Genotyping, antifungal susceptibility, enzymatic activity, and phenotypic variation in Candida albicans from esophageal candidiasis

Abstract

Background: Esophageal candidiasis is the most frequent form of esophagitis. The pathogenicity of Candida spp. is related to a combination of microbial factors, hydrolytic enzyme secretion and phenotypic switching. This study was designed to investigate esophageal candidiasis, antifungal activity, enzymatic activity patterns, phenotyping, and genotyping profiles of Candida albicans species.

Methods: Nine hundred thirty-three visited patients were evaluated, and esophageal biopsies from patients were included in this study during 2019-2020. Direct smear, Gram staining, and culture on CHROMagar were performed for each sample. Isolated species were identified with conventional procedures and PCR-RFLP. Susceptibility to antifungals was determined according to CLSI guidelines. ABC typing, phenotype switching, hemolysin, proteinase, phospholipase, and esterase activity were also determined with the appropriate protocols.

Results: Twenty-three (2.5%) patients (mean age 55.2 years) were diagnosed with esophageal candidiasis. The species isolated were 19(82.6%) C. albicans, 3(13.1%) C. glabrata, and 1(4.3%) C. tropicalis. Genotype A (57.9%) was the predominant type in C. albicans isolates. 50% of C. albicans isolates exhibited a white phenotype. A high level of phospholipase (47.4%), hemolysin (68.4%), and proteinase activity (36.8%) was observed in the C. albicans isolates. Only three C. glabrata isolates displayed non-wild type susceptibility to voriconazole and itraconazole.

Conclusion: This study shows that C. albicans are still the most frequent isolates from patients with esophageal candidiasis. The predominance of genotype A, the white phenotype, and strong hemolysin activity may indicate a high prevalence of pathogenicity in these isolates. Sensitivity to antifungal drugs was greatest for amphotericin and fluconazole.

Keywords: Candida albicans; antifungals; enzymatic activity; esophageal candidiasis; genotyping; phenotypic variation.

FIGURE 1

Examples of genotypes A, B, and C obtained via PCR RFLP of C. albicans isolates