4th Annual BMRP Investigator Meeting - Abstract

Pathogenic Yersinia DNA Detection in Crohn’s Disease

Laura Lamps

Department of Pathology, University of Arkansas for Medical Sciences (Little Rock, Arkansas, U.S.A.)

Background: Pathogenic Yersinia species (enterocolitica and pseudotuberculosis) are a common cause of food-borne bacterial enteritis and geographic areas with a high incidence of Crohn’s disease (CD) have some of the highest rates of Yersinia infection.  We developed the first molecular assays designed specifically to detect and perform biogroup analysis of pathogenic Yersinia DNA in archival pathology materials.  In the current study, we evaluated a multi-institutional cohort of CD cases for the presence of Yersinia DNA and determined the biogroup (virulence) of the Yersinia positive cases.

Materials and Methods: 142 archival CD resection specimens were evaluated.  Following DNA extraction, three PCR assays were performed.  The first detects chromosomal virulence gene (ail) fragments present only in pathogenic Yersinia species.  The second detects a plasmid- encoded virulence gene (YopP/J) that affects bacteria/macrophage interactions.  The third assay determines the biogroup of Yersinia present, indicating whether the strain is high or low virulence.

Results: All 142 cases have been analyzed.  Twenty-three percent of cases (33/142)) were ail positive, 17.6% were Yop positive and 7% were positive for both genes; thus, a total of 47.6% of CD cases contained Yersinia DNA by PCR.  Biogroup analysis of the Yersinia-positive cases showed that all but one CD case contained DNA indicating a low virulence Yersinia biogroup, whereas a control group of cases with fulminant, suppurative Yersinia infection contained a high virulence strain.  We also gained access to an additional cohort of pediatric CD biopsy samples and found that 12.3% of these cases were positive for either ail and/or Yop.

Conclusions: A significant percentage of CD cases (in both adult and pediatric populations) are positive for pathogenic Yersinia DNA by PCR analysis, detecting genes that are involved in invasion and bacteria/macrophage interactions.  In addition, the vast majority of Yersinia-positive CD cases contain DNA from a low virulence strain.  These preliminary data raise the possibility that Yersinia, specifically low virulence strains that may be able to persist in the host for an extended period of time, play a role in the pathogenesis of CD.