Clinical implications of resistance in the management of respiratory tract infections.

Antibiotic resistance among the three major respiratory pathogens (Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis) has increased dramatically over the past 15 years, around the world. With S pneumoniae, penicillin resistance is reported in almost a quarter of isolates, with multiple resistance an increasing problem. The major concern with H influenzae is ampicillin resistance, mediated through two different mechanisms. In the case of M catarrhalis, beta-lactamase production is almost universal, although resistance to other antibiotics is rare. The increasing prevalence of resistance underscores the need for new effective antibiotics. The new quinolones have a spectrum of activity that parallels the range of common respiratory pathogens.