title: Emergence and evolution of an international cluster of MDR Bacteroides fragilis isolates.
abstract: The aim of this study was to examine the antibiotic resistance profiles, antibiotic resistance mechanisms and possible 'clonal' nature of some MDR Bacteroides fragilis strains that simultaneously harboured cfiA, nimB, IS1186 and IS4351.
  
  
  
  Antibiotic susceptibilities were determined by Etests and antibiotic resistance genes and different genetic elements were detected by applying PCR methods. The environments of the cfiA and nimB genes were also determined by sequencing. The transferability of the cfiA, nimB and tet(Q) genes was tested by conjugation. The genetic relatedness of the test strains was tested by ERIC-PCR or PFGE. The complete genome sequences of two strains (B. fragilis BF8 and O:21) were determined by next-generation sequencing.
  
  
  
  Most of the seven B. fragilis strains tested displayed multidrug resistance phenotypes; five strains were resistant to at least five types of antibiotics. Besides the common genetic constitution, ERIC-PCR implied high genetic relatedness. Similarities in some of the antibiotic resistance mechanisms [carbapenems (cfiA) and metronidazole (nimB)] also confirmed their common origin, but some other resistance mechanisms {MLSB [erm(F)] and tetracycline [tet(Q)]} and PFGE typing revealed differences. In B. fragilis BF8 and O:21, erm(F) and tet(X) genes were found with IS4351 borders, thus constituting Tn4351. All the strains were tet(Q) positive and transferred this gene in conjugation experiments, but not the cfiA and nimB genes.
  
  
  
  An international cluster of MDR B. fragilis strains has been identified and characterized. This 'clone' may have emerged early in the evolution of division II B. fragilis strains, which was suggested by the low-complexity ERIC profiles and differences in the PFGE patterns.
authors.affiliation: Institute of Clinical Microbiology, Faculty of Medicine, University of Szeged, Szeged, Hungary soki.jozsef@med.u-szeged.hu.
authors.forename: József
authors.initials: J
authors.lastname: Sóki
authors.affiliation: Department of Clinical Microbiology, Biomedical Laboratory Science, Umeå University, Umeå, Sweden.
authors.forename: Maria
authors.initials: M
authors.lastname: Hedberg
authors.affiliation: Centre for Infection and Immunity, School of Medicine, Dentistry and Biomedical Sciences, Queen's University, Belfast, UK.
authors.forename: Sheila
authors.initials: S
authors.lastname: Patrick
authors.affiliation: SeqOmics Biotechnology Ltd, Mórahalom, Hungary.
authors.forename: Balázs
authors.initials: B
authors.lastname: Bálint
authors.affiliation: SeqOmics Biotechnology Ltd, Mórahalom, Hungary.
authors.forename: Róbert
authors.initials: R
authors.lastname: Herczeg
authors.affiliation: SeqOmics Biotechnology Ltd, Mórahalom, Hungary Institute of Biochemistry, Biological Research Centre of the Hungarian Academy of Sciences, Szeged, Hungary.
authors.forename: István
authors.initials: I
authors.lastname: Nagy
authors.affiliation: Department of Microbiology and Immunology, Stritch School of Medicine, Loyola University, Chicago, IL, USA.
authors.forename: David W
authors.initials: DW
authors.lastname: Hecht
authors.affiliation: Institute of Clinical Microbiology, Faculty of Medicine, University of Szeged, Szeged, Hungary.
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Nagy
authors.affiliation: Institute of Clinical Microbiology, Faculty of Medicine, University of Szeged, Szeged, Hungary.
authors.forename: Edit
authors.initials: E
authors.lastname: Urbán
mesh_terms: D001442:Bacteroides Infections / Q000453:epidemiology / Q000382:microbiology*; D001441:Bacteroides fragilis / Q000145:classification* / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification; D016000:Cluster Analysis; D003227:Conjugation, Genetic; D004251:DNA Transposable Elements; D052978:Disk Diffusion Antimicrobial Tests; D024901:Drug Resistance, Multiple, Bacterial; D016521:Electrophoresis, Gel, Pulsed-Field; D023061:Gene Order; D022761:Gene Transfer, Horizontal; D005798:Genes, Bacterial; D016680:Genome, Bacterial; D005838:Genotype; D014943:Global Health; D059014:High-Throughput Nucleotide Sequencing; D006801:Humans; D058889:Molecular Typing; D016133:Polymerase Chain Reaction; D017422:Sequence Analysis, DNA
chemical_list: D004251:DNA Transposable Elements