Clinical, Epidemiological Fungal Profile and Antifungal Susceptibility Pattern of Pathogenic Yeast and Yeast-Like Fungi Causing Systemic Mycoses in Patients on Immunosuppressive Therapy in a Tertiary Care Hospital

Abstract

Introduction: Systemic yeast infections are increasingly encountered in immunosuppressed patients, particularly among those exposed to corticosteroids, cytotoxic therapy, prolonged intensive care, and transplant-related immunomodulation. Invasive candidiasis continues to impose substantial mortality, while species replacement with non-albicans Candida and variable azole susceptibility have made empirical therapy less dependable.

Aim: To define the clinical and epidemiological profile of systemic mycoses caused by pathogenic yeasts and yeast-like fungi in immunosuppressed adults, and to evaluate the antifungal susceptibility pattern of the recovered isolates.

Materials and Methods: This hospital-based cross-sectional study was conducted at the Institute of Microbiology, Madras Medical College, in collaboration with Rajiv Gandhi Government General Hospital, Chennai, from August 2021 to August 2022. Three hundred adults receiving immunosuppressive therapy and clinically suspected to have systemic fungal infection were evaluated. Specimens were processed by direct microscopy, culture, CHROMagar-based presumptive identification, and conventional phenotypic methods. Antifungal susceptibility testing was performed according to CLSI M27-A3 and M44-A recommendations.

Results: Of 300 suspected patients, 32 were microbiologically confirmed to have systemic mycoses, giving a positivity rate of 10.7%. Males accounted for 65.6% of cases, and the 41–60-year age group constituted the largest cluster (59.4%). Diabetes mellitus was present in all proven cases, either alone or in combination with systemic hypertension. The respiratory tract was the most frequent site of involvement (43.8%), and blood was the most common specimen source (28.1%). Candida species accounted for 87.5% of isolates, with Candida tropicalis being the predominant pathogen (31.3%), followed by Candida glabrata (25.0%). Amphotericin B retained 100% activity against all isolates tested, whereas reduced azole susceptibility was most evident in C. glabrata and, to a lesser degree, C. tropicalis.

Conclusion: Systemic yeast infections in this cohort were driven predominantly by non-albicans Candida species, with clear evidence of heterogeneous azole susceptibility. Routine species-level identification and antifungal susceptibility testing are therefore central to timely, targeted therapy in immunosuppressed patients.