Sinusitis, the most frequently reported chronic disease, has a significant impact on health and economics, with 20 million Americans affected annually. It accounts for a large number of physician visits and restricted activity days, and is the fifth most common diagnosis for which antibiotics are prescribed.

There has been an increasing push in the US for guidelines for sinusitis treatment. The aim is to set a standard that will be acceptable to users, utilize clinical experience and expertise, assist physicians in the management of frequent and routine clinical problems, and to promote evidence-based medicine while restricting costs. Current rhinosinusitis guidelines were developed using a therapeutic outcome mathematical model utilizing efficacy plus resistance patterns.

Efficacy of the cephalosporins and newer macrolides is declining against S. pneumoniae, with only fluoroquinolones and amoxicillin-clavulanic acid retaining good activity.

The apparent relative weakness of some cephalosporins and macrolides against H. influenzae is also surprising, while fluoroquinolones remain active against this pathogen.

In regard to M. catarrhalis, some of the second-generation cephalosporins are not active despite their general use in the primary care situation.

A percentage of bacterial infections will respond without any therapy. On the other hand, an agent with 100% efficacy will still show a lower clinical response compared to bacterial response, as some patients will have a viral rather than bacterial disease. When comparing the efficacy of agents for rhinosinusitis, fluoroquinolones are the most effective, followed by amoxicillin-clavulanic acid.

Fluoroquinolones reflect essentially 100% activity against the three major pathogens causing rhinosinusitis. High-dose amoxicillin-clavulanic acid is also very effective. Extended spectrum second- or third-generation cephalosporins have a low 82 to 85% efficacy, and trimethoprim sulfamethoxazole and macrolides even lower. With their greater clinical efficacy fluoloqunolones are recommended in the guidelines for patients with moderate or severe disease who have failed therapy with other agents.