Validation of the T86I mutation in the gyrA gene as a highly reliable real time PCR target to detect Fluoroquinolone-resistant Campylobacter jejuni

BMC Infect Dis. 2020 Jul 16;20(1):518. doi: 10.1186/s12879-020-05202-4.


Background: Campylobacter jejuni is a leading cause of bacterial diarrhea worldwide, and increasing rates of fluoroquinolone (FQ) resistance in C. jejuni are a major public health concern. The rapid detection and tracking of FQ resistance are critical needs in developing countries, as these antimicrobials are widely used against C. jejuni infections. Detection of point mutations at T86I in the gyrA gene by real-time polymerase chain reaction (RT-PCR) is a rapid detection tool that may improve FQ resistance tracking.

Methods: C. jejuni isolates obtained from children with diarrhea in Peru were tested by RT-PCR to detect point mutations at T86I in gyrA. Further confirmation was performed by sequencing of the gyrA gene.

Results: We detected point mutations at T86I in the gyrA gene in 100% (141/141) of C. jejuni clinical isolates that were previously confirmed as ciprofloxacin-resistant by E-test. No mutations were detected at T86I in gyrA in any ciprofloxacin-sensitive isolates.

Conclusions: Detection of T86I mutations in C. jejuni is a rapid, sensitive, and specific method to identify fluoroquinolone resistance in Peru. This detection approach could be broadly employed in epidemiologic surveillance, therefore reducing time and cost in regions with limited resources.

Keywords: Antimicrobial resistance; Campylobacter jejuni; Ciprofloxacin; T86I; gyrA.

Publication types

  • Validation Study

MeSH terms

  • Amino Acid Substitution
  • Campylobacter Infections / diagnosis*
  • Campylobacter Infections / drug therapy
  • Campylobacter Infections / microbiology
  • Campylobacter jejuni / genetics*
  • Campylobacter jejuni / isolation & purification
  • Child
  • Ciprofloxacin / therapeutic use
  • DNA Gyrase / genetics*
  • DNA Mutational Analysis / methods
  • Diarrhea / diagnosis
  • Diarrhea / drug therapy
  • Diarrhea / microbiology
  • Drug Resistance, Bacterial / genetics*
  • Fluoroquinolones / therapeutic use*
  • Humans
  • Isoleucine / genetics
  • Microbial Sensitivity Tests
  • Peru
  • Point Mutation*
  • Real-Time Polymerase Chain Reaction / methods*
  • Threonine / genetics


  • Fluoroquinolones
  • Isoleucine
  • Threonine
  • Ciprofloxacin
  • DNA Gyrase