FIG 2.

Toxin A and B digital ELISA results. Toxin A (A) and toxin B (B) digital ELISA results for groups of samples testing positive versus negative on other assays (i.e., NAAT positive versus NAAT negative, TC positive versus TC negative, and cytotoxicity positive versus cytotoxicity negative). The mean signals in each group are indicated by horizontal lines. The calculated clinical cutoffs for each digital ELISA (29.4 pg/ml for the toxin A assay and 23.3 pg/ml for the toxin B assay) are shown as dotted lines spanning each figure. (A) Arrow indicates a sample that was excluded from calculation of the cutoff because it was an extreme outlier and substantially distorted the mean for that assay. NAAT, nucleic acid amplification testing; TC, toxigenic culture.