Pathogens in the Nasopharynx Before and After Antibiotic Treatment for Acute Otitis Media.

BACKGROUND: Limited data exist on whether the timing or duration of treatment for acute otitis media (AOM) affects nasopharyngeal carriage. We studied the eradication of pathogens (Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis) in relation to timing (immediate vs. delayed) and duration (5 vs. 10 days) of antibiotic treatment. METHODS: A secondary analysis of 3 randomized clinical trials: the Turku antibiotic versus placebo trial, the Pittsburgh antibiotic versus placebo trial and the Pittsburgh 5- versus 10-day trial (ClinicalTrials.gov registration numbers NCT00299455, NCT00377260 and NCT01511107, respectively). We investigated the change in AOM pathogen colonization rate in relation to timing (immediate vs. delayed antibiotic initiation) and duration (5 vs. 10 days) of antibiotic treatment for AOM. We included children aged 6-35 months with AOM who had nasopharyngeal samples collected both before and after treatment. RESULTS: Antibiotic treatment with amoxicillin-clavulanate significantly reduced the carriage of S. pneumoniae and M. catarrhalis but had very little effect on the carriage of H. influenzae. The timing of treatment did not affect the eradication rates of nasopharyngeal pathogens. Antibiotic treatment eradicated S. pneumoniae and M. catarrhalis in 78% (95% confidence interval [CI], 72-83) and 85% (95% CI, 72-95) of cases, while H. influenzae was eradicated in only 20% (95% CI, 12-29) of cases. CONCLUSIONS: In most cases, H. influenzae carriage in the nasopharynx persisted despite antibiotic treatment with amoxicillin-clavulanate. This should be considered when choosing antibiotic treatment for children with a relapse of AOM.