Journal of Consumer Protection and Food Safety

A new 7-plex PCR assay for simultaneous detection of shiga toxin-producing

Escherichia coli O157 and Salmonella Enteritidis in meat products

Yuexia Wanga1, Biao Suoa2*

1 College of Life Sciences, Henan Agricultural University, 63 Nongye Rd. Zhengzhou,

Henan Province 450002, China

2 College of Food Science & Technology, Henan Agricultural University, 63 Nongye

Rd. Zhengzhou, Henan Province 450002, China

*Corresponding author:

Biao Suo

E-mail: [email protected] a Yuexia Wang and Biao Suo contributed equally to this work.

1 Supplemental Table 1. Bacterial strains used in the specificity test of multiplex PCR

Strains Multiplex PCR Results

invA SdfI rfbE eae stx1 stx2 IAC S. enterica Enteritidis CMCC 50335 + + - - - - - S. enterica Enteritidis ATCC 13076 + + - - - - - S. enterica Typhimurium ATCC 13311 + ------S. enterica Typhimurium ATCC 14028 + ------S. enterica Infantis ATCC 51741 + ------S. enterica Anatum ATCC 9270 + ------S. enterica Montevideo ATCC 8387 + ------S. enterica Gallinarum CMCC 50770 + ------S. enterica Saintpaul ATCC 9712 + ------S. enterica Vellore ATCC 15611 + ------S. enterica Tallahassee ATCC 12002 + ------E. coli O157:H7 ATCC 43895 - - + + + + - E. coli O157:H7 ATCC 43890 - - + + + - - E. coli O157:H7 ATCC 43889 - - + + - + - E. coli O157:H7 ATCC 43888 - - + + - - - L. monocytogenes ATCC54002 ------Enterobacter sakazakii ATCC29544 ------Staphylococcus aureus ATCC 2593 ------Enterococcus faecalis ATCC 49452 ------Enterobacter sakazakii ATCC 29544 ------Proteus mirabilis ATCC 12453 ------Citrobacter freundii ATCC 8090 ------Aeromonas hydrophila ATCC 7965 ------Enterococcus avium ATCC 14025 ------Staphylococcus epidermidis ATCC 11993 ------Staphylococcus simulaus ATCC 13044 ------Micrococcus luteus ATCC 9341 ------(+) Positive results; (-) Negative results.

2 Supplemental Table 2. Comparison results of traditional microbiological method and multiplex PCR in detection of meat samples.

Food name Detection method

Multiplex PCR Microbiological analysis

E. coli O157 Salmonella IAC E. coli O157 Salmonella (Enteritidis) rfbE eae stx1 stx2 invA sdfI

Raw sausage 1 (A) + + + + + + - + + (+) Raw sausage 2 (N) ------+ - - (-) Raw sausage 3 (N) - - - - + + + - + (+) Raw sausage 4 (N) ------+ - - (-) Raw sausage 5 (C) ------+ - - (-) Cooked ham 1 (A) + + + + + + - + + (+) Cooked ham 2 (N) ------+ - - (-) Cooked ham 3 (N) ------+ - - (-) Cooked ham 4 (N) ------+ - - (-) Cooked ham 5 (C) ------+ - - (-) Raw Duck 1 (A) + + + + + + - + + (+) Raw Duck 2 (N) ------+ - - (-) Raw Duck 3 (N) ------+ - - (-) Raw Duck 4 (N) + + - - - - + + - (-) Raw Duck 5 (C) ------+ - - (-) Raw Beef 1 (A) + + + + + + - + + (+) Raw Beef 2 (N) ------+ - - (-) Raw Beef 3 (N) + + - - + + + - + (+) Raw Beef 4 (N) ------+ - - (-) Raw Beef 5 (C) ------+ - - (-) Raw Chicken 1 (A) + + + + + + - + + (+) Raw Chicken 2 (N) ------+ - - (-) Raw Chicken 3 (N) - - - - + + + - + (+) Raw Chicken 4 (N) - - - - + - + - + (-) Raw Chicken 5 (C) ------+ - - (-) Raw Lamb 1 (A) + + + + + + - + + (+) Raw Lamb 2 (N) - - - - + + + - + (+) Raw Lamb 3 (N) ------+ - - (-) Raw Lamb 4 (N) ------+ - - (-) Raw Lamb 5 (C) ------+ - - (-) Raw pork 1 (A) + + + + + + - + + (+) Raw pork 2 (N) ------+ - - (-) Raw pork 3 (N) + + - + + + - + + (+) Raw pork 4 (N) - - - - + - + - + (-)

3 Raw pork 5 (C) ------+ - - (-) (N) naturally contaminated food; (A) artificially contaminated food; (C) negative control; (+) positive results; (-) negative results.