Abbreviations: CDI, Clostridium difficile infection; PCR, polymerase chain reaction; SOC, standard of care.

^aSevere infection was defined as a Zar score of 2 or higher. The Zar score ranges from 1 to 8 and is based on the following factors: age greater than 60 years (1 point), body temperature higher than 38.3°C (100°F) (1 point), albumin level lower than 2.5 g per deciliter (1 point), peripheral white cell count higher than 15 000 per cubic millimeter within 48 hours (1 point), endoscopic evidence of pseudomembranous colitis (2 points), and treatment in an intensive care unit (2 points).

^bThe determination of whether a participant was immunocompromised was made on the basis of medical history or use of immunosuppressive therapy.

^cIncluded are systemic antibiotics other than the standard of care antibiotic that was given to treat C. difficile infection.

^dRenal impairment was defined as a serum creatinine level of 1.5 mg per deciliter (133 μmol per liter) or higher.

^eHepatic impairment was defined as having 2 or more of the following: an albumin level of 3.1 g per deciliter or lower, an alanine aminotransferase level at least 2 times the upper limit of the normal range, a total bilirubin level at least 1.3 times the upper limit of the normal range, or mild, moderate, or severe liver disease (as reported on the Charlson Index).

^fThe denominators used to calculate percentages are the numbers of participants who had a positive culture.