Phenotypic Typing and Epidemiological Survey of Antifungal Resistance of Species Detected in Clinical Samples of Italian Patients in a 17 Months' Period

Introduction: Yeast pathogens are emerging agents of nosocomial as well as community-acquired infections and their rapid and accurate identification is crucial for a better management of high-risk patients and for an adequate treatment.

Methods: We performed a retrospective review of 156 yeast isolates collected during a 17 months' period of regular clinical practice at the Microbiology Department of San Camillo Hospital in Treviso, Italy and analyzed by the traditional culture-based method combined with matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS).

Results: Out of all the samples collected MALDI-TOF MS was able to characterize with a MT score ≥1.7 (accurate result at species level) 12 different yeast and yeast-like species from 140 samples: (63.7%), (13.6%), (6.5%), (5.7%), (2.1%), (2.1%), (2.1%), (1.4%), (0.7%), (0.7%), (0.7%), (0.7%). Susceptibility testing toward seven common antifungal agents showed a characteristic MIC distribution of isolates for echinocandins: particularly we noticed that 72% and 46% of showed an MIC value close to clinical breakpoint as defined by EUCAST, respectively for anidulafungin and micafungin.

Conclusion: Accurate identification of microorganisms and the study of their antifungal susceptibility allow to understand the epidemiology of a particular area, permitting the choice of the most appropriate early antifungal treatment.