Fecal bile acid profiles predict recurrence in patients with primary Clostridioides difficile infection

1. Background Factors that influence recurrence risk in primary Clostridioides difficile infection (CDI) are poorly understood, and tools to predict recurrence are lacking. Perturbations in microbial-derived bile acids (BAs) contribute to CDI pathogenesis and may be relevant to primary disease prognosis. Aims To define stool bile acid profiles and microbial bile-metabolising functionality in primary CDI patients, and explore signatures predicting recurrence. Methods Weekly stool samples were collected from primary CDI patients from the last day of anti-CDI therapy until recurrence, or through eight weeks post-completion otherwise. Ultra-high performance liquid chromatography-mass spectrometry (UHPLC-MS) was used to profile bile acids, and bacterial bile salt hydrolase (BSH) activity was measured to determine primary BA deconjugation capacity. Multivariate and univariate models were used to define differential BA trajectories in recurrers versus non-recurrers, and assess fecal bile acids as predictive markers for recurrence. Results Twenty (36%) out of 56 patients (median age 57, 64% male) recurred, with 80% of recurrence occurring within the first nine days post-antibiotic treatment. Principal component analysis (PCA) of stool bile acid profiles demonstrated clustering of samples by recurrence status and post-treatment time point. Longitudinal fecal bile acid trajectories in non-recurrers showed a recovery of secondary bile acids and their derivatives in non-recurring patients that was not observed in recurrers. BSH activity increased over time amongst patients who did not relapse (β= 0.056; likelihood ratio test p =0.018). A joint longitudinal-survival model identified five stool bile acids with AUROC > 0.73 for prediction of recurrence within nine days post-CDI treatment. Conclusions Gut bile acid metabolism dynamics differ in primary CDI patients between those who develop recurrence versus those who do not. Individual bile acids show promise in primary CDI patients as potential novel biomarkers to predict CDI recurrence.