Final answer:
Brain abscesses following CSOM are commonly caused by bacteria such as Streptococcus pneumoniae, Neisseria meningitidis, and Haemophilus influenzae, which also cause bacterial meningitis.
Step-by-step explanation:
The most common brain abscess following chronic suppurative otitis media (CSOM) is typically caused by bacteria that are also responsible for causing bacterial meningitis. The three most common causative agents of bacterial meningitis are Streptococcus pneumoniae, Neisseria meningitidis, and Haemophilus influenzae. These microbes are similar in their ability to access the central nervous system and cause serious infections such as meningitis and abscess formation. They can spread via the bloodstream or directly from an infection nearby such as the sinuses, nasopharynx, or middle ear.