title: Characterisation of multidrug-resistant Shiga toxin-producing Escherichia coli cultured from pigs in China: co-occurrence of extended-spectrum β-lactamase- and mcr-1-encoding genes on plasmids.
abstract: Identification of Enterobacteriaceae harbouring the plasmid-mediated transferable colistin resistance gene mcr-1 presents a new challenge to public health. The aim of this study was to characterise multidrug-resistant Shiga toxin-producing Escherichia coli (STEC) harbouring the mcr-1 gene on plasmids cultured from pigs in China. Using CHROMagar™ ECC plates combined with stx gene detection by PCR, 93 STEC were recovered from 326 faecal, 351 small intestine content and 326 colon content samples taken from healthy pigs in 2011 and 2012 in China. This study, in which ten colistin-resistant isolates with minimum inhibitory concentrations (MICs) of 8-12 mg/L were identified and found to be positive by PCR for the mcr-1 gene, is a follow-up to an earlier investigation. Plasmid profiling by S1-nuclease digestion followed by pulsed-field gel electrophoresis (PFGE) identified several high-molecular-weight plasmids and these were typed by PCR-based replicon typing (PBRT). Two of the ten isolates, namely STEC-CQ09 (O116:H11/CC23/ST88) and CQ10 (O2:H32/ST3628), were selected for further study as described in this report.
authors.affiliation: Key Laboratory of Food Safety Risk Assessment, Ministry of Health, China National Center for Food Safety Risk Assessment, Beijing, China.
authors.forename: Li
authors.initials: L
authors.lastname: Bai
authors.affiliation: UCD-Centre for Food Safety, School of Public Health, Physiotherapy and Sports Science, University College Dublin, Belfield, Dublin 4, Ireland.
authors.forename: Daniel
authors.initials: D
authors.lastname: Hurley
authors.affiliation: Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, State Key Laboratory for Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Changping, Beijing, China.
authors.forename: Juan
authors.initials: J
authors.lastname: Li
authors.affiliation: Zhejiang Provincial Center for Disease Control and Prevention, Zhejiang, China.
authors.forename: Qiong
authors.initials: Q
authors.lastname: Meng
authors.affiliation: College of Veterinary Medicine, Northwest A&F University, No. 22 Xinong Road, Yangling, Shaanxi 712100, China.
authors.forename: Juan
authors.initials: J
authors.lastname: Wang
authors.affiliation: Key Laboratory of Food Safety Risk Assessment, Ministry of Health, China National Center for Food Safety Risk Assessment, Beijing, China; UCD-Centre for Food Safety, School of Public Health, Physiotherapy and Sports Science, University College Dublin, Belfield, Dublin 4, Ireland. Electronic address: sfanning@ucd.ie.
authors.forename: Séamus
authors.initials: S
authors.lastname: Fanning
authors.affiliation: Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, State Key Laboratory for Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Changping, Beijing, China. Electronic address: xiongyanwen@icdc.cn.
authors.forename: Yanwen
authors.initials: Y
authors.lastname: Xiong
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D002681:China; D003091:Colistin / Q000494:pharmacology; D003106:Colon / Q000382:microbiology; D024881:Drug Resistance, Bacterial; D016521:Electrophoresis, Gel, Pulsed-Field; D004927:Escherichia coli Infections / Q000382:microbiology / Q000662:veterinary*; D029968:Escherichia coli Proteins / Q000235:genetics*; D005243:Feces / Q000382:microbiology; D007421:Intestine, Small / Q000382:microbiology; D008826:Microbial Sensitivity Tests; D058889:Molecular Typing; D010957:Plasmids / Q000032:analysis*; D016133:Polymerase Chain Reaction; D054323:Shiga-Toxigenic Escherichia coli / Q000235:genetics* / Q000302:isolation & purification*; D013552:Swine / Q000382:microbiology*; D001618:beta-Lactamases / Q000235:genetics*
chemical_list: D000900:Anti-Bacterial Agents; D029968:Escherichia coli Proteins; C000614037:MCR-1 protein, E coli; D001618:beta-Lactamases; D003091:Colistin
keywords: China; Colistin resistance; Food-producing animals; STEC; Shiga toxin-producing Escherichia coli; mcr-1