Candida parapsilosis sensu stricto: prevalence and antifungal susceptibility profile in patients with underlying immunodeficiencies

Authors

• YW Lim
• H Zarkoob
• MJ Song
• M Ferrer

Abstract

Candida parapsilosis sensu stricto (C. parapsilosis SS) is a leading cause of invasive candidiasis in southern Europe, Latin America and Asia. Although it is generally considered susceptible to triazoles, clonal expansion of fluconazole-resistance has been reported in health care settings in some countries. In this study, we aimed to determine the prevalence and associated mutations of fluconazole-resistance phenotypes of C. parapsilosis SS isolated from patients with underlying immunodeficiencies at NIH Clinical Center.

A total of 43 C. parapsilosis SS isolates were tested. Species level identification was confirmed by Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF) and PCR-sequencing of the internal transcribed spacer and D1/D2 region of ribosomal DNA gene. Antifungal susceptibility testing was performed using broth microdilution. The results were analyzed using current Clinical and Laboratory Standards Institute (CLSI) M60-Ed2-2020 breakpoints.

Overall, C. parapsilosis SS was the primary contributor of yeast related blood stream infections, accounting for 24% of infections. All of the isolates tested were 100% susceptible to anidulafungin, caspofungin and amphotericin B. The susceptibility rate of micafungin was 93.3% and 97.6% of the isolates were found to be susceptible to voriconazole. Of all isolates tested, one was susceptible-dose dependent (MIC 4 μg/ml) and one was resistant (MIC ≥ 8 μg/ml) to fluconazole. Both isolates were sourced from blood.

In conclusion, prevalence of C. parapsilosis SS among clinical yeast isolates was significantly high in our Center. Further studies are warranted to explore the molecular mechanism of fluconazole resistance and its association to prior azole use in these isolates.

Scientific Focus Area: Microbiology and Infectious Diseases

This page was last updated on Monday, September 25, 2023