Título

CANDIDA SPECIES CAUSING FUNGAL KERATITIS: MOLECULAR IDENTIFICATION, ANTIFUNGAL SUSCEPTIBILITY, BIOFILM FORMATION, AND CLINICAL ASPECTS

Objetivo

The study aimed to evaluate the clinical aspects, molecular identification, biofilm formation, and antifungal
susceptibility profile of Candida species isolated from fungal keratitis.

Método

Thirteen Candida isolates from 13 patients diagnosed with Candida keratitis were retrieved and grown in pure culture. Species
identification was performed by micromorphology analysis and ITS-rDNA sequencing. The broth microdilution
method tested the minimum inhibitory concentration (MIC) of four antifungal drugs (fluconazole, amphotericin
B, voriconazole, and anidulafungin). The biofilms were cultured and incubated with antifungal drugs for 24
hours. The XTT reduction assay measured the biofilm activity. Biofilm MICs were calculated based on a 50%
reduction in metabolic activity compared with the activity of the drug-free control.

Resultado

Among isolates, two were C.albicans, 10 C. parapsilosis (sensu stricto), and one C. orthopsilosis. All isolates were classified as susceptible or intermediate to all four antifungal drugs. Four isolates were very low biofilm producers (30%). Nine isolates
were biofilm producers, and all biofilms samples were unsusceptible to all drugs tested. Previous ocular surgery
was the most common underlying condition for fungal keratitis (84.6%), and C. parapsilosis was the most
frequent Candida species (76.9%). Four patients (30.7%) needed keratoplasty, whereas two (15.3%) required
evisceration.

Conclusão

The biofilm formation ability of Candida isolates decreased antifungal susceptibility compared
with planktonic cells. Despite in vitro antifungal susceptibility, almost half of patients were unresponsive to
clinical treatment and needed surgery.