Sheep mastitis Staphylococcus epidermidis biofilm effects on cell adhesion and inflammatory changes

Abstract

Mastitis in sheep is an important disease as it causes a decrease in milk yield and quality. Staphylococcus epi- dermidis is recognized as the main cause of mastitis in sheep. Its ability to produce biofilm is believed to con- tribute to mammary gland pathology. The aim of this study was to assess the influence of S. epidermidis biofilm production on cell adhesion and on the inflammatory response of the mammary gland. A total of 109 S. epi- dermidis isolates from mastitic sheep milk samples were analyzed for in vitro slime production, assessed by Congo red agar test (CRA), and for biofilm formation, evaluated by tissue culture plate assay (TCP). The influence of biofilm production was estimated on the adherence of bacteria to mammary cells and on the mammary gland inflammatory reaction. Only 7.3% isolates produced slime on CRA and 8% produced biofilm according to TCP. The relation between slime production in CRA and biofilm production analyzed by TCP was highly significant (P < 0.001). The differences between biofilm production and different recorded inflammatory situations were non significant (P ≥ 0.05). Adherence to mammary epithelium cells ranged from 0.05% to 1.23%. Biofilm production was not related to cell adhesion. Moreover, S. epidermidis isolates that induced different degrees of inflammation did not express differences in their ability to adhere to mammary epithelium. The present study suggests that biofilm production by sheep mastitis S. epidermidis is unlikely to affect either cell adhesion or mammary gland in- flammatory response.