Erythromycin resistance in Streptococcus pyogenes in Italy

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M Bassetti1, G Manno, A Collidà

  • 1Infectious Diseases Department, University of Genoa, G. Gaslini Children's Hospital, Genoa, Italy. mattba@tin.it

Emerging Infectious Diseases
|April 11, 2000
PubMed

Insights

Macrolide resistance in Streptococcus pyogenes impacts treatment success for acute pharyngitis in children. Erythromycin-resistant strains showed lower eradication rates with clarithromycin, indicating treatment failure.

Area of Science:

  • Pediatric infectious diseases
  • Microbiology
  • Pharmacology

Background:

  • Acute pharyngitis is a common childhood illness.
  • Streptococcus pyogenes is a primary bacterial cause of acute pharyngitis.
  • Antibiotic resistance, particularly to macrolides, is a growing concern.

Purpose of the Study:

  • To investigate the prevalence of macrolide resistance in Streptococcus pyogenes causing acute pharyngitis in Italian children.
  • To evaluate the clinical effectiveness of clarithromycin in treating S. pyogenes infections based on macrolide susceptibility.
  • To identify factors associated with treatment failure.

Main Methods:

  • Prospective study design.
  • Isolates of Streptococcus pyogenes collected from children with acute pharyngitis.
  • Macrolide susceptibility testing performed on bacterial isolates.
  • Clinical outcomes assessed following clarithromycin treatment.

Main Results:

  • 38.3% of 180 Streptococcus pyogenes isolates were resistant to macrolides.
  • Clarithromycin eradicated S. pyogenes in 63.1% of patients with erythromycin-resistant strains (n=19).
  • Eradication rates were higher (88%) in patients with erythromycin-susceptible strains (n=25).
  • Constitutive macrolide resistance phenotype correlated with treatment failure.

Conclusions:

  • Macrolide resistance in Streptococcus pyogenes is prevalent in Italian children with acute pharyngitis.
  • Clarithromycin effectiveness is significantly reduced in the presence of erythromycin-resistant S. pyogenes.
  • The constitutive-resistant phenotype is a predictor of macrolide treatment failure in pediatric pharyngitis.

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