Fig. 1

Study design and sample collection timeline. Relative timeline (days) of samples collected from patients diagnosed with initial Clostridium difficile infection (CDI) (index sample = 0 days) categorized into three patient groups (nonrecurrent, recurrent, and reinfected). Patients who did not develop recurrence (n = 42) remained free of a subsequent CDI diagnosis. Patients with recurrent disease (n = 32) were diagnosed with CDI (positive clinical lab result) 14–56 days following index sample collection. Patients diagnosed with another CDI index outside of the recurrence window (>56 days) were considered reinfected (n = 19) NA = test not available