ESCHERICHIA COLI RESISTENTE A ANTIMICROBIANOS ISOLADA DE BOVINOS E AVES / ANTIMICROBIAL DRUG RESISTANT Escherichia coli FROM CATTLE AND POULTRY

Os antimicrobianos utilizados em animais de producao nao atuam somente contra bacterias patogenicas, mas tambem contra bacterias comensais. Estas bacterias, especialmente aquelas populacoes do trato digestorio, sao constantemente expostas a acao dos antimicrobianos e consequentemente para sobreviverem desenvolvem resistencia. Estes micro-organismos sao ainda constantemente excretados no ambiente pelas fezes disseminando-se por outros ecossistemas. O presente trabalho teve como objetivo determinar os niveis de resistencia das populacoes bacterianas comensais em bovinos e aves saudaveis. Foram coletadas amostras de suabe retal de 45 bovinos leiteiros e suabe cloacal de 80 frangos de corte. Um total de 179 cepas de Escherichia coli (aves=91, bovinos=88) foram isolada e identificadas atraves de testes bioquimicos, bem como foram submetidas a testes de sensibilidade frente aos antimicrobianos (KONEMAN, 2008; NCCLS, 2003). Os isolados oriundos do trato digestorio das aves se mostraram mais resistentes aos antimicrobianos Eritromicina (96,7%), Ampicilina (84,6%), Estreptomicina (79,1%), Cefalotina (78,0%), Sulfa+Trimetoprim (68,1%) e Tetraciclina (67%). Enquanto que os isolados oriundos dos bovinos se mostraram mais resistentes a Eritromicina (97,7%), Cefalotina (95,5%), Ampicilina (73,9%) e Tetraciclina (38,6%). Quando comparada a resistencia entre as populacoes, os isolados oriundos das aves se mostraram mais resistentes a seis dos nove antimicrobianos testados (Ampicilina, Enrofloxacina, Estreptomicina, Neomicina, Sulfa+Trimetoprim e Tetraciclina), enquanto que os isolados oriundos dos bovinos apresentaram maior resistencia a 3 antimicrobianos (Cefalotina, Eritromicina e Gentamicina). As maiores diferencas de resistencia entre as populacoes foram observadas nos antimicrobianos Estreptomicina (aves: 79,1%, bovinos: 15,9%), Sulfa+Trimetoprim (aves: 68,1%, bovinos: 10,2%) e Tetraciclina (aves: 67,0%, bovinos: 38,6%). As populacoes de E. coli provenientes do trato digestorio das aves, se mostraram mais resistentes aos antimicrobianos que as populacoes oriundas dos bovinos. Alem disso, resultados demonstraram que as populacoes bacterianas comensais, podem ser um reservatorio genetico de resistencia antimicrobiana, podendo disseminar genes de resistencia a outras bacterias comensais e/ou patogenicas. SUMMARY The antimicrobials used in animal production not only act against pathogenic bacteria, but also against commensal bacteria. These bacteria, especially those populations of the digestive tract, which are constantly exposed to the action of antimicrobial, develop resistance to survive. These micro-organisms are still constantly excreted into the environment through feces spreading to other ecosystems. This study aimed to determine the levels of resistance of commensal bacterial populations in healthy cattle and poultry. Rectal swabs of 45 dairy cows and 80 cloacal swabs of broilers were collected. A total of 179 strains of Escherichia coli (91 birds and 88 cattle) were isolated and identified by biochemical tests and were tested for antimicrobial sensitivity (Koneman, 2008; NCCLS, 2003). The isolates from the digestive tract of birds were more resistant to the antibiotics erythromycin (96.7%), ampicillin (84.6%), streptomycin (79.1%), cephalothin (78.0%), trimethoprim+sulfa (68.1%) and tetracycline (67%). Furthermore, isolates from cattle were resistant to erythromycin (97.7%), cephalothin (95.5%), ampicillin (73.9%) and tetracycline (38.6%). The comparison of the resistance between populations showed that isolates from poultry were resistant to six of the nine antibiotics tested (ampicillin, Enrofloxacin, Streptomycin, Neomycin, Sulfa +Trimethoprim and Tetracycline), while the isolates from cattle showed greater resistance to 3 antibiotics (cephalothin, erythromycin and gentamicin). The greatest differences in resistance among populations were observed for Streptomycin (birds: 79.1%, cattle: 15.9%), sulfa+trimethoprim (birds: 68.1%, cattle: 10.2%) and tetracycline (birds: 67.0%, cattle: 38.6%). Populations of E. coli from the digestive tract of birds were more resistant to antimicrobials than the cattle populations. Additionally, results demonstrated that commensal bacterial populations can be a genetic reservoir of antimicrobial resistance that can spread resistant genes to other commensal and/or pathogenic bacteria.