Antimicrobial Susceptibility Profile of Bacteria in Mastitis Cow Milk Samples

Bovine mastitis is a cause of major financial losses in the dairy industry worldwide. Bovine mastitis is defined as the inflammatory response of the udder tissue due to either physical trauma or infections caused by different microorganisms, especially bacteria. More than 135 pathogenic agents have been identified from bovine mastitis. The aim of the study was to identify the bacterial genera involved in mastitis etiology in cattle and to test the antimicrobial susceptibility to antibiotics. The samples were collected before morning milking and evaluated by microscopic and cultural examination, and further identified using biochemical methods. The evaluation of antimicrobial susceptibility was performed using Kirby-Bauer disk diffusion test. Overall, Staphylococcus spp., Bacillus spp., Streptococcus spp., Micrococcus spp., Escherichia spp. and Trueperella spp. were identified. The most frequent bacterial associations were observed for Staphylococcus-Bacillus, Bacillus-Streptococcus and Staphylococcus-Micrococcus. Regarding the antimicrobial sensitivity profile, the majority of the bacterial strains we have isolated were classified as sensitive, with the exception of Escherichia coli, with one strain being resistant to all tested antibiotics. Among the antimicrobials, the Amoxicillin and clavulanic acid was the most efficient one and Trimethoprim/Sulfamethoxazole did not exhibit an inhibitory activity in 19 milk samples.