title: Diversity of antimicrobial resistance genes and class-1-integrons in phylogenetically related porcine and human Escherichia coli.
abstract: Antimicrobial resistant bacteria and resistance genes can be transferred between the microbial flora of humans and animals. To assess the dimension of this risk, we compared the phylogenetic ancestry of human and porcine tetracycline-insusceptible Escherichia coli. Further, we compared the resistance gene profiles (tetA/tetB/tetC/tetD/tetM/sulI/sulII/sulIII/strA-strB/addA) and the prevalence of class-1-integrons in isolates of identical and different phylogroups by endpoint-PCR. This is the first genotypic comparison of antimicrobial resistance in E. coli from humans and animals which allows for the phylogenetic ancestry of the isolates. E. coli isolates from diseased humans belonged regularly to phylogroup B2 (24.3%) or D (30.9%) and were rarely not typeable (7.2%); by contrast, isolates from pig manure were regularly not typeable (46.7%) and rarely grouped into phylogroup B2 (2.2%) or D (2.9%). Class-1-integrons were detected in 40.8% of clinical (n=152), in 9.5% of community-derived (n=21) and in 10.9% of porcine (n=137) E. coli. The prevalence of sulI (42.4%/16.0%) in phylogroup A and of tetA, tetB and sulII in phylogroup B1 differed significantly between human clinical and porcine strains. Human clinical isolates (except B2-isolates) carried significantly more different resistance genes per strain, compared to porcine or community-derived isolates. ERIC-PCR-analysis of B2- (and D-) isolates with identical genetic profiles revealed that only a minor part was clonally related. The dominant resistance gene profiles differed depending on phylogroup and source. Human and porcine isolates do not exceedingly share their genes, and might rapidly adapt their resistance gene equipment to meet the requirements of a new environment. The study underlines that resistance gene transfer between human and porcine isolates is limited, even in phylogenetically related isolates.
authors.affiliation: Technische Universität München, Weihenstephaner Berg 3, 85354 Freising, Germany. Christina.Hoelzel@wzw.tum.de
authors.forename: Christina Susanne
authors.initials: CS
authors.lastname: Hölzel
authors.forename: Katrin Susanne
authors.initials: KS
authors.lastname: Harms
authors.forename: Johann
authors.initials: J
authors.lastname: Bauer
authors.forename: Ilse
authors.initials: I
authors.lastname: Bauer-Unkauf
authors.forename: Stefan
authors.initials: S
authors.lastname: Hörmansdorfer
authors.forename: Peter
authors.initials: P
authors.lastname: Kämpf
authors.forename: Gabriele
authors.initials: G
authors.lastname: Mölle
authors.forename: Cornelia
authors.initials: C
authors.lastname: Oehme
authors.forename: Petra
authors.initials: P
authors.lastname: Preikschat
authors.forename: Karin
authors.initials: K
authors.lastname: Schwaiger
mesh_terms: D000818:Animals; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D004926:Escherichia coli / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000382:microbiology*; D014644:Genetic Variation; D005838:Genotype; D006801:Humans; D032023:Integrons / Q000235:genetics*; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D013552:Swine; D013553:Swine Diseases / Q000382:microbiology*