Sinusitis is a common condition that often is treated with antibiotics. However, because antibiotics are effective only in cases of bacterial sinusitis, this treatment is excessive for most patients, who have infections of viral origin. Such overuse of antibiotics contributes to the growing number of resistant bacterial organisms. Unfortunately, distinguishing bacterial from viral infections can be difficult. In an abstract of a Cochrane Database systematic review, with commentary by Tang and Frazee, studies comparing antibiotics with placebo or antibiotics from different classes for acute maxillary sinusitis were reviewed.

The primary outcomes included clinical cure and clinical improvement. Among the 32 trials included in this review, different techniques were used for diagnostic confirmation, and 20 trials were double-blinded. Use of penicillin improved the clinical cure rate over that achieved with placebo. Amoxicillin did not significantly improve the clinical cure rate, but the results varied widely. Radiographic improvement followed all antibiotic treatments. There was no significant difference in outcomes when comparing newer, nonpenicillin antibiotics with penicillin, or newer, nonpenicillin antibiotics with amoxicillin-clavulanate potassium. Dropouts related to adverse events were significantly higher in the amoxicillin-clavulanate group than in the cephalosporin group. Relapse rates were 7.7 percent and did not differ significantly between any antibiotic class.

The Cochrane Database systematic review authors conclude that in acute maxillary sinusitis, confirmed radiographically or by aspiration, limited evidence supports treatment with amoxicillin or penicillin for seven to 14 days. The moderate benefits of treatment should be weighed against the potential for adverse events.

Tang and Frazee comment that accurate diagnosis is important to prevent overtreatment of viral sinusitis. The standard criterion is a positive sinus aspirate culture. Computed tomography is the most accurate indirect test, followed by plain radiography and clinical criteria. Clinical criteria that have been recommended by the Centers for Disease Control and Prevention (CDC) are noted in (the accompanying table). Antibiotics seem to have limited utility, because many patients spontaneously improve. The recommended CDC strategy is to use decongestants alone in patients with early sinusitis and antibiotics after seven days of symptoms. If evidence of severe disease is present, immediate antibiotic treatment is appropriate. Because the predominant organism in sinus infections is Streptococcus pneumoniae, local resistance patterns should determine the choice of antibiotic, with high-dose amoxicillin and broader spectrum antibiotics being used for penicillin-resistant S. pneumoniae or for treatment failures.

Tang and Frazee conclude that the use of amoxicillin or another narrow-spectrum antibiotic is appropriate in the management of acute maxillary sinusitis but only if the diagnosis is made by strict criteria.