[Bacteremia caused by anaerobes: analysis of 131 episodes]

Despite the efficacy of modern antimicrobials bacteremia by anaerobes (AB) continues to present a high mortality rate. The aim of this study was to determine the relative frequency and clinical significance of isolations of anaerobic bacteria in blood cultures and to know the prognostic factors of AB.

From total of 231 patients observed over a period of six and a half years in the Fundación Jiménez Díaz, 131 episodes of AB were retrospectively analyzed with special attention being given to microbiologic, epidemiologic and clinical factors.

The relative frequency of AB was 7.5%. Clinical significance was found in 86 out of the 131 episodes (66%). The isolation of Bacteroides spp. was clinically significant in 89% while Clostridium spp. was so only in 33% (p < 0.001). Mortality related with AB was 32%. The following factors were considered related to bad prognosis statistical analysis (p < 0.05): admission to medical areas, rapid and finally fatal underlying disease, presence of septic shock, renal failure, inappropriate antimicrobial treatment and the absence of drainage for the septic foci.

Anaerobic bacteremia remains an important cause of bacteremia and carries a high mortality rate. Two thirds of the episodes of anaerobic bacteremia are deemed to be clinically significant. Correct antimicrobian treatment and surgical drainage of any septic foci significantly improves prognosis.