Characterization of virulence factors, antifungal resistance with ERG-11 gene among Candida species isolated from pulmonary samples

Abstract

BackgroundCandida is a part of the normal oropharyngeal flora and the upper respiratory tract. Candida albicans(C. albicans), is the predominant species causing respiratory tract infections associated with pneumonia. Resistance to azole antifungal agents among the C. albicans may be due to alteration of the target enzymes, which are encoded in ERG11 gene. The biofilm formation may also be a cause to antifungal resistance. Materials and methodsThis study was conducted at Chettinad Hospital and Research Institute. Samples were collected from June 2018–June 2019, for a period of 1 year. After species confirmation, virulence factor among the Candida species were identified by hemolysis test, coagulase test and biofilm formation. Genotypic confirmation of C. albicans and their azole resistance due to ERG 11 gene were done using multiplex PCR. ResultsIn our study, 31 (55%) C. albicans, 8 (14%) Candida glabrata(C. glabrata) and 10 (17%) Candida tropicalis(C. tropicalis), three Aspergillus flavus(A. flavus), two Aspergillus fumigatous (A. fumigatous), one Aspergillus niger (A. niger) and one Mucor species were isolated. In C. albicans, 31 were positive for Germ tube and Chalmydospore formation. Six of candida species were isolated along with bacterial co infection. Among the Candida isolates, 17 (55%) C. albicans strains were strongly biofilm positive and 14(45%) were negative. The susceptibility pattern of (n = 31) C. albicans were as follows: fluconazole (21(68%) S, 10(32%) R), voriconazole (22(71%)S),9(21%) R) and Amphotericin B 31(100%) S). Among the 19 C. albicans, four were positive for ERG11 gene. ConclusionThe isolation of C. albicans and non - albicans from respiratory specimens should be reconsidered as these organisms are re-emerging pathogens. Speciation is needed due to variation in species pathogenicity and their susceptibility.