Persistence and dynamic structures of diverse cephalosporinase genes in nontyphoidal Salmonella in cross-sectional surveillance in Taiwan

Yuarn Jang Lee, Yu Chu Chang, I. Hui Lee, Kuo Hao Ho, Shiuh Bin Fang, Tsai Ling Lauderdale, Ting Wen Chen, Ku Chung Chen, Chih Hung Huang, Tzu Wen Huang*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Objectives: Nontyphoidal Salmonella (NTS) is a major foodborne pathogen causing from acute gastroenteritis to bacteraemia, particularly in paediatric and elderly patients. Antimicrobial resistance of NTS, especially resistance to extended-spectrum cephalosporins, has emerged over the past decades. Methods: Thirteen NTS isolates resistant to ceftriaxone or cefotaxime were collected from a teaching hospital in Taipei, and another three from a tertiary hospital, in New Taipei City, Taiwan, from September 2018 to December 2019. Ten other archived isolates from 2000 to 2017 were also obtained. Complete genomes of the 26 isolates were obtained. Serovars, sequence types, resistomes, genetic relatedness, and sequence comparison of plasmids were analyzed. Results: Serogroups B, C2 and E were significantly associated with ampicillin resistance. Over 90% of these 26 isolates are susceptible to carbapenems and colistin. Genomic epidemiology of these isolates shows that blaCMY-2-harbouring isolates in different serovars were prevalent over two decades, presumably resulting from highly mobile IncI1 plasmid harbouring blaCMY-2. One type of the IncI1 plasmids contained a mobile element, IS26, which might be involved in the acquisition of antimicrobial resistance genes. Two emerging serovars, S. Goldcoast ST358 harbouring blaCTX-M-55 on IncHI2 plasmids and S. Anatum ST64 harbouring blaDHA-1 on IncA/C2 plasmids persisted in Taiwan, possibly through the clonal spread. Integration of complete or partial plasmid sequences into host chromosomes or multiplications of the antimicrobial resistance genes also appears to be mediated by IS26, in the two emerging clones. Conclusion: The dynamic movement of cephalosporinase genes mediated by IS26 in NTS is of great concern.

Original languageEnglish
Article number106944
JournalInternational Journal of Antimicrobial Agents
Issue number4
StatePublished - Oct 2023


  • Amplification
  • Chromosome integration
  • Epidemiology
  • Foodborne pathogen
  • Insertion sequence
  • Whole-genome sequencing


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