title: Analysis of the pathogenicity locus in Clostridium difficile strains.
abstract: The genes for Clostridium difficile toxins A and B (tcdA and tcdB) are part of a 19.6-kb pathogenicity locus (PaLoc) that includes the genes tcdD, tcdE, and tcdC. To determine whether the C. difficile PaLoc is a stable and conserved genetic unit in toxigenic strains, a multiplex polymerase chain reaction was used to analyze 50 toxigenic, 39 nontoxigenic, and 2 toxin-defective isolates. The respective amplicons were identified for tcdA-E in the toxigenic isolates; these were absent in the nontoxigenic isolates. C. difficile P-829 lacked at least a fragment of tcdD, tcdB, tcdE, and tcdC, but tcdA was present. C. difficile 8864 had deletions in the tcdA and tcdC genes. These data suggest that the PaLoc is highly stable in toxigenic C. difficile, nontoxigenic isolates lack the unit, and isolates with a defective PaLoc can still cause clinical disease. Further studies are needed to define the role of individual genes in the pathogenesis of C. difficile-associated diarrhea.
authors.affiliation: Department of Internal Medicine, Division of Infectious and Immunologic Diseases, University of California, Davis Medical Center, Sacramento, CA 95817, USA. stcohen@ucdavis.edu
authors.forename: S H
authors.initials: SH
authors.lastname: Cohen
authors.forename: Y J
authors.initials: YJ
authors.lastname: Tang
authors.forename: J
authors.initials: J
authors.lastname: Silva
mesh_terms: D001426:Bacterial Proteins; D001427:Bacterial Toxins / Q000235:genetics*; D016360:Clostridioides difficile / Q000235:genetics* / Q000378:metabolism / Q000472:pathogenicity*; D004269:DNA, Bacterial / Q000032:analysis; D004268:DNA-Binding Proteins / Q000235:genetics; D004761:Enterocolitis, Pseudomembranous / Q000382:microbiology*; D004768:Enterotoxins / Q000235:genetics*; D004783:Environmental Microbiology; D005798:Genes, Bacterial; D006801:Humans; D016366:Open Reading Frames; D016133:Polymerase Chain Reaction; D012097:Repressor Proteins / Q000235:genetics; D014774:Virulence / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D001427:Bacterial Toxins; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; D004768:Enterotoxins; D012097:Repressor Proteins; C105615:TcdC protein, Clostridium difficile; C105616:TcdD protein, Clostridium difficile; C041348:tcdA protein, Clostridium difficile; C031815:toxB protein, Clostridium difficile