To determine prognostic factors that independently predict response to antimicrobial therapy in children with acute sinusitis.

A total of 206 children meeting a priori clinical criteria for acute sinusitis who were prescribed antimicrobial therapy by their primary care provider were included. The severity of symptoms in the 8-12 days after treatment was initiated was followed with the use of a validated scale. We examined the univariate and multivariate association between factors present at the time of diagnosis (symptoms, signs, nasopharyngeal culture result, radiograph results) and time to resolution of symptoms. This study was conducted 8-10 years after the 7-valent pneumococcal conjugate vaccination was introduced but before introduction of the 13-valent pneumococcal conjugate vaccination.

Children with proven nasopharyngeal colonization with Streptococcus pneumoniae improved more rapidly (6.5 vs 8.5 median days to symptom resolution) than those who were not colonized with S pneumoniae. Age and radiograph findings did not predict time to symptom resolution.

In children with acute sinusitis, proven nasopharyngeal colonization with S pneumoniae at presentation independently predicted time to symptom resolution. Future randomized, placebo-controlled trials could investigate the usefulness of testing for the presence of nasopharyngeal pathogens as a predictor of response to treatment.