Etiologic Agent in different phases of lactation in cows producing milk for human consumption in the region of Imperatriz – Ma

Abstract

This study aimed to record the predominant etiologic agents of microorganism sensitivity to bovine mastitis in farm animals producing milk for human consumption and the different stages of infection from it. Milk samples were collected at the first milking and before it was done in each quarter of the rapid test California Mastitis Test, after which his result was taken for the new sample lactocultura and sensitivity testing to antibiotics. The samples were conditioned in a thermal box and led the multidisciplinary laboratory animal biology at the State University of Maranhão. Sample of milk was 0.5 mL and added to test tubes with 4.5 mL of Brain Heart Infusion (BHI) for dilutions up to 10 ³. Then they were placed in the incubator for 24 hours at 37 ° C. After 24 hours of emissions, the serial dilution 10 ³ milk in BHI (1mL) was transferred to Petri dishes containing agar specific for the growth of Staphylococcus sp, and the plates were placed in the incubator for 24 hours at 37° C for growth of colonies, microorganisms were isolated in specific agar and identified by means of differential staining of Gram and catalase production, performed in a slide, adding to a colony, 0.2 mL of H2O2 (hydrogen peroxide) 3%. The proof of the sensitivity strains of Staphylococcus spp isolated from milk samples were performed by using disks impregnated with antibiotics. The strains were grown in test tubes containing BHI and incubated at 37 ° C for 24 hours. After incubation, a swab moistened in broth was cultivated and sown in Petri dishes containing Mueller-Hinton agar. The antibiotics used in the tests were: Penicillin G (PEN 10), Chloramphenicol (CLO 30), cephalothin (CFL 30) and amikacin (AMI 30), which showed greater sensitivity to cephalothin active principle with an inhibition halo of 3.4 cm in diameter on average followed by Chloramphenicol at 3.0 cm in diameter, the Amikacin with 2.0 cm and finally diameter penicillin G with a halo of bacterial inhibition of only 1.6 cm in diameter. Cows in second lactation had a high rate of contamination was detected and clinical mastitis in 73% of cows tested and index of bacterial resistance to penicillin G.