Lactobacillus rhamnosus bacteremia: an emerging clinical entity

Lactobacillus spp. are ubiquitous commensals of the normal human flora that are only occasionally found in clinical infections. Their role in human disease is established for infectious endocarditis but is controversial for other infections. We sought to characterize clinically associated Lactobacillus spp. We conducted a retrospective study, which consisted of the screening of Lactobacillus isolates obtained in our laboratory from January 2004 to December 2009. The polymerase chain reaction (PCR) assay was selected as the gold standard method. The isolates were first identified using API Coryne strips, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), and 16S rRNA gene sequencing. Lactobacillus tuf gene-based identification was used when the 16S rRNA results were inconclusive. Among the 60 strains of Lactobacillus spp. obtained in our laboratory, L. rhamnosus was the most commonly isolated species and was found in blood cultures from 16 patients. Combined with 45 patients reported in the literature, we found that patients presenting with L. rhamnosus bacteremia experienced nosocomial infections associated with both immunosuppression (66 %) and catheters (83 %).