Carriage rates of each toxin type of Clostridium difficile in infants. On the basis of the qPCR counts for three genes (16S rRNA, tcdA, and tcdB), the toxin types (A+ B+, A− B+, or A− B−) of predominant C. difficile strains in individual specimens were identified. The rates of carriage of each toxin type of C. difficile were calculated with respect to each stool specimen group.