Antibiotic Regimens Otitis Media (Table 128-4) Current treatment recommendations for otitis media are based on the following points: (1) Acute otitis media is the most common diagnosis leading to an antibiotic prescription in the United States. (2) The diagnosis is often based on inadequate evidence for true middle-ear infection. (3) In proven cases, S. pneumoniae and H. influenzae are the most likely causes. (4) Because penetration into a closed space may be reduced, high serum levels of an effective antibiotic are required to treat otitis caused by intermediately or fully resistant pneumococci. (5) S. pneumoniae is more likely than Haemophilus and.