Molecular epidemiology and antifungal susceptibility of Cryptococcus neoformans isolates from Ugandan AIDS patients

Abstract

Little is known of the antifungal susceptibility patterns and molecular epidemiology of Cryptococcus neoformans from tropical regions. We studied 164 clinical isolates of C. neoformans from 120 Ugandan AIDS patients with cryptococcal meningitis by analyzing their electrophoretic karyotypes and antifungal susceptibility profiles. Computer-assisted analysis of karyotype patterns was performed to generate dendrograms. MICs of fluconazole and flucytosine were determined by reference methods. A total of 43 distinguishable DNA types were identified among the 164 isolates. Only 30 patients (25%) were infected with their own unique strain of C. neoformans, whereas 75% of the patients shared their infecting strain with at least one other patient. Among 17 patients with more than one CSF isolate of C. neoformans, sequential isolates were identical or highly related in 12 (71%) and were different in five patients (29%). The isolates were susceptible to both fluconazole and flucytosine and there were no instances in which a stepwise increase in either fluconazole or flucytosine MICs was observed among serial isolates. These findings suggest that the epidemiology of cryptococcal disease in AIDS patients from tropical regions may be somewhat different from that observed in more temperate climates.