First Report of Fluconazole-Resistant Candida parapsilosis Harbouring the G458S ERG11p Substitution in a Brazilian...

Fluconazole-resistant Candida parapsilosis is a matter of concern.

To investigate fluconazole resistance among Candida parapsilosis complex isolates from patients admitted to three Brazilian hospitals, and to characterise resistance mechanisms and clonal relatedness.

A total of 76 C. parapsilosis complex isolates were collected from 60 patients hospitalised at three medical centres (H1-H3) located in Vitória, Espírito Santo state (2017-2023). Of these, 38 isolates were obtained from bloodstream cultures, four from catheter tips and 34 from an ICU surveillance study conducted at H1. In vitro susceptibility testing was performed according to the E.Def 7.4 EUCAST method. C. parapsilosis sensu stricto isolates were genotyped using microsatellite markers, and the ERG11 gene was sequenced in resistant isolates.

Candida parapsilosis sensu stricto was the most common species (65/76 isolates; 85.5%), followed by C. orthopsilosis (n = 8, 10.5%), and C. metapsilosis (n = 3, 4%). Among the C. parapsilosis sensu stricto isolates, 5/65 (7.7%) were fluconazole-resistant, harboured the G458S ERG11p substitution, and were detected in 2019 and 2020. Only one fluconazole-resistant isolate was also voriconazole-resistant; all isolates were susceptible to the remaining agents. Fluconazole-resistant isolates sourced from H2 were grouped into two unrelated genotypes, and recovered from patients with haematological malignancies, tumours and central nervous system disorders. Only two patients had a history of azole exposure.

This is the first report of fluconazole-resistant C. parapsilosis sensu stricto isolates harbouring the G458S ERG11p substitution in Brazil. Here reported isolates showed resistance to fluconazole alone, which is an unusual pattern among C. parapsilosis sensu stricto isolates harbouring the G458S substitution.