Characterisation of candida species isolated from clinical specimens at University Teaching Hospital, Lusaka, Zambia

Abstract

Candida species have emerged as successful pathogens in both invasive and mucosal infections, especially in immunocompromised patients. Additionally, there is increasing resistance of Candida species to antifungal agents, and this has greatly contributed to the high morbidity and mortality amongst affected patients. In Zambia, little is known about the distribution of Candida species and their antifungal susceptibility patterns from patients with candidiasis. Speciation of Candida species is important as knowledge of the infecting species is important for guiding therapy. The objective of this study was, therefore, to characterise Candida species isolated from different clinical specimens at the University Teaching Hospital in Lusaka. This was a laboratory-based cross-sectional study involving the identification of 96 Candida species obtained from various clinical specimens, and determination of their antifungal susceptibility patterns. Identification of the isolates was achieved by the use of the API 20C AUX kit, followed by DNA sequencing of the Internal Transcribed Spacer region of the ribosomal DNA, whilst the agar-based E-test, using fluconazole, amphotericin B, flucytosine, and caspofungin, was used for antifungal susceptibility testing. Data obtained showed that Candida albicans were the predominant species (66.7%), followed by C. lusitaniae (12.2%), C. glabrata (6.7%), C. tropicalis (5.6%), C. parapsilosis (3.3%), C. quilliermondii (3.3%), C. pelliculosa (1.1%) and C. keyr (1.1%). Most of the Candida species exhibited high levels of resistance to fluconazole and amphotericin B, but were sensitive to caspofungin and flucytosine. C. albicans was resistant to fluconazole (18.3%,) with an MIC90 of 256 g/ml and amphotericin B (10%) with MIC90 of 1.5µg/ml. C. glabrata was the most resistant species against amphotericin B (66.6%) with an MIC90 of 2µg/ml. The antifungal susceptibility testing further revealed that C. albicans and most of the non-albicans species exhibited multi-drug resistance to all the antifungal agents tested. Therefore, species identification and antifungal susceptibility testing are recommended for infection control and treatment guidance of the Candida infection.