Aetiology
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Cliquez ici pour les guides de pratique clinique sur l'otite moyenne aiguë et leur mise en œuvre dans le contexte belgePublished by: ebpracticenet adminLast published: 2024Acute otitis media (NL versie)Published by: ebpracticenet adminLast published: 2024Respiratory viruses account for most cases of otitis media and are self-limiting.[6] Co-infections of the middle ear with a virus and a bacterium demonstrate the role that both play in the development of acute, suppurative otitis media.[7]
The most common bacteria responsible for AOM are Streptococcus pneumoniae (approximately 40%), non-typable Haemophilus influenzae (25% to 30%), and Moraxella catarrhalis (10% to 15%).[7][8] Viral infections, especially those caused by respiratory syncytial virus, influenza virus, and adenovirus, confer a risk of AOM.[6]
Unfortunately, an aetiological diagnosis in a clinic setting is not feasible.
Pathophysiology
Under normal conditions the mucociliary action and ventilatory function of the eustachian tube clear the nasopharyngeal flora that enter the middle ear. However, upper respiratory viruses can infect the nasal passages, eustachian tube, and middle ear, causing inflammation and impairing these processes. This may then contribute to the development of AOM.[7][9][10]
A middle ear effusion develops, and nasopharyngeal bacteria contaminate the effusion.[11] The middle ear effusion provides a good medium for bacterial growth, which then precipitates a suppurative, inflammatory response.
Suppuration and subsequent pressure against the tympanic membrane lead to pain and fever, which are typical symptoms of AOM.
In more severe cases, the tympanic membrane may perforate and cause a purulent otorrhoea. The inflammatory process may also involve the mastoid air cells. Fortunately, AOM is usually self-limiting.[12]
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