title: Mechanisms of hypervirulent Clostridium difficile ribotype 027 displacement of endemic strains: an epidemiological model.
abstract: Following rapid, global clonal dominance of hypervirulent ribotypes, Clostridium difficile now constitutes the primary infectious cause of nosocomial diarrhoea. Evidence indicates at least three possible mechanisms of hypervirulence that facilitates the successful invasion of these atypical strains: 1) increased infectiousness relative to endemic strains; 2) increased symptomatic disease rate relative to endemic strains; and 3) an ability to outcompete endemic strains in the host's gut. Stochastic simulations of an infection transmission model demonstrate clear differences between the invasion potentials of C. difficile strains utilising the alternative hypervirulence mechanisms, and provide new evidence that favours certain mechanisms (1 and 2) more than others (3). Additionally, simulations illustrate that direct competition between strains (inside the host's gut) is not a prerequisite for the sudden switching that has been observed in prevailing ribotypes; previously dominant C. difficile strains can be excluded by hypervirulent ribotypes through indirect (exploitative) competition.
authors.affiliation: London School of Hygiene and Tropical Medicine, Department of Disease Control, London, Keppel Street WC1E 7HT.
authors.forename: Laith
authors.initials: L
authors.lastname: Yakob
authors.affiliation: Department of Microbiology, Queen Elizabeth II Medical Centre, The University of Western Australia, Nedlands, WA, Australia 6009.
authors.forename: Thomas V
authors.initials: TV
authors.lastname: Riley
authors.affiliation: The University of Queensland, UQ Centre for Clinical Research, Herston, Queensland, Australia 4029.
authors.forename: David L
authors.initials: DL
authors.lastname: Paterson
authors.affiliation: Communicable Diseases Unit, Queensland Department of Health, Herston, QLD, Australia 4006.
authors.forename: John
authors.initials: J
authors.lastname: Marquess
authors.affiliation: 1] School of Veterinary Science, University of Queensland, Gatton, Australia 4343 [2] Children's Health and the Environment Program, Queensland Children's Medical Research Institute, The University of Queensland, Herston, Queensland, Australia.
authors.forename: Ricardo J Soares
authors.initials: RJ
authors.lastname: Magalhaes
authors.affiliation: Research School of Population Health, Australian National University, Canberra, ACT, Australia.
authors.forename: Luis
authors.initials: L
authors.lastname: Furuya-Kanamori
authors.affiliation: Research School of Population Health, Australian National University, Canberra, ACT, Australia.
authors.forename: Archie C A
authors.initials: AC
authors.lastname: Clements
mesh_terms: D000465:Algorithms; D016360:Clostridioides difficile / Q000145:classification / Q000235:genetics / Q000472:pathogenicity*; D019353:Endemic Diseases; D004761:Enterocolitis, Pseudomembranous / Q000453:epidemiology / Q000382:microbiology* / Q000635:transmission; D005060:Europe / Q000453:epidemiology; D006801:Humans; D008962:Models, Theoretical; D021521:Ribotyping; D013045:Species Specificity; D013269:Stochastic Processes; D014774:Virulence