title: pCERC3 from a commensal ST95 Escherichia coli: A ColV virulence-multiresistance plasmid carrying a sul3-associated class 1 integron.
abstract: The rare sulphonamide resistance gene sul3 was found in the commensal Escherichia coli ST95 strain 22.1-R1 that was isolated in 2010 from the faeces of a healthy Australian adult. The genome of 22.1-R1 was sequenced and a 144,344bp RepFII/FIB plasmid, pCERC3, carrying sul3 was assembled. The sul3 gene is part of a class 1 integron featuring a sul3-containing conserved segment (sul3-CS) that replaced the classic sul1-containing 3'-conserved segment (3'-CS) usually seen in class 1 integrons. The integron contained the cassette array dfrA12-orfF-aadA2-cmlA1-aadA1-qacH, conferring resistance to trimethoprim, streptomycin, spectinomycin, chloramphenicol and quaternary ammonium compound. Two additional antibiotic resistance genes, blaTEM (ampicillin resistance) and tetA(B) (tetracycline) were adjacent to the integron, forming a single resistance region. In pCERC3, the sul3-type class 1 integron was flanked by sequence derived from the tnp and mer modules of Tn21 and was in the same location as In2, the sul1-containing In5-type class 1 integron of Tn21. At one end the sequence extends into Tn2670-derived sequence and then into sequence derived from the plasmid NR1 (R100). Examination of the sequences of eleven more complete sul3-containing plasmids in GenBank confirmed the relationship between sul3-associated integrons and Tn21/Tn2670/NR1. This suggests that the events that formed sul3-associated class 1 integrons occurred within the Tn21/Tn2670 context, most likely in NR1 or a related plasmid. The backbone of pCERC3 is most closely related to the backbones of ColV virulence plasmids and contains a complete ColV operon as well as several virulence associated genes and gene clusters. Hence, pCERC3 is both an antibiotic resistance and virulence plasmid.
authors: School of Life and Environmental Sciences, The University of Sydney, NSW, Australia.
authors: Robert A
authors: RA
authors: Moran
authors: Department of Biochemistry and Molecular Biology and Centre for Systems Genomics, University of Melbourne, VIC, Australia.
authors: Kathryn E
authors: KE
authors: Holt
authors: School of Life and Environmental Sciences, The University of Sydney, NSW, Australia. Electronic address: ruth.hall@sydney.edu.au.
authors: Ruth M
authors: RM
authors: Hall
mesh_terms: D000328:Adult; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001483:Base Sequence; D002701:Chloramphenicol / Q000494:pharmacology; D004094:Dihydropteroate Synthase / Q000235:genetics*; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics*; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification; D029968:Escherichia coli Proteins / Q000235:genetics*; D006801:Humans; D032023:Integrons / Q000235:genetics*; D008826:Microbial Sensitivity Tests; D058885:Multilocus Sequence Typing; D010957:Plasmids / Q000235:genetics*; D000644:Quaternary Ammonium Compounds / Q000494:pharmacology; D017422:Sequence Analysis, DNA; D000198:Spectinomycin / Q000494:pharmacology; D013307:Streptomycin / Q000494:pharmacology; D013753:Tetracycline Resistance / Q000235:genetics; D014295:Trimethoprim / Q000494:pharmacology; D018440:beta-Lactam Resistance / Q000235:genetics; D001618:beta-Lactamases / Q000235:genetics
chemical_list: D000900:Anti-Bacterial Agents; D029968:Escherichia coli Proteins; D000644:Quaternary Ammonium Compounds; D002701:Chloramphenicol; D000198:Spectinomycin; D014295:Trimethoprim; D004094:Dihydropteroate Synthase; C487459:Sul3 protein, E coli; D001618:beta-Lactamases; D013307:Streptomycin
keywords: Class 1 integron; ColV multiple resistance plasmid; Commensal E. coli; Escherichia coli ST95; Iron uptake systems; sul3 sulphonamide resistance gene