Dual role of Helicobacter and Campylobacter species in IBD: a systematic review and meta-analysis.
To conduct a comprehensive global systematic review and meta-analysis on the association between Helicobacter pylori infection and IBD. As bacterial antigen cross-reactivity has been postulated to be involved in this association, published data on enterohepatic Helicobacter spp (EHS) and Campylobacter spp and IBD was also analysed.



Electronic databases were searched up to July 2015 for all case-control studies on H. pylori infection/EHS/Campylobacter spp and IBD. Pooled ORs (P-OR) and 95% CIs were obtained using the random effects model. Heterogeneity, sensitivity and stratified analyses were performed.



Analyses comprising patients with Crohn's disease (CD), UC and IBD unclassified (IBDU), showed a consistent negative association between gastric H. pylori infection and IBD (P-OR: 0.43, p value <1e-10). This association appears to be stronger in patients with CD (P-OR: 0.38, p value <1e-10) and IBDU (P-OR: 0.43, p value=0.008) than UC (P-OR: 0.53, p value <1e-10). Stratification by age, ethnicity and medications showed significant results. In contrast to gastric H. pylori, non H. pylori-EHS (P-OR: 2.62, p value=0.001) and Campylobacter spp, in particular C. concisus (P-OR: 3.76, p value=0.006) and C. showae (P-OR: 2.39, p value=0.027), increase IBD risk.



H. pylori infection is negatively associated with IBD regardless of ethnicity, age, H. pylori detection methods and previous use of aminosalicylates and corticosteroids. Antibiotics influenced the magnitude of this association. Closely related bacteria including EHS and Campylobacter spp increase the risk of IBD. These results infer that H. pylori might exert an immunomodulatory effect in IBD.
School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, New South Wales, Australia.
Natalia
N
Castaño-Rodríguez
School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, New South Wales, Australia.
Nadeem O
NO
Kaakoush
Department of Paediatrics, University Malaya Medical Centre, Kuala Lumpur, Malaysia.|University Malaya Pediatrics and Child Health Research Group, University Malaya, Kuala Lumpur, Malaysia.
Way Seah
WS
Lee
School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, New South Wales, Australia.
Hazel M
HM
Mitchell
D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D002167:Campylobacter; D002169:Campylobacter Infections / Q000150:complications / Q000453:epidemiology*; D003093:Colitis, Ulcerative / Q000453:epidemiology*; D003424:Crohn Disease / Q000453:epidemiology*; D016481:Helicobacter Infections / Q000150:complications / Q000453:epidemiology*; D016480:Helicobacter pylori; D006801:Humans; D065840:Protective Factors; D012307:Risk Factors; D013272:Stomach Diseases / Q000453:epidemiology / Q000382:microbiology
D000900:Anti-Bacterial Agents
CAMPYLOBACTER; HELICOBACTER PYLORI; INFLAMMATORY BOWEL DISEASE; META-ANALYSIS