Prevalence of infectious pathogens in Crohn's disease

The importance of infectious pathogens in Crohn's disease (CD) is still under debate. Therefore, we examined a panel of potential viral and bacterial pathogens in a large series of CD patients and controls. Archival tissue from 76 patients, 56 with CD and 20 control patients, with normal colon mucosa (n=10) and non-steroid anti-inflammatory drug (NSAID)-induced colitis (n=10) were examined using PCR-based detection methods for human cytomegalovirus (CMV), Epstein-Barr virus (EBV), herpes simplex virus 1, 2 (HSV1,2), adenovirus (AD), varicella-zoster virus (VZV), human herpes virus 6 (HHV6), human herpes virus 8 (HHV8), Mycobacterium tuberculosis complex (Mtbc), atypical mycobacteria (nM/MG1), including Mycobacterium avium (subspecies paratuberculosis, MAP), Stenotrophomonas maltophilia (Sm), and Yersinia enterocolitica (Ye). In CD patients, positive PCR results were achieved in 19 cases (34%). Sm was most frequent in 10 of 56 cases (17.9%) followed by EBV (6/56, 10.7%), nM/MG1 (4/56, 7.1%), including MAP, HHV6, and CMV (2/56, 3.6%), and finally Mtbc and AD (1/56, 1.8%). The control patients showed positive PCR results in 12 patients (12/20, 60%), nine of them with only weak signals, suggesting a persistent infection. In addition, we compared typical pathomorphological features of CD patients with the PCR results and found a significant correlation between EBV infection and mural abscesses (P=0.014). Our data demonstrate that several potential pathogens can be detected in a sizeable fraction of specimens from patients with CD, but also in control patients, suggesting that the analyzed infectious pathogens may be associated with the disease, but do not represent an obligatory cause.