13-YEAR EVOLUTION OF AZOLE RESISTANCE IN YEAST ISOLATES AND PREVALENCE OF RESISTANT STRAINS CARRIED BY CANCER-PATIENTS AT A LARGE MEDICAL-CENTER

Drug resistance is emerging in many important microbial pathogens, inc luding Candida albicans. We performed fungal susceptibility tests with archived isolates obtained from 1984 through 1993 and fresh clinical isolates obtained from 1994 through 1997 by testing their susceptibili ties to fluconazole, ketoconazole, and miconazole and compared the res ults to the rate of fluconazole use. All isolates recovered prior to 1 993 were susceptible to fluconazole. Within 3 years of widespread azol e use, we detected resistance to all agents in this class. In order to assess the current prevalence of resistant isolates in our hematologi c malignancy and transplant patients,we obtained rectal swabs from hos pitalized, non-AIDS, immunocompromised patients between June 1995 and January 1996. The swabs were inoculated onto sheep's blood agar plates containing 10 mu g of vancomycin and 20 mu g of gentamicin/ml of agar . One hundred one yeasts were recovered from 97 patients and were test ed for their susceptibilities to amphotericin B, fluconazole, flucytos ine, ketoconazole, and miconazole. The susceptibility pattern was then compared to those for all clinical isolates obtained throughout the m edical center. The antifungal drug histories for each patient,were als o assessed. The yeasts from this surveillance study were at least as s usceptible as the overall hospital strains. There did not appear to be a direct linkage between prior receipt of antifungal agent therapy an d carriage of a new, drug-resistant isolate. Increased resistance to n ewer antifungal agents has occurred at our medical center, but it is n ot focal to any high-risk patient population that we studied. Monitori ng of susceptibility to antifungal agents appears to be necessary for optimizing clinical therapeutic decision making.