Human intestinal spirochetosis, irritable bowel syndrome, and colonic polyps: A systematic review and meta‐analysis

Human colonic spirochetosis (CS) is usually due to Brachyspira pilosicoli or Brachyspira aalborgi infection. While traditionally considered to be commensal bacteria, there are scattered case reports and case series of gastrointestinal (GI) symptoms in CS and reports of colonic polyps with adherent spirochetes. We performed a systematic review and meta‐analysis investigating the association between CS and GI symptoms and conditions including the irritable bowel syndrome (IBS) and colonic polyps. Following PRISMA 2020 guidelines, a systematic search of Medline, CINAHL, EMBASE, and Web of Science was performed using specific keywords for CS and GI disease. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using a random‐effects model. Of 75 studies identified in the search, 8 case–control studies met the inclusion criteria for meta‐analysis and 67 case series studies met the inclusion criteria for pooled prevalence analysis. CS was significantly associated with diarrhea (n = 141/127, cases/controls, OR: 4.19, 95% CI: 1.72–10.21, P = 0.002) and abdominal pain (n = 64/65, OR: 3.66, 95% CI: 1.43–9.35, P = 0.007). CS cases were significantly more likely to have Rome III‐diagnosed IBS (n = 79/48, OR: 3.84, 95% CI: 1.44–10.20, P = 0.007), but not colonic polyps (n = 127/843, OR: 8.78, 95% CI: 0.75–103.36, P = 0.084). In conclusion, we found evidence of associations between CS and both diarrhea and IBS, but not colonic polyps. CS is likely underestimated due to suboptimal diagnostic methods and may be an overlooked risk factor for a subset of IBS patients with diarrhea.