Multiple transmissible genes encoding fluoroquinolone and third-generation cephalosporin resistance co-located in non-typhoidal Salmonella isolated from food-producing animals in China

Research output: Contribution to journalArticlepeer-review


  • Hong-Xia Jiang
  • Li Song
  • Ji Liu
  • Xiao-Hua Zhang
  • Yan-Na Ren
  • Wen-Hui Zhang
  • Jing-Yuan Zhang
  • Ya-Hong Liu
  • David O Ogbolu
  • Zhen-Ling Zeng

Colleges, School and Institutes

External organisations

  • College of Veterinary Medicine, National Reference Laboratory of Veterinary Drug Residues, South China Agricultural University (SCAU), Guangzhou 510642, China.
  • China Institute of Veterinary Drug Control, Beijing 100081, China.


The aim of this study was to identify genes conferring resistance to fluoroquinolones and extended-spectrum β-lactams in non-typhoidal Salmonella (NTS) from food-producing animals in China. In total, 31 non-duplicate NTS were obtained from food-producing animals that were sick. Isolates were identified and serotyped and the genetic relatedness of the isolates was determined by pulsed-field gel electrophoresis of XbaI-digested chromosomal DNA. Antimicrobial susceptibility was determined using Clinical and Laboratory Standards Institute methodology. The presence of extended-spectrum β-lactamase (ESBL) and fluoroquinolone resistance genes was established by PCR and sequencing. Genes encoded on transmissible elements were identified by conjugation and transformation. Plasmids were typed by PCR-based replicon typing. The occurrence and diversity of numerous different transmissible genes conferring fluoroquinolone resistance [qnrA, qnrD, oqxA and aac(6')-Ib-cr] and ESBLs (CTX-M-27 and CTX-M-14), and which co-resided in different isolates and serovars of Salmonella, were much higher than in European countries. Furthermore, different plasmids encoded fluoroquinolone resistance (ca. 6kb) and β-lactam resistance (ca. 63kb) and these co-resided in isolates with mutations in topoisomerase genes (gyrA and parC) giving very resistant Salmonella. The presence of multidrug-resistant bacteria in food-producing animals in countries that export foodstuffs suggests that global transfer of antibiotic resistances from country to country on food is possible.

Bibliographic note

Copyright © 2013 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.


Original languageEnglish
JournalInternational Journal of Antimicrobial Agents
Publication statusPublished - 17 Dec 2013