Resistant respiratory pathogens and extended-spectrum antibiotics.

Traditional antibiotics such as amoxicillin, tetracycline and erythromycin remain the drugs of first choice for most bacterial respiratory infections. However, the usefulness of these agents varies, depending on local bacterial resistance patterns and patient factors. In the United States, amoxicillin and penicillin resistance currently occurs in 20 to 30 percent of Streptococcus pneumoniae strains, 30 to 40 percent of Haemophilus influenzae strains and 70 to 90 percent of Moraxella catarrhalis strains. For infections with these pathogens, selective use of the newer extended-spectrum oral antibiotics may be indicated. Cefuroxime axetil (a second-generation cephalosporin), cefpodoxime (a third-generation cephalosporin), amoxicillin-clavulanate (a beta-lactamase inhibitor combination agent) and clarithromycin or azithromycin (extended-spectrum macrolides) are all relatively effective against organisms that are commonly resistant to penicillin and amoxicillin.