Surveillance of the prevalence, antibiotic susceptibility, and genotypic characterization of invasive candidiasis in a teaching hospital in China between 2006 to 2011

BACKGROUND: Invasive candidiasis is an important nosocomial infection associated with high mortality among immunosuppressive or critically ill patients. We described the incidence of invasive candidiasis in our hospital over 6 years and showed the antifungal susceptibility and genotypes of the isolated yeast. METHOD: The yeast species were isolated on CHROMagar Candida medium and identified using an yeast identification card, followed by analysis of the D1/D2 domain of 26S rDNA. The susceptibilities of the isolates to flucytosine, amphotericin B, fluconazole, itraconazole, and voriconazole were tested using the ATB FUNGUS 3 system, and that to caspofungin was tested using E-test strips. C. albicans was genotyped using single-strand conformation polymorphism of CAI (Candida albicans I) microsatellite DNA combined with GeneScan data. RESULTS: From January 2006 to December 2011, a total of 259 isolates of invasive Candida spp. were obtained from 253 patients, among them 6 patients had multiple positive samples. Ninety-one stains were from blood and 168 from sterile fluids, accounting for 6.07% of all pathogens isolated in our hospital. Most of these strains were C. albicans (41.29% in blood/59.06% in sterile body fluids), followed by C. tropicalis (18.06%/25.72%), C. parapsilosis (17.42%/5.43%), C. glabrata (11.61%/3.99%) and other Candida spp. (11.61%/5.80%). Most Candida spp. were isolated from the ICU. The new species-specific CLSI candida MIC breakpoints were applied to these date. Resistance to fluconazole occurred in 6.6% of C. albicans isolates, 10.6% of C. tropicalis isolates and 15.0% of C. glabrata isolates. For the 136 C. albicans isolates, 54 CAI patterns were recognized. The C. albicans strains from blood or sterile body fluids showed no predominant CAI genotypes. C. albicans isolates from different samples from the same patient had the same genotype. CONCLUSIONS: Invasive candidiasis has been commonly encountered in our hospital in the past 6 years, with increasing frequency of non-C. albicans. Resistance to fluconazole was highly predictive of resistance to voriconazole. CAI SSCP genotyping showed that all C. albicans strains were polymorphic. Invasive candidiasis were commonly endogenous infection.