title: Increasing prevalence of extended-spectrum cephalosporin-resistant Escherichia coli in food animals and the diversity of CTX-M genotypes during 2003-2012.
abstract: The aim of this study was to investigate the trends and the diversity of CTX-M types of extended-spectrum β-lactamase (ESBL) in Escherichia coli isolated from food animals in China over a ten-year period. From 2003 to 2012, 2815 E. coli isolates collected from diseased animals (chickens, pigs, and waterfowl) were screened for the prevalence of CTX-M genes. CTX-M-positive isolates were tested for their susceptibilities to 10 antimicrobial agents and the clonal relationship of CTX-M-producing E. coli isolates was also assessed. Overall, 677 (20.1%) of the 2815 E. coli isolates carried CTX-M genes. Eighteen different types of CTX-M ESBLs were identified, with CTX-M-14, CTX-M-55, and CTX-M-65 being the most dominant genotypes. The occurrence of CTX-M-producing E. coli increased significantly from 5.7% in 2003-2005 to 35.3% in 2009-2012 (p<0.0001). High genetic heterogeneities were observed in the CTX-M-producing E. coli isolates. Most CTX-M-producing strains were also resistant to other classes of antimicrobials. Compared to isolates carrying CTX-M-9 subgroup of ESBLs, isolates carrying CTX-M-1 subgroup ESBLs showed significantly higher resistance rates to ceftazidime, amikacin, and fosfomycin (p<0.01). The study reported the dramatic increase of CTX-M ESBLs in E. coli isolated from animals overtime in China. The increasing incidence of CTX-M-55 with high hydrolytic activity against ceftazidime and the widely spread co-resistance in CTX-M-producing isolates alarm the serious antimicrobial resistance situation in China and highlight the need for urgent control strategies to limit the dissemination of those resistant genes in China.
authors.affiliation: College of Veterinary Medicine, National Reference Laboratory of Veterinary Drug Residues (SCAU), South China Agricultural University, Guangzhou 510642, China.
authors.forename: Lili
authors.initials: L
authors.lastname: Rao
authors.affiliation: College of Veterinary Medicine, National Reference Laboratory of Veterinary Drug Residues (SCAU), South China Agricultural University, Guangzhou 510642, China.
authors.forename: Luchao
authors.initials: L
authors.lastname: Lv
authors.affiliation: College of Veterinary Medicine, National Reference Laboratory of Veterinary Drug Residues (SCAU), South China Agricultural University, Guangzhou 510642, China.
authors.forename: Zhenling
authors.initials: Z
authors.lastname: Zeng
authors.affiliation: Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong Special Administrative Region.
authors.forename: Sheng
authors.initials: S
authors.lastname: Chen
authors.affiliation: College of Veterinary Medicine, National Reference Laboratory of Veterinary Drug Residues (SCAU), South China Agricultural University, Guangzhou 510642, China.
authors.forename: Dandan
authors.initials: D
authors.lastname: He
authors.affiliation: College of Veterinary Medicine, National Reference Laboratory of Veterinary Drug Residues (SCAU), South China Agricultural University, Guangzhou 510642, China.
authors.forename: Xiaojie
authors.initials: X
authors.lastname: Chen
authors.affiliation: College of Veterinary Medicine, China Agricultural University, Beijing, China.
authors.forename: Congming
authors.initials: C
authors.lastname: Wu
authors.affiliation: College of Veterinary Medicine, China Agricultural University, Beijing, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Wang
authors.affiliation: College of Veterinary Medicine, National Reference Laboratory of Veterinary Drug Residues (SCAU), South China Agricultural University, Guangzhou 510642, China.
authors.forename: Tong
authors.initials: T
authors.lastname: Yang
authors.affiliation: College of Veterinary Medicine, National Reference Laboratory of Veterinary Drug Residues (SCAU), South China Agricultural University, Guangzhou 510642, China.
authors.forename: Peng
authors.initials: P
authors.lastname: Wu
authors.affiliation: College of Veterinary Medicine, National Reference Laboratory of Veterinary Drug Residues (SCAU), South China Agricultural University, Guangzhou 510642, China.
authors.forename: Yahong
authors.initials: Y
authors.lastname: Liu
authors.affiliation: College of Veterinary Medicine, National Reference Laboratory of Veterinary Drug Residues (SCAU), South China Agricultural University, Guangzhou 510642, China. Electronic address: jhliu@scau.edu.cn.
authors.forename: Jian-Hua
authors.initials: JH
authors.lastname: Liu
mesh_terms: D000818:Animals; D002511:Cephalosporins / Q000494:pharmacology*; D002681:China; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D004926:Escherichia coli / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics; D004927:Escherichia coli Infections / Q000453:epidemiology / Q000662:veterinary*; D005516:Food Microbiology; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology; D014644:Genetic Variation; D005838:Genotype; D015995:Prevalence; D001618:beta-Lactamases / Q000235:genetics / Q000378:metabolism*
chemical_list: D002511:Cephalosporins; D001618:beta-Lactamases
keywords: Animal reservoirs; CTX-M; Escherichia coli; Food animals; Fosfomycin