Table 2. Comparison of Ct values by Real-Time PCR in 10 different pre-enrichment broths after artificial inoculation of 7.2 CFU/g of Cronobacter spp. (Enterobacter sakazakii) into dried infant formula

In the inoculation volume of 7.2 CFU/g Cronobacter spp. (E. sakazakii)
	Type of 10 different pre-enrichment										Positive control	Negative control	Negative control
	TSB	TSB-0.6% YE	DW	VRBG	EE	TSB-0.1% SP	NB	VRBL	BHI	PBS	Cronobacter spp. (E. sakazakii)	Salmonella Enteritidis	Deionized water
Ct value	22.72	25.82	23.43	28.27	21.37	22.31	24.95	23.02	21.92	24.34	22.49	ND	ND

PCR, polymerase chain reaction; TSB, tryptic soy broth; YE, yeast extract; DW, distilled water; VRBG, violet red bile glucose; EE, Enterobacteriaceae enrichment; SP, sodium pyruvate; NB, nutrient broth; VRBL, violet red bile lactose; BHI, brain heart infusion; PBS, phosphate buffered saline; ND, not detected.