In vitro post-antifungal effect (PAFE) elicited by chlorhexidine gluconate on oral isolates of Candida albicans

Abstract

The post-antifungal effect (PAFE) is defined as the suppression of growth that persists following brief exposure of yeasts and other fungi to antimycotics and subsequent removal of the drug. There is no data available on the PAFE of chlorhexidine gluconate on oral isolates of Candida albicans. As chlorhexidine gluconate is by far the commonest antiseptic mouth wash prescribed in dentistry, the main aim of this investigation was to measure the PAFE of 10 oral isolates of C, albicans following limited exposure (30 min) to sub-therapeutic concentrations of this antiseptic. The PAFE was determined as the difference in time (h) required for the growth of the drug- free control and the drug-exposed test cultures to increase to 0.05 absorbance level at 520 nm following removal of the antifungal agent. The mean duration of PAFE elicited by 0.005, 0.0025 and 0.00125% chlorhexidine gluconate was 9.91(± 1.43) h, 1.65 (± 0.21) h and 0.67 (± 0.12) h, respectively. These findings, reported here for the first time, indicate that even a brief exposure to sub-therapeutic and sub-lethal levels of chlorhexidine gluconate may suppress the growth of oral C. albicans isolates, thereby minimising the pathogenic potential of this opportunistic fungus.