Aislamiento de bacterias gram positivas de leche cruda con residuos de antimicrobianos

isolation of gram-positive bacteria from raw milk with antimicrobial residues. two hundred samples of raw milk were collected at the receiving plants located in three areas of high milk production in zulia state, venezuela. the ctt test and trial disk were used in order to detect the presence of antimicrobials. the positive samples were inoculated in tripticase soy broth, human blood agar and manitol salt agar in order to isolate gram-positive bacterias. the identification of species was performed through biochemical tests. it was found that 45 samples (22,5%) of analyzed milk contained antimicrobials, and bacterial growth was obtained in 35 of them. 100 strains were isolated namely: 44 staphylococcus, 19 streptococcus, 17 enterococcus, 9 bacillus, 4 micrococcus, corynebacterium and 3 lactococcus. the most frecuently isolate specie was s. aureus, the main producing agent of bovine mastitis in zulia state, a microorganism frequently associated in the country to food-borne intoxications, associated to cheese processed from raw milk. it is recommended to apply control programs for the of antibiotics