Bacteroides fragilis Bacteremia in the Surgical Population: A 7 Year Review at a Large Tertiary Care Center

Author(s):
Albert Hsu, University of Miami-Miller School of Medicine; Casey Allen; Jonathan Meizoso; Juliet Ray, University of Miami-Miller School of Medicine; Carl Schulman, University of Miami-Miller School of Medicine; Kenneth Proctor, University of Miami-Miller School of Medicine; Nicholas Namias, University of Miami School of Medicine

Background:

Bacteroides fragilis is the most common anaerobic organism causing bacteremia in humans. However, the clinical significance of a positive B. fragilis blood culture in guiding surgical management remains undetermined.

Hypothesis:

We sought to determine if B. fragilis bacteremia is indicative of need for urgent operative or radiological drainage.

Methods:

This is a retrospective study of all patients with a positive B. fragilis blood culture admitted to a major tertiary care center from January 2007 to December 2013. Patient records were reviewed to determine if there was a potential surgical source for the anaerobic bacteremia defined as the presence of any intra-abdominal or soft tissue infection that may require an operative or radiologically guided percutaneous intervention.

Results:

82 patients had a positive B. fragilis blood culture. 38 patients (46%) had a non-surgical source: age 61 (53-73) years, 47% male, LOS 10 (6-22) days, and mortality of 24%. 44 patients (54%) had a potential surgical source: age 53 (48-61) years, 57% male, LOS 19 (12-54) days, and mortality of 23%. 24 patients required urgent drainage of an intra-abdominal infection; 17 patients required operative drainage and 7 patients required radiologically guided percutaneous drainage. Time to operative intervention was 2.5 +/- 4.0 days and time to percutaneous drainage was 2.7 +/- 3.1 days. Nine of the 17 patients requiring operative intervention had the procedure performed on the same day as the positive culture. Mortality was 29% in patients requiring operative drainage and 14% in patients requiring percutaneous drainage. Three patients had developed sepsis and multi-system organ failure from an intra-abdominal infection, however did not undergo any intervention and all died. Three patients had an intra-abdominal infection not associated with sepsis that was treated only with antibiotics and all survived. Four patients had a soft tissue infection that was treated with debridement or amputation. Overall, 32 of the 44 patients (73%) with a potential surgical source for a positive B. fragilis blood culture had indications for an operative or radiologically guided percutaneous intervention.

Conclusions:

A positive B. fragilis blood culture is highly suggestive of the need for an infection source control procedure. This knowledge may confirm clinical suspicion and help guide recognition and treatment of surgical patients with an intra-abdominal or soft tissue infection.