Comparison of four methods for DNA typing of clinical isolates of Candida glabrata

A series of 35 isolates of Candida glabrata from 29 subjects (five AIDS patients and 24 HIV-seronegative individuals) was typed by electrophoretic karyotyping (EK), restriction fragment length polymorphism (RFLP) analysis, random amplification of polymorphic DNA (RAPD) and inter-repeat PCR (IR-PCR). The rank order of discriminatory ability among the four methods was as follows: EK (25 DNA types) > RAPD (19 DNA types) > IR-PCR (14 DNA types) > RFLP (4 DNA types). A composite DNA type was defined for each of the strains as the combination of types obtained by the four molecular methods. A total of 32 DNA types was obtained by this procedure; each individual harboured their own specific isolate (DNA type). Neither source of isolation nor HIV status was associated with a given DNA type. In three of five cases, initial and relapse isolates from individual patients were assigned to the same DNA type. These findings indicate that EK is the most useful method for the investigation of inter-strain variations within this Candida species.