Relative growth measurement of Candida species in a single concentration of fluconazole predicts the clinical response to fluconazole in HIV infected patients with oral candidosis

The growth of 113 Candida spp, isolated prospectively from 104 HIV-positive patients treated for thrush was determined using a single concentration of 3 mg/L (10(-5) M) fluconazole relative to growth in drug free medium. Using a receiver operator characteristic curve, a relative growth in fluconazole of greater than or equal to 88% best discriminated between isolates from 56 patients who responded to treatment with fluconazole and 48 who failed to respond to 7 days, treatment with at least 100 mg/d drug with a sensitivity of 98% and a specificity of 96%. When the isolates from the eight patients with mixed infections due to both resistant and susceptible yeasts were excluded, the sensitivity and specificity both reached 100%. Relative growth of Candida spp. in a single concentration of fluconazole can therefore be used to accurately predict the clinical response to standard fluconazole treatment of thrush in patients infected with HIV.