Characterisation, Biofilm Formation and Antifungal Susceptibility Pattern of Candida Species in Cancer Patients at Kidwai Memorial Institute of Oncology, Bengaluru

Background: Biofilm formation is seen in many pathogens like bacteria, fungi etc. It is one of the virulence factors of Candida species, an important pathogen and commensal. Indiscriminate use of antifungal agents, especially azole group in cancer patients may contribute to emergence of resistance in Candida isolates. Biofilm producing property of Candida also contributes to non-response to antifungals. Hence, speciation and detection of biofilm is useful for clinical management of Candida infections in cancer patients. Aims of this prospective study was to detect biofilm formation and antifungal susceptibility to Candida species isolated from different clinical samples in cancer patients. Methods: A total of 40 clinically significant isolates of Candida species from various clinical samples were characterised with Gram’s stain, germ tube test, carbohydrate fermentation test, chromogenic media and micro morphology on cornmeal agar. Biofilm formation was detected by three standard methods-Tissue culture plate method, Tube method and Congo red agar method. Antifungal susceptibility testing was performed manually with two antifungal agents of the azole group (fluconazole-25µg, voriconazole-1µg). Results: Out of 40 candida isolates, 13 were Candida albicans and 27 were nonalbicans Candida (C.tropicalis-14, C.parapsilosis-5, C.glabrata-3, C.krusei-2, C.guilliermondii-2, and C.lusitaniae- 1). Biofilm production was seen in 31 Candida species (8 C.albicans and 23 nonalbicans Candida). Antifungal susceptibility was performed for all isolates of which 12 were fluconazole resistant and 3 were voriconazole resistant. Conclusion: C.tropicalis (35%) was the most common candida species isolated from cancer patients. Biofilm formation was seen in 78% of Candida species (C.albicans -26% and nonalbicans candida-74%). Thirty percent Candida isolates were fluconazole resistant and 8% were voriconazole resistant. Considering high prevalence of nonalbicans Candida species and species-specific intrinsic resistance to antifungals in few of them, it is important to speciate candida isolates causing infections in cancer patients along with their biofilm formation and antifungal susceptibilities.