Analysis of an outbreak of echinocandin-resistant clonal Candida parapsilosis complex harbouring ERG11Y132F and FKS1S656P mutations

Abstract

Aim: We aimed to analyse echinocandin-resistant (ECR) Candida parapsilosis complex candidaemia episodes. Methods: A retrospective cohort study was conducted at Koç University Hospital from 1st January 2018 to 30th March 2022, during the COVID-19 pandemic. A total of 307 candidaemia isolates were obtained from 249 patients. A total of 272 episodes had mono-candidaemia, while 16 episodes had poly-candidaemia. Antifungal susceptibility with broth microdilution with environmental microbiological sampling were obtained. Sequencing and amplification of the resistance genes with genotyping were carried out, and pulse field gel electrophoresis was performed in the isolates. Results: Of the 272 isolates that caused mono-candidaemia, 139 (51.1%) were identified as C. parapsilosis complex, with 64 (46%) demonstrating micafungin resistance. The isolates yielded Y132F mutation in the ERG11, and S656P mutation in the FKS1 genes, primarily genotypes A and A1. The 30-day mortality rates were 51.6% (33/64) for ECR C. parapsilosis complex, 38.9% (14/36) for fluconazole-resistant C. parapsilosis complex, and 35.9% (14/39) for fluconazole-susceptible C. parapsilosis complex. Environmental cultures showed that 23 of 60 samples yielded ECR C. parapsilosis complex, predominantly from interior parts and handles of infusion pumps used in oncology wards with a total clonal similarity with the clinical isolates. Conclusions: This is the first report of the FKS1S656P mutation in ECR C. parapsilosis complex isolates from Turkey, and it highlights a significant outbreak associated with an unnoticed gap in cleaning of the interior parts of infusion pumps. Enhanced cleaning protocols, combined with on-site feedback, resulted in no new cases within the next 2 months. © 2025 The Healthcare Infection Society