Clonal Candidemia Outbreak by Candida parapsilosis Carrying Y132F in Turkey: Evolution of a Persisting Challenge

Abstract

As the second leading etiological agent of candidemia in Turkey and the cause of severe fluconazole-non-susceptible (FNS) clonal outbreaks, <i>Candida parapsilosis</i> emerged as a major health threat at Ege University Hospital (EUH). Evaluation of microbiological and pertinent clinical profiles of candidemia patients due to <i>C</i>. <i>parapsilosis</i> in EUH in 2019-2020. <i>Candida parapsilosis</i> isolates were collected from blood samples and identified by sequencing internal transcribed spacer ribosomal DNA. Antifungal susceptibility testing was performed in accordance with CLSI M60 protocol and <i>ERG11</i> and HS1/HS2-<i>FKS1</i> were sequenced to explore the fluconazole and echinocandin resistance, respectively. Isolates were typed using a multilocus microsatellite typing assay. Relevant clinical data were obtained for patients recruited in the current study. FNS <i>C</i>. <i>parapsilosis</i> isolates were recovered from 53% of the patients admitted to EUH in 2019-2020. Y132F was the most frequent mutation in Erg11. All patients infected with <i>C</i>. <i>parapsilosis</i> isolates carrying Y132F, who received fluconazole showed therapeutic failure and significantly had a higher mortality than those infected with other FNS and susceptible isolates (50% <i>vs</i>. 16.1%). All isolates carrying Y132F grouped into one major cluster and mainly recovered from patients admitted to chest diseases and pediatric surgery wards. The unprecedented increase in the number of Y132F <i>C</i>. <i>parapsilosis</i>, which corresponded with increased rates of fluconazole therapeutic failure and mortality, is worrisome and highlights the urgency for strict infection control strategies, antifungal stewardship, and environmental screening in EUH.