title: Detection of the cytolethal distending toxin locus cdtB among diarrheagenic Escherichia coli isolates from humans in Iran.
abstract: Cytolethal distending toxin (CDT) represents an emerging family of newly described bacterial products that are produced by a number of pathogens. Genes encoding this toxin were identified as a cluster of three adjacent genes, cdt-A, cdt-B and cdt-C. Five cdt genetic variants, designated cdt-I, cdt-II, cdt-III, cdt-IV and cdt-V, have been identified so far. To determine the presence of cdt genes among Escherichia coli isolates, a PCR assay was employed. Using multiplex primers designed for detection of E. coli cdt genes, PCR analysis indicated the presence of cdt genes in 37.5% of these isolates. While specific primers were located in the cdt-B locus for detection of cdt-I, cdt-II, cdt-III and cdt-IV, in multiplex PCR positive isolates indicated that a cdt-I-like gene was present in 45.3% of these isolates. However, in 52% of the isolates, the cdt-III-like gene could be detected. It should be mentioned that in 30.8% of these isolates, cdt-II and -III were detected simultaneously. In 2.6% of the isolates, the cdt-IV gene was present. The cnf-1 gene was detected in 29.4% of strains carrying the cdt-I gene; however, the cnf-2 gene was detected only in 23.1% of the cdt-III-like strains. Furthermore, the data obtained by PCR analysis indicated the presence of cdt-like genes among our E. coli isolates, although in the CHO cell assay, all isolates showed a cytopathic effect characteristic of CDT.
authors.affiliation: Molecular Biology Unit, Pasteur Institute of Iran, Tehran 13164, Iran. saeidbouzari@yahoo.com
authors.forename: Saeid
authors.initials: S
authors.lastname: Bouzari
authors.forename: Mana
authors.initials: M
authors.lastname: Oloomi
authors.forename: Eric
authors.initials: E
authors.lastname: Oswald
mesh_terms: D000818:Animals; D001427:Bacterial Toxins / Q000235:genetics* / Q000378:metabolism / Q000633:toxicity; D016466:CHO Cells; D002648:Child; D002675:Child, Preschool; D006224:Cricetinae; D017931:DNA Primers; D004269:DNA, Bacterial / Q000032:analysis; D003967:Diarrhea / Q000382:microbiology*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism / Q000472:pathogenicity*; D004927:Escherichia coli Infections / Q000382:microbiology*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism; D005798:Genes, Bacterial; D006801:Humans; D007492:Iran; D008969:Molecular Sequence Data; D009693:Nucleic Acid Hybridization / Q000379:methods; D016133:Polymerase Chain Reaction / Q000379:methods
chemical_list: D001427:Bacterial Toxins; D017931:DNA Primers; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; C067044:cytolethal distending toxin