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High macrolide resistance in Streptococcus pyogenes strains isolated from children with pharyngitis in China

Xiaorong Liu1, Xuzhuang Shen, Hesheng Chang

  • 1Beijing Children's Hospital affiliated to Capital Medical University, Beijing 100045, China.

Pediatric Pulmonology
|April 11, 2009
PubMed
Abstract

Insights

Streptococcus pyogenes in Chinese children shows high macrolide resistance, primarily due to the ermB gene. This resistance may stem from widespread antibiotic overuse in China.

Area of Science:

  • Microbiology
  • Infectious Diseases
  • Antimicrobial Resistance

Background:

  • Streptococcus pyogenes (group A Streptococcus) is a common cause of pharyngitis in children.
  • Macrolide antibiotics are frequently used to treat S. pyogenes infections.
  • Rising antimicrobial resistance poses a significant public health threat.

Purpose of the Study:

  • To investigate macrolide resistance patterns in S. pyogenes from Chinese children.
  • To characterize the phenotypes and genotypes of macrolide-resistant S. pyogenes isolates.
  • To explore potential correlations between resistance and antibiotic usage.

Main Methods:

  • Collected 188 S. pyogenes isolates from children with pharyngitis in China.
  • Determined minimum inhibitory concentrations (MICs) for nine antibiotics.
  • Assessed macrolide resistance phenotypes using double-disk diffusion.
  • Amplified macrolide resistance genes (mefA, ermB, ermA) via PCR.

Main Results:

  • Over 95% of isolates exhibited macrolide resistance; 92% were tetracycline-resistant.
  • All isolates remained sensitive to penicillin, chloramphenicol, cefradine, and levofloxacin.
  • The constitutive Macrolide-Lincosamide-Streptogramin B (cMLS) phenotype was predominant (98.8%), associated with the ermB gene (98.2%).
  • No M-phenotype or mefA gene was detected.
  • High macrolide consumption from 2000-2006 was noted.

Conclusions:

  • The cMLS phenotype and the ermB gene are the primary mechanisms of macrolide resistance in S. pyogenes in this population.
  • High macrolide resistance rates in S. pyogenes are evident.
  • Overuse of macrolides in China may be linked to the observed high resistance rates.

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