Direct identification of Ruminococcus gnavus by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) on a positive anaerobic blood culture bottle

Abstract We report a case of bloodstream infection with the anaerobic bacterium Ruminococcus gnavus ( R. gnavus ), associated with intestinal perforation in a patient undergoing chemotherapy for multiple myeloma and cancer of the sigmoid colon. Gram staining of positive anaerobic blood cultures revealed both diplococci and short chains of gram-positive cocci. MALDI-TOF MS done directly on the blood culture bottle identified the bacterium as R. gnavus , and 16S rRNA gene sequencing confirmed the identification.