Lactobacillus bacteremia: Pathogen or prognostic marker?

Lactobacillus bacteremia is a rare event and its epidemiology is poorly known. Whether Lactobacillus bacteremia is a contaminant, a risk factor, or a risk marker of death remains an open question.

We conducted a retrospective study of patients presenting with Lactobacillus bacteremia (LB), between January 2005 and December 2014, at the Grenoble University Hospital.

LB was observed in 38 patients (0.34% of all positive blood cultures). Cancer (40%), immunosuppression (37%), and use of central venous devices (29%) were frequently associated with LB. We observed a significant increase with time in the number of Lactobacillus positive blood cultures among all blood cultures performed (P=0.04). LBs were divided into two clinical-biological presentations: secondary bacteremia with a known portal of entry (n=30) and isolated bacteremia (n=8). Case fatality was 31% at D28, 55.2% at 1 year in the secondary bacteremia group, and 12.5% (both at D28 and 1 year) in the isolated bacteremia group. Secondary bacteremia with a known portal of entry was significantly associated with case fatality after adjustment for age, co-infection, cancer, immunosuppression, diabetes, and sex (OR 14.9 [1.04-216] P=0.047) for fatality at one year, but not for D28 fatality (P=0.14).

Lactobacillus bacteremia may be an important marker of disease severity rather than a pathogen, suggesting comorbidities. It should not be considered a contaminant, but should lead physicians to screen for associated infections and underlying diseases.