FIG 3.

Longitudinal changes in bacterial counts and genotypes of toxigenic Clostridium difficile isolates in 18 infants. Circles and squares indicate the detection of toxigenic C. difficile and nontoxigenic C. difficile by qPCR, respectively. The sizes of the symbols reflect bacterial numbers as determined by qPCR, where small symbols indicate <6.0 log₁₀ cells/g stool, medium symbols indicate 6.0 to 8.0 log₁₀ cells/g stool, and large symbols indicate >8.0 log₁₀ cells/g stool. A minus symbol means that no C. difficile was detected by qPCR. “ns,” no samples. Circles filled with color indicate the isolation of a C. difficile strain by stool culture, and each color corresponds to a genotype of toxigenic C. difficile identified by PCR ribotyping. For each infant, strains that were confirmed to be monophyletic are linked with a line.