TABLE 4

Reproducibility of the Portrait Toxigenic C. difficile Assaye

Study site% positive Portrait results (no. of specimens with result by Portrait/total no. of specimens)
Moderate positiveaLow positivebHigh negativec
1100 (30/30)100 (30/30)10.0 (3/30)
2100 (30/30)100 (30/30)3.3 (1/30)
393.3 (28/30)d90.0 (27/30)d0.0 (0/30)
Total97.8 (88/90)96.7 (87/90)4.4 (4/90)
  • a Samples contained a CFU input equal to approximately three times the limit of detection.

  • b C95 density. The samples contained a CFU input equal to the assay limit of detection. The positivity rate was expected to be ∼95.0%.

  • c C5 concentration. The samples contained a CFU input approximately 10-fold lower than the assay limit of detection. The positivity rate was expected to be 5.0%.

  • d Repeat testing of this reproducibility panel at this site demonstrated 30/30 (100%) positive results.

  • e A C. difficile toxinotype O, tcdA- and tcdB-positive strain (ATCC 43255) was used for this study.