Event Title

Comparison of Escherichia Coli 0157:H7 with a Laboratory Strain on their Ability to Colonize Produce

Location

CSU Ballroom

Start Date

16-4-2013 10:00 AM

End Date

16-4-2013 12:00 PM

Student's Major

Biological Sciences

Student's College

Science, Engineering and Technology

Mentor's Name

Dorothy Wrigley

Mentor's Department

Biological Sciences

Mentor's College

Science, Engineering and Technology

Description

Foodborne outbreaks associated to the contamination of fresh produce by Escherichia coli (EHEC) O157:H7 are a growing concern. Leafy-green vegetables such as spinach and lettuce are vulnerable to contamination through irrigation water, storage practices, and food processing via cross contamination. I hypothesized that EHEC would adhere to lettuce better than a laboratory strain of

E. coli (Ecls). Survival and adherence of E. coli was determined by inoculating known numbers of the different strains onto pieces of washed lettuce, then storing the lettuce at 4°C for 24 hours. After washing to remove non adhered bacteria, the number of adherent bacteria on the lettuce was determined by a plate count. The results did not support the hypothesis. While both strains exhibit concentration dependent adherence, more Ecls adhered than EHEC. 30 to 100 % of the Ecls was recovered at 24 hr while less than 20% of the EHEC was recovered. A greater percentage of low concentration inocula adhered than higher concentrations. Thus, EHEC will adhere to lettuce in a refrigerator but it does not do as well as laboratory strains. This difference may help in the development of washing procedures to ensure that this pathogenic bacterium is removed from lettuce prior to sale to consumers.

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Apr 16th, 10:00 AM Apr 16th, 12:00 PM

Comparison of Escherichia Coli 0157:H7 with a Laboratory Strain on their Ability to Colonize Produce

CSU Ballroom

Foodborne outbreaks associated to the contamination of fresh produce by Escherichia coli (EHEC) O157:H7 are a growing concern. Leafy-green vegetables such as spinach and lettuce are vulnerable to contamination through irrigation water, storage practices, and food processing via cross contamination. I hypothesized that EHEC would adhere to lettuce better than a laboratory strain of

E. coli (Ecls). Survival and adherence of E. coli was determined by inoculating known numbers of the different strains onto pieces of washed lettuce, then storing the lettuce at 4°C for 24 hours. After washing to remove non adhered bacteria, the number of adherent bacteria on the lettuce was determined by a plate count. The results did not support the hypothesis. While both strains exhibit concentration dependent adherence, more Ecls adhered than EHEC. 30 to 100 % of the Ecls was recovered at 24 hr while less than 20% of the EHEC was recovered. A greater percentage of low concentration inocula adhered than higher concentrations. Thus, EHEC will adhere to lettuce in a refrigerator but it does not do as well as laboratory strains. This difference may help in the development of washing procedures to ensure that this pathogenic bacterium is removed from lettuce prior to sale to consumers.

Recommended Citation

Huwae, Karenzha. "Comparison of Escherichia Coli 0157:H7 with a Laboratory Strain on their Ability to Colonize Produce." Undergraduate Research Symposium, Mankato, MN, April 16, 2013.
http://cornerstone.lib.mnsu.edu/urs/2013/poster-session-A/11