Evaluation of Biofilm Production and Antifungal Susceptibility to Fluconazole in Clinical Isolates of Candida spp. in Both Planktonic and Biofilm Form

Candida spp. are an important opportunistic pathogen that can represent a possible cause of severe infections, especially in immunocompromised individuals. The clinical impact of Candida spp. depends, in part, on the ability to form biofilms, communities of nestled cells into the extracellular matrix. In this study, we compared the biofilm formation ability of 83 strains of Candida spp. isolated from blood cultures and other materials, such as respiratory samples, urine, and exudate, and their sensitivity to fluconazole (FLZ). Strains were divided into tertiles to establish cut-offs to classify isolates as low, moderate, or high biofilm producers (<0.26, 0.266–0.839, >0.839) and biofilms with low, moderate, or high metabolic activity (<0.053, 0.053–0.183, >0.183). A non-linear relationship between biofilm production and metabolic activity was found in C. glabrata and C. tropicalis. In addition, the increase in minimum biofilm eradication concentrations (MBEC50) compared to the Minor Inhibitory Concentration (PMIC) of the planktonic form in Candida spp. confirms the role of biofilm in the induction of resistance to FLZ.