Abstract
Intractable functional constipation (IFC) is the most severe form of constipation, but its etiology has long been unknown. We hypothesized that IFC is caused by refractory infection by a pathogenic bacterium. Here, we isolated from patients with IFC a Shigella species — peristaltic contraction–inhibiting bacterium (PIB) — that significantly inhibited peristaltic contraction of the colon by production of docosapentenoic acid (DPA). PIB colonized mice for at least 6 months. Oral administration of PIB was sufficient to induce constipation, which was reversed by PIB-specific phages. A mutated PIB with reduced DPA was incapable of inhibiting colonic function and inducing constipation, suggesting that DPA produced by PIB was the key mediator of the genesis of constipation. PIBs were detected in stools of 56% (38 of 68) of the IFC patients, but not in those of non-IFC or healthy individuals (0 of 180). DPA levels in stools were elevated in 44.12% (30 of 68) of the IFC patients but none of the healthy volunteers (0 of 97). Our results suggest that Shigella sp. PIB may be the critical causative pathogen for IFC, and detection of fecal PIB plus DPA may be a reliable method for IFC diagnosis and classification.
Authors
Xin Chen, Tian-Tian Qiu, Ye Wang, Li-Yang Xu, Jie Sun, Zhi-Hui Jiang, Wei Zhao, Tao Tao, Yu-Wei Zhou, Li-Sha Wei, Ye-Qiong Li, Yan-Yan Zheng, Guo-Hua Zhou, Hua-Qun Chen, Jian Zhang, Xiao-Bo Feng, Fang-Yu Wang, Ning Li, Xue-Na Zhang, Jun Jiang, Min-Sheng Zhu
Figure 4
Knockdown of the KS gene disrupts the inhibitory effect of PIB on colon contraction.
Copyright © 2026 American Society for Clinical Investigation
ISSN: 0021-9738 (print), 1558-8238 (online)