Increasing importance of viruses in acute otitis media.

Acute otitis media is generally considered a simple bacterial infection that can be effectively treated with antibiotics. However, despite the extensive use of broad-spectrum antibiotics, poor clinical response to treatment of acute otitis media is common in children. Numerous studies ranging from animal experiments to extensive clinical studies have clearly demonstrated that respiratory viruses play a crucial role in the aetiology and pathogenesis of acute otitis media. Viral infection of the upper respiratory tract initiates the whole cascade of events that finally leads to the development of acute otitis media as a complication. Respiratory viruses induce a release of inflammatory mediators in the nasopharynx, increase bacterial colonization and adherence, and have a suppressive effect on the host's immune defense. Recent data indicate that at least some types of viruses actively invade the middle ear. Viruses also seem to enhance the inflammatory process in the middle ear and impair the outcome of the disease. Vaccines against the major viruses predisposing to acute otitis media hold a great promise for the prevention of this disease. Major advances in the management of acute otitis media will require further research into the mechanisms of viral infection, viral-bacterial interaction and the host inflammatory response during viral infection.