Table 3.

Comparison of LAMP and qPCR assays in ground beef samples spiked with low levels of individual STEC strains of seven serogroups

Cell level (no. of CFU/25 g)	Target gene	Avg LAMP Tt (min) after enrichment ofa:					Avg qPCR CT (cycles) after enrichment ofa:
		6 h	8 h	10 h	12 h	24 h	6 h	8 h	10 h	12 h	24 h
1–2	stx1	20.5 ± 4.3A	17.0 ± 3.5AB	15.8 ± 3.1B	15.9 ± 2.7B	16.1 ± 3.3B	37.4 ± 2.2A	32.5 ± 3.3B	29.4 ± 2.2B	30.2 ± 1.9B	30.5 ± 3.3B
	stx2	28.2 ± 3.3A	22.4 ± 0.8B	20.4 ± 0.6B	20.3 ± 0.3B	20.5 ± 1.1B	37.7 ± 1.5A	30.1 ± 3.4B	28.4 ± 1.6B	29.4 ± 1.4B	29.0 ± 2.6B
	eae	27.7 ± 12.4A	19.6 ± 4.8B	18.8 ± 4.2B	18.6 ± 4.0B	18.9 ± 4.2B	34.7 ± 2.2A	28.3 ± 2.9B	26.1 ± 2.0B	27.3 ± 2.1B	27.1 ± 2.6B
10–20	stx1	22.0 ± 7.7A	15.9 ± 3.4B	15.1 ± 3.4B	15.1 ± 3.0B	15.2 ± 2.8B	36.0 ± 3.5A	28.9 ± 3.6B	26.4 ± 3.5B	27.2 ± 2.8B	26.2 ± 3.4B
	stx2	23.4 ± 0.6A	19.4 ± 0.4B	18.5 ± 0.6B	19.1 ± 0.7B	19.2 ± 0.7B	35.4 ± 2.3A	27.8 ± 3.9B	25.9 ± 3.0B	26.8 ± 2.1B	26.1 ± 3.0B
	eae	23.2 ± 7.1A	18.5 ± 4.2AB	18.0 ± 4.1AB	17.2 ± 4.0B	17.6 ± 4.0AB	31.8 ± 4.4A	26.0 ± 2.8B	24.0 ± 3.0B	24.4 ± 3.3B	23.7 ± 3.4B

^aNone of the 4-h-enrichment samples tested positive by either LAMP or qPCR. After 6 h enrichment, one out of six stx₁-positive strains was negative for LAMP, whereas two were negative for qPCR. In each row within LAMP or qPCR, T_t or C_T values followed by different uppercase letters are statistically significant (P < 0.05).