We, together with other reports, suggest the importance of quantifying toxins to evaluate CDI cases.50–52 Incorporating adjunctive biomarkers, such as interleukin-1β (IL-1β), better distinguishes CDI from asymptomatic carriage and non-CDI diarrhea.53 Here, CdtR regulates both toxin production and secretion and is essential for C. difficile virulence in mice, suggesting that it may serve as an adjunctive biomarker for CDI diagnosis. Here, IL1B is linked to clostridium difficile infection.