title: Molecular characterization of a 21.4 kilobase antibiotic resistance plasmid from an α-hemolytic Escherichia coli O108:H- human clinical isolate.
abstract: This study characterizes the 21.4 kilobase plasmid pECTm80 isolated from Escherichia coli strain 80, an α hemolytic human clinical diarrhoeal isolate (serotype O108:H-). DNA sequence analysis of pECTm80 revealed it belonged to incompatibility group X1, and contained plasmid partition and toxin-antitoxin systems, an R6K-like triple origin (ori) replication system, genes required for replication regulation, insertion sequences IS1R, ISEc37 and a truncated transposase gene (Tn3-like ΔtnpA) of the Tn3 family, and carried a class 2 integron. The class 2 integron of pECTm80 contains an intact cassette array dfrA1-sat2, encoding resistance to trimethoprim and streptothricin, and an aadA1 gene cassette truncated by the insertion of IS1R. The complex plasmid replication system includes α, β and γ origins of replication. Pairwise BLASTn comparison of pECTm80 with plasmid pE001 reveals a conserved plasmid backbone suggestive of a common ancestral lineage. Plasmid pECTm80 is of potential clinical importance, as it carries multiple genes to ensure its stable maintenance through successive bacterial cell divisions and multiple antibiotic resistance genes.
authors.affiliation: School of Biological Sciences, University of Wollongong, New South Wales, Australia.
authors.forename: Fay E
authors.initials: FE
authors.lastname: Dawes
authors.forename: Dieter M
authors.initials: DM
authors.lastname: Bulach
authors.forename: Alexander
authors.initials: A
authors.lastname: Kuzevski
authors.forename: Karl A
authors.initials: KA
authors.lastname: Bettelheim
authors.forename: Carola
authors.initials: C
authors.lastname: Venturini
authors.forename: Steven P
authors.initials: SP
authors.lastname: Djordjevic
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Walker
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D003227:Conjugation, Genetic / Q000187:drug effects; D004251:DNA Transposable Elements / Q000235:genetics; D004352:Drug Resistance, Microbial / Q000235:genetics*; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification; D006801:Humans; D032023:Integrons / Q000235:genetics; D010957:Plasmids / Q000187:drug effects / Q000235:genetics*
chemical_list: D000900:Anti-Bacterial Agents; D004251:DNA Transposable Elements