Molecular mechanisms of antimicrobial resistance and phylogenetic relationships of Salmonella enterica isolates from febrile patients in Yangon, Myanmar

Trans R Soc Trop Med Hyg. 2019 Oct 11;113(10):641-648. doi: 10.1093/trstmh/trz053.

Abstract

Background: Enteric fever is common in southeast Asia. However, there is little information on the circulating Salmonella enterica strains causing enteric fever in Myanmar.

Methods: We performed antimicrobial susceptibility testing and whole genome sequencing on S. enterica bloodstream isolates from febrile patients aged ≥12 y attending two hospitals in Yangon, Myanmar, from 5 October 2015 through 4 October 2016. We identified the serovar of S. enterica, determined antimicrobial susceptibility and the molecular mechanisms of resistance. We analysed phylogenetic relationships among Myanmar S. enterica isolates and those with isolates from neighbouring countries.

Results: Of 73 S. enterica isolated, 39 (53%) were serovar Typhi and 34 (47%) were Paratyphi A. All isolates were susceptible to ampicillin, chloramphenicol and trimethoprim-sulfamethoxazole but resistant to ciprofloxacin. We identified mutations in chromosomal genes gyrA, gyrB and parC as responsible for fluoroquinolone resistance. All S. enterica Typhi isolates were of 4.3.1 subclade (formerly known as H58) and formed two closely related genotypic clusters; both clusters were most closely related to isolates from India from 2012. All S. enterica Paratyphi A were lineage C, clade C4 and were closely related.

Conclusion: Our study describes currently circulating S. enterica serovars in Myanmar, the genetic basis of their antimicrobial resistance and provides a genotypic framework for epidemiologic study.

Keywords: Salmonella Paratyphi A; Salmonella Typhi; microbial; Myanmar; drug resistance; phylogeny; typhoid fever.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Anti-Bacterial Agents / therapeutic use
  • Child
  • Drug Resistance, Bacterial / genetics
  • Female
  • Humans
  • Male
  • Microbial Sensitivity Tests
  • Middle Aged
  • Myanmar
  • Phylogeny
  • Salmonella Infections / drug therapy*
  • Salmonella Infections / microbiology
  • Salmonella enterica / drug effects*
  • Salmonella enterica / genetics
  • Salmonella paratyphi A / drug effects
  • Salmonella paratyphi A / genetics
  • Salmonella typhi / drug effects
  • Salmonella typhi / genetics
  • Typhoid Fever / drug therapy
  • Typhoid Fever / microbiology
  • Whole Genome Sequencing
  • Young Adult

Substances

  • Anti-Bacterial Agents