[Detection and significance of biofilm formation in yeasts isolated from hemocultures].

BACKGROUND: Yeasts of the genus Candida are important opportunistic pathogens responsible for severe bloodstream infections in immunocompromised patients. An important virulence factor that allows them to colonize plastic implants and to survive in the blood is their ability to form biofilm. The purpose of the study was to assess, how frequently this virulence factor occurred in yeasts of the genus Candida isolated from blood cultures.

MATERIALS AND METHODS: Cultures of the various strains in wells of microtitre plates were used to demonstrate the presence of biofilms. In total, we tested 72 isolates of yeasts of the genus Candida from the blood culture: C. albicans (33), C. parapsilosis (19), C. tropicalis (11), C. glabrata (4), C. krusei (3), C. lipolytica (1) and C. lusitaniae (1).

RESULTS: The ability to form biofilm was demonstrated in 26 strains. The largest number of biofilm-positive strains was found in C. parapsilosis (13) and C. tropicalis (7). The formation of biofilms was far less frequent in the strains of C. albicans (4). The formation of biofilms was also demonstrated in C. krusei (2) and C. glabrata (1).

CONCLUSION: The increasing frequency of fungal bloodstream infections is due to the increasing use of catheters and implants. The biofilm formation in these yeasts is the chief factor of virulence promoting such infections. The demonstration of biofilm formation in an isolated strain is indicative of the probable existence of a biofilm focus and of possible difficulties during antimycotic therapy.