Enterohepatic Helicobacter Species as a Potential Causative Factor in Inflammatory Bowel Disease: A Meta-Analysis

The Helicobacter species in the gut microbiota comprise Helicobacter pylori (H pylori) and enterohepatic Helicobacter species (EHS), which can colonize the intestinal mucosa. However, it is unclear whether EHS are associated with inflammatory bowel disease (IBD). Therefore, we conducted this meta-analysis to examine the association between EHS and IBD. PubMed, Scopus, Cochrane Library, and Web of Science databases, as well as abstracts from conference proceedings were searched to identify studies that used polymerase chain reaction to detect Helicobacter species in intestinal samples from patients with IBD. After screening, we carefully reviewed 20 of the 2955 identified studies, and performed a meta-analysis of the findings from 14 studies (11 adult studies and 3 pediatric studies) using STATA v12.0. These studies evaluated 1407 individuals, including 433 patients with Crohn's disease, 306 patients with ulcerative colitis, and 668 controls. The prevalence of Helicobacter species was higher among the patients with IBD, compared to that among the controls, which corresponded to a pooled risk ratio (RR) of 1.59 (95% confidence interval [CI]: 1.12–2.27). The RRs for adult and pediatric patients with IBD were 1.61 (95% CI: 1.03–2.52) and 1.76 (95% CI: 1.17–2.64), respectively. Compared to the controls, the patients with IBD tended to have a higher prevalence of EHS in the intestinal mucosa (RR: 2.01, 95% CI: 1.36–2.98), although the prevalence of H pylori was not significantly higher (RR: 1.22, 95% CI: 0.77–1.95). Compared to the controls, the RRs for EHS in patients with Crohn's disease and ulcerative colitis were 1.72 (95% CI: 1.20–2.47) and 3.27 (95% CI: 0.93–11.44), respectively. It appears that EHS was associated with IBD, while intestinal H pylori infection was not significantly associated with IBD. Further studies are needed to determine the involvement of EHS in the microbiological etiology of IBD.