Changes in susceptibility of oral Candida dubliniensis isolates to lysozyme and lactoferrin following brief exposure to drugs with antifungal properties (#303)
Objective: Salivary constituents such as lysozyme and lactoferrin have anti-candidal activity on oral Candida. Candida dubliniensis is associated with recurrent oral candidiasis. Such Candida-associated infections could be managed with drugs with anti-candidal properties such as nystatin, amphotericin B, caspofungin, ketoconazole, fluconazole and chlorhexidine. Candida undergo to a brief exposure to therapeutic agents in the mouth, due to the diluent effect of saliva and the cleansing effect of the oral musculature. There is no evidence on the influence of limited exposure to these drugs with anti-candidal properties on the sensitivity of C. dubliniensis isolates to lactoferrin and lysozymes. Hence, this study observed the changes in the sensitivity of C. dubliniensis isolates to anti-candidal action of lactoferrin and lysozyme after transitory exposure to sub-lethal concentrations of aforesaid antifungals. Materials and Methods: After determination of the minimum inhibitory concentration (MIC), twenty C. dubliniensis isolates were exposed to sub-lethal concentrations (×2MIC) of nystatin, amphotericin B, caspofungin, ketoconazole, fluconazole and chlorhexidine for 1 hour. Drugs were removed by dilution and thereafter the susceptibility of these isolates to lysozyme and lactoferrin was determined by a colony forming unit quantification in-vitro assay. C. dubliniensis CD36 and C. albicans ATCC 90028 were used as reference strains. Results: Exposure of C. dubliniensis isolates to nystatin, amphotericin B, caspofungin, ketoconazole, fluconazole and chlorhexidine resulted in an increase of susceptibility to lysozyme by 9.45%, 30.82%, 30.04%, 50.64%, 55.60% and 50.18%, respectively (p < 0.05 to p< 0.001). Exposure of C. dubliniensis isolates to nystatin, amphotericin B, caspofungin, ketoconazole, fluconazole and chlorhexidine resulted in an increase of susceptibility to lactoferrin by 13.54%, 16.43%, 17.58%, 19.60%, 21.32% and 18.73%, respectively (p < 0.05 to p< 0.001). Conclusion: Brief exposure to nystatin, amphotericin B, caspofungin, ketoconazole, fluconazole and chlorhexidine, a scenario all too familiar in the niches of the oral cavity, could enhance the antifungal effect of lysozyme and lactoferrin on C. dubliniensis isolates in vitro, thereby possibly implicating a synergistic effect, when interacting together. Acknowledgments: The work was supported by Kuwait University Research Grant No. DB 01/16.