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Table 2 Cut-offs of the two bead sets with B and D1 LPS

From: A bead-based suspension array for the detection of Salmonella antibodies in pig sera

Beads with S. Typhimurium LPS (B) compared with a commercial BC1D1 ELISA
Relative sensitivity (%) 90.6 92.2 93.8 95.3 96.9 98.4 100
Relative specificity (%) 98.2 97.3 93.7 93.7 91.9 63.7 62.2
Cut-off (MFI) 1713 1668 1453 1406 1311 636 617
E+ Bb- (FN) 6 5 4 3 2 1 0
E- Bb + (FP) 2 3 7 7 9 40 42
Bb+ 60 62 67 68 71 103 106
Beads with S. Enteritidis LPS (D1) compared with a commercial BC1D1 ELISA
Relative sensitivity (%) 65.6       
Relative specificity (%) 100       
Cut-off (MFI) 1105       
E+ Db- (FN) 22       
E- Db + (FP) 0       
Db+ 42       
E+ Bb- Db+ 2       
  1. Data of 175 sera from slaughter pigs were subjected to ROC analysis using the results of a BC1D1 LPS ELISA as criterion (111 ELISA negatives, 64 ELISA positives). For the bead set with B LPS (upper table), specificities and cut-offs are given for sensitivities ranging from 90 to 100%. In addition, the numbers of false negatives (E+ Bb-), false positives (E- Bb+) and the total of positives on the B beads (Bb+) are given. For the bead set with D1 LPS (lower table), for 100% specificity the corresponding sensitivity and cut-off are given, as well as the numbers of false negatives (E+ Db-), false positives (E- Db+), the total of positives on the D beads (Db+), and the number of ELISA positives that are negative on B beads but positive on D1 beads (E+ Bb- Db+). As the used ELISA is assumed to be the perfect test, sensitivity and specificity related to this ELISA are referred to as ‘relative sensitivity’ and ‘relative specificity’. Abbreviations: E+, ELISA positive; E-, ELISA negative; Bb+, positive on B beads; Bb-, negative on B beads; D+, positive on D1 beads; D-, negative on D1 beads, FN, false negative; FP, false positive