Mohamed Mabrouk

Kazakhstan

Comparative study of virulence factors and colony morphology of Candida isolates in COVID-19 era in Almaty

Y. Koloskova1, B. Ramazanova1, K. Mustafina1, A. Kalmyrzayev1, D. Bunyayeva1, T. Begadilova1, M. Mohamed Ahmed1
1. Microbiology and viriology, Asfendiyarov Kazakh National Medical University, Almaty, Kazakhstan

Abstract

Background

Candida species can transition into invasive pathogens under immunosuppressive conditions. COVID-19 has created an environment conducive to such transitions, mainly driven by immune suppression, prolonged antibiotic use, and corticosteroid therapy. These factors increased fungal colonization and virulence. Post-COVID-19 patients represent an understudied population in this context. This study also addresses the lack of regional data by focusing on Candida species isolated from COVID-19 convalescents in Almaty.

Methods

From 2021 to 2024, 186 nasopharyngeal swabs were collected from post-COVID-19 patients in Almaty. Candida species were identified using CHROM agar. Colony types were induced on Sabouraud agar with 1% NaCl. Enzyme activity (protease, phospholipase, hemolysin) was assessed according Price method.

Results

Candida was isolated from 94 patients (50.5%). C. albicans (34.5%) and C. tropicalis (20%) were most common. Five colony morphotypes were observed, with ring-shaped being dominant (71.2%). Dotted-ring and dome-shaped colonies showed the highest enzymatic activity. Only 21% of strains were fluconazole sensitive. Most isolates showed moderate to high protease and hemolytic activity, with strong phospholipase activity in C. tropicalis and C. glabrata.

Conclusions

The Candida strains from post-COVID-19 patients showed high virulence and fluconazole resistance. Phenotypic switching correlated with the pathogenic enzyme activity as the colony morphology offered a practical marker for predicting virulence in clinical settings.