Otitis media: focus on antimicrobial resistance and new treatment options.

Antimicrobial resistance among organisms that cause acute otitis media (AOM) and new approaches in the prevention and treatment of AOM are discussed. Organisms commonly responsible for causing AOM include Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis. The evolution of pneumococcal resistance to penicillins, erythromycin, trimethoprim-sulfamethoxazole, and oral cephalosporins may require treatment with agents such as vancomycin or rifampin in certain patients. H. influenzae and M. catarrhalis are becoming increasingly resistant to penicillins, trimethoprim-sulfamethoxazole, oral cephalosporins, and macrolides. Mechanisms of resistance include changes in penicillin-binding proteins, production of beta-lactamase, alterations in target enzymes, and inhibition of drug access to the site of action. Because of changing resistance patterns and the limited spectra of activity of many currently available antimicrobials, new antimicrobials have been developed in the hope of improving therapy. While amoxicillin and trimethoprim-sulfamethoxazole are appropriate first-line agents, children at risk for resistant infections may be treated initially with cefuroxime axetil, cefpodoxime proxetil, cefprozil, or amoxicillin-clavulanate. After local resistance patterns, patient adherence to therapy, in vitro data, and cost factors have been weighed, other agents to consider include loracarbef, clarithromycin, azithromycin, and ceftriaxone. Along with the efforts to improve treatment, research is focusing on the prevention of otitis media with bacterial and viral vaccines. The emergence of resistant strains of organisms causing AOM has complicated its treatment.