Polymicrobial osteomyelitis: report of three cases and review of the literature.

Five percent of patients with acute osteomyelitis and 30%-60% of patients with chronic osteomyelitis have polymicrobial infections. Three illustrative cases and a review of the literature involving 104 patients are presented in this report. There were 2.4 isolates per child among the 31 pediatric cases ad 3.9 isolates per adult among the 71 adult cases reviewed. Staphylococcus aureus was the single most common isolate involved in polymicrobial disease in both adults and children. In adults, one-third of the aerobic isolates were gram-negative bacterial species; some enterococci were also involved. Of the isolates from adults, 46% were anaerobic. The number of isolates per case was similar for the acute (3.2) and chronic (3.1) forms of infection. Polymicrobial osteomyelitis resulted most frequently from spread of infection from a contiguous focus (59% of cases) or occurred in the patient with peripheral vascular insufficiency or neuropathy (17% of cases); however, the hematogenous route can produce polymicrobial disease (13% of cases). Bones mot often involved are those of the skull, face, and feet. Standard antibiotic therapy for monomicrobial osteomyelitis with semisynthetic penicillins or cephalosporins may lead to failures of treatment in polymicrobial disease.