Clinical utility of the new fluoroquinolones for treating respiratory and urinary tract infections

Increasing antimicrobial resistance among most common urinary and respiratory tract pathogens has been the catalyst for the development of fluoroquinolones that are effective against these prevalent resistant organisms. Important attributes of the newly developed fluoroquinolones include once-daily dosing, maintained extensive tissue penetration and high oral bioavailability added to targeted antibacterial activities, all pharmacodynamic characteristics that may reduce the need for parenteral therapy or prevent patients being hospitalised. Some fluoroquinolones also offer same-dose bioequivalency between iv. and oral formulations, a feature that allows iv.-to-oral dosing (step-down or 'switch' therapy) without the need for dosage adjustments. These features suggest that the newer fluoroquinolones may be near-ideal agents for the empirical treatment of many common infections. This review discusses the efficacy and clinically relevant antimicrobial and pharmacokinetic qualities of the fluoroquinolones in comparison with other agents traditionally used to treat patients with urinary and respiratory tract infections.