BioMed Research International

Research Article

A Fast, Reliable, and Sensitive Method for Detection and Quantification of Listeria monocytogenes and Escherichia coli O157:H7 in Ready-to-Eat Fresh-Cut Products by MPN-qPCR

Table 3

Enumeration of E. coli O157:H7 in samples of rocket, mix salad and piel de sapo melons raw, processed, and at 3 days of shelf life by the MPN-qPCR method and using fliC H7 and rfbE as target genes.
 Sample3-tube dilution
(mL homogenized)		Positive tubes
(MPN)		Positive
(conventional method)		Positive fliC H7
(qPCR)		Positive rfbE 
(qPCR)		MPN-qPCR
RocketRaw0.1/0.01/0.0011/1/0n.d.0/0/00/0/0n.d.
Processed1/0.1/0.012/2/0n.d.0/0/00/0/0n.d.
3-day shelf life1/0.1/0.011/3/0n.d.0/0/00/0/0n.d.
Mix saladRaw0.1/0.01/0.0010/3/0n.d.0/1/00/0/0+/−1
Processed1/0.1/0.012/3/0n.d.0/0/00/0/0n.d.
3-day shelf life1/0.1/0.013/2/0n.d.0/0/00/0/0n.d.
Piel de sapo melonsRaw1/0.1/0.011/0/0n.d.0/0/00/0/0n.d.
Processed10/1/0.11/1/0n.d.0/0/00/0/0n.d.
3-day shelf life10/1/0.11/2/0n.d.0/0/00/0/0n.d.
+ for fliC (H7) gene and negative for rfb (O157) gene.