Genetically related micafungin-resistant Candida parapsilosis blood isolates harbouring novel mutation R658G in hotspot 1 of Fks1p: A new challenge?

Amir Arastehfar, Farnaz Daneshnia, Süleyha Hilmioglu-Polat, MacIt Ilkit, Melike Yasar, Furkan Polat, Dilek Yeşim Metin, Ülküm Zafer Dokumcu, Weihua Pan, Ferry Hagen, Teun Boekhout, David S. Perlin, Cornelia Lass-Flörl

Research output: Contribution to journalArticlepeer-review

6 Scopus citations


Background: Echinocandin resistance rarely occurs in clinical Candida parapsilosis isolates and the underlying mechanism is unknown. Objectives: To determine the prevalence of echinocandin resistance and the underlying mechanism for a large collection of C. parapsilosis blood isolates and to determine whether the echinocandin-resistant isolates were clonally related. Methods: C. parapsilosis blood isolates (n = 213) were subjected to antifungal susceptibility testing (CLSI M27), for micafungin, anidulafungin, amphotericin B and, if appropriate, caspofungin. Hotspot (HS) 1 and HS2 of FKS1 were sequenced for all isolates (n = 213) and microsatellite typing was performed for echinocandin-resistant isolates. Results: All isolates were susceptible to amphotericin B and two isolates were intermediate to anidulafungin (MIC = 4 mg/L), while micafungin resistance was noted in four isolates (MIC >8 mg/L); three of which were also fluconazole resistant and therefore were MDR. Interestingly, micafungin-resistant isolates, but not those intermediate to anidulafungin, carried novel mutation R658G in HS1 of Fks1p; three of which also harboured Y132F+K143R in Erg11. The first isolate (MICR1) was recovered in November 2017 from a patient admitted to paediatric gastroenterology who showed therapeutic failure under caspofungin treatment. MICR2-MICR4 were collected during 2018-19 and were recovered from three echinocandin-naive paediatric-surgery patients; the isolates shared the same genotype. Conclusions: Herein, for the first time (to the best of our knowledge), we identified micafungin-resistant C. parapsilosis blood isolates harbouring a novel mutation in HS1 of FKS1, which was likely attributable to in vitro micafungin resistance and in vivo caspofungin therapeutic failure. The acquisition of micafungin-resistant C. parapsilosis isolates in echinocandin-naive patients likely implicates clonal expansion, as supported by the close genetic relatedness of MICR2-MICR4.

Original languageEnglish (US)
Pages (from-to)418-422
Number of pages5
JournalJournal of Antimicrobial Chemotherapy
Issue number2
StatePublished - Feb 1 2021
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Pharmacology
  • Microbiology (medical)
  • Infectious Diseases
  • Pharmacology (medical)

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