Prevalence of mastitis and characterization of bacterial agents isolated from dairy herds in the microregion of Garanhuns, state of Pernambuco, Brazil.

Abstract

The aims of the present study were to establish the prevalence of bovine clinical and subclinical mastitis in dairy herds located in the microregion of Garanhuns in the state of Pernambuco, Brazil, determine antimicrobial susceptibility as well as identify antimicrobial resistance mechanisms and the production of biofilm in the bacterial groups isolated. The study was conducted in 10 herds of dairy cattle. The number of lactating cows per herd ranged from 22 to 90, totaling 477 animals. The prevalence of clinical and subclinical mastitis ranged from 2.7 to 18.2% and 38.9 to 76%, respectively. The bacterial genera isolated from the cows with mastitis were Staphylococcus, Streptococcus and Corynebacterium, with respective frequencies of 75.2, 17 and 2.6%. Among the species identified, the most frequent was Staphylococcus aureus in both clinical and subclinical mastitis. The antimicrobial susceptibility test of the isolates of Staphylococcus and Streptococcus revealed high rates of resistance to penicillin and tetracycline. Biofilm production was found in 95.4% of Staphylococcus genera whereas none of the samples presented efflux pumps. In conclusion, high rates of mastitis were found in the herds analyzed. Moreover, the etiological agents are bacteria that have the potential for biofilm production and are resistant to the main groups of antimicrobials used for the control of the disease, making bovine mastitis a challenge for veterinarians who work in the studied region.