18D-11 |
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S.-H. KIM1, K.-W. Chang1, Y.-M. Tzou1, C.-I. Wei1, and H. An2. (1) Dept. of Nutritional Sciences, Oklahoma State Univ., 301 HES, Stillwater, OK 74078, (2) School of Pharmacy, Univ. of Southern California, 1985 Zonal Ave., B-4 Pharmaceutical Sciences Ctr., Los Angeles, CA 90089-9121 Routine use of antibiotics in agricultural and medical practices has resulted in widespread and development of horizontal transfer of antibiotic-resistance genes through mobile genetic elements, such as plasmids, transposons, and integrons. Therefore, increased multidrug-resistant bacteria and spread of antibiotic-resistant genes in food chains could be a public health concern. In this study to reveal the possible dissemination of antibiotic-resistance genes in food chains, the prevalent multidrug-resistant bacteria were isolated from animal farms and meat products and identified. A possibility of transmission of antibiotic-resistance genes to other bacterial species was evaluated. Bacteria were isolated from feces, water, and feeds collected from turkey, chicken, and cattle farms and retail meat products, such as ground turkey, ground beef, and chicken breast using MacConkey agar. Antibiotic-resistant bacteria were examined by Kirby-Bauer disc diffusion test and identified by using API 20E kit. The types of antibiotic resistance genes located in class 1 integrons and plasmids were determined by polymerase chain reaction assay and DNA sequencing. Plasmid harbored with antibiotic-resistant genes were transconjugated to antibiotic susceptible E. coli. Minimum inhibitory concentrations of antibiotics for the transconjugants and donor cells were then determined. Multidrug-resistant K. pneumoniae were frequently detected in test samples collected from animal farms and retail meat products. They were resistant to ampicillin, tetracycline, streptomycin, gentamycin, and kanamycin. Plasmid-mediated class 1 integron was detected as a carrier of aadA1 conferring resistance to streptomycin and spectinomycin. The isolates possessed blaSHV-1 and tetA conferring resistance to amplicillin and tetracycline, respectively. Horizontal transfer of these antibiotic-resistant genes to E. coli was demonstrated by transconjugation. Our study showed that multidrug-resistant K. pneumoniae prevalently distributed in animal farms and retail meat products. This bacterial species could serve as a reservoir of antibiotic-resistant genes and contribute to dissemination of these antibiotic-resistance genes to other bacterial species in food chains and environments.
Session 18D, Food Microbiology: General
2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana |