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

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.