title: A novel MLST sequence type discovered in the first fatal case of Laribacter hongkongensis bacteremia clusters with the sequence types of other human isolates.
abstract: Laribacter hongkongensis is a gram-negative, facultative anaerobic, motile, S-shaped, asaccharolytic, urease-positive bacillus in the Neisseriaceae family of β-proteobacteria. To date, all patients with L. hongkongensis infection have survived, including the two patients with L. hongkongensis bacteremia and patients with L. hongkongensis gastroenteritis. In this study, we describe the clinical, microbiological and molecular characterization of the first fatal case associated with L. hongkongensis bacteremia in a patient with colonic carcinoma that metastasized to the liver. The identity of the isolate was confirmed via phenotypic tests and 16S rRNA gene sequencing. Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS), using the Bruker database extended with L. hongkongensis reference strains, also identified the isolate as L. hongkongensis, with a top match score of 2.473. Multilocus sequence typing revealed a new sequence type (ST), and phylogenetic analysis and eBURST demonstrated unambiguously that the ST of the isolate was clustered with two other STs found exclusively in human patients, consistent with the theory that some clones of L. hongkongensis could be more virulent than others. Underlying liver diseases and ascites potentially represent distinct risk factors for invasive L. hongkongensis infection. More widespread use of MALDI-TOF MS for identification and improvements of selective media should facilitate the identification of more cases of L. hongkongensis infection.
authors.affiliation: Department of Microbiology, Kwong Wah Hospital , Hong Kong, China.
authors.forename: Cindy Ws
authors.initials: CW
authors.lastname: Tse
authors.affiliation: Department of Microbiology, The University of Hong Kong , Hong Kong, China.
authors.forename: Shirly Ot
authors.initials: SO
authors.lastname: Curreem
authors.affiliation: Department of Microbiology, Kwong Wah Hospital , Hong Kong, China.
authors.forename: Ingrid
authors.initials: I
authors.lastname: Cheung
authors.affiliation: Department of Pathology, Hong Kong Sanatorium and Hospital , Hong Kong, China.
authors.forename: Bone Sf
authors.initials: BS
authors.lastname: Tang
authors.affiliation: Department of Microbiology, The University of Hong Kong , Hong Kong, China.
authors.forename: Kit-Wah
authors.initials: KW
authors.lastname: Leung
authors.affiliation: Department of Microbiology, The University of Hong Kong , Hong Kong, China ; Research Centre of Infection and Immunology, The University of Hong Kong , Hong Kong, China ; State Key Laboratory of Emerging Infectious Diseases, The University of Hong Kong , Hong Kong, China ; Carol Yu Centre for Infection, The University of Hong Kong , Hong Kong, China.
authors.forename: Susanna Kp
authors.initials: SK
authors.lastname: Lau
authors.affiliation: Department of Microbiology, The University of Hong Kong , Hong Kong, China ; Research Centre of Infection and Immunology, The University of Hong Kong , Hong Kong, China ; State Key Laboratory of Emerging Infectious Diseases, The University of Hong Kong , Hong Kong, China ; Carol Yu Centre for Infection, The University of Hong Kong , Hong Kong, China.
authors.forename: Patrick Cy
authors.initials: PC
authors.lastname: Woo
keywords: bacteraemia; infections