Which of the following is NOT a symptom of C. diff infection?

C. difficile infection is primarily characterized by gastrointestinal symptoms due to the pathogenic effects of the bacteria on the gut lining. Common symptoms include fever, which is often a response to infection, anorexia, as patients may lose their appetite due to the underlying gastrointestinal distress, and nausea, which is frequently reported by individuals affected by the infection.

In contrast, joint swelling is not associated with C. difficile infections. This symptom is more indicative of inflammatory or autoimmune conditions rather than a gastrointestinal infection. Thus, while the other symptoms are aligned with the clinical presentation of a C. difficile infection, joint swelling does not fit within the typical symptomatology associated with this infection.