Prevalence and Global Distribution of Bacterial Species Associated with Acute Otitis Media in Children: Systematic...

Background/Objectives: Acute otitis media (AOM) remains a leading cause of pediatric morbidity and a primary indication for antibiotic prescription worldwide. Given the potential for serious complications and the evolving landscape of antimicrobial resistance, up-to-date epidemiological data on causative bacteria are essential. This study aimed to assess the global prevalence of major bacterial pathogens in pediatric AOM and evaluate variations across geographic regions and temporal periods (pre-2000 vs. post-2000). Methods: A systematic search of PubMed, Embase, and Web of Science (1980-2025) was conducted to identify studies reporting middle ear fluid culture results in children (0-18 years) with AOM. Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, 45 studies encompassing 16,305 AOM episodes were included. Data were synthesized from North America, Europe, the Middle East, Asia, Oceania, and Africa. Pooled prevalence estimates and 95% confidence intervals (CIs) were calculated using a random-effects model, and heterogeneity was assessed via the I² statistic. Results: The overall pooled culture-positive rate was 66.6% (95% CI, 62.2-70.8%). Regional pooled estimates ranged from 56.1% in the Middle East (95% CI, 40.3-70.6%; underlying counts, 3776/10,652) to 77.5% in North America (95% CI, 68.2-84.7%; underlying counts, 1567/2125). Streptococcus pneumoniae was the most prevalent pathogen, with a pooled proportion of 29.0% (95% CI, 26.3-31.8%), followed by Haemophilus influenzae (22.3%; 95% CI, 19.3-25.6%) and Moraxella catarrhalis (4.6%; 95% CI, 3.4-6.1%). While S. pneumoniae remained the leading pathogen in most regions, H. influenzae showed marked geographic variability, peaking in the Middle East at 27.5% (95% CI, 17.0-41.2%; underlying counts, 2280/10,652) and reaching its lowest level in Asia at 13.5% (95% CI, 7.8-22.4%; underlying counts, 336/1854). The pooled culture-positive rate declined from 72.5% before 2000 (95% CI, 67.6-76.9%; underlying counts, 5769/8199) to 59.4% in 2000 and later (95% CI, 52.1-66.3%; underlying counts, 6661/15,707), although S. pneumoniae remained the predominant isolate in both periods. Conclusions:S. pneumoniae remains the primary bacterial driver of pediatric AOM globally. However, the observed geographic disparities and the temporal shift in pathogen prevalence following pneumococcal conjugate vaccine (PCV) introduction underscore the necessity for region-specific empirical antibiotic selection. These findings highlight the critical need for sustained microbiological surveillance to inform future vaccination and treatment strategies.