Epidemiologia de candidemia em quatro hospitais gerais de Belo Horizonte, MG, Brasil, e avaliação da formação de biofilmes por espécies de Candida

Abstract

The present study investigated the epidemiology of candidemia and the antifungal drug susceptibility pattern of Candida spp. isolates at four tertiary hospitals in Belo Horizonte, Brazil. Additionally, the biofilm formation process of Candida spp. bloodstream isolates in the presence of preformed bacteria biofilm and antifungal drugs were also evaluated. Over five years, a total of 4824 episodes of bloodstream infection were identified, and Candida species accounted for 168 cases (3.5%). Candida albicans was the most frequently isolated Candida species in all hospitals, but Candida species other than C. albicans accounted for 55% of isolates, including predominantly Candida parapsilosis and Candida tropicalis. Azole resistance was restricted to only 8.9% of all Candida isolates. Candidemia was mostly documented in Intensive Care Unit Patients. The crude mortality rate was 50%, and hematological malignancy, neutropenia, acute renal failure, high Acute Physiology and Chronic Health Evaluation II score and use of central venous catheter (CVC) were conditions associated with risk of death. In order to investigate interactions between Candida species and bacteria in biofilm grown a modified drip Flow Reactor model was used. Counts of viable microorganisms in the mixed biofilm were determined and converted to colony forming unit. Scanning Electron Microscopy (SEM) analysis was used to characterize the structure and morphology of polimicrobial biofilms. Viable counts of C. albicans and C. tropicalis per cm2 of CVC decreased in the presence of P. aeruginosa (p=<0.05). C. albicans was inhibited by preformed biofilm of S. epidermidis isolates. C. parapsilosis did not show competitive interactions with bacteria biofilm. Finally, the activity of Caspofungina (CAS) and amphotericin B (AMB) against C. albicans, C. tropicalis and C. parapsilosis biofilms were assessed. Paradoxical growth (PG) in the presence of high CAS concentrations was observed. With the exception of C. parapsilosis, C. albicans and C. tropicalis, biofilms displayed PG. Microscopic changes in cell morphology were observed for biofilm cells with PG. Specifically, the accumulation of enlarged, conical and atypical cells were associated with PG.