Table 1.

Comparison of the PMS-phage assay and culture for testing bovine bulk tank milk^a

Source (no.) of milk samples	Milk conditionb	No. of samples positive by both culture and PMS-phage assay	No. of samples positive by culture and negative by PMS-phage assay	No. of samples negative by culture and positive by PMS-phage assay	No. of samples negative by both culture and PMS-phage assay	Kappa value (P valuec)
Northern Ireland (25)	Fresh	2	1	8	14	0.151 (0.0455)
United States (19)	Frozen	2	0	2	15	0.612 (0.4795)

^aHPC decontamination preceded culturing of Northern Ireland milk samples, and PMS preceded culturing of milk samples from the United States.

^bFresh milk was 24 h old; frozen milk was kept at −70°C for several months and thawed for testing.

^cDetermined by McNemar's test using GraphPad InStat 3.0 (GraphPad Software, La Jolla, CA).