Factors associated with acute otitis media in children due to penicillin intermediately resistant Streptococcus pneumoniae

ObjectivesThis study was conducted to analyze the association between recent antimicrobial use and acute otitis media (AOM) due to Streptococcus pneumoniae intermediately resistant to penicillin (PISP). The influence of drug resistance on the clinical course of AOM was also assessed.MethodsA retrospective cohort study was conducted in infants at Japanese Red Cross Medical Center, Tokyo. Children included in the study were under 24 months of age and diagnosed with AOM due to infection with S. pneumoniae between April 2002 and March 2007. Crude risk ratios (cRR) of PISP infection in cases with recent antibiotic use and other factors were obtained. The Mantel–Haenszel estimate was applied for the adjustment of cRR.ResultsOf 35 children, 13 had AOM due to penicillin-susceptible S. pneumoniae (PSSP) and 22 had AOM due to PISP. The adjusted risk ratio (aRR) of penicillin antibiotic use within 1 month was 1.99 (95% confidence interval (CI): 1.36–2.92), and the aRR of penicillin antibiotic use within 1 week was 1.93 (95% CI: 1.33–2.67). Recent use of penicillin antibiotics was an associated factor for AOM due to PISP. The clinical course was not clearly different between cases infected with PSSP and those with PISP.ConclusionRecent use of penicillin antibiotics might be a selective pressure for PISP.