Study of biofilm formation as a virulence marker in Candida species isolated from various clinical specimens

Abstract

Background: Candida species can be either commensals or opportunistic pathogens with the capacity to bring about several infections, extending from superficial to life-threatening. Nosocomial infections owing to Candida are also getting progressively significant. Early and precise diagnosis, correct treatment, and prohibition of candidemia owing to biofilms create a big task for microbiologists and clinicians worldwide. In addition to this is the emerging trend of antifungal drug resistance among the biofilm-producing strains of Candida. Objective: To detect biofilm production in Candida species isolated from various clinical samples obtained from patients at a tertiary-care hospital in Ahmedabad. Materials and Methods: A total of 67 Candida species (26 Candida albicans and 41 nonalbicans Candida species) isolated from various specimens (urine, sputum, endotracheal tube secretion, tissue, oral swabs, and other samples) were included in the study. The various Candida isolates were identified by using conventional methods, and their ability to produce biofilm was detected by the tube method and Congo red agar method. Result: Of 67 Candida species, Candida tropicalis [38 (56.78%)] was the predominant species isolated. Biofilm positivity was seen with 46 (68.65%) isolates, and the biofilm production was observed more with non-albicans Candida species [30 (65.21%)] when compared with C. albicans species [16 (34.78%)]. Among the non-albicans Candida species, strong biofilm producers were Candida parapsilosis and C. tropicalis. Biofilm positivity was found to be higher in the tissue, endotracheal aspirate, and urine of Candida isolates when compared with isolates from other sites. Conclusion: This study suggests an increasing prevalence of non-albicans Candida species in the various clinical samples isolated and shows them as strong biofilm producers when compared with C. albicans species. These data suggest that biofilm formation as a potential virulence factor might show a higher significance for non-albicans Candida species than for C. albicans and that the biofilm structure varies with the different species and strains of Candida, the nature of the colonized surface, and its localization. Thus, more remains to be determined about biofilms formed by the non-albicans Candida species, as they are now frequently encountered species in catheter-associated candidemias.