Final answer:
The primary event leading to otitis media with effusion is typically a Viral Upper Respiratory Infection which causes blockage of the eustachian tubes, leading to fluid buildup. This condition facilitates the growth of bacteria from the respiratory tract, which often results in acute otitis media.
Step-by-step explanation:
The most significant precipitating event leading to otitis media with effusion (OME) is c. Viral URI (Upper Respiratory Infection). Any blockage of the eustachian tubes, with or without infection, can lead to the accumulation of fluid in the middle ear, which is referred to as OME. This fluid offers an ideal environment for microbial growth, and secondary bacterial infections can often follow. A common cause of such blockage and subsequent effusion is a viral URI. This condition can result in increased pressure on the eardrum due to fluid buildup in the middle ear. Other factors that can facilitate OME in young children include multiple upper respiratory infections, shorter and less-angled eustachian tubes, and behaviors such as lying down while bottle feeding which can create negative pressure that encourages fluid and bacteria from the nasopharynx to enter the middle ear.
Acute otitis media (AOM), a more severe form of middle ear infection, is marked by the formation of pus that cannot drain, leading to bulging of the tympanic membrane and ear pain. The usual causative agents of AOM include bacteria from the respiratory tract that become trapped in the eustachian tube. As for bacterial rhinosinusitis, it is commonly triggered by a preceding viral infection that compromises the normal defenses of the respiratory mucosa, allowing bacteria to invade.