title: Distinct bacterial colonization patterns of Escherichia coli subtypes associate with rheumatoid factor status in early inflammatory arthritis.
abstract: OBJECTIVE
  The aetiology of RA is unknown; however, bacterial exposure, particularly to Escherichia coli, Proteus mirabilis and Klebsiella pneumoniae, has been linked to disease pathogenesis. The strongest association was observed for RF(+) RA. We compare colonization patterns of these bacteria, and the anti-bacterial antibody levels in early onset RF(+) and RF(-) inflammatory arthritis.
  
  
  METHODS
  Bacteria isolated from stool and urine of early-stage RF(+) and RF(-) patients recruited to the Early Arthritis Registry were biochemically identified and genotyped. IgM and IgA anti-bacterial and RF antibodies were assessed by ELISA.
  
  
  RESULTS
  Differences in the types of colonizing pathogenic E. coli were identified. RF(+) patients were more commonly colonized with phylogenetic Group D E. coli, whereas RF(-) patients were more commonly colonized with phylogenetic Group B2 E. coli and these individuals also had lower joint scores and inflammatory markers yet higher IgA anti-E. coli antibody responses.
  
  
  CONCLUSIONS
  These studies link the type of colonizing bacteria in the gut and urine with the immune response (anti-bacterial and RF) in early-onset inflammatory arthritis and provide evidence for a role of the host-pathogen response in the aetiology of RF.
authors.affiliation: Research Institute of McGill University Health Centre, Montreal, QC, Canada. marianna.newkirk@mcgill.ca
authors.forename: Marianna M
authors.initials: MM
authors.lastname: Newkirk
authors.forename: Ariella
authors.initials: A
authors.lastname: Zbar
authors.forename: Murray
authors.initials: M
authors.lastname: Baron
authors.forename: Amee R
authors.initials: AR
authors.lastname: Manges
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000907:Antibodies, Bacterial / Q000276:immunology; D001172:Arthritis, Rheumatoid / Q000276:immunology* / Q000382:microbiology; D004926:Escherichia coli / Q000276:immunology*; D005260:Female; D006801:Humans; D007711:Klebsiella pneumoniae / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D011513:Proteus mirabilis / Q000276:immunology*; D012217:Rheumatoid Factor / Q000276:immunology*; D013223:Statistics as Topic; D011795:Surveys and Questionnaires; D013997:Time Factors
chemical_list: D000907:Antibodies, Bacterial; D012217:Rheumatoid Factor