From 154 food samples, including vegetables (lettuce), milk and meals served at school it was possible to isolate and identify 400 Gram negative bacilli distributed among 339 enteric bacteria (Escherichia, Shigella, Citrobacter, Klebsiella, Enterobacter, Serratia and Proteus) and other 61 non enteric bacilli (Acinetobacter, Flavobacterium, Aeromonas and Pseudomonas). Submitting this cultures to the drugs sulfadiazine (Su), streptomycin (Sm), tetracycline (Tc), chloramphenicol (Cm), kanamycin (Km), ampicillin (Ap), nalidixic acid (Nal) and gentamycin (Gm) it was observed only six stocks susceptible to all drugs and total sensibility to Gm. Among enteric bacteria the profiles Su (27,6%) and Su-Ap (39,6%) predominated, while for the non enteric bacilli percentages of 18.0 for Ap and 9.8 for Su-Ap were detected. Aiming to better characterization of resistance, experiments of conjugation were made with standard strains of Escherichia coli K 12. Great concern was raised by the recognition of these cultures due to the elevated R+ taxes for the enteric bacilli that were close to 90% (milk and food at school) and about 70% in relation to lettuce.