A case of persistent bacteraemia by Ralstonia mannitolilytica and Ralstonia pickettii in an intensive care unit Monica Basso,1,* Carolina Venditti,2,* Giammarco Raponi,3 Anna Sara Navazio,3 Francesco Alessandri,4 Emanuela Giombini,2 Carla Nisii,2 Antonino Di Caro,2 Mario Venditti31Department of Molecular Medicine, University of Padova, Padova, Italy; 2Laboratory of Microbiology, L. Spallanzani National Institute for Infectious Diseases, Rome, Italy; 3Department of Public Health and Infectious Diseases, Sapienza University of Rome, Rome Italy; 4Department of Anesthesia and Intensive Care Medicine, Sapienza University of Rome, Rome, Italy*These authors contributed equally to this workAbstract: The Ralstonia spp. genus is a group of non-fermentative, Gram-negative bacteria often resistant to many antibiotics, which are emerging as opportunistic pathogens frequently associated with infections in hospital settings. We present herein a case of combined R. pickettii and R. mannitolilytica persisting and relapsing bacteraemia, possibly caused by a septic arterial thrombosis secondary to the rupture of an internal carotid artery aneurysm. Microbiology studies showed that both Ralstonia isolates produced biofilm and carried class D oxacillinase genes. When confronted with infections caused by members of the Ralstonia genus, identification to the species level is crucial for correct clinical management, as the two species show different antibiotic susceptibility patterns.Keywords: Ralstonia pickettii, Ralstonia mannitolilytica, bacteraemia, endovascular infection