Fluconazole-resistant Candida parapsilosis clonally related genotypes: first report proving the presence of endemic isolates harbouring the Y132F ERG11 gene substitution in Spain

Abstract

Objectives: We report here for the first time the presence of Candida parapsilosis isolates harbouring the Y132F ERG11 gene substitution in patients admitted to a Spanish hospital.

Methods: We studied the available (n = 104) C parapsilosis isolates from patients admitted to the Son Espases reference hospital in the Balearic Islands from 1 April 2019 to 30 November 2020. Isolates were sourced from 70 patients: catheter (n = 41), blood cultures (n = 37), lower respiratory tract (n = 15), intra-abdominal (n = 8), and other samples (n = 3). Isolates were genotyped and tested for antifungal susceptibilities to amphotericin B, triazoles, anidulafungin, and micafungin using EUCAST E.Def 7.3.2. The ERG11 gene was sequenced in fluconazole-resistant isolates.

Results: Among the 104 isolates, fluconazole and voriconazole resistance was found in 87 (84%) and 30 (29%) isolates, respectively; all isolates were fully susceptible to echinocandins and amphotericin B. All fluconazole-resistant isolates harboured the Y132F substitution in the ERG11 gene and were grouped into 11 clonally related genotypes. A genotype accounted for 70% (61/87) of fluconazole-resistant isolates. Genotypes involving the fluconazole-resistant isolates were different from those found in the remaining fluconazole-susceptible genotypes. Fifty-six patients harboured fluconazole-resistant genotypes, and 35 of the 56 had candidaemia (48%), abdominal candidiasis (17%), or other forms of candidiasis (35%). Only 20% of the study patients infected by fluconazole-resistant genotypes had a history of azole use.

Discussion: Fluconazole resistance in C parapsilosis isolates from patients admitted to this reference hospital is not attributable to prior azole use, but rather to the presence of a group of fluconazole-resistant C parapsilosis genotypes that have become endemic