Antimicrobial-resistant Shigella infections from Iran: an overlooked problem?

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Mercedeh Tajbakhsh1, Lourdes García Migura, Mohammad Rahbar

  • 1Research Center for Gastroenterology and Liver Disease, Shahid Beheshti University, Medical Sciences, Tehran, Iran.

The Journal of Antimicrobial Chemotherapy
|February 21, 2012
PubMed
Abstract

Insights

Antimicrobial resistance is high in Iranian Shigella isolates, with new resistance genes like CTX-15, CMY-2, and qnrS1 emerging. These findings highlight the need for strategies to control the spread of resistant Shigella strains.

Area of Science:

  • Microbiology
  • Infectious Diseases
  • Genetics

Background:

  • Shigella is a significant cause of bacterial dysentery worldwide.
  • Antimicrobial resistance in Shigella poses a growing public health threat.
  • Limited data exists on antimicrobial resistance patterns and specific resistance genes in Shigella isolates from Iran.

Purpose of the Study:

  • To assess antimicrobial resistance levels in Shigella isolates from Iranian patients.
  • To identify genes responsible for cephalosporin resistance and plasmid-mediated quinolone resistance (PMQR).
  • To determine the genetic relatedness among Shigella isolates.

Main Methods:

  • Collected 44 Shigella isolates from Iranian patients (2008-2010).
  • Serotyped and determined minimum inhibitory concentrations (MICs).
  • Screened for cephalosporin resistance genes (blaCTX-M-15, blaCMY-2) and PMQR genes (qnrS1) using PCR.
  • Performed pulsed-field gel electrophoresis (PFGE) for genetic relatedness.

Main Results:

  • All isolates exhibited resistance to at least three classes of antimicrobials.
  • blaCTX-M-15 and blaCMY-2 genes were detected in Shigella sonnei and Shigella flexneri isolates.
  • The qnrS1 gene was identified in a Shigella flexneri isolate with ciprofloxacin resistance.
  • PFGE revealed low genetic diversity among Shigella sonnei isolates, suggesting an endemic clone.

Conclusions:

  • This study reports the first detection of extended-spectrum β-lactamase (ESBL)-producing, AmpC β-lactamase-producing, and PMQR Shigella in Iran.
  • The emergence of CTX-15, CMY-2, and qnrS1 genes is concerning and may impact shigellosis treatment.
  • Implementation of control strategies is crucial to minimize the spread of resistant Shigella strains.

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