title: Mycobacterium avium subspecies paratuberculosis and Crohn's disease granulomas.
abstract: OBJECTIVE
  Chronic infection with Mycobacterium avium subspecies paratuberculosis (M. paratuberculosis) has been proposed as a cause of Crohn's disease. Although numerous investigators have examined the link between M. paratuberculosis and Crohn's disease, the evidence remains controversial. The aim of this study was to examine intestinal granuloma from Crohn's patients for M. paratuberculosis using a semi-nested M. paratuberculosis-specific IS900 polymerase chain reaction (PCR).
  
  
  METHODS
  Paraffin-embedded ileal or colonic tissues of patients with Crohn's disease were analyzed. Microdissection of this tissue into "granulomas" and "not granulomas" was performed. On the basis of sequences reported in GenBank alignments, we designed primer sets specific for M. paratuberculosis. The presence of the M. paratuberculosis was examined by semi-nested IS900-specific PCR with human beta-actin gene as a control for DNA quality.
  
  
  RESULTS
  Biopsies from 20 Crohn's patients were examined. Human beta-actin gene was amplified in all samples. M. paratuberculosis DNA was detected in the microdissected granuloma in 1 (5%) patient with Crohn's disease and in none of the "not granuloma" tissues.
  
  
  CONCLUSIONS
  M. paratuberculosis DNA can rarely be detected within Crohn's granuloma. These results do not support M. paratuberculosis as the primary etiology of Crohn's disease.
authors.affiliation: Department of Medicine, Michael E. DeBakey Veterans Affairs Medical Center, and Baylor College of Medicine, Houston, Texas, USA.
authors.forename: Sonia
authors.initials: S
authors.lastname: Toracchio
authors.forename: Hala M T
authors.initials: HM
authors.lastname: El-Zimaity
authors.forename: Carlos
authors.initials: C
authors.lastname: Urmacher
authors.forename: Seymour
authors.initials: S
authors.lastname: Katz
authors.forename: David Y
authors.initials: DY
authors.lastname: Graham
mesh_terms: D000328:Adult; D001483:Base Sequence; D003424:Crohn Disease / Q000382:microbiology* / Q000473:pathology; D004269:DNA, Bacterial / Q000032:analysis*; D005260:Female; D006099:Granuloma / Q000382:microbiology* / Q000473:pathology; D006801:Humans; D007413:Intestinal Mucosa / Q000382:microbiology / Q000473:pathology; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D016927:Mycobacterium avium subsp. paratuberculosis / Q000302:isolation & purification*; D016612:Paraffin Embedding; D010283:Paratuberculosis / Q000175:diagnosis*; D016133:Polymerase Chain Reaction; D011336:Probability; D012016:Reference Values; D012189:Retrospective Studies; D012680:Sensitivity and Specificity
chemical_list: D004269:DNA, Bacterial