Retrospective analysis of two hundred and twelve cases of bacteremia due to anaerobic microorganisms.

Cases of bacteremia caused by anaerobic microorganisms and occurring during a four year period in a non-selected patient group in a Spanish general hospital were analysed retrospectively. Microbiological data was collected on 212 patients and clinical data on 103 patients. Cases of anaerobic bacteremia represented 8.6% of the total number of cases of bacteremia. Of the 232 anaerobic microorganisms causing bacteremia, gram-negative bacilli were responsible in 113 cases (48.7%), gram-positive bacilli in 92 cases (39.6%), gram-positive cocci in 25 cases (10.7%), and Veillonella spp. in two cases (0.8%). The most important clinical features were fever (64%), anemia (56%), septic shock (22%) and metastatic abscesses (21%). Patients with anaerobic bacteremia were hospitalized for an average of 51.7 days. The overall mortality was 32% and factors associated with poor prognosis were severe underlying disease, nosocomial acquisition, presence of shock, presence of metastatic foci of infection, and absence of adequate surgical drainage. The mortality rate of patients who received adequate antimicrobial therapy was 30% and that of patients who received inadequate treatment or none was 29%. It is concluded that anaerobic bacteremia has a significant rate of morbidity and mortality and that underlying disease and surgical debridement and/or drainage have greater prognostic significance than the use of antimicrobial agents.