Virulence factors of Candida tropicalis isolated from thecoastal environment of Northeast Brazil
Candida tropicalis, coastal environment, virulence factors.
Several studies have been conducted regarding the health risks associated with recreational use of beaches contaminated with domestic sewage. These wastes contain several microorganisms, including Candida tropicalis, an etiologic agent of both superficial and systemic infections, and an indicator of fecal contamination of the environment. In this context, the objectives of this study were: (1) To confirm the identification of yeasts present in the sand of Ponta Negra Beach, Natal city, Rio Grande do Norte State, Brazil; (2) To evaluate the major virulence factors of C. tropicalis, namely: ability to adhere to human buccal epithelial cells (HBEC), morphogenesis on solid medium, biofilm formation, proteinase secretion, hemolytic activity and halotolerance. Sixty two environmental strains of C. tropicaliswere analyzed, which showed widely varying results for the various virulence factors evaluated. In general, isolates showed adhesiveness to HBEChigher than the reference strain C. tropicalis ATCC 13803, besides being highly biofilm producer. Regarding morphogenesis, most isolates showed wrinkled phenotype on Spider agar (34 isolates; 54. 8%). With regard to enzymatic activity, most of the isolates produced more proteinase than the reference strain C. tropicalis ATCC 13803. In addition, 35 isolates (56.4%) showed high hemolytic activity (index of hemolysis> 0.55). Finally, 85.4% of the strains were resistant to 15% sodium chloride, which corroborates to the high survival rate of C. tropicalis in marine environment. Our results demonstrate that C. tropicalis isolates derived from a sandy beach in Northeastern Brazil are able to fully express virulence attributes and show high capacity for persistence in the coastal environment. This pathogenic potential highlights health risk for the population who are exposed during tourism practices.
Key Words: Candida tropicalis, coastal environment, virulence factors.