Aspects of acute otitis media etiology and pathogenesis

Otitis media (OM) remains a major cause of morbidity worl­d­wide, representing one of the complications of up­per res­­pi­­ra­­to­­ry tract (URT) infections, especially in small chil­dren. The etiology of acute otitis media (AOM) can be viral, bac­te­rial, viral-bacterial or bacterial-bacterial co­in­fec­tions. The most common bacterial agents causing oti­tis media are Streptococcus pneumoniae, Hae­mo­phi­lus in­flu­en­zae and Moraxella catarrhalis. Vi­ru­ses that can cause URT infections (respiratory syncytial vi­rus, co­ro­na­vi­ru­ses, in­flu­en­za viruses, adenoviruses etc.) are in­crea­sing­ly re­cog­nized as contributors to the poly­mi­cro­bial pathogenesis of otitis media. Other bacterial agents (Strep­to­co­ccus pyogenes, Sta­phy­lo­coc­cus aureus, Pseu­do­mo­nas aeruginosa) have been rarely detected. Re­gar­ding the patho­ge­ne­sis of AOM, multiple me­cha­nisms con­tri­bu­ting to the synergistic relationship bet­ween URT viruses and primary bac­te­rial pathogens of oti­tis media have been iden­ti­fied and, although each of them has a specific effect, they all fall into the general ca­te­go­ry of com­pro­mi­sing the host’s im­mune func­tion and res­pi­ra­to­ry tract defense. An ini­tial vi­ral in­fec­tion of the URT is ne­ces­sary, which in­du­ces in­flam­ma­tion at this level and in the Eu­s­ta­­chian tube, pro­mo­ting bac­te­rial superinfection of the mid­­dle ear. Pre­ven­ting viral and bac­te­rial infections of the up­per res­pi­ra­to­ry tract in­fec­tions as­so­cia­ted with acute otitis me­­dia could reduce the in­ci­dence of middle ear infections in child­­hood.