Characterization of Candida parapsilosis complex strains isolated from invasive fungal infections

In the present work, we studied the distribution of Candida parapsilosis complex species and the antifungal susceptibility of clinical isolates collected during an Italian surveillance study of yeast invasive fungal infections (IFIs) in intensive care units (ICUs). Minimum inhibitory concentrations (MICs) were determined using the Clinical and Laboratory Standards Institute (CLSI) reference broth microdilution method. BanI digestion patterns of the secondary alcohol dehydrogenase polymerase chain reaction (PCR) products were used to identify C. parapsilosis sensu stricto, C. orthopsilosis, and C. metapsilosis. A total of 138 C. parapsilosis isolates were stored (January 2007-December 2008). The overall frequency of C. parapsilosis complex in IFIs was 22%. Of the 138 tested isolates, 95% were C. parapsilosis sensu stricto, 3.6% were C. orthopsilosis, and 1.4% were C. metapsilosis. The MIC50 values (expressed as μg/ml) for anidulafungin, caspofungin, and micafungin for C. parapsilosis complex were 2, 1, and 2, respectively, and the MIC90 values were 4, 2, and 4, respectively. The MIC50 and MIC90 values for itraconazole and posaconazole were 0.12 and 0.25, respectively, and for fluconazole, they were 1 and 4, respectively. This study, the most comprehensive study conducted to date to evaluate the frequency and antifungal susceptibility profiles of C. parapsilosis complex isolates from critically ill patients in Italy, highlights the low prevalence of C. orthopsilosis and C. metapsilosis in IFIs.