Purpose Oral thrush by Candida species is a common ailment of individuals suffering from HIV infection. These species show a high resistance to antifungal drugs used for the treatment. Hence our study was conducted to determine the aetiology and antifungal susceptibility patterns of Candida isolates causing oral thrush in HIV patients.
Materials and Methods: Isolation of Candida species was attempted from 60 cases of oral thrush in HIV infected patients at the Department of Microbiology, Kasturba Medical College, Mangalore. Isolates were identified to species level based on chlamydospore formation; ability to form germ tube; assimilation/fermentation of carbohydrates; production of urease enzyme; formation of pellicle/surface film on Sabouraud’s dextrose broth; growth on Sabouraud’s Dextrose Agar (SDA) with cycloheximide and growth on SDA at 370C and 450C. Antifungal drug susceptibility testing was done by macro broth dilution test using azole group such as fluconazole, itraconazole and ketoconazole.
Results 56 Candida species were isolated of which C.albicans was the predominant isolate (84%), followed by C.tropicalis (8%), C.glabrata (3.5%), C.parapsilosis and C.kefyr (1.8% each). Most isolates (53) showed significantly higher resistance to fluconazole than the standard pathogenic control strain C.albicans NCPF 3153A. 31 isolates (66%) of C.albicans had Minimum Inhibitory Concentration (MIC) values 8 times that of control for ketoconazole. 23 isolates had MIC for itraconazole of 0.5 µg/ml which was only twice as high as that of control (0.125 µg/ml), all others having comparatively equivalent MIC to itraconazole.
Conclusion Our study indicates that although C.albicans is the predominant species, there are other species prevalent and causing infection in our HIV infected population. MIC’s of our Candida isolates to commonly used antifungals such as fluconazole, ketoconazole and itraconazole were significantly higher than the control strain used in the study. Our study indicated that itraconazole was the most effective among the azole group of drugs.
- Minimum Inhibitory Concentration
- Oral thrush