Respiratory tract infections: at-risk patients, who are they? Implications for their management with levofloxacin.

Two of the most serious respiratory tract infections are community-acquired pneumonia (CAP) and acute exacerbations of chronic bronchitis (AECB). The most common pathogens found in patients with these infections are Haemophilus influenzae and Streptococcus pneumoniae. Pseudomonas aeruginosa is also relatively common, particularly in elderly patients with AECB. S. pneumoniae and P. aeruginosa are also of concern in relation to the development of resistance to antimicrobial drugs. The administration of antibiotics at doses that result in concentrations exceeding the mutant prevention concentration at the site of infection is one strategy to prevent the development of drug-resistant pathogens. AECB is associated with a high risk of in-hospital mortality, particularly in patients treated in the intensive care unit. CAP is also associated with significant risks and often requires treatment under hospital supervision. Several patient-related factors help identify those patients who are most at risk of mortality and morbidity. Treatment should be tailored towards the severity of the disease. The fluoroquinolones, such as levofloxacin, are an effective treatment option for AECB and CAP. Compared with many other antibiotics, resistance to levofloxacin remains low for most infecting pathogens. The oral bioavailability of levofloxacin is over 99%, enabling simple switching from intravenous to oral therapy during treatment. It is also preferentially distributed to compartments in the lung, thus achieving high concentrations at the site of respiratory tract infections. Combined with cover of the major infecting pathogens found in patients with AECB and CAP, and a cost-effective treatment compared with many alternative therapies, levofloxacin is an attractive option for the treatment of at-risk patients with these respiratory tract infections.