Which organism is the most common cause of acute otitis media?

Which organism is the most common cause of acute otitis media?

• A. Streptococcus pneumoniae
• B. Moraxella catarrhalis
• C. Haemophilus influenzae
• D. Pseudomonas aeruginosa

Answer: (A)

Acute otitis media is most often a post-viral infection of the middle ear where bacteria ascend through the Eustachian tube after mucosal inflammation. The leading cause in this setting is Streptococcus pneumoniae, a encapsulated gram-positive diplococcus that commonly colonizes the nasopharynx and can invade the middle ear when the tympanic cavity becomes isolated and fluid builds up. Its virulence and efficiency at establishing infection in the middle ear explain why it tops the list of culprits in acute cases. Other bacteria, such as Moraxella catarrhalis and non-typeable Haemophilus influenzae, also contribute to many cases, so they’re frequent but secondary players. Pseudomonas aeruginosa is more typical of different ear infections, such as chronic otitis externa or cases with tympanostomy tubes or special risk factors, rather than classic acute otitis media in healthy children.

Acute otitis media is most often a post-viral infection of the middle ear where bacteria ascend through the Eustachian tube after mucosal inflammation. The leading cause in this setting is Streptococcus pneumoniae, a encapsulated gram-positive diplococcus that commonly colonizes the nasopharynx and can invade the middle ear when the tympanic cavity becomes isolated and fluid builds up. Its virulence and efficiency at establishing infection in the middle ear explain why it tops the list of culprits in acute cases.

Other bacteria, such as Moraxella catarrhalis and non-typeable Haemophilus influenzae, also contribute to many cases, so they’re frequent but secondary players. Pseudomonas aeruginosa is more typical of different ear infections, such as chronic otitis externa or cases with tympanostomy tubes or special risk factors, rather than classic acute otitis media in healthy children.