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ARS Home » Northeast Area » Wyndmoor, Pennsylvania » Eastern Regional Research Center » Dairy and Functional Foods Research » Research » Publications at this Location » Publication #285634

Title: Detection and quantitation of Escherichia coli O157:H7 in raw milk by direct qPCR

item Paul, Moushumi
item Van Hekken, Diane
item Brewster, Jeffrey

Submitted to: International Dairy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/16/2013
Publication Date: 6/19/2013
Publication URL:
Citation: Paul, M., Van Hekken, D.L., Brewster, J.D. 2013. Detection and quantitation of Escherichia coli O157:H7 in raw milk by direct qPCR. International Dairy Journal. 32:53-60. Available:

Interpretive Summary: Drinking raw milk is becoming increasingly popular in the US based on the idea that it may be healthier and more nutritious than pasteurized milk. Unfortunately, raw milk can pose a severe health risk if pathogens that are normally killed by the pasteurization process are present in sufficient numbers to cause disease. Current methods can determine the presence but not the level of pathogens in milk. In this study, an improved method was developed for the fast, sensitive measurement of pathogen levels in raw milk. This quantitative information can better support efforts to understand and control the health risks associated with raw milk.

Technical Abstract: There has been a shift in US food consumption patterns toward unprocessed foods perceived to be healthier. Part of this trend is increasing consumption of raw, unpasteurized milk. Raw milk can be a source of pathogens that cause serious or fatal illness, particularly in immuno-compromised individuals. Methods exist for pathogen detection in foods, including milk, but require fresh samples, toxic chemicals, or complicated DNA extractions. We developed an improved method to detect and quantify Escherichia coli O157 in raw milk using direct quantitative PCR (qPCR). This methodology can concentrate bacteria from large sample volumes, effectively remove inhibitors without use of toxic or flammable reagents, and efficiently extract DNA in a fast, single-tube step. Escherichia coli O157:H7 inoculated into raw milk was detected at 1 cfu/mL from a 10 mL sample with results obtained in less than 3 hours.