[Chlorhexidine and Polident Induce the Formation of Candida albicans Persistence].

OBJECTIVE

To investigate the mechanism by which chlorhexidine and Polident, commonly used denture cleansers, induce the formation of persistence in Candida albicans (C.a.), which is the causative agent of denture stomatitis.

METHODS

C.a. biofilms were formed and treated with 0-40000 μg/mL chlorhexidine and Polident. Surviving colonies were counted, and dose- and time-dependent curves were plotted. The distribution of persisters was observed via vital staining, and retention was verified by isolating surviving colonies. Transcriptomic analysis was performed on strains treated with chlorhexidine for 2 and 6 hours to explore the mechanisms of persister formation. Metabolic changes in persisters were assessed using the MTT assay. Exogenous glucose was added to validate the role of denture cleansers in regulating persister metabolism.

RESULTS

After treating C.a. biofilms with chlorhexidine and Polident, the dose- and time-response curves of viable cells both exhibited a biphasic bactericidal pattern, indicating the formation of C.a. persisters. The biofilm structure was disrupted, and persisters were mostly distributed in the middle and upper layers. Transcriptomic analysis showed marked downregulation of the TCA cycle and aerobic respiration, but upregulation of glycolysis. The MTT assay verified that chlorhexidine and Polident suppressed persister metabolism, while the addition of glucose reduced the persister populations; there was a statistically significant difference compared to the control group (P < 0.05).

CONCLUSION

High concentrations of chlorhexidine and Polident can induce the formation of C.a. persisters, which are mainly distributed in the upper and middle layers of biofilms. The persisters can resuscitate after drug removal, increasing the risk of recurrent infections. C.a. shifts from the tricarboxylic acid cycle and aerobic respiration to glycolysis to maintain a low metabolic level. Exogenous glucose can activate their metabolism and decrease the number of persisters.