A multiplex single nucleotide polymorphism typing assay for detecting mutations that result in decreased fluoroquinolone susceptibility in Salmonella enterica serovars Typhi and Paratyphi A

Yajun Song, Philippe Roumagnac, François Xavier Weill, John Wain, Christiane Dolecek, Camila J. Mazzoni, Kathryn E. Holt, Mark Achtman

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33 Citations (Scopus)

Abstract

Objectives: Decreased susceptibility to fluoroquinolones has become a major problem for the successful therapy of human infections caused by Salmonella enterica, especially the life-threatening typhoid and paratyphoid fevers. Methods: By using Luminex xTAG beads, we developed a rapid, reliable and cost-effective multiplexed genotyping assay for simultaneously detecting 11 mutations in gyrA, gyrB and parE of S. enterica serovars Typhi and Paratyphi A that result in nalidixic acid resistance (NalR) and/or decreased susceptibility to fluoroquinolones. Results: This assay yielded unambiguous single nucleotide polymorphism calls on extracted DNA from 292 isolates of Salmonella Typhi (NalR=223 and NalS=69) and 106 isolates of Salmonella Paratyphi A (NalR=24 and NalS=82). All of the 247 NalR Salmonella Typhi and Salmonella Paratyphi A isolates were found to harbour at least one of the target mutations, with GyrA Phe-83 as the most common one (143/223 for Salmonella Typhi and 18/24 for Salmonella Paratyphi A). We also identified three GyrB mutations in eight NalS Salmonella Typhi isolates (six for GyrB Phe-464, one for GyrB Leu-465 and one for GyrB Asp-466), and mutations GyrB Phe-464 and GyrB Asp-466 seem to be related to the decreased ciprofloxacin susceptibility phenotype in Salmonella Typhi. This assay can also be used directly on boiled single colonies. Conclusions: The assay presented here would be useful for clinical and reference laboratories to rapidly screen quinolone-resistant isolates of Salmonella Typhi and Salmonella Paratyphi A, and decipher the underlying genetic changes for epidemiological purposes.

Original languageEnglish
Article numberdkq175
Pages (from-to)1631-1641
Number of pages11
JournalJournal of Antimicrobial Chemotherapy
Volume65
Issue number8
DOIs
Publication statusPublished - 28 May 2010
Externally publishedYes

Keywords

  • DNA gyrase
  • Genotyping
  • Mechanisms of resistance
  • Salmonella

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