Submitted to: Avian Diseases
Publication Type: Peer reviewed journal
Publication Acceptance Date: 6/26/2001
Publication Date: 10/1/2001
Citation: Hofacre, C.L., White, D.G., Maurer, J.J., Morales, C., Lobsinger, C., Jackson, C.R. 2001. Characterization of antibiotic-resistant bacteria in rendered animal products. Avian Diseases. V. 45. P. 953-961 Interpretive Summary: Rendered animal protein products intended for poultry consumption are potential sources of antimicrobial resistant bacteria on farms that do not use antimicrobials. Meat and bone meal, poultry meal, feather meal, and blended meal were all tested for the presence of gram-negative bacteria including Salmonella. All except feather meal contained gram- negative bacteria and both meat and bone meal and blended meal contained Salmonella as well. A large number of feed samples contained bacteria resistant to ampicillin, amoxicillin, clavulanic acid or cephalothin while few samples contained bacteria resistant to ciprofloxacin, kanamycin, or trimethoprim/sulfamethoxazole. Acinetobacter calcoaceticus, Citrobacter freundii, and Enterobacter cloacae were the most commonly isolated antibiotic resistant bacteria in feed ingredients. Isolates of C. freundii (6/8), E. cloacae (3/5), and E. coli were also found to contain class I integrons which suggest that the resistance is capable of dissemination to various other bacteria. Researchers as well as stakeholders in the antimicrobial resistance issues can use this information. For understanding potential sources where antimicrobial resistant bacteria can exist.
Technical Abstract: Antibiotics are used in food animal production to treat diseases and also to improve performance. Antibiotics are not used on all farms and antibiotic resistance is occasionally found on these farms. Rendered animal protein products are often included in poultry feeds and could potentially serve as a source of antibiotic resistant bacteria. One hundred sixty-five rendered animal protein products from cattle, poultry, and fish were aseptically collected from poultry feed mills. Fifty-five percent of the poultry meal samples had detectable levels of gram- negative bacteria ranging from 40 to 10,440 CFU/g of sample. Poultry meal and meat and bone meal had the greatest number of samples with bacteria resistant to 5 or more antibiotics. A high percentage of feed samples (85%) contained bacteria resistant to amoxicillin, ampicillin, clavulanic acid or cephalothin, while few samples contained bacteria resistant to ciprofloxacin, kanamycin, or trimethoprin/sulfamethoxazole. Acinetobacter calcoaceticus, Citrobacter freundii, and Enterobacter cloacae were the most commonly isolated antibiotic resistant bacteria. Isolation for Salmonella was also performed with 14% of the meat and bone meal samples containing Salmonella sp. Only one of the meat and bone meal isolates, S. livingstone, was resistant to 5 or more antibiotics. Many of the antibiotic resistant bacteria contained integrons, genetic elements that mediate multiple drug resistance.