Unveiling Ruminococcus gnavus bacteremia: Clinical characteristics and implications.

Introduction: Ruminococcus gnavus is a microbiota-forming, gram-positive coccus reportedly associated with several diseases, such as Crohn's disease. The number of in vitro studies on it is increasing. However, its clinical information is lacking in the literature, with only a few case reports published to date. To elucidate the significance of this organism, we describe its clinical characteristics in this study.

Methods: During the study period (2013-2022), we identified 11 patients with R. gnavus bacteremia and conducted a retrospective chart review. Cases identified to be contaminated were excluded. We found 11 reports of R. gnavus bacteremia on PubMed and reviewed their clinical characteristics.

Results: Eleven R. gnavus bloodstream infection cases were identified in our facility. The median age of the patients was 83 years (interquartile range: 73.75-87.25). Seven cases had at least one documented intestinal lesion including three with malignancy cases, and two cases had uncompensated cirrhosis. In most cases, bacterial translocation was suspected as the entry mechanism. Among the 11 R. gnavus bloodstream infections, 7 (63.6 %) were associated with intestinal lesions, and 2 (18.2 %) had a history of suspected bacterial translocation without documented intestinal lesions.

Conclusion: To the best of our knowledge, this is the largest cohort study on R. gnavus bloodstream infections. Intestinal entry was suspected in more than 80 % of cases in both our cohort and the literature review cohort. For cases of bacteremia with an unknown etiology due to R. gnavus, a thorough examination of gastrointestinal lesions should be performed.