TABLE 2.

PMA-direct-qPCR for discriminating between live and dead bacteria^a

PMA concn (μM)	CT
	C. sakazakii (1.0 × 107CFU or cells/ml)		E. coli (1.0 × 107 CFU or cells/ml)
	Live	Dead	Live	Dead
0	19.2 ± 0.24	18.9 ± 0.28	19.4 ± 0.41	19.0 ± 0.35
10	19.7 ± 0.31	24.9 ± 0.51	19.9 ± 0.38	25.5 ± 0.59
100	21.8 ± 0.54	39.7 ± 0.77	23.1 ± 0.72	38.4 ± 1.11
250	26.8 ± 0.79	ND × 2	26.9 ± 0.78	ND × 2

^aC. sakazakii and E. coli cells were suspended in sterile distilled water. Dead cells were prepared by boiling in sterile distilled water for 3 min. qPCR (50 cycles) was performed in duplicate, and the C_T values are presented as means ± SD (n = 2). ND × 2, no-amplification results were obtained in duplicate.