Emergence of Nosocomial Candidemia at a Teaching Hospital in Taiwan from 1981 to 2000: Increased Susceptibility of Candida Species to Fluconazole

Abstract

The incidence of nosocomial Candida fungemia increased 36- fold from 1981 (0.8/10,000 discharges) to 2000 (28.8/10,000 discharges) at the National Taiwan University Hospital, a 2000-bed teaching hospital in northern Taiwan. To understand the current status of resistance to available antifungal agents among Candida species causing invasive infections, the in vitro susceptibilities of 222 isolates (collected from July, 1999-June, 2001) were determined. Among all of the Candida species tested, 6% and 7% were resistant to fluconazole and itraconazole, respectively. The MIC90 values of voriconazole and amphotericin B were 0.5 and 1 mug/ml, respectively, although some isolates of C. krusei ( amphotericin B and voriconazole MIC, >64 mug/ml) and C tropicalis and C. glabrata ( voriconazole MICs, >64 mug/ml) were less susceptible to voriconazole or amphotericin B. About one-half of the C glabrata isolates belonged to susceptible dose-dependent (SDD, 36%) or resistant (12%) categories for fluconazole and 96% belonged to SDD (56%) or resistant (40%) category for itraconazole. When compared with fluconazole susceptibility data of blood Candida isolates recovered from patients treated at the same hospital ( NTUH) from two different time periods (January, 1994, to June, 1995, and January, 1997, to June, 1999 described in previous reports), the incidence of increased susceptibility of non-krusei Candida isolates to fluconazole was evident. This trend of increasing susceptibility for fluconazole did not correlate to the increasing use of this agent in the hospital. None of the random amplified polymorphic DNA patterns generated by arbitrarily primed PCR using four random oligonucleotide primers for 14 isolates, which exhibited fluconazole MICs of greater than or equal to 16 mug/ml, were identical, indicating an absence of clonal dissemination among these isolates in the hospital.