title: Cefotaxime resistant Escherichia coli collected from a healthy volunteer; characterisation and the effect of plasmid loss.
abstract: In this study 6 CTX-M positive E. coli isolates collected during a clinical study examining the effect of antibiotic use in a human trial were analysed. The aim of the study was to analyse these isolates and assess the effect of full or partial loss of plasmid genes on bacterial fitness and pathogenicity. A DNA array was utilised to assess resistance and virulence gene carriage. Plasmids were characterised by PCR-based replicon typing and addiction system multiplex PCR. A phenotypic array and insect virulence model were utilised to assess the effect of plasmid-loss in E. coli of a large multi-resistance plasmid. All six E. coli carrying bla CTX-M-14 were detected from a single participant and were identical by pulse field gel electrophoresis and MLST. Plasmid profiling and arrays indicated absence of a large multi-drug resistance (MDR) F-replicon plasmid carrying blaTEM, aadA4, strA, strB, dfrA17/19, sul1, and tetB from one isolate. Although this isolate partially retained the plasmid it showed altered fitness characteristics e.g. inability to respire in presence of antiseptics, similar to a plasmid-cured strain. However, unlike the plasmid-cured or plasmid harbouring strains, the survival rate for Galleria mellonella infected by the former strain was approximately 5-times lower, indicating other possible changes accompanying partial plasmid loss. In conclusion, our results demonstrated that an apparently healthy individual can harbour bla CTX-M-14 E. coli strains. In one such strain, isolated from the same individual, partial absence of a large MDR plasmid resulted in altered fitness and virulence characteristics, which may have implications in the ability of this strain to infect and any subsequent treatment.
authors.affiliation: Department of Bacteriology and Food Safety, Animal Health and Veterinary Laboratories Agency, Addlestone, Surrey, United Kingdom.
authors.forename: Miranda
authors.initials: M
authors.lastname: Kirchner
authors.affiliation: Department of Bacteriology and Food Safety, Animal Health and Veterinary Laboratories Agency, Addlestone, Surrey, United Kingdom.
authors.forename: Manal
authors.initials: M
authors.lastname: Abuoun
authors.affiliation: Department of Bacteriology and Food Safety, Animal Health and Veterinary Laboratories Agency, Addlestone, Surrey, United Kingdom.
authors.forename: Muriel
authors.initials: M
authors.lastname: Mafura
authors.affiliation: Department of Bacteriology and Food Safety, Animal Health and Veterinary Laboratories Agency, Addlestone, Surrey, United Kingdom.
authors.forename: Mary
authors.initials: M
authors.lastname: Bagnall
authors.affiliation: Department of Bacteriology and Food Safety, Animal Health and Veterinary Laboratories Agency, Addlestone, Surrey, United Kingdom.
authors.forename: Theresa
authors.initials: T
authors.lastname: Hunt
authors.affiliation: School of Biosciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom.
authors.forename: Christopher
authors.initials: C
authors.lastname: Thomas
authors.affiliation: Institute for Laboratory and Transfusion Medicine at the Heart and Diabetes Centre, University Hospital of the Ruhr University, Bochum, Germany.
authors.forename: Jan
authors.initials: J
authors.lastname: Weile
authors.affiliation: Department of Bacteriology and Food Safety, Animal Health and Veterinary Laboratories Agency, Addlestone, Surrey, United Kingdom.
authors.forename: Muna F
authors.initials: MF
authors.lastname: Anjum
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002439:Cefotaxime / Q000494:pharmacology*; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D004926:Escherichia coli / Q000187:drug effects* / Q000235:genetics* / Q000302:isolation & purification / Q000502:physiology; D005838:Genotype; D064368:Healthy Volunteers; D006801:Humans; D010641:Phenotype; D010957:Plasmids / Q000235:genetics*; D001618:beta-Lactamases / Q000235:genetics
chemical_list: D000900:Anti-Bacterial Agents; C071167:beta-lactamase CTX-2; D001618:beta-Lactamases; D002439:Cefotaxime