Levofloxacin has good activity against S. pneumoniae and, as with other modern fluoroquinolones, the MIC90 (and distribution) is unchanged, irrespective of the presence of resistance to either penicillins or macrolides. Overall, levofloxacin resistance is 0.8% according to a recent survey, which found low levels of resistance in some parts of Europe and South America; varying from 0-1.6% (2). However, fluoroquinolone resistance is a potential concern and must be closely monitored. Pharmacodynamic analyses based on serum parameters indicate levofloxacin to achieve Cmax/MIC ratios adequate to predict therapeutic success in pneumococcal CAP (3). Levofloxacin lung epithelial lining fluid concentrations are two-fold greater than in serum, and 10-120-fold greater than in alveolar macrophages (4). Population modeling has shown mean penetration ratios of 3.8, suggesting that therapy will be highly effective in most patients (5).

Levofloxacin is licensed by the US FDA for infections due to drug-resistant S. pneumoniae (DRSP) and an evaluation of four clinical trials noted success in 97% of patients with CAP caused by macrolide-resistant pathogens (6).

Fluoroquinolones also have a much wider spectrum against CAP pathogens than many other classes, with excellent activity against H. influenzae, Mycoplasma pneumoniae and C. pneumoniae and, of course, Legionella pneumophila (7, 8).

Fluoroquinolones also have an excellent track record in management of AECB, where their impressive potency against both H. influenzae and M. catarrhalis is a clear advantage in comparison with b-lactams and macrolides (9).