Multiplex real-time polymerase chain reaction assay for simultaneous detection and quantification of Salmonella species, Listeria monocytogenes, and Escherichia coli O157:H7 in ground pork samples.
Salmonella sp., Listeria monocytogenes, and Escherichia coli O157:H7 are foodborne pathogens capable of causing serious gastrointestinal illness. We previously described simultaneous detection of these pathogens by multiplex polymerase chain reaction (PCR) in 44 types of spiked food samples, including meat, produce, fish, and dairy products, targeting genes specific for each pathogen. Based on the previous work, a multiplex real-time PCR assay using fluorescent probes was developed to detect and accurately quantify Salmonella sp., L. monocytogenes, and E. coli O157:H7 in ground pork samples. The detection sensitivity for this method was 2.0 x 10(2) CFU/mL for each pathogen, and the quantification range was 10(2)-10(7) CFU/mL with a high correlation coefficient (R(2) > 0.99) and high PCR efficiency (84.2% to 99.2%). When this protocol was used for the detection of each of the pathogens in spiked pork samples, one cell per 25 g of inoculated sample after enrichment for 20 h could be detected within 24 h. As a result, this multiplex real-time PCR assay will be valuable as a screening method for foods contaminated with these pathogens.
Food Hygiene Laboratory, National Food Research Institute, Tsukuba, Japan. skawasa@affrc.go.jp
Susumu
S
Kawasaki
Pina M
PM
Fratamico
Naoko
N
Horikoshi
Yukio
Y
Okada
Kazuko
K
Takeshita
Takashi
T
Sameshima
Shinichi
S
Kawamoto
D000818:Animals; D015169:Colony Count, Microbial; D004269:DNA, Bacterial / Q000302:isolation & purification; D019453:Escherichia coli O157 / Q000235:genetics / Q000254:growth & development / Q000302:isolation & purification*; D005456:Fluorescent Dyes; D005516:Food Microbiology; D005517:Foodborne Diseases / Q000517:prevention & control; D057230:Limit of Detection; D008089:Listeria monocytogenes / Q000235:genetics / Q000254:growth & development / Q000302:isolation & purification*; D008460:Meat / Q000382:microbiology*; D016133:Polymerase Chain Reaction / Q000379:methods*; D012477:Salmonella enteritidis / Q000235:genetics / Q000254:growth & development / Q000302:isolation & purification*; D034421:Sus scrofa
D004269:DNA, Bacterial; D005456:Fluorescent Dyes