OBJECTIVES Acute otitis media (AOM) is a common childhood condition with viral and bacterial causation. Routine immunization programs currently include 7-valent Pneumococcal Conjugate Vaccine (PCV-7), associated with AOM reduction caused by Streptococcus pneumoniae only. The study objective was to conduct a systematic literature review to identify current microbiological picture associated with AOM. METHODS OVID (Medline, Current Content and International Pharmaceutical Abstract databases), EMBASE, Google and Google Scholar engines were searched with the following combination of key-words: “acute otitis media”, “bacteria$” and “vir$”. Eligible articles were in English, published between 1995 and 2008, and described studies of pediatric AOM patients with cultures for bacterial and viral isolates. RESULTS Of the 398 articles screened, 24 separate studies were included (range = 25-623 subjects). Based on a fixed-effects meta-analysis across all studies, pathogens isolated were more frequently bacterial (74%) than viral (19%). Compared with the 15 international studies, U.S. studies recorded a similar isolation rate for bacterial (73% vs. 74%) and higher isolation rate for viral pathogens (23% vs. 17%). Twenty-three studies included data on the specific bacterial pathogens cultured. Based on a fixed-effects meta-analysis of patients in these studies, S. pneumoniae and Haemophilus influenzae were isolated with similar frequency (35% vs. 36%) and Moraxella catarrhalis at 6%. Slightly higher isolation rates of M. catarrhalis (10%) and lower rates of H. influenzae (31%) were observed in U.S. patients, compared with international patients. CONCLUSIONS Bacterial pathogens are frequently associated with AOM in pediatric populations worldwide and were isolated 3-times more often than viral pathogens. S. pneumoniae and H. influenzae are the bacterial pathogens most commonly isolated in AOM cases, with nearly equal frequency. A vaccine that addresses more than one cause of AOM would be expected to greatly reduce the clinical and economic burden associated with this common condition.