Our data confirm the pathogenic role of biofilm in C. albicans infections. Its importance was further enhanced by a lack of contribution from extracellular enzymes, detected in both NP and BP strains. In addition, we demonstrated anidulafungin efficacy in treating biofilm-related invasive candidiasis.

The newly available AST-YS01 Vitek 2 cards were evaluated, and the results were compared with those obtained by the CLSI M27-A2 microdilution reference method. Clinical fungal isolates, including 614 isolates of Candida spp., 10 Cryptococcus neoformans isolates, 1 Geotrichum capitatum isolate, and 2 quality control strains, were tested for their susceptibilities to amphotericin B, fluconazole, and voriconazole using both methods. The majority of fungal isolates were susceptible to all antifungal agents tested: the MIC 90 values determined by the Vitek 2 and CLSI methods were 0.5 and 1 g/ml, respectively, for amphotericin B; 8 and 16 g/ml, respectively, for fluconazole; and <0.12 and 0.25 g/ml, respectively, for voriconazole. Overall there was excellent categorical agreement (CA) between the methods (99.5% for amphotericin B, 92% for fluconazole, 98.2% for voriconazole), but discrepancies were observed within species. The CAs for fluconazole were low for Candida glabrata and Candida krusei when the results of the CLSI method at 48 h were considered. Moreover, the fully automated commercial system did not detect the susceptibility of Cryptococcus neoformans to voriconazole. The Vitek 2 system can be considered a valid support for antifungal susceptibility testing of fungi, but testing of susceptibility to agents not included in the system (e.g., echinocandins and posaconazole) should be performed with other methods.

No abstract

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 MIC(50) values (expressed as μg/ml) for anidulafungin, caspofungin, and micafungin for C. parapsilosis complex were 2, 1, and 2, respectively, and the MIC(90) values were 4, 2, and 4, respectively. The MIC(50) and MIC(90) 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.

Although there has been an overall good coverage of Candida glabrata infections by the echinocandins, emergence of antifungal resistance during therapy has been reported. We investigated, by using an invertebrate host model, the fitness of sequential C. glabrata isolates with different echinocandins susceptibility patterns. The studied strains were isolated from a case of recurrent fungemia with a fatal outcome due to C. glabrata that developed cross-resistance to echinocandins during caspofungin therapy. The sequential strains isolated post-therapy showed a S663P mutation in the Fks2p hot spot 1. In vivo study in the invertebrate host Galleria mellonella did not suggest a fitness cost related to the acquired antifungal resistance, the three isolates displayed a similar rate of killing (P  =  0.54). We observed a clear correlation between emergence of antifungal resistance and persistence of the causal agent, probably aided by the unchanged fitness and unresponsiveness in vivo to the adopted therapy.