Circulation of Fluconazole-ResistantC. albicans, C. aurisandC. parapsilosisBloodstream Isolates Carrying Y132F, K143R or T220L Erg11p Substitutions in Colombia

Abstract

AbstractAlthoughCandidaspp., is a common cause of bloodstream infections and is often associated with high mortality rates, its resistance to antifungal drugs, and the molecular mechanisms involved have been poorly studied in Colombia. Here, 123 bloodstream isolates ofCandidaspp. were collected. MALDI-TOF MS identification and fluconazole (FLC) susceptibility patterns were assessed on all isolates. Subsequently, sequencing ofERG11, TAC1orMRR1, and efflux pumps were performed for resistant isolates. Out of 123 clinical strains,C. albicansaccounted for 37.4%, followed byC. tropicalis26.8%,C. parapsilosis19.5%,C. auris8.1%,C. glabrata4.1%,C. krusei2.4% andC. lusitaniae1.6%. Resistance to FLC reached 18%. Erg11 amino acid substitutions associated with FLC-resistance (Y132F, K143R or T220L) were found in 58% of 19 FLC-resistant isolates. Furthermore, novel mutations were found in all genes studied. Regarding efflux pumps, 42% of 19 FLC-resistantCandidaspp strains showed significant efflux activity. Finally, six of the 19 FLC-resistant isolates neither harbored resistance-associated mutations nor showed efflux pump activity. AlthoughC. albicansremain the most predominant species, non-C. albicansspecies comprise a high proportion (62.6%). Among FLC-resistant species,C. auris(70%) andC. parapsilosis(25%) displayed the highest percentages of resistance. In 68% of FLC-resistant isolates, a mechanism that could explain their phenotype was found (e.g. mutations, flux pump activity or both). We provide evidence that endemic isolates harbor amino acid substitutions related with resistance to one of the most used molecules in the hospital setting, with Y132F being the most frequently detected one.