Additional Sites of Infection

Bacteroides

• Pulmonary - In addition to intraabdominal infections, B. fragilis group is found in 15% of lung abscesses, again most commonly in mixed infections.
• Endocarditis - Uncommon, most often associated with a previously damaged heart valve.
• Bacteremia - The most common anaerobe pathogen isolated in blood, and second only to E. coli as a cause of intraabdominal sepsis.
• Skin and bone

  Necrotizing fasciitis - involving facia and a life threatening emergency, these are also usually mixed anaerobic infections, seen most commonly in diabetic patients.

  Diabetic foot ulcers - almost always a mixed infection of aerobes and anaerobes in diabetic ulcers (a common malady).

  Bone - occasional/rare cause of bone infection (osteomyelitis), and usually found as a single pathogen. The source is usually contiguous soft tissue infection.

Provotella Group

• Oral - P. melanogenica, P. oralis, P. gingivalae

  These organisms are frequent causes of oral infections including gingivitis, Vincent's angina, and tooth abscess. It is not clear how often, and what significance their role in infections is but they are frequently isolated. The most important aspect of disease associated with P. melanogenica is it's resistance to penicillin (see below). Most oral infections are treated with penicillin.

• Virulence - unclear what virulence factors may play role, although P. gingivalae has been shown to have attachment fimbriae.

  Other diseases associated with the oral Prevotella species includes brain abscess, and lung abscess. P. melanogenica is more often isolated than B. fragilis in these infections.

• Pelvic gram negative anaerobes P. bivia, P. disiens:

  These organisms are important constituents of normal flora of vagina. Although they are not the most common organism in vaginal flora, they account for 2/3 of pelvic abscesses. Typical infections involving these organisms include - tubo-ovarian abscess, post cesarean section, and vaginal hysterectomy. Less common are salpingitis or endometritis without abscess formation.

• Virulence - virtually nothing known. Until recently, these pathogens were originally identified as B. fragilis. Important difference from B. fragilis group is that these pathogens almost never are isolated in blood (don't cause sepsis).

Veillonella Species
Gram negative cocci, 2nd most common organism in saliva, of questionable pathogenicity in oral and pleuro pulmonary infections. Frequently found in mixed infections, but it is difficult to interpret significance when found.

Fusobacterium
Fusobacterium nucleatum is the most common human pathogen of this genus. It is a spindle shaped gram negative resident of the oral cavity and colon.

• It is somewhat less virulent than Bacteroides and Prevotella overall, not frequently isolated, but is usually found in mixed infections.
• Sites of infections include - pleuropulmonary, peritonitis, pelvic abscess, Lemeire's syndrome (jugular vein thrombosis with metastatic abscesses) 2o to Ludwig's Angina, and sinusitis.
• Fusobacterium does have a biologically active Endotoxin.