reductions of C. difficile spores achieved after 1 or 3 hours of incubation in pH altered aqueous and alcoholic CHG solutions (0.04% w/v). Elevating the pH to ≥9.5 significantly enhanced the killing of spores in either aqueous or alcoholic CHG solutions (P <0.001 for each comparison to pH 4.0). In aqueous or alcoholic CHG solutions, increasing the pH to ≥9.5 enhanced heat killing of spores by ≥1log₁₀CFU after 3 hours of incubation. The means of the data from experiments conducted in triplicate are presented. Error bars indicate standard error.