Quinolones: clinical use and formulary considerations.

Quinolones are broad-spectrum antibiotics active primarily against aerobic gram-negative organisms. All quinolones have activity against oral anaerobes, but only trovafloxacin provides coverage against Bacteroides fragilis, the primary anaerobe of the abdomen/pelvis. In addition, quinolones are very active against atypical pulmonary pathogens, e.g., Legionella, but trovafloxacin is the least active against Chlamydia. As with other antibiotics, the selection of quinolones depends not simply on the degree of microbiologic activity but also on safety profile and cost. Ciprofloxacin and trovafloxacin are associated with central nervous system side effects. Photosensitivity reactions may occur with sparfloxacin. Trovafloxacin is associated with more adverse reactions than any other quinolone, and its gastrointestinal side effects are most frequent among the quinolones. Resistance potential is highest with ciprofloxacin and lowest with levofloxacin. Sparfloxacin and grepafloxacin are available only as oral formulations. Among the parenteral quinolones, ciprofloxacin and trovafloxacin are the most expensive, levofloxacin, the least expensive. Levofloxacin is preferred for general use alone or in combination because it has virtually no side effects, induces no resistance, and is the least expensive and most versatile quinolone currently available.