TABLE 3.
BD Max discrepant results for prospective and retrospective specimens
| Target | No. (%) of discrepant results (n = 19) | Specimen originb | Specimen type | Type of discrepancy | Discrepant analysis resulta |
|---|---|---|---|---|---|
| Vibrio | 8 (42.1) | 7 prospective, 1 retrospective | 5 Cary-Blair preserved, 3 unpreserved | False positive | 5/8 were negative by both xEBP and alternate PCR, 2/8 were repeat positive by the xEBP and negative by alternate PCR, 1/8 was unavailable for retesting |
| Plesiomonas shigelloides | 4 (21.1) | 3 prospective, 1 retrospective | 2 Cary-Blair preserved, 2 unpreserved | False positive | 1/4 was negative by both xEBP and alternate PCR, 3/4 were repeat positive by the xEBP and negative by alternate PCR |
| Yersinia enterocolitica | 1 (5.3) | 1 prospective | 1 Cary-Blair preserved | False positive | 1/1 was negative by both xEBP and alternate PCR |
| ETEC | 6 (31.6) | 4 prospective, 2 retrospective | 3 Cary-Blair preserved, 3 unpreserved | 5 false positive, 1 false negative | 1/6 was negative by both xEBP and alternate PCR, 1/6 was repeat positive by the xEBP and negative by alternate PCR, 2/6 were repeat positive by the xEBP and positive by alternate PCR and sequencing, 2/6 were unavailable for retesting |
a
Discrepant analysis included repeat testing on the xEBP assay and an alternate PCR followed by bidirectional sequencing.
b
Three discrepant retrospective results were not available for discrepant analysis due to limited specimen volume (one ETEC false negative, one ETEC false positive, and one Vibrio false positive).