title: Reclassification of Clostridium difficile as Clostridioides difficile (Hall and O'Toole 1935) Prévot 1938.
abstract: The recent proposal by Lawson and Rainey (2015) to restrict the genus Clostridium to Clostridium butyricum and related species has ramifications for the members of the genera that fall outside this clade that should not be considered as Clostridium sensu stricto. One such organism of profound medical importance is Clostridioides difficile that is a major cause of hospital-acquired diarrhea and mortality in individuals. Based on 16S rRNA gene sequence analysis, the closest relative of Clostridium difficile is Clostridium mangenotii with a 94.7% similarity value and both are located within the family Peptostreptococcaceae that is phylogenetically far removed from C. butyricum and other members of Clostridium sensu stricto. Clostridium difficile is Clostridium mangenotii each produce abundant H2 gas when grown in PYG broth and also produce a range of straight and branched chain saturated and unsaturated fatty acids with C16:0 as a major product. The cell wall peptidoglycan contains meso-DAP as the diagnostic diamino acid. Based on phenotypic, chemotaxonomic and phylogenetic analyses, novel genus Clostridioides gen. nov. is proposed for Clostridium difficile as Clostridioides difficile gen. nov. comb. nov. and that Clostridium mangenotii be transferred to this genus as Clostridioides mangenotii comb. nov. The type species of Clostridioides is Clostridioides difficile.
authors.affiliation: Department of Microbiology and Plant Biology, University of Oklahoma, Norman, USA. Electronic address: paul.lawson@ou.edu.
authors.forename: Paul A
authors.initials: PA
authors.lastname: Lawson
authors.affiliation: R. M. Alden Research Laboratory, Culver City, CA, 90230, USA.
authors.forename: Diane M
authors.initials: DM
authors.lastname: Citron
authors.affiliation: R. M. Alden Research Laboratory, Culver City, CA, 90230, USA.
authors.forename: Kerin L
authors.initials: KL
authors.lastname: Tyrrell
authors.affiliation: Infectious Diseases Section, VA Medical Center West Los Angeles, 90073, USA; Department of Medicine, The David Geffen School of Medicine at the University of California, Los Angeles, CA, USA; Department of Microbiology, Immunology, and Molecular Genetics, The David Geffen School of Medicine at the University of California, Los Angeles, CA, USA.
authors.forename: Sydney M
authors.initials: SM
authors.lastname: Finegold
mesh_terms: D005075:Biological Evolution; D016360:Clostridioides difficile / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification; D004269:DNA, Bacterial / Q000235:genetics*; D005243:Feces / Q000382:microbiology; D018703:Founder Effect; D019015:Geologic Sediments / Q000382:microbiology; D006801:Humans; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics*; D012988:Soil Microbiology; D009626:Terminology as Topic
chemical_list: D004269:DNA, Bacterial; D012336:RNA, Ribosomal, 16S
keywords: 16S rRNA; Clostridioides; Clostridium difficile; Taxonomy