Etiology and antimicrobial therapy of acute maxillary sinusitis.

Eighty-one adults with symptoms of acute sinusitis were studied by direct needle puncture and aspiration of the maxillary sinus (105 sinuses). Fifty-nine bacterial strains were isolated in titers of greater than or equal to 10(4) colony-forming units/ml; Streptococcus pneumoniae and Haemophilus influenzae accounted for 64% of the isolates. Other bacteria recovered included anaerobes (12%), Neisseria species (8.5%). Streptococcus pyogenes (3%), alpha-hemolytic Streptococcus (3%), non-group A beta-hemolytic Streptococcus (3%), Staphylococcus aureus (2%), Pseudomonas aeruginosa (2%), and Escherichia coli (2%). Viruses were isolated from 11 sinuses; these isolates included rhinovirus (six), influenza A (H3N2) virus (three), and two types of parainfluenza virus (one each). The efficacy of therapy with orally administered ampicillin, amoxicillin, or trimethoprim-sulfamethoxazole was evaluated by a repeat sinus puncture and culture. Clinical and bacteriologic responses to all three regimens were good.