Prevalence, distribution, and antifungal susceptibility profiles of Candida parapsilosis, C. orthopsilosis, and C. metapsilosis in a tertiary care hospital

Abstract

Candida parapsilosis, an emergent agent of nosocomial infections, was previously made up of a complex of three genetically distinct groups (groups I, II, and III). Recently, the C. parapsilosis groups have been renamed as distinct species: C. parapsilosis sensu stricto, C. orthopsilosis, and C. metapsilosis. In Portugal, no data pertaining to the distribution and antifungal susceptibility of these Candida species are yet available. In the present report, we describe the incidence and distribution of C. parapsilosis sensu stricto, C. orthopsilosis, and C. metapsilosis among 175 clinical and environmental isolates previously identified by conventional methods as C. parapsilosis. We also evaluated the in vitro susceptibilities of the isolates to fluconazole, voriconazole, posaconazole, amphotericin B, and two echinocandins, caspofungin and anidulafungin. Of the 175 isolates tested, 160 (91.4%) were identified as C. parapsilosis sensu stricto, 4 (2.3%) were identified as C. orthopsilosis, and 5 (2.9%) were identified as C. metapsilosis. Six isolates corresponded to species other than the C. parapsilosis group. Interestingly, all isolates from blood cultures corresponded to C. parapsilosis sensu stricto. Evaluation of the antifungal susceptibility profile showed that only nine (5.6%) C. parapsilosis sensu stricto strains were susceptible-dose dependent or resistant to fluconazole, and a single strain displayed a multiazole-resistant phenotype; two (1.3%) C. parapsilosis sensu stricto strains were amphotericin B resistant. All C. orthopsilosis and C. metapsilosis isolates were susceptible to azoles and amphotericin B. A high number of strains were nonsusceptible to the echinocandins (caspofungin and anidulafungin).

FIG. 1.

Discrimination of C. parapsilosis (group I), C. orthopsilosis, and C. metapsilosis isolates according to their SADH gene restriction profiles. (a) Amplification of a 716-bp SADH gene fragment from the genomic DNA of isolates provided genetic confirmation of the C. parapsilosis groups (lanes 1, 2, 4, 5, and 6); the amplification of smaller SADH gene fragments corresponds to misidentified C. parapsilosis species (lane 3). (b) Representative SADH gene restriction profile for C. metapsilosis (lane 1), C. orthopsilosis (lane 2), and C. parapsilosis (lane 3) type strains. Lanes M, 100-bp ladder.