[Bacteremia due to strict anaerobes].

Objective: Anaerobic bacteremia represents 0.5-12% of all bacteremias and its mortality is high, ranging from 25-44%. The aim was to know our data to compare them with existing data and demonstrate the importance of actively searching for these microorganisms in blood culture samples.

Methods: A retrospective descriptive study in which the medical records of patients with significant episodes of anaerobic bacteremia were reviewed over a period of 8 years (2014-2022).

Results: A total of 59,898 blood cultures were processed, of which 10,451 were positive (17%). An anaerobic microorganism was identified in 209 patients. Anaerobic bacteremia accounted for 2.11% of the total number of positive blood cultures. The mean age was 63.55 years (17-96), 66% of whom were men. The origin was community in 63.64%, of nosocomial origin in 15.31% and associated with health care in 17.70%. The focus of infection was the abdominal (39.23%), followed by the respiratory (13.88%) and skin and soft tissues (13.39%). The most frequent comorbidities were: arterial hypertension (49.76%), dyslipidemia (29.67%), neoplasia (26.32%) and diabetes (26.32%). The main species isolated were the group Bacteroides spp. (44.50%) (n=93) highlighting Bacteroides group fragilis (n=65), followed by Clostridium spp. (20%) (n=42) highlighting Clostridium perfringens (n=30). The clinical evolution was good in 67.46%. The mean length of stay was 27.8 days and was associated with 20% mortality.

Conclusions: Bacteremias due to anaerobes represented 2.11% of the total number of true bacteremias, so we consider the active search for these microorganisms to be appropriate.