Antibiotic Concentrations in Middle Ear Effusions

Penicillin G and oxytetracycline were present in measurable concentrations in effusions taken from the middle ear of patients with acute suppurative otitis media, following an intramuscular injection of either drug from 1 to 3 hours earlier. Fluid taken from the middle ear space of patients with secretory otitis media given similar injections contained quantities of oxytetracycline too low to measure accurately, while penicillin activity was readily measurable and comparable to levels found in patients with acute suppurative otitis media. When the antibiotic concentrations present in these effusions were considered in terms of the accepted in vitro inhibitory concentrations of the common middle ear pathogens, penicillin appeared to be the drug better suited for the management of most acute middle ear bacterial infections. Oxytetracycline, on the basis of its in vitro antibacterial activity and the concentrations achieved in the middle ear fluid, does not appear to be the drug of choice if the pathogen is Strep. pyogenes, D. pneumoniae, or Staph. aureus. A limited number of observations suggests that penicillin, though not the ideal drug, has more promise than oxytetracycline in the management of middle ear infections due to H. influenzae. Preliminary observations suggest that penicillin given by mouth results in concentrations in middle ear effusions adequate to suppress a large proportion of the pathogenic gram-positive cocci that cause middle ear infection. An extensive study of this problem is needed. Other antibiotics should be studied to find an agent that both enters the middle ear in concentrations equal to or in excess of those needed to inhibit H. influenzae in vitro and possesses the activity of penicillin against the common gram-positive pathogens responsible for middle ear infections.