Virulence Factors and Azole-Resistant Mechanism of Candida Tropicalis Isolated From Candidemia

Abstract Background Virulence factors intensify the pathogenicity of Candida species in candidemia. Limited knowledge exists regarding the azole-resistant mechanism and virulence factors of Candida tropicalis. Consequently, we aimed to evaluate the virulence factors and the molecular mechanisms of azole resistance among C. tropicalis isolated from bloodstream infection. Materials and methods Forty-five C. tropicalis isolates recovered from candidemia patients were evaluated for virulence factors, including extracellular enzymatic activities, cell surface hydrophobicity (CHS), and biofilm formation. Antifungal susceptibility pattern and expression level of ERG11, UPC2, MDR1, and CDR1 genes of eight azole resistance C. tropicalis isolates were assessed. Results The isolates expressed different frequencies of virulence determinants as follows: coagulase 4 (8.9%), phospholipase 4 (8.9 %), proteinase 31 (68.9 %), CSH 43 (95.6 %), esterase 43 (95.6 %), hemolysin 44 (97.8%), and biofilm formation 45 (100%). All the isolates were susceptible to amphotericin B and showed the highest resistance to voriconazole. The high expression of ERG11 and UPC2 genes in fluconazole-resistant C. tropicalis isolates were observed. Conclusion C. tropicalis isolated from candidemia patients extensively displayed capacities for biofilm formation, hemolysis, esterase activity, and hydrophobicity. In addition, the overexpression of ERG11 and UPC2 genes can be considered as one of the possible mechanisms of azole resistance.