Table 2.

The effect of DNA levels on IC and stx2 detection.

Reaction	IC spikea	O157 spikeb	Total DNAc	IC expd	stx2 expe
1	0	0	100 ng	0	0
2	0	2126	100 ng	0	2720
3	276	0	100 ng	72	0
4	276	2126	100 ng	84	2795
5	0	0	1 μg	0	0
6	0	2126	1 μg	0	2740
7	276	0	1 μg	78	0
8	276	2126	1 μg	87	2705

^aIC spike level (molecules per reaction) based on known MW of the pHCred plasmid.

^bE. coli O157 (RM1484) genomic DNA, number of molecules/reaction, based on 5.1 × 10⁶ bp.

^cDNA per reaction, primarily sediment DNA from a pathogen-negative sample.

^dIC template levels per reaction as detected by ddPCR, average of four experiments.

^estx2 template levels per reaction as detected by ddPCR, average of four experiments.