Bacterial susceptibility and tympanocentesis in acute otitis media

Tympanocentesis and subsequent culture of middle ear fluid have been used to identify the three most common bacterial pathogens responsible for otitis media, Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis. In vitro assessments of antibiotic activity have demonstrated that azithromycin, clarithromycin and erythromycin are equally active against M. catarrhalis, azithromycin is more active than erythromycin and clarithromycin against H. influenzae and clarithromycin and erythromycin are more active than azithromycin against S. pneumoniae. Although regional variations in the distribution of pathogens responsible for otitis media may exist, regional variations in susceptibility rates to azithromycin and clarithromycin have not been demonstrated. Susceptibility testing also suggests that more S. pneumoniae strains are susceptible to the macrolides azithromycin and clarithromycin than to penicillin, cefixime and cefaclor. Tympanocentesis before, during or after antibiotic treatment for acute otitis media can be used to correlate bacteriologic and clinical efficacy. Overall, tympanocentesis assists the physician in choosing the appropriate antimicrobial agent for treatment of otitis media.