Retrospective study on mastitis pathogens and their susceptibility to antibiotics in dairy farms of São Miguel (Azores) - association with herds´ holdings and management practices

Abstract

Bovine mastitis is the most prevalent disease in the production of dairy cattle worldwide. The present study aimed to characterize the main etiological agents of mastitis and the corresponding susceptibility patterns in 700 milk samples submitted to the Azorean regional laboratory in 2013. A questionnaire was also performed to determine the relationship of the isolated agents with different types of management practices and features of the dairy farms that produced the analyzed milk samples. Environmental agents were the ones more frequently isolated namely Escherichia coli and Streptococcus uberis. Contagious agents were less frequently isolated, of which Staphylococcus aureus was the most frequently isolated. Amoxicilin plus clavulanic acid was the antibiotic combination to which a larger number of agents was susceptible to. Some management practices were significantly associated with the isolation of certain bacteria in mastitic milk samples, namely the extension of the dry periods and the use of internal teat sealant.