Related Experiment Video

Updated: Aug 15, 2026

High Throughput, Real-time, Dual-readout Testing of Intracellular Antimicrobial Activity and Eukaryotic Cell Cytotoxicity
09:09

High Throughput, Real-time, Dual-readout Testing of Intracellular Antimicrobial Activity and Eukaryotic Cell Cytotoxicity

Published on: November 16, 2016

Telithromycin activity is reduced by efflux in Streptococcus pyogenes

Rafael Cantón1, Annarita Mazzariol, María-Isabel Morosini

  • 1Servicio de Microbiología, Hospital Universitario Ramón y Cajal, Carretera. de Colmenar, Km 9.1, 28034-Madrid, Spain.

The Journal of Antimicrobial Chemotherapy
|February 12, 2005
PubMed
Abstract

Insights

Telithromycin can be pumped out of Streptococcus pyogenes by efflux mechanisms. The mef(A) gene is linked to this telithromycin efflux, impacting antibiotic effectiveness.

Area of Science:

  • Microbiology
  • Molecular Biology
  • Pharmacology

Background:

  • Streptococcus pyogenes is a significant human pathogen.
  • Antibiotic resistance, particularly efflux-mediated resistance, is a growing concern.
  • Telithromycin is a ketolide antibiotic used to treat S. pyogenes infections.

Purpose of the Study:

  • To determine if telithromycin is a substrate for efflux pumps in Streptococcus pyogenes.
  • To investigate the genetic basis of telithromycin resistance in S. pyogenes.

Main Methods:

  • Analysis of telithromycin Minimum Inhibitory Concentrations (MICs) in Italian and Spanish S. pyogenes strains.
  • Investigation of efflux mechanisms using radiolabeled [(3)H]telithromycin.
  • Detection of efflux pump genes, including mef(A) and erm(B).

Main Results:

  • Telithromycin MICs were significantly higher in strains expressing the mef(A) gene (M phenotype) compared to susceptible strains.
  • A distinct telithromycin efflux was observed in mef(A)-positive strains, but not in erm(B)-positive or susceptible strains.
  • An msr-like sequence was identified in strains exhibiting telithromycin efflux.

Conclusions:

  • Telithromycin is actively removed from S. pyogenes by efflux pumps.
  • The mef(A) gene is demonstrably involved in telithromycin efflux.
  • The complexity of S. pyogenes efflux systems suggests potential involvement of other genes in telithromycin resistance.

More Related Videos

System for Efficacy and Cytotoxicity Screening of Inhibitors Targeting Intracellular Mycobacterium tuberculosis09:57

System for Efficacy and Cytotoxicity Screening of Inhibitors Targeting Intracellular Mycobacterium tuberculosis

Published on: April 5, 2017

Assay Development for High-Throughput Drug Screening Against Mycobacteria07:50

Assay Development for High-Throughput Drug Screening Against Mycobacteria

Published on: October 25, 2024

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...
Mechanism of Antibiotic Resistance in MRSA01:25

Mechanism of Antibiotic Resistance in MRSA

Antibiotic resistance in bacteria arises when microorganisms evolve the ability to withstand drugs designed to kill them or inhibit their growth, rendering once-effective treatments useless. This phenomenon, driven by genetic change and selection under antibiotic exposure, poses a profound threat to modern medicine. Mechanisms include drug-inactivating enzymes (e.g., β-lactamases), efflux pumps that eject antibiotics, mutations altering antibiotic targets, decreased drug uptake, and acquisition...
Inhibitors of Gram-positive Cell Wall Synthesis01:23

Inhibitors of Gram-positive Cell Wall Synthesis

Bacterial cell walls are typically rigid structures composed mainly of peptidoglycan, a mesh-like polymer that provides mechanical strength and maintains cell shape. The synthesis of peptidoglycan is a crucial process in bacterial growth and serves as a primary target for many antibiotics.Mechanism of Action of Beta-Lactam AntibioticsBeta-lactam antibiotics, such as penicillin, inhibit peptidoglycan synthesis in actively growing cells. These antibiotics share a characteristic four-membered...
Inhibitors of Bacterial Protein Synthesis01:25

Inhibitors of Bacterial Protein Synthesis

Aminoglycosides constitute a highly potent class of bactericidal antibiotics that exert their antimicrobial effects by targeting the bacterial ribosome, specifically disrupting protein synthesis. These polycationic molecules consist of amino-modified sugars linked via glycosidic bonds to an aminocyclitol core such as 2-deoxystreptamine or streptamine. Their strong positive charges facilitate tight binding to the negatively charged phosphate backbone of ribosomal RNA (rRNA), primarily at the 16S...
Inhibitors of Bacterial DNA Synthesis01:28

Inhibitors of Bacterial DNA Synthesis

Bacterial pathogens depend on precise and efficient DNA replication to sustain infection. Two type II topoisomerases—DNA gyrase and topoisomerase IV—are critical to this process, as they resolve DNA supercoiling and unlink chromosomes during replication. Fluoroquinolones, synthetic derivatives of quinolones, exploit this mechanism by stabilizing the transient DNA–enzyme cleavage complex, preventing strand religation, and causing lethal double-strand breaks. These antibiotics are selectively...
Antiprotozoal Agents01:21

Antiprotozoal Agents

Leishmaniasis is a widespread parasitic disease caused by several Leishmania species. It affects millions of people each year and remains a major public health problem in endemic regions. First-line treatment relies on pentavalent antimonials, including meglumine antimoniate and sodium stibogluconate. Even so, how these drugs work has not been fully clear, especially their interaction with parasite-specific biochemical pathways. One key target is trypanothione reductase (TR), an enzyme that...