Related Experiment Video

Updated: Jun 26, 2026

Gastric Mucosa Quantitative Polymerase Chain Reaction Analysis for Detecting Helicobacter pylori and Antibiotic Resistance
05:23

Gastric Mucosa Quantitative Polymerase Chain Reaction Analysis for Detecting Helicobacter pylori and Antibiotic Resistance

Published on: March 7, 2025

Erythromycin resistance in Streptococcus pyogenes and macrolide consumption in a central Italian region

F Montagnani1, L Stolzuoli, L Croci

  • 1Clinic and Laboratory of Infectious Diseases, Molecular Biology Department, University of Siena, Ospedale Le Scotte, Piano 0 lotto IV, Viale Bracci 16, Siena, Italy. montagnani2@unisi.it

Infection
|January 13, 2009
PubMed
Abstract

Insights

Macrolide resistance in Streptococcus pyogenes decreased significantly in Italy. Once-daily macrolide use correlated with increased resistance, suggesting selective pressure from long-acting antibiotics.

Area of Science:

  • Microbiology
  • Epidemiology
  • Pharmacology

Background:

  • Investigated macrolide resistance in Streptococcus pyogenes in central Italy (2001-2006).
  • Examined the correlation between antibiotic consumption and resistance fluctuations.

Purpose of the Study:

  • To determine macrolide resistance trends in S. pyogenes.
  • To assess the relationship between macrolide consumption patterns and resistance rates.

Main Methods:

  • Tested macrolide and lincosamide susceptibility of 1,419 S. pyogenes isolates using the Kirby Bauer method.
  • Evaluated macrolide consumption (defined daily dose/1,000 inhabitants/day).
  • Used Spearman's correlation to assess associations between resistance and macrolide use (pooled, once, twice, or thrice daily).

Main Results:

  • 320 strains (22.6%) exhibited erythromycin resistance (11.4% M phenotype, 11.2% MLS phenotype).
  • Erythromycin resistance significantly decreased from 28.1% (2001) to 15.6% (2006) (p < 0.01).
  • No significant correlation found between overall macrolide consumption and resistance; however, a significant correlation existed between resistance rates and once-daily macrolide use in the preceding 6 months (r = 0.747, p = 0.008).

Conclusions:

  • The study highlights a significant decrease in macrolide resistance over time.
  • Once-daily macrolide regimens, potentially due to long-acting agents, showed a selective pressure effect on S. pyogenes resistance.
  • Local epidemiology can be influenced by specific antibiotic usage patterns within short timeframes.

Related Concept Videos

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...
Clinical Significance of Antibiotic Resistance01:25

Clinical Significance of Antibiotic Resistance

Methicillin-resistant Staphylococcus aureus (MRSA) presents a critical public health threat, arising from its capacity to resist β-lactam antibiotics due to acquisition of the mecA gene within the staphylococcal cassette chromosome mec (SCCmec). This gene encodes penicillin-binding protein 2a (PBP2a), which impairs binding efficacy of methicillin and other β-lactams. MRSA has evolved into distinct clonal lineages impacting humans and animals alike, reinforcing its significance within the One...
Development of Antibiotic Resistance01:30

Development of Antibiotic Resistance

Antibiotic resistance is a major public health concern that arises when bacteria evolve mechanisms to withstand the effects of antibiotic treatments. This resistance can be intrinsic, acquired through genetic mutations, or transferred between bacteria via horizontal gene transfer. The development of antibiotic resistance poses significant challenges in treating bacterial infections and necessitates ongoing research to develop new therapeutic strategies.Intrinsic resistance occurs when bacterial...
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...
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...
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...