title: Prevalence and identity of cdt-related sequences in necrotoxigenic Escherichia coli.
abstract: The cytolethal distending toxins (CDT) are responsible for the mitosis block at G2/M and the cycle arrest of cells in culture. Escherichia coli isolated from humans and animals with intestinal and extra-intestinal diseases can be positive for the production of a CDT-like cytopathic effect or for the presence of cdt-related genes. The purpose of this study was to compare the prevalence and the identity of cdt-related sequences in necrotoxigenic E. coli (NTEC). A collection of 98 bovine type 2 NTEC (NTEC2) and 45 bovine, 20 canine, 3 feline, 65 human and 129 porcine type 1 NTEC (NTEC1) isolates was studied by colony hybridisation and PCR assays specific for the cdtB genes encoding the B sub-unit of the CDT-I, CDT-II, CDT-III and CDT-IV toxins produced by E. coli. cdtB-III sequences were frequent amongst bovine NTEC2, since 83% of these isolates were positive by colony hybridisation and/or PCR, whereas cdtB-related sequences were rare amongst NTEC1, since only 2 bovine (4%), 3 canine (15%), 10 human (15%) and 13 porcine (10%) of these isolates were positive. The 28 probe-positive NTEC1 harboured cdtB-IV sequences (13 isolates), cdtB-I sequences (10 isolates), or still unidentified cdt-related sequences (5 isolates). After comparison with previously published and unpublished results of phenotypic assay on cell cultures, existence of other cdt-related sequences is suggested amongst NTEC1. The differences between NTEC1 and NTEC2 in their CDT profiles may have implication for the pathogenesis of those two classes of pathogenic E. coli.
authors.affiliation: Bactériologie, Département des Maladies infectieuses et parasitaires, Faculté de Médecine Vétérinaire, Université de Liège, Liège, Belgium. jg.mainil@ulg.ac.be
authors.forename: Jacques G
authors.initials: JG
authors.lastname: Mainil
authors.forename: Etienne
authors.initials: E
authors.lastname: Jacquemin
authors.forename: Eric
authors.initials: E
authors.lastname: Oswald
mesh_terms: D000818:Animals; D001427:Bacterial Toxins / Q000096:biosynthesis / Q000235:genetics*; D002415:Cats; D002417:Cattle; D017931:DNA Primers; D015342:DNA Probes; D004285:Dogs; D004926:Escherichia coli / Q000235:genetics* / Q000472:pathogenicity; D004927:Escherichia coli Infections / Q000453:epidemiology / Q000382:microbiology*; D006801:Humans; D009693:Nucleic Acid Hybridization; D016133:Polymerase Chain Reaction / Q000662:veterinary; D015995:Prevalence; D013552:Swine
chemical_list: D001427:Bacterial Toxins; D017931:DNA Primers; D015342:DNA Probes; C067044:cytolethal distending toxin