Análise fenotípica e molecular da produção de biofilmes por estirpes de Staphylococcus aureus isoladas de casos de mastite subclínica bovina

Abstract

Biofilm formation is considered an advantage for Staphylococcus aureus mastitis isolates, facilitating bacterial persistence in the udder. It requires attachment to mammary epithelium, proliferation and accumulation of cells in multilayers and enclosing in a polymeric matrix known as exopolysaccharide. The objective of this study was to evaluate the ability of Staphylococcus aureus isolated from bovine subclinical mastitis for formation of biofilms. A total of 94 Staphylococcus aureus strains obtained from milk samples of cows suffering from subclinical mastitis in dairy herds on two properties in the state of São Paulo were evaluated. These strains were characterized by in vitro biofilm formation, and by the presence of icaA and icaD genes which are responsible for intercellular adhesion. The results revealed that 98.9% of the isolates produced biofilm in vitro by adherence in sterile 96-well U bottom polystyrene tissue culture plates; 95.7% of the isolates possessed the icaA and icaD genes. These bacterial isolates biofilm producers may impair eradication of chronic mastitis, rendering antibiotherapy less effective. The detection of biofilm forming ability in mastitis isolates may provide useful information for more adequate therapeutic regimen and for preventive actions in the control of those bacterial isolates in bovine herds.