Differential diagnosis of purulent and non-purulent acute maxillary sinusitis in young adults.

In acute maxillary sinusitis, purulence could best be assessed from sinus washings, but evaluation based on aspirates was also reliable, provided that the amount of secretion was adequate. Injection-aspirates were of negligible diagnostic value in this respect. Sinus washings and aspirates which were clinically defined as purulent were almost invariably indicative of bacterial infection. The bacterial etiology was most accurately obtained by sinus aspiration. Only 14.5% of cultured specimens were negative for pathogenic bacteria. In maxillary sinusitis, judged to be non-purulent, 52.5% of cultures grew a pathogen. The most common pathogen was Haemophilus influenzae, which accounted for 90% of these isolations. There was a clear correlation between occurrence of many PMNs and pathogen positive culture in non-purulent cases. Thus, antimicrobial therapy which is effective against Haemophilus influenzae seems indicated in most cases of non-purulent maxillary sinusitis.