IDENTIFICATION AND SUSCEPTIBILITY TO ANTIBIOTICS OF BACTERIA ISOLATED FROM MASTITIS MILK FROM THE NORTHERN MESOREGION OF THE STATE OF RIO DE JANEIRO

Milk production is one of the main activities of Brazilian livestock farming. Among the diseases that cause the greatest economic losses to producers, mastitis is the most recurrent. 805 cows were tested using the “California Mastitis Test” (CMT) on 54 farms in the northern mesoregion of the State of Rio de Janeiro. 45.96% (370) tested positive for subclinical mastitis. Milk samples were then collected and subjected to culture and identification of microorganisms according to routine laboratory tests, and an antibiogram was performed shortly thereafter. In 28.4% (105) of the samples, Staphylococcus aureus was identified, followed by 25.1% (93) Streptococcus spp., 10.8% (40) Streptococcus agalactiae, Staphylococcus spp., 8.4% (31), 7.8% (29) Corynebacterium bovis, 0.8% (3) Streptococcus sanguis, 23.2% (86) of the plates with culture medium showed no growth. The antibiogram of 105 strains of Staphylococcus aureus, 83.8% (88) demonstrated resistance to penicillin, it was also observed that 24.7% (26) were resistant to tetracycline. Of the 40 strains of Streptococcus agalactiae, 57.5% (23) were resistant to tetracycline, 18 (45%) were resistant to enrofloxacin and 11 (27.5%) were resistant to gentamicin. The bacteria Staphylococcus aureus, Staphylococcus spp. and Streptococcus agalactiae were the most isolated and showed resistance to antibiotics. These results are of concern for both animal and human health, since Staphylococcus aureus in particular can infect humans.