Detection of Cronobacter spp.and Samonella spp.in powder infant formula by duplex PCR

A duplex PCR assay was developed to detect Cronobacter spp. and Samonella spp. in powder infant formula ( PIF) .Two sets of specific primers were designed according to the conservative region of 16 S rDNA gene sequences of Cronobacter and Samonella.The genomic DNA was extracted and used as the templates for duplex PCR after the 4- hour pre- enrichment.As the results showed that, two DNA fragments of 140 bp and 630 bp were amplified by two pairs of specific primers. The detection limit of this protocol could be 100 CFU /g for both Cronobacter spp. and Samonella spp., and bacteria interference didn't affect the detection sensitivity. A great sensitivity and specificity ( ≥95%) was observed in the detection of artificially contaminated PIF samples.Thus, the duplex PCR assay for joint detection of Cronobacter spp. and Samonella spp. in powder infant formula was sensitive, accurate, and also applicable to investigate and monitor these two pathogens in dairy products.