TABLE 2.

Cross-contamination studies on automated extraction instruments

Extraction instrumentTrue-positive/false-positive resultsa (n)
Checkerboard patternColumn-by-column patternRow-by-row patternPlate-by-plate pattern
MagNA Pure16/0 (32)16/0 (32)16/0 (32)32/0 (64)
BioRobot M48 v.124/2 (48)ND∗NDND
BioRobot M48 v.224/0 (48)ND∗24/0 (48)48/0 (96)
  • a Positive and negative specimens were alternated by position (checkerboard), column, row, and plate. After two false-positive results were found with checkerboard analysis by BioRobot M48 (BioRobot M48, v.1), the instrument software was rewritten. The new software (BioRobot M48, v.2) was retested with the four specimen configurations. ND, not done. ∗, The BioRobot M48 extraction platform is not configured in columns; therefore, this was not tested.