Prevalence of bacterial infection responsible for bovine mastitis

Mastitis continues to be the most economically important disease of dairy cattle, and current data on mastitis is even less readily available. To investigate into the prevalence of the pathogens responsible for bovine mastitis, 100 raw milk samples were obtained from the dairy cows with clinical or sub-clinical bovine mastitis in 5 farms in Jiangsu Province, China. All the samples were submitted to bacterial isolation and identification by morphologic examination and biotyping. The data revealed that Escherichia coli was the commonest organism in mastitis cases, being implicated in 82% cases, and Streptococcus uberis (53%) continues to be a prevalent pathogen closely followed by Staphylococcus aureus (41%), Streptococcus dysgalactiae (29%) and Streptococcus agalactiae (27%). In addition, Str. uberis and S. aureus were more frequently associated with clinical mastitis than sub-clinical case, while the infection rates of other bacteria were similar. Further more, Staphylococcus epidermids (15%) and Staphylococcus saprophyticus (10%), previously considered as naught pathogenic bacteria, were also detected in the diseased mammary gland of the problem cows.