Increased carriage of resistant non-pneumococcal alpha-hemolytic streptococci after antibiotic therapy

Area of Science:

• Microbiology
• Pediatrics
• Infectious Diseases

Background:

• Acute otitis media (AOM) is a common childhood infection often treated with antibiotics.
• The nasopharyngeal microbiome plays a crucial role in respiratory health and susceptibility to infections.
• Understanding the impact of antibiotic therapy on bacterial colonization is essential for managing AOM and antibiotic resistance.

Purpose of the Study:

• To compare the colonization and antibiotic resistance rates of non-pneumococcal alpha-hemolytic streptococci (AHS) and Streptococcus pneumoniae in children undergoing antibiotic treatment for AOM.
• To investigate the effect of amoxicillin/clavulanate versus azithromycin on the nasopharyngeal carriage of these streptococcal species.

Main Methods:

• A randomized controlled trial involving children aged 6 months to 6 years diagnosed with AOM.
• Participants received either amoxicillin/clavulanate or azithromycin for 10 days.
• Nasopharyngeal swabs were collected before, and at 2 weeks and 2 months after antibiotic therapy for bacterial identification and susceptibility testing.

Main Results:

• Antibiotic therapy significantly increased the nasopharyngeal carriage rate of non-pneumococcal AHS from 14% to 32% at 2 weeks (P =.02).
• In contrast, the carriage of Streptococcus pneumoniae decreased from 51% to 27% at 2 weeks (P =.002).
• The prevalence of penicillin-resistant AHS strains rose from 9% to 36% by 2 months post-treatment.

Conclusions:

• Amoxicillin/clavulanate and azithromycin treatments disrupt the nasopharyngeal microbial balance, favoring the growth of non-pneumococcal AHS over S. pneumoniae.
• A significant proportion of the increased AHS isolates were multidrug-resistant.
• Drug-resistant AHS may serve as a reservoir for antibiotic resistance genes, potentially impacting S. pneumoniae resistance, which warrants further investigation.