VARIATIONS IN FLUCONAZOLE SUSCEPTIBILITY AND ELECTROPHORETIC KARYOTYPE AMONG ORAL ISOLATES OF CANDIDA-ALBICANS FROM PATIENTS WITH AIDS AND ORAL CANDIDIASIS

DNA subtyping by pulsed-field gel electrophoresis and in vitro suscept ibility testing were used to study strain variation and fluconazole re sistance in Candida albicans isolates from patients with AIDS undergoi ng azole (fluconazole and clotrimazole) therapy for oropharyngeal cand idiasis. A total of 29 patients suffered 71 episodes of oropharyngeal candidiasis. Overall, 121 isolates of C. albicans recovered throughout the course of treatment of each infection were available for further characterization. DNA subtyping revealed a total of 61 different DNA s ubtypes. In vitro susceptibility testing of the 121 isolates by using proposed standard methods of the National Committee for Clinical Labor atory Standards revealed MICs of fluconazole ranging from less-than-or -equal-to 0.125 to >64 mug/ml. The MIC for 50% of isolates tested was 0.25 mug/ml, and the MIC for 90% of isolates tested was 8.0 mug/ml. MI Cs were greater-than-or-equal-to 64 mug/ml for only 7.4% of the isolat es tested. The majority (62%) of the patients with oropharyngeal candi diasis and undergoing azole therapy were infected or colonized with mo re than one DNA subtype, and the introduction or selection of strains with a more resistant DNA subtype during the course of fluconazole the rapy was not uncommon. With one exception, this did not appear to have an adverse effect on clinical outcome. In contrast, for patients with AIDS and oropharyngeal candidiasis infected with a single DNA subtype of C. albicans, an increase in fluconazole MICs for the infecting str ain was rarely demonstrated over the course of therapy.