High diversity of plasmids harbouring blaCMY-2 among clinical Escherichia coli isolates from humans and companion animals in the upper Midwestern USA

Valeria Bortolaia, Katrine H. Hansen, Christine A. Nielsen, Thomas R. Fritsche, Luca Guardabassi

Research output: Contribution to journalJournal articleResearchpeer-review


Objectives: To determine the population structure and genetic relatedness of plasmids encoding CMY-2 β-lactamase in clinical Escherichia coli from humans and companion animals within a defined geographical area. Methods: In total, 42 human and 73 companion animal isolates displaying an AmpC phenotype were isolated at a regional diagnostic reference laboratory in the upper Midwestern USA during 2009-11. Following PCR screening for transferable AmpC genes and plasmid transformation, blaCMY-2-positive plasmids were characterized by S1 nuclease PFGE, PCR-based replicon typing, antimicrobial susceptibility testing of transformants, conjugation experiments, plasmid multilocus sequence typing and restriction fragment length polymorphism. Results: blaCMY-2 occurred in 6 (14%), 56 (86%) and 6 (75%) isolates from humans, dogs and cats, respectively. Usually plasmids carrying blaCMY-2 were conjugative (78%) and did not contain additional resistance genes (82%). The replicon types were IncI1 (52%), IncA/C (13%), IncFII (10%), IncI2 (5%), IncL/M (3%), IncB/O (2%) or non-typeable (15%). Related IncI1/ST12 plasmids were detected in one human and five canine isolates, while the remaining plasmids did not show similarity across host species. A novel epidemiological linkage of blaCMY-2 with IncL/M plasmids and a new CMY gene variant (blaCMY-108) were found in human isolates. Conclusions: This study is one of the first One Health attempts to compare plasmids encoding CMY-2 β-lactamase among clinical isolates from humans and companion animals in the same region. The results indicate an unforeseen heterogeneity of plasmid backgrounds and suggest limited exchange between the two populations, in which blaCMY-2 occurred at very different frequencies and was harboured by distinct plasmid types. © The Author 2014. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved.
Original languageEnglish
JournalJournal of Antimicrobial Chemotherapy
Issue number6
Pages (from-to)1492-1496
Number of pages5
Publication statusPublished - 2014
Externally publishedYes


  • The Faculty of Health and Medical Sciences
  • AmpC
  • antimicrobial resistance
  • dogs
  • cats
  • Pharmacology
  • Pharmacology (medical)
  • Infectious Diseases
  • Medicine (all)
  • Antimicrobial resistance
  • Cats
  • Dogs
  • beta lactamase AmpC
  • beta lactamase
  • beta-lactamase CMY-2
  • article
  • bacterium isolate
  • cat
  • dog
  • Escherichia coli
  • genetic variability
  • nonhuman
  • phenotype
  • plasmid
  • population structure
  • replicon
  • United States
  • animal
  • Escherichia coli Infections
  • genetics
  • genotype
  • human
  • microbial sensitivity test
  • microbiology
  • molecular genetics
  • Animals
  • beta-Lactamases
  • Genetic Variation
  • Genotype
  • Humans
  • Microbial Sensitivity Tests
  • Midwestern United States
  • Molecular Sequence Data
  • Plasmids
  • Genetics - General
  • Genetics - Animal
  • Genetics - Human
  • Biochemistry studies - Nucleic acids, purines and pyrimidines
  • Enzymes - General and comparative studies: coenzymes
  • Pathology - General
  • Pathology - Diagnostic
  • Physiology and biochemistry of bacteria
  • Genetics of bacteria and viruses
  • Medical and clinical microbiology - Bacteriology
  • Veterinary science - General and methods
  • Veterinary science - Microbiology
  • Animals, Carnivores, Chordates, Mammals, Nonhuman Vertebrates, Nonhuman Mammals, Vertebrates
  • Bacteria, Eubacteria, Microorganisms
  • Animals, Chordates, Humans, Mammals, Primates, Vertebrates
  • genetic relatedness


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