ANAEROBIC BACTEREMIA

The results of early studies showed that anaerobes accounted for 20% o f an bacteremias; more-recent data suggest that these organisms accoun t for similar to 4% (0.5%-9%) of bacteremias (or approximately one cas e per 1,000 admissions), with variation by geographic location, hospit al patient demographics, and especially, patient age. Elderly persons seem to be at increased risk for developing anaerobic bacteremia while young children (2-5 years of age) are at the least risk. Bacteroides fragilis is the most common blood isolate recovered from patients with anaerobic bacteremia; this organism and species of the B. fragilis gr oup account for similar to 55% of anaerobic bacteremias. B. fragilis b acteremia is associated with a mortality of 19%, with a mortality risk of 3.2; a 16-day increase in hospital stay; and often, intra-abdomina l disease. Associated risks for mortality include chronic liver diseas e and congestive heart failure. There is value in performing separate anaerobic blood cultures; clinicians at each institution should determ ine the prevalence of anaerobic bacteremia and use this information to guide blood-culture practices.