Shift in Candida species causing candidemia: A seven-year study from a university hospital and evaluation of the rise of Candida parapsilosis sensu stricto

Abstract

Background: Candidemia ranks the fourth most prevalent infection in healthcare settings. Notably, non-Candida albicansCandida species, particularly Candida parapsilosis, have experienced a worldwide increase as causative agents of candidemia in recent years.

Aims: This study aimed to assess shifts in prevalence and antifungal susceptibility of C. parapsilosis among candidemia-causing species over time, alongside investigating clonal relationships among isolates.

Methods: We analyzed Candida species in candidemia episodes from January 2016 to December 2022. MALDI-TOF MS identified Candida isolates at the species level, and the identification of the species within C. parapsilosis complex was achieved via the restriction fragment length polymorphism method. Fluconazole susceptibility testing followed EUCAST guidelines. Clonal relationships among C. parapsilosis isolates were assessed using three methods: AP-PCR, REA-PFGE, and electrophoretic karyotyping.

Results: Across a seven-year period, Candida prevalence among all blood cultures was 2.1% (679 cases). The most prevalent Candida species were C. parapsilosis (33.7%), C.albicans (32.7%), Nakaseomyces glabratus (formerly Candida glabrata) (14.4%), and Candida tropicalis (8%). Notably, C. parapsilosis isolation rates increased annually from 2016 to 2022. Fluconazole susceptibility of C. parapsilosis isolates declined over time, with rates decreasing from 100% in 2016 to 72.6% in 2022. Electrophoretic karyotyping exhibited superior discrimination in clonal relationship analysis (D=0.9875).

Conclusions: Our findings highlight a concerning trend of increasing fluconazole resistance in C. parapsilosis sensu stricto over the study period. Electrophoretic karyotyping has emerged as a robust method for assessing clonal relationships. While no dominant outbreak isolate was identified, the high clustering rate suggests the potential of C. parapsilosis as a significant nosocomial infection agent in the future.

Keywords: Candida parapsilosis; Candidemia; Cariotipado electroforético; Electrophoretic karyotyping; Epidemiology; Epidemiología; Fluconazol; Fluconazole; Fluconazole susceptibility; Sensibilidad al fluconazol.