title: Molecular Characterization of Plasmids Encoding CTX-M β-Lactamases and their Associated Addiction Systems Circulating Among Escherichia coli from Retail Chickens, Chicken Farms, and Slaughterhouses in Korea.
abstract: Extended-spectrum β-lactamases (ESBLs), particularly those of the CTX-M types, are the predominant resistance determinants of Escherichia coli that are rapidly spreading worldwide. To determine CTX-M types, E. coli isolates were collected from retail chickens (n = 390) and environmental samples from chicken farms (n = 32) and slaughterhouses (n = 67) in Korea. Fifteen strains harboring blaCTX-M genes were isolated from 358 E. coli isolates. The most common CTX-M type was eight of CTX-M-15, followed by six of CTX-M-1 and one of CTX-M- 14. The blaCTX-M genes were identified in the isolates from retail chickens (n = 9), followed by feces, water pipes, floors, and walls. Conjugations confirmed the transferability of the plasmids carrying blaCTX-M genes to the recipient E. coli J53 strain. Furthermore, eight addiction systems carried by the replicons in CTX-M types were confirmed. The dominant system was identified as ccdAB, vagCD, and pndAC in donor strains and transconjugants. The clonal relationship between the two strains carrying blaCTX-M genes indicates that E. coli may transmit from the farm to retail chickens, suggesting a possible public health risk. Our findings demonstrate that the detection of CTX-M types in E. coli isolates is important for tracking ESBL production in animals, and suggest linkage of multiple addiction systems in plasmids bearing blaCTX-M genes.
authors.affiliation: Laboratory of Food Safety and Evaluation, Department of Biotechnology, Korea University, Seoul 136-713, Republic of Korea.
authors.forename: Su-Jin
authors.initials: SJ
authors.lastname: Jo
authors.affiliation: Laboratory of Food Safety and Evaluation, Department of Biotechnology, Korea University, Seoul 136-713, Republic of Korea.
authors.forename: Gun-Jo
authors.initials: GJ
authors.lastname: Woo
mesh_terms: D000003:Abattoirs; D000383:Agriculture; D000818:Animals; D002645:Chickens / Q000382:microbiology*; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics*; D004927:Escherichia coli Infections / Q000382:microbiology / Q000635:transmission / Q000662:veterinary; D029968:Escherichia coli Proteins / Q000235:genetics*; D005243:Feces / Q000382:microbiology; D010957:Plasmids / Q000235:genetics* / Q000302:isolation & purification*; D011201:Poultry Diseases / Q000382:microbiology; D056910:Republic of Korea; D001618:beta-Lactamases / Q000235:genetics*
chemical_list: D029968:Escherichia coli Proteins; D001618:beta-Lactamases; C000602253:beta-lactamase CTX-M, E coli
keywords: Addiction systems; CTX-M types; Chicken farms; Escherichia coli; Retail chickens; Slaughterhouses