Prior fluconazole exposure as an independent risk factor for fluconazole resistant candidosis in HIV positive patients: a case-control study.

OBJECTIVES To determine if prior fluconazole exposure was an independent risk factor for fluconazole resistant candidosis in HIV positive patients. METHODS Twenty five HIV positive cases with fluconazole resistant oral candidosis were matched by CD4 lymphocyte count and time since first episode of candidosis to 25 HIV positive controls with susceptible candidosis. For each individual a history of prior azole prophylaxis was compiled from computerised pharmacy records and review of case notes. RESULTS The total days of prior azole therapy prescribed was significantly greater for cases than controls. These differences were attributable to prescriptions for secondary prophylaxis against recurrent candidosis, the cases having received significantly longer continuous azole prophylaxis than controls, with no difference in days of prior azole therapy remaining between the two groups if prophylactic prescriptions were excluded. The total cumulative dose of fluconazole received was significantly higher for cases than controls, though mean daily fluconazole doses did not differ significantly between the two groups. CONCLUSION Even after controlling for degree of immunosuppression and duration of recurrent candidosis, the association between prior azole exposure and fluconazole resistant candidosis remains significant and largely reflects differences in the prescription of secondary antifungal prophylaxis.