Stool Interleukin-1 beta Differentiates Clostridioides difficile Infection (CDI) From Asymptomatic Carriage and Non-CDI Diarrhea

Clostridioides difficile diagnostics cannot reliably distinguish infection from colonization. Stool IL-1 beta is >40-fold higher in CDI vs carriers and non-CDI diarrhea; correlating to stool toxin in CDI, not in carriers. Stool IL-1 beta, pivotal in CDI pathobiology, is a promising biomarker. Background Despite advances in the understanding and diagnosis of Clostridioides difficile infection (CDI), clinical distinction within the colonization-infection continuum remains an unmet need. Methods By measuring stool cytokines and antitoxin antibodies in well-characterized cohorts of CDI (diarrhea, nucleic acid amplification test [NAAT] positive), non-CDI diarrhea (NCD; diarrhea, NAAT negative), asymptomatic carriers (ASC; no diarrhea, NAAT positive) and hospital controls (CON; no diarrhea, NAAT negative), we aim to discover novel biological markers to distinguish between these cohorts. We also explore the relationship of these stool cytokines and antitoxin antibody with stool toxin concentrations and disease severity. Results Stool interleukin (IL) 1 beta, stool immunoglobulin A (IgA), and immunoglobulin G (IgG) anti-toxin A had higher (P < .0001) concentrations in CDI (n = 120) vs ASC (n = 43), whereas toxins A, B, and fecal calprotectin did not. Areas under the receiver operating characteristic curve (ROC-AUCs) for IL-1 beta, IgA, and IgG anti-toxin A were 0.88, 0.83, and 0.83, respectively. A multipredictor model including IL-1 beta and IgA anti-toxin A achieved an ROC-AUC of 0.93. Stool IL-1 beta concentrations were higher in CDI compared to NCD (n = 75) (P < .0001) and NCD + ASC+ CON (CON, n = 75) (P < .0001), with ROC-AUCs of 0.83 and 0.86, respectively. Stool IL-1 beta had positive correlations with toxins A (rho(A) = +0.55) and B (rho(B) = +0.49) in CDI (P < .0001) but not in ASC (P > .05). Conclusions Stool concentrations of the inflammasome pathway, proinflammatory cytokine IL-1 beta, can accurately differentiate CDI from asymptomatic carriage and NCD, making it a promising biomarker for CDI diagnosis. Significant positive correlations exist between stool toxins and stool IL-1 beta in CDI but not in asymptomatic carriers.