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Korean J Food Sci Anim Resour. 2017;37(6):799-803. doi: 10.5851/kosfa.2017.37.6.799. Epub 2017 Dec 31.

Comparison of Upgraded Methods for Detecting Pathogenic Escherichia coli in Foods Using Centrifugation or Filtration.

Choi Y1,2, Lee H1,2, Lee S1,2, Kim S1,2, Lee J1,2, Ha J1,2, Oh H1,2, Yoon Y1,2.

Author information

1
Department of Food and Nutrition, Sookmyung Women's University, Seoul 04310, Korea.
2
Risk Analysis Research Center, Sookmyung Women's University, Seoul 04310, Korea.

Abstract

In the present study, centrifugation and filtration pretreatments were evaluated to decrease sample preparation time and to improve the sensitivity and specificity of multiplex polymerase chain reaction (PCR) for the detection of low levels of pathogenic Escherichia coli in various foods. Pathogenic E. coli (E. coli NCCP11142, E. coli NCCP14037, E. coli NCCP 14038, E. coli NCCP14039, and E. coli NCCP15661) was inoculated into pork, beef, and baby leafy vegetables at 1, 2, and 3 Log CFU/g. The samples were shaken 30 times (control), then centrifuged or filtered. DNA extracts from the samples were subjected to PCR using the PowerchekTM Diarrheal E. coli 8-plex Detection Kit. In the pork samples, no E. coli was detected in the control samples, while E. coli were detected in 100% of 3-Log CFU/g inoculated and centrifuged samples, and in 100% of 2 and 3-Log CFU/g inoculated, and filtered samples. In the beef samples, all control samples appeared to be E. coli-negative, while E. coli was detected in 50-75% of centrifuged samples, regardless of inoculated level, and in 100% of 2 and 3-Log CFU/g inoculated, and filtered samples. In baby leafy vegetables, E. coli were not detected in 25-50% of the control samples, while E. coli were detected in 0-25% of the centrifuged samples, and 75-100% of the filtered samples, depending on the inoculum amount. In conclusion, filtration pretreatment can be used to minimize sample preparation time, and improve the sensitivity and specificity of rapid detection of pathogenic E. coli in various foods.

KEYWORDS:

Escherichia coli; centrifugation; filtration; polymerase chain reaction; rapid detection; sample pretreatment

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