Related Experiment Video

Updated: Aug 18, 2026

Forward Genetic Approaches in Chlamydia trachomatis
09:03

Forward Genetic Approaches in Chlamydia trachomatis

Published on: October 23, 2013

Clonal spread of pediatric isolates of ciprofloxacin-resistant, emm type 6 Streptococcus pyogenes

Rodrigo Alonso1, Estibaliz Mateo, Marc Galimand

  • 1Departamento de Inmunología, Microbiología y Parasitología, Facultad de Farmacia, Universidad del País Vasco, Paseo de la Universidad, 7 01006-Vitoria-Gasteiz, Spain. oipalmor@vc.ehu.es

Journal of Clinical Microbiology
|May 6, 2005
PubMed

Insights

Streptococcus pyogenes isolates resistant to ciprofloxacin showed a specific mutation in the parC gene. This finding is crucial for understanding fluoroquinolone resistance in this bacterium.

Area of Science:

  • Microbiology
  • Genetics
  • Infectious Diseases

Background:

  • Emerging fluoroquinolone resistance in Streptococcus pyogenes poses a significant public health threat.
  • Understanding the genetic basis of this resistance is critical for effective treatment strategies.

Purpose of the Study:

  • To investigate the molecular mechanisms of ciprofloxacin resistance in community-acquired Streptococcus pyogenes isolates.
  • To identify specific genetic mutations associated with reduced susceptibility to fluoroquinolones.

Main Methods:

  • Analysis of 24 Streptococcus pyogenes isolates exhibiting ciprofloxacin resistance.
  • Sequencing of quinolone resistance-determining regions (QRDRs) in the gyrA and parC genes.
  • Pulsed-field gel electrophoresis (PFGE) for strain typing.

Main Results:

  • All 24 isolates were resistant to ciprofloxacin but susceptible to levofloxacin, gatifloxacin, and moxifloxacin.
  • A T/G mutation in the parC gene, resulting in a Ser79Ala substitution in the ParC protein, was identified in all resistant isolates.
  • The majority of isolates belonged to emm type 6, with 18 being indistinguishable and 2 closely related by PFGE.

Conclusions:

  • The identified parC gene mutation (Ser79Ala) is strongly associated with ciprofloxacin resistance in Streptococcus pyogenes.
  • This specific mutation may confer cross-resistance to certain fluoroquinolones while maintaining susceptibility to others.
  • The genetic homogeneity of the emm type 6 isolates suggests a potential clonal spread of this resistant strain.

More Related Videos

Constructing Mutants in Serotype 1 Streptococcus pneumoniae strain 519/4306:06

Constructing Mutants in Serotype 1 Streptococcus pneumoniae strain 519/43

Published on: September 11, 2020

Related Concept Videos

Streptococcal Pharyngitis01:27

Streptococcal Pharyngitis

Streptococcal pharyngitis, commonly known as “strep throat,” is an acute infection of the oropharyngeal tissues caused by the Gram‑positive Group A Streptococcus (Streptococcus pyogenes). Transmission occurs primarily through respiratory droplets expelled during coughing, sneezing, or talking.Mechanisms of Host Entry and Immune EvasionUpon entering the host, S. pyogenes adheres to the mucosal epithelial cells of the pharynx via surface proteins, notably lipoteichoic acid and the antiphagocytic...
Bacterial Gastroenteritis01:18

Bacterial Gastroenteritis

Bacterial gastroenteritis, characterized by diarrhea, abdominal cramps, and vomiting, is often caused by ingestion of contaminated food or water and is frequently associated with pathogenic Escherichia coli strains. These microbes exploit two principal mechanisms to inflict disease.Shiga toxin–producing E. coli, also referred to as STEC—notably O157:H7—release Shiga toxins that target ribosomes, blocking protein synthesis. The B subunit of the toxin binds the host glycolipid receptor...