Bacteriology of acute otitis media in adults

--The objective of this study was to determine the bacteriology of acute otitis media in adults. Although this has frequently been studied in children, no data have recently been reported from adults in the United States. Additionally, information on the prevalence of Haemophilus influenzae as a causative organism in acute otitis media in adults has not been available.

--Middle-ear aspirates for cultures were obtained by myringotomy from adults meeting entry criteria.

--Emergency department, Eye and Ear Hospital of Pittsburgh, Pa.

--Thirty-four patients (volunteer sample) met the eligibility requirements. Exclusion criteria included history of chronic otitis media, recent antibiotic therapy, immunosuppressive illnesses, or prior otologic surgery.

--Ten days of oral cefuroxime axetil (250 mg) was prescribed.

--Patients were followed closely for at least 6 weeks. Aerobic and anaerobic cultures were incubated and evaluated per the scheduled protocol.

--Haemophilus influenzae and Streptococcus pneumoniae were grown on culture of specimens from nine and seven patients (26% and 21%), respectively. Twenty-two percent (2/9) of the H influenzae isolates and the single isolate of Moraxella catarrhalis produced beta-lactamase (9% overall).

--The present results suggest that, as in children, amoxicillin would be an appropriate first-line agent for empiric therapy of acute otitis media in adults. Antimicrobials inactive against H influenzae (eg, penicillin V, cephalexin, erythromycin, or tetracyclines) are not appropriate for initial therapy. Antimicrobials with efficacy against organisms producing beta-lactamase, such as cefuroxime axetil, which was used to treat the study patients, do not appear to be required for routine initial therapy in adults. However, they would be appropriate when an organism producing beta-lactamase is isolated from the middle ear or when a patient fails to improve rapidly on amoxicillin therapy.