title: [Antimicrobial drugs in poultry nutrition: resistance levels in Escherichia coli].
abstract: In a battery experiment, a hundred of day old broiler chicks (Hubbard) divided into ten groups, were fed for eight weeks with 50, 75 or 100mg/Kg of ration of chloramphenicol and tetraciclyne; 40, 80 or 120mg/ 2 liters of drinking water of nitrofurazone. During three months defecated feces from each bird were sampled and analysed at intervals of 15 days for the isolation of Escherichia coli strains which were submitted to the determination of drug resistance. The results showed that utilization of antimicrobial drugs selected a resistant population of Escherichia coli at 300 microgram/ml of chloramphenicol tetraciclyne and 30 microgram/ml of nitrofurazone, during the dietary period. In addition the characterization of the R factor made by conjugation against apropriated recepient strains, demonstrated it's presence in some of the tested strains has only been noted the mobilization of the tetraciclyne marker.
mesh_terms: D000821:Animal Feed; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002645:Chickens / Q000254:growth & development*; D002701:Chloramphenicol / Q000008:administration & dosage; D004352:Drug Resistance, Microbial; D004926:Escherichia coli / Q000187:drug effects* / Q000302:isolation & purification; D005243:Feces / Q000382:microbiology; D009583:Nitrofurazone / Q000008:administration & dosage; D011815:R Factors; D013752:Tetracycline / Q000008:administration & dosage
chemical_list: D000900:Anti-Bacterial Agents; D002701:Chloramphenicol; D013752:Tetracycline; D009583:Nitrofurazone
vernacular_title: Drogas antimicrobianas em nutrição de aves: níveis de resistência em Escherichia coli.