Acute sinusitis is estimated to occur in 0.5 to 2 percent of adults with common colds and in 5 to 10 percent of children with such infections. Gwaltney and colleagues review recent studies on the efficacy of antibiotics in the treatment of acute sinusitis.

They focused on two types of clinical trials: placebo-controlled studies of antibiotic treatment without proof of bacterial infection by sinus aspirate, and uncontrolled trials of antibiotics where sinus aspirates were used to verify the presence and clearance of bacterial infection.

According to the authors, no clinical sign or symptom has been demonstrated to have high sensitivity or specificity for acute bacterial sinusitis, nor has any constellation of clinical features correlated well with documented bacterial infection. The only clinical criterion that the authors agreed had some evidence for accuracy was failure of the common cold to improve after seven to 10 days.

The most reliable method for confirming bacterial infection is sinus aspirate. The maxillary sinus ostium cannot be entered endoscopically, and intranasal swab specimens from the middle meatus do not confirm or exclude infection within the sinus cavity reliably. Even computed tomographic scanning of the sinuses has limited power to detect infection or document bacterial clearance.

Nine placebo-controlled trials of antibiotics for treatment acute sinusitis were reviewed. None of these trials used sinus aspirates to confirm the clearance of bacterial infections. For the reasons noted above, the authors questioned the validity of any clinical findings from these trials. The weighted, pooled rate for clinical improvement after seven to 14 days among participants receiving placebo was above 50 percent in these controlled studies.

Four studies reviewed pre- and post-treatment sinus aspirate findings. None of these trials was placebo-controlled; instead, different dosages and different antibiotics were compared. When antibiotics were given at dosages known to produce serum levels above the known minimal inhibitory concentration for the causative bacterial organisms, the clearance rate ranged from 90 to 96 percent. Subtherapeutic antibiotic dosing decreased the clearance rate range to 20 to 74 percent.

The authors conclude that the results from studies of antibiotic treatment for acute sinusitis where sinus aspirate confirmation of bacterial infection and clearance is not used are always open to question. Studies of antibiotic treatment that are based on sinus aspirate culture results show high clearance rates.