Evidence of Fluconazole-Resistant Candida parapsilosis Genotypes Spreading across Hospitals Located in Madrid, Spain and Harboring the Y132F ERG11p Substitution

Abstract

We have been monitoring the antifungal resistance in Candida parapsilosis isolates collected from inpatients at Madrid metropolitan area hospitals for the last 3 years. The study aimed to elucidate the presence of fluconazole-resistant C. parapsilosis genotypes in Madrid. From January 2019 to December 2021, a total of 354 C. parapsilosis isolates (n = 346 patients) from blood (76.6%) or intraabdominal samples were collected and genotyped using species-specific microsatellite markers. Antifungal susceptibilities to amphotericin B, the triazoles, micafungin, anidulafungin, and ibrexafungerp were performed according to EUCAST E.Def 7.3.2; the ERG11 gene was sequenced in fluconazole-resistant isolates. A total of 13.6% (n = 48/354) isolates (one per patient) were found to be resistant to fluconazole and non-wild-type to voriconazole but fully susceptible to ibrexafungerp. Resistant isolates were mostly sourced from blood (n = 45/48, 93.8%) and were detected in five hospitals. Two hospitals accounted for a high proportion of resistant isolates (n = 41/48). Resistant isolates harbored either the Y132F ERG11p amino acid substitution (n = 43) or the G458S substitution (n = 5). Isolates harboring the Y132F substitution clustered into a clonal complex involving three genotypes (one genotype accounted for n = 39/43 isolates) that were found in four hospitals. Isolates harboring the G458S substitution clustered into another genotype found in a fifth hospital. C. parapsilosis genotypes demonstrating resistance to fluconazole have been spreading across hospitals in Madrid, Spain. Over the last 3 years, the frequency of isolation of such isolates and the number of hospitals affected is on the rise.

Keywords: C. parapsilosis; G458S; Y132F; fluconazole resistance; microsatellite genotyping.

FIG 1

Hospitals in which fluconazole-resistant isolates were detected. The number of fluconazole-resistant isolates (red) and fluconazole-susceptible isolates (green) grouped by clinical source (blood cultures or intraabdominal samples) are shown.

FIG 2

Timeline of the detection of fluconazole-resistant C. parapsilosis isolates over time at each of the five affected hospitals (represented in different lines). Colored symbols refer to a fluconazole-resistant C. parapsilosis isolate from blood cultures otherwise indicated by an asterisk that represents isolates from intraabdominal samples. Red indicates isolates within the clonal complex (CP-451, bar; CP-673, oval; and CP-674, triangle) of genotypes harboring the Y132F substitution. Blue indicates isolates within the CP-675 genotype harboring the G458S substitution. Arrows indicate the first or last time when resistant isolates were detected.

FIG 3

Minimum spanning tree showing the C. parapsilosis fluconazole-resistant isolates harboring the Y132F substitution (isolates from hospitals in Madrid [red], isolates from Son Espases hospital [orange]), the G458S substitution (blue); and fluconazole-susceptible isolates (green). Circles represent different genotypes and the circle size of the number of isolates belonging to the same genotype. Connecting lines between the circles show profile similarities. The solid bold line indicates differences in only 1 marker, the solid line indicates differences in 2 markers, the dashed line indicates differences in 3 markers, and the dotted line indicates differences in 4 or more markers. R, resistant; S, susceptible. CP-673 and CP-674 genotypes differ from CP-451 at markers B and CP6 microsatellite markers.