Hemophilus influenzae septic arthritis in adults

Hemophilus influenzae is an important but uncommon cause of adult septic arthritis. We report two cases and review 23 previously published cases. Two-thirds of the patients had systemic diseases, local factors, or both which predisposed them to septic arthritis. The acute disease was monarticular in 48%, polyarticular in 24%, and accompanied by tenosynovitis and/or bursitis in 28% of cases. Extraarticular sites of H. influenzae infection were found in 60% of cases. These sites represented either likely portals of bacterial entry or foci of infection resulting from hematogenous dissemination of H. influenzae. The most characteristic synovial fluid finding was the presence of Gram-negative pleomorphic microorganism. However, misinterpretation of the Gram-stained smear was common and led to an erroneous initial diagnosis in several instances. Prompt sterilization of the infected synovial fluid was the rule once an appropriate antimicrobial agent was administered. A favorable outcome was reported in 88% of cases.