What is the most common cause of acute otitis media?

The most common cause of acute otitis media is indeed Streptococcus pneumoniae. This bacterium is a type of gram-positive cocci that is often found in the upper respiratory tract and is a leading pathogen responsible for various infections, particularly in children.

Acute otitis media typically arises following a viral upper respiratory infection, which can lead to Eustachian tube dysfunction, allowing for bacterial colonization and subsequent infection of the middle ear. Streptococcus pneumoniae is particularly adept at causing this syndrome due to its ability to adhere to the epithelial surfaces of the middle ear and its virulence factors, which enable it to evade the host's immune response.

The other bacteria listed tend to cause infections in different contexts or are less commonly associated with acute otitis media. For instance, Staphylococcus aureus is more frequently implicated in skin and soft tissue infections or in cases of otitis externa. Escherichia coli and Pseudomonas aeruginosa are typically associated with other types of infections and are not common causative agents of acute otitis media, further emphasizing the predominant role of Streptococcus pneumoniae in this condition.