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

Abstract

Milk production is one of the main activities of Brazilian livestock. Among the diseases that cause the most economic losses to the producer, mastitis is the most recurrent. 805 cows were tested by the "CaliforniaMastitis Test" (CMT) in 54 farms in the northern mesoregion of the State of Rio de Janeiro. 45.96% (370) tested positive for subclinical mastitis. Next, milk samples were collected and submitted to culture and identification of microorganisms according to routine laboratory tests and soon after, the antibiogram was performed. Staphylococcus aureus was identified in 28.4% (105) of the samples, 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 had no growth. The antibiogram of 105 strains of Staphylococcus aureus, 83.8% (88) were resistant to penicillin, and 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 demonstrated resistance to antibiotics. These results are of concern to both animal and human health, as Staphylococcus aureus can infect humans.