Impact of azithromycin on oropharyngeal carriage of Group A Streptococcus and nasopharyngeal carriage of macrolide-resistant Streptococcus pneumoniae

Julia Y. Morita, Emily Kahn, Terry Thompson, Leslye Laclaire, Bernard Beall, Giovanni Gherardi, Katherine L. O'Brien, Ben Schwartz

Research output: Contribution to journalArticle

Abstract

Background. Invasive group A streptococcal (GAS) infections are a cause of serious morbidity and high mortality. There is a need for a simple, effective antimicrobial regimen that could be used to prevent invasive GAS disease in high risk situations. To assess azithromycin as a chemoprophylactic agent, we evaluated its efficacy for eradication of oropharyngeal (OP) GAS and its impact on the nasopharyngeal (NP) colonization rate of macrolide-resistant Streptococcus pneumoniae. Methods. We obtained OP and NP swabs for GAS and pneumococcus culture, respectively, from 300 schoolmates of a child with an invasive GAS infection. GAS culture-positive students were treated with daily azithromycin (12 mg/kg/day) for 5 days. We obtained follow-up OP and NP swabs at 9 (Day 17) and 24 (Day 32) days posttreatment from those students identified as GAS carriers on Day 0 and determined macrolide susceptibility of GAS and pneumococcal isolates. Results. Of the 300 students swabbed 152 (50%) carried GAS in their oropharynx. On Day 17, efficacy of azithromycin for GAS eradication was 95% (140 of 147) for all students. NP colonization rates for pneumococci decreased from 46% (67 of 146) to 12% (17 of 144; P < 0.001) by Day 17 and to 20% (27 of 137; P < 0.001) by Day 32. The prevalence of erythromycin- resistant pneumococcal isolates increased from 2% (3 of 146) to 4% (6 of 144) by Day 17 and to 8% (11 of 137; P = 0.04) by Day 32. Conclusions. Azithromycin is an effective short course regimen for eradication of oropharyngeal GAS. However, azithromycin selected for macrolide-resistant strains of pneumococci. These findings highlight the importance of determining the appropriate circumstances for antimicrobial prophylaxis to prevent invasive GAS infections.

Original languageEnglish (US)
Pages (from-to)41-46
Number of pages6
JournalPediatric Infectious Disease Journal
Volume19
Issue number1
DOIs
StatePublished - Jan 2000

Keywords

  • Antimicrobial resistance
  • Carriage
  • Colonization
  • Group A Streptococcus
  • Macrolide
  • Streptococcus pneumoniae

ASJC Scopus subject areas

  • Pediatrics, Perinatology, and Child Health
  • Microbiology (medical)
  • Infectious Diseases

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