TABLE 3.

Combined results after resolution of discrepancies

Target and specimen type	No. of specimens with BD Max EBP result with reference to culture/EIA or alternate PCRa				Total no. of specimensc	PPA (95% confidence interval)	P value for PPAd	NPA (95% confidence interval)	P value for NPAd
	True positive	False negative	False positive	True negative
Campylobacter
Total	195	5	31	3,170	3,401	97.5 (94.3–99.2)		99.0 (98.6–99.3)
Prospective	66	1	29	2,797	2,893	98.5 (91.3–99.7)	0.867	99.0 (98.5–99.3)	0.525
Retrospectiveb	129	4	2	373	508	97.0 (92.5–98.8)		99.5 (98.1–99.9)
Salmonella
Total	219	6	8	3,307	3,540	97.3 (94.3–99.0)		99.8 (94.5–99.9)
Prospective	53	5	7	2,857	2,922	91.4 (81.0–97.1)	0.005	99.8 (99.5–99.9)	1.000
Retrospective	166	1	1	450	618	99.4 (96.7–99.9)		99.8 (98.8–100)
Shigella
Total	124	1	1	3,340	3,466	99.2 (95.6–99.9)		100 (99.8–100)
Prospective	33	0	1	2,889	2,923	100 (89.3–100)	1.000	100 (99.8–100)	1.000
Retrospective	91	1	0	451	543	98.9 (94.1–99.8)		100 (99.2–100)
Shiga toxins
Total	85	0	8	2,437	2,530	100 (95.7–100)		99.7 (99.4–99.9)
Prospective	19	0	8	2,347	2,374	100 (82.2–100)	1.000	99.7(99.3–99.9)	1.000
Retrospective	66	0	0	90	156	100 (94.5–100)		100 (95.9–100)

^aFor Campylobacter spp., Salmonella spp., and Shigella spp., a positive result by either culture or alternate PCR was considered a true-positive result. For the resolution of discrepant results for Shiga toxins, results of alternate PCR were considered true-positive results.

^bResults for all retrospective samples were confirmed by alternate PCR and bidirectional sequencing prior to testing with the BD Max EBP assay. Discrepancies were not further resolved.

^cThe number of prospective specimens varies by target due to differences in compliance with the study protocol and unresolved results.

^dP value for testing of the significance of the difference between prospective and retrospective data sets.