Prevalence and Characterization of Monophasic Salmonella Serovar 1,4,[5],12:i:- of Food Origin in China

PLoS One. 2015 Sep 11;10(9):e0137967. doi: 10.1371/journal.pone.0137967. eCollection 2015.

Abstract

Salmonella enterica subsp. enterica serovar 1,4,[5],12:i:- is a monophasic variant of Salmonella Typhimurium, which has recently been recognized as an emerging cause of infection worldwide. This bacterium has also ranked among the four most frequent serovars causing human salmonellosis in China. However, there are no reports on its contamination in Chinese food. Serotyping, polymerase chain reaction, antibiotic resistance, virulotyping, and multilocus sequence typing (MLST) assays were used to investigate the prevalence of this serological variant in food products in China, and to determine phenotypic and genotypic difference of monophasic isolates and Salmonella Typhimurium isolated over the same period. Salmonella 1,4,[5],12:i:- was prevalent in various food sources, including beef, pork, chicken, and pigeon. The study also confirmed the high prevalence (53.8%) of resistance to ampicillin, streptomycin, sulfonamides, and tetracycline in Salmonella 1,4,[5],12:i:-, which was higher than that in Salmonella Typhimurium. Moreover, Salmonella 1,4,[5],12:i:- isolates in our study were different from Salmonella Typhimurium isolates by the absence of three plasmid-borne genes (spvC, pefA, and rck) and the presence of gipA in all isolates. All Salmonella 1,4,[5],12:i:- isolates demonstrated MLST pattern ST34. Genomic deletions within the fljBA operon and surrounding genes were only found in Salmonella 1,4,[5],12:i:- isolates, with all isolates containing a deletion of fljB. However, hin and iroB were identified in all Salmonella 1,4,[5],12:i:- isolates. Three different deletion profiles were observed and two of them were different from the reported Salmonella 1,4,[5],12:i:- clones from Spain, America, and Italy, which provided some new evidence on the independent evolution of the multiple successful monophasic clones from Salmonella Typhimurium ancestors. This study is the first report of Salmonella 1,4,[5],12:i:- in food products from China. The data are more comprehensive and representative, providing valuable information for epidemiological studies, risk management, and public health strategies.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anti-Bacterial Agents / pharmacology
  • China / epidemiology
  • Drug Resistance, Bacterial
  • Food Microbiology / statistics & numerical data*
  • Gene Deletion
  • Genes, Bacterial
  • Humans
  • Microbial Sensitivity Tests
  • Multilocus Sequence Typing
  • Polymerase Chain Reaction
  • Prevalence
  • Salmonella Food Poisoning
  • Salmonella Infections / epidemiology
  • Salmonella Infections / microbiology
  • Salmonella enterica / classification*
  • Salmonella enterica / drug effects
  • Salmonella enterica / genetics
  • Salmonella enterica / isolation & purification
  • Salmonella typhimurium / classification
  • Salmonella typhimurium / genetics
  • Salmonella typhimurium / isolation & purification
  • Serogroup
  • Virulence / genetics

Substances

  • Anti-Bacterial Agents

Grants and funding

The authors' study was supported by the Science and Technology Projects of Guangdong (2013B050800026, JMZ; 2014A040401055, XJY) and the Science and Technology Projects of Guangzhou (201300000074, JMZ). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.