Anaerobic osteomyelitis can occur as an acute hematogenous infection in younger patients, as a superinfection of chronic staphylococcal osteomyelitis, or as an indolent infection of bone and joint prostheses. Bacteroides species cause most cases of anaerobic osteomyelitis, but other anaerobes may be implicated, including peptococci, Veillonella species, and even Propionibacterium species. Although P. acnes can occasionally cause endocarditis and bacteremia, this organism usually appears in blood cultures as a contaminant from the skin. Fusobacterium species and other anaerobes can also cause serious bacteremias. In approximately two thirds of cases of anaerobic bacteremia, the portal of entry is the gastrointestinal tract.
Polymicrobial bacteremia occurs commonly.
Clinical features of anaerobic bacteremias may include hypotension and shock, jaundice, septic phlebitis, and metastatic infections of distant sites. The oropharynx is the most common portal of entry, followed by the gastrointestinal and genitourinary tracts and the skin. The clinical features resemble those of typical subacute endocarditis.