The role of new quinolones in the treatment of respiratory tract infections.

Infections of the respiratory tract are the leading cause of antibacterial prescribing in both hospital and community practice. The microbial aetiology is diverse in both of these settings and differs in the distribution and virulence of the pathogens. Furthermore, in recent years the antibacterial susceptibility of many of the common pathogens has changed significantly. In particular, penicillin resistance has emerged among pneumococci, while beta-lactamase production among Haemophilus influenzae and many Gram-negative bacilli has led to alterations in first-line therapy options. The fluoroquinolone antibacterials have been used in selected respiratory tract infections, but concerns have remained with regard to their efficacy in infections caused by marginally susceptible organisms, and in particular pneumococcal infections. The availability of a number of quinolones with enhanced Gram-positive activity, which includes Streptococcus pneumoniae, is of considerable interest. In vitro data and preliminary clinical experience with sparfloxacin suggest that managing pneumococcal lung disease with this and future agents is a distinct possibility. One caveat must be considered, and that is the potential for more resistant strains of pneumococci emerging, against which even these new quinolones could prove less effective.