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P2-259 Thermal Inactivation of Non-O157 Shiga Toxin-Producing Escherichia coli in Laboratory Media

Monday, July 27, 2015
Exhibit Hall (Oregon Convention Center)
Jagpinder Brar , Purdue University , West Lafayette , IN
Sydney Corkran , Purdue University , West Lafayette , IN
Matthew Bailey , Purdue University , West Lafayette , IN
Bruce Applegate , Purdue University , West Lafayette , IN
Arun Bhunia , Purdue University , West Lafayette , IN
Jolena Waddell , Tarleton State University , Stephenville , TX
Manpreet Singh , Purdue University , West Lafayette , IN
Introduction: In recent times, a total of 46 outbreaks of non-O157 Shiga Toxin-producing Escherichia coli (STEC) have been reported. It has caused 1,727 illnesses and 144 hospitalizations in the United States as a result of which the Food Safety and Inspection services (FSIS) has declared non-O157 as an adulterant in ground or cooked beef and enforced a zero tolerance policy.

Purpose: The objective of this research was to determine thermal inactivation of non-O157 STECs in order to develop and validate mathematical models that can accurately predict elimination of these pathogens from ground beef containing varying fat levels and salt contents.

Methods: Decimal reduction time (D-values) for non-O157 strains were compared to O157:H7 strain of STEC in Tryptic Soy Broth (TSB) supplemented with 50-ppm nalidixic acid (NAL). Six strains of STECs; O26:H1, O45:H2, O103:H2, O111:H8, O121:H9, O145:Non-motile and O157:H7 (ATCC 43895) were used in this study. NAL resistance was developed in each strain and used for the experiments. D-values for O157 and non-O157 STEC strains were calculated at 55, 60, and 65°C.

Results: At 55°C, D-value of O157:H7 strain was not different (P > 0.05) from O111:H8 but it was lower (P < 0.05) than other non-O157 strains. Among the non-O157 group, O45:H2 had higher (P < 0.05) D-value than O26:H1 and O111:H8. At 60°C, there was no difference (P > 0.05) among the non-O157 group, while the D-value of O157:H7 was lower (P < 0.05) than all the non-O157 strains used in our study. Similarly, at 65°C no differences (P > 0.05) among the non-O157 strains were observed. D-values of O157:H7 were similar (P > 0.05) to that of O26:H1, O45:H2 and O145:Non-motile and lower (P < 0.05) than other strains of non-O157 group.

Significance: Results from this study will help the food industry in understanding and addressing problems associated with non-O157 STEC strains.

Back to: Poster Session 2 – Laboratory and Detection Methods; Meat, Poultry and Eggs; Dairy and Beverages; Food Law and Regulation; General Microbiology; Modeling and Risk Assessment
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