Speciation of Candida isolates obtained from diarrheal stool

Abstract

Candida is the most common fungi causing diarrhea. As pathogenesis and susceptibility to antifungals might vary in different species of Candida, their speciation is essential. The aim of this study was to identify different species of Candida and investigate their antifungal susceptibility pattern. Of 2036 diarrheal stool samples, 212 samples were microscopically positive for budding yeast cells. We selected 50 of these samples and cultured on blood agar and MacConkey agar and incubated at 37°C for 18–24 h. Tiny colonies confirmed by means of Gram staining as budding yeast cells were subcultured on Sabouraud’s dextrose agar. Speciation of Candida was carried out using the germ tube test and inoculation into chrome agar and corn meal agar. Antifungal susceptibility testing was carried out as per CLSI guidelines using voriconazole, fluconazole, itraconazole, and amphotericin B. Candida was mostly isolated from children younger than 12 years (50%) and from male patients. A total of 64 isolates were obtained. Candida krusei (52%) was the most common isolate, followed by Candida tropicalis (16%), Candida albicans (0.02%), and Candida parapsilosis (0.01%). The isolates were mostly susceptible to voriconazole (97.4%), itraconazole (79.4%), amphotericin B (66.6%), and fluconazole (18%). Candida diarrhea was mostly seen in individuals younger than 12 years, most commonly caused by C. krusei. Resistance to fluconazole was high. A rising resistance to amphotericin B is alarming. Speciation of Candida is important to see the difference in antifungal susceptibility in different species.