Abstract
The Candida parapsilosis group encompasses three species: C. parapsilosis, C. orthopsilosis, and C. metapsilosis. Here, we describe the incidence and echinocandin susceptibility profile of bloodstream isolates of these three species collected from patients admitted to an Italian university hospital from 2007 to 2014. Molecular identification of cryptic species of the C. parapsilosis complex was performed using polymerase chain reaction amplification of the gene encoding secondary alcohol dehydrogenase, followed by digestion with the restriction enzyme BanI. Minimum inhibitory concentrations were determined using the broth microdilution method according to European Committee for Antimicrobial Susceptibility Testing (EUCAST EDef 7.2) and Clinical Laboratory Standards Institute (CLSI M27-A3) guidelines, and the results were compared with those obtained using the E-test and Sensititre methods. Of the 163 C. parapsilosis complex isolates, 136 (83.4%) were identified as C. parapsilosis, and 27 (16.6%) as C. orthopsilosis. The species-specific incidences were 2.9/10,000 admissions for C. parapsilosis and 0.6/10,000 admissions for C. orthopsilosis. No resistance to echinocandins was detected with any of the methods. The percent essential agreement (EA) between the EUCAST and E-test/Sensititre methods for anidulafungin, caspofungin, and micafungin susceptibility was, respectively, as follows: C. parapsilosis, 95.6/97.8, 98.5/88.2, and 93.4/96.3; C. orthopsilosis, 92.6/92.6, 96.3/77.8, and 63.0/66.7. The EA between the CLSI and E-test/Sensititre methods was, respectively, as follows: C. parapsilosis, 99.3/100, 98.5/89.0, and 96.3/98.5; C. orthopsilosis, 96.3/92.6, 100/81.5, and 92.6/88.9. Only minor discrepancies, ranging from 16.9% (C. parapsilosis) to 11.1% (C. orthopsilosis), were observed between the CLSI and E-test/Sensititre methods. In conclusion, this epidemiologic study shows a typical C. parapsilosis complex species distribution, no echinocandin resistance, and it reinforces the relevance of using commercially available microbiological methods to assess antifungal susceptibility. These data improve our knowledge of the national distribution of species of the psilosis group, as there are very few studies of these species in Italy.
Highlights
Candida spp. are important causative agents of nosocomial fungal infections, and they are associated with significant morbidity, prolonged hospital stays, high mortality, and increased healthcare costs
Genotypic differences allowed the taxonomic division of the C. parapsilosis complex into three groups that were recognized as separate species: C. parapsilosis, C. orthopsilosis, and C. metapsilosis
Only one national study of the epidemiology of invasive candidiasis caused by the C. parapsilosis complex has been published [11], which showed that 95, 3.6, and 1.4% of the C. parapsilosis complex strains were identified as C. parapsilosis, C. orthopsilosis, and C. metapsilosis, respectively
Summary
Candida spp. are important causative agents of nosocomial fungal infections, and they are associated with significant morbidity, prolonged hospital stays, high mortality, and increased healthcare costs. While Candida albicans is the most common cause of such infections, recent epidemiologic studies have reported increasing candidemia due to the Candida parapsilosis complex [1,2,3], which has become the predominant yeast in some pediatric and hematology wards [4, 5]. The members of the C. parapsilosis complex differ from each other regarding their virulence and echinocandin susceptibility. In vitro infection models have suggested that C. metapsilosis is the least virulent species [8, 9], and this is in line with its low clinical relevance compared with C. parapsilosis and C. orthopsilosis [10, 11]. In vitro susceptibility data on anidulafungin (AND), caspofungin (CSP), and micafungin (MCF) indicate that C. parapsilosis is less susceptible than C. metapsilosis and C. orthopsilosis [12, 13]
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