Antibiotic Residues and Drug Resistant Bacteria in Beef, and Chicken Tissues

Chicken and bovine tissues from Hermosillo, Mexico, were analyzed for penicillin, tetracycline, streptomycin, chloramphenicol and gentamycin presence and concentration using a biological radio‐assay (Charm Test II). The samples were also analyzed for antiobiotic resistant bacteria. The concentrations found varied widely for each antibiotic family and were above FDA tolerance limits. Penicillin was not detected in the samples. Almost 50% of beef tissues presented two different antiobiotics, while three were commonly found in chicken. E. coli, S. epidermidis, H. alvei, E. agglomerans, P. mirabilis, Salmonella sp., Citrobacter, E. aerogenes; and S. aureus were among the most commonly found microorganisms. They mainly presented antibiotic resistance to penicillin, tetracycline and streptomycin.