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Macrolide and Clindamycin Resistance in Group a Streptococci Isolated From Children With Pharyngitis

Gregory P DeMuri1, Alana K Sterkel, Phillip A Kubica

  • 1From the *Department of Pediatrics, University of Wisconsin School of Medicine and Public Health, †Department of Pathology and Laboratory Medicine, University of Wisconsin School of Medicine and Public Health, ‡Department of Pathology and Laboratory Medicine, University of Wisconsin, and §Department of Medicine, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin.

The Pediatric Infectious Disease Journal
|December 1, 2016
PubMed

Insights

Group A Streptococcus (GAS) pharyngitis treatment faces challenges due to macrolide resistance. A 5-year study in Wisconsin found 15% of GAS strains resistant to azithromycin, indicating a need for careful antibiotic selection.

Area of Science:

  • Pediatric infectious diseases
  • Microbiology
  • Clinical pharmacology

Background:

  • Group A Streptococcus (GAS) causes significant pediatric pharyngitis.
  • Macrolide antibiotics like azithromycin are commonly used for GAS pharyngitis.
  • Emerging antibiotic resistance necessitates monitoring treatment efficacy.

Purpose of the Study:

  • To determine macrolide resistance rates of GAS in a primary care setting.
  • To analyze trends in resistance over a 5-year period.
  • To discuss implications for clinical treatment decisions.

Main Methods:

  • Throat swabs collected from children with pharyngitis (May 2011-May 2015).
  • GAS identification via throat culture.
  • Erythromycin and clindamycin susceptibility testing using Kirby-Bauer disk diffusion.
  • Detection of inducible macrolide resistance (D-test).

Main Results:

  • 143 GAS isolates identified.
  • 15% of GAS isolates showed nonsusceptibility to erythromycin and clindamycin.
  • Inducible resistance (D-test positive) found in 12% of isolates.
  • No significant change in resistance rates over the study period.

Conclusions:

  • Consistent macrolide nonsusceptibility rates observed in GAS pharyngitis.
  • Azithromycin use should be restricted to penicillin-allergic patients.
  • Susceptibility testing is crucial when prescribing macrolides for GAS pharyngitis.

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