title: IncI1 Plasmids Carrying Various blaCTX-M Genes Contribute to Ceftriaxone Resistance in Salmonella enterica Serovar Enteritidis in China.
abstract: Resistance to extended-spectrum β-lactams in Salmonella, in particular, in serotypes such as Salmonella enterica serovar Enteritidis that are frequently associated with clinical infections, is a serious public health concern. In this study, phenotypic characterization of 433 clinical S. Enteritidis strains obtained from a nationwide collection of the Chinese Center for Disease Control and Prevention during the period from 2005 to 2010 depicted a trend of increasing resistance to ceftriaxone from 2008 onwards. Seventeen (4%) of the strains were found to be resistant to ceftriaxone, 7% were found to be resistant to ciprofloxacin, and 0.7% were found to be resistant to both ciprofloxacin and ceftriaxone. Most of the ceftriaxone-resistant S. Enteritidis strains (15/17) were genetically unrelated and originated from Henan Province. The complete sequence of an IncI1 plasmid, pSE115, which belonged to a novel sequence type, was obtained. This 87,255-bp IncI1 plasmid was found to harbor a blaCTX-M-14 gene in a novel multidrug resistance region (MRR) within the tra locus. Although the majority of strains were also found to contain conjugative IncI1 plasmids with a size similar to that of pSE115 (∼90 kb) and harbor a variety of blaCTX-M group 1 and group 9 elements, the novel MRR site at the tra locus in pSE115 was not detectable in the other IncI1 plasmids. The findings from this study show that cephalosporin resistance in S. Enteritidis strains collected in China was mainly due to the dissemination of IncI1 plasmids carrying blaCTX-M, resembling the situation in which IncI1 plasmids serve as major vectors of blaCTX-M variants in other members of the Enterobacteriaceae.
authors.affiliation: State Key Laboratory of Chirosciences, Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong Shenzhen Key Laboratory for Food Biological Safety Control, Food Safety and Technology Research Centre, The Hong Kong PolyU Shenzhen Research Institute, Shenzhen, People's Republic of China.
authors.forename: Marcus Ho-yin
authors.identifier: http://orcid.org/0000-0001-5472-8337
authors.initials: MH
authors.lastname: Wong
authors.affiliation: State Key Laboratory for Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention (ICDC), Chinese Center for Disease Control and Prevention, Beijing, People's Republic of China.
authors.forename: Biao
authors.initials: B
authors.lastname: Kan
authors.affiliation: State Key Laboratory of Chirosciences, Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong Shenzhen Key Laboratory for Food Biological Safety Control, Food Safety and Technology Research Centre, The Hong Kong PolyU Shenzhen Research Institute, Shenzhen, People's Republic of China.
authors.forename: Edward Wai-chi
authors.initials: EW
authors.lastname: Chan
authors.affiliation: State Key Laboratory for Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention (ICDC), Chinese Center for Disease Control and Prevention, Beijing, People's Republic of China yanmeiying@icdc.cn sheng.chen@polyu.edu.hk.
authors.forename: Meiying
authors.initials: M
authors.lastname: Yan
authors.affiliation: State Key Laboratory of Chirosciences, Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong Shenzhen Key Laboratory for Food Biological Safety Control, Food Safety and Technology Research Centre, The Hong Kong PolyU Shenzhen Research Institute, Shenzhen, People's Republic of China yanmeiying@icdc.cn sheng.chen@polyu.edu.hk.
authors.forename: Sheng
authors.initials: S
authors.lastname: Chen
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D002443:Ceftriaxone / Q000494:pharmacology*; D018550:Cephalosporin Resistance / Q000187:drug effects / Q000235:genetics*; D002681:China; D003227:Conjugation, Genetic; D005798:Genes, Bacterial; D006801:Humans; D008826:Microbial Sensitivity Tests; D010957:Plasmids / Q000235:genetics*; D012477:Salmonella enteritidis / Q000187:drug effects* / Q000235:genetics* / Q000302:isolation & purification; D001618:beta-Lactamases / Q000235:genetics
chemical_list: D000900:Anti-Bacterial Agents; D002443:Ceftriaxone; D001618:beta-Lactamases