Defining resistance: breakpoints and beyond implications for pediatric respiratory infection.

The emergence of isolates of Streptococcus pneumoniae with reduced susceptibility to penicillins, cephalosporins, trimethoprim-sulfamethoxazole, and macrolide antibiotics requires a re-evaluation of strategies for the treatment of community-acquired respiratory disease. One response has been the consideration of withholding initial antimicrobial therapy for children with acute otitis media (AOM). Review of clinical studies supports a reduction in suppurative complications, and a more rapid resolution of signs and symptoms as well as the course of middle ear disease in children treated with antimicrobial agents. Breakpoints established by the NCCLS for in vitro susceptibility reporting may not reflect clinical efficacy at all sites of disease. Clinical studies of AOM due to penicillin-resistant S. pneumoniae report success with both cefuroxime and amoxicillin-clavulanic acid, however, microbiologic studies suggest an increase in persistent infection in children with disease due to isolates with reduced susceptibility. Successful therapy for AOM due to highly resistant isolates (MIC > or = 2.0 micrograms/ml for penicillin) has been reported with clindamycin, ceftriaxone, and high-dose amoxicillin. The current risk of AOM due to a resistant S. pneumoniae remains low in most U.S. communities. Amoxicillin remains appropriate for most children, ongoing surveillance for resistance and close monitoring of response to therapy is necessary.