Food Forensics

Food Forensics: The Case of the Dirty Refrigerator
April 2009
By Emily Terrell

Investigative Report:
Mike, Mary, Jake, and Emma are best friends and normally do everything together; however, last week, Mary, and Jake got really sick with nausea, vomiting, and abdominal pain. When they didn’t get better after two days, they were taken to hospital where they were treated for Salmonella poisoning. Now, the Centers for Disease Control and Prevention (CDC) is hoping that you will help them find the source of the contamination.

Your Task:
Decipher which meal gave Mary and Jake Salmonella poisoning, which food carried the contamination, and what Salmonella strain is responsible for their illness.

Evidence:

  • Pulsed Field Gel Electrophoresis (PFGE) genetic fingerprints of Salmonella strains isolated from Mary and Jake
  • PFGE fingerprints of all food products containing Salmonella from Mary and Jake’s home refrigerators
  • PFGE fingerprints from the CDC’s Salmonella strain database
  • Mary and Jake’s lists of what they ate during the two days before they became ill

 

1. Mary and Jake’s Salmonella PFGE fingerprints


6.5.1 food forensics image1.jpgLane A: DNA Ladder
Lane B: Mary’s Salmonella Fingerprint
Lane C: Jake’s Salmonella Fingerprint

 

 

 

 

 

 

2. Salmonella PFGE Fingerprints from Mary and Jake’s refrigerators


6.5.1 food forensics image2.jpgLane A: DNA Ladder

Lane B: Unidentifiable restaurant leftovers (Jake’s house)

Lane C: Raw chicken breast (Mary’s house)

Lane D: Eggs (Jake’s house)

Lane E: Cutting board (Mary’s house)

Lane F:  Raw chicken thighs (Jake’s house)

Lane G: Peanut butter (Mary’s house)


3. CDC Salmonella PFGE fingerprint database

6.5.1 food forensics image3.jpg
Lane A: DNA Ladder

Lane B: Salmonella 1 (pathogenic)

Lane C: Salmonella 2 (benign)

Lane D: Salmonella 3 (benign)

Lane E: Salmonella 4 (benign)

Lane F: Salmonella 5 (pathogenic)

Lane G: Salmonella 6 (pathogenic)


4. Eating records for two days prior to illness.
Brackets indicate where the meal took place.

Meal

Mary

Jake

Breakfast 1

Cold cereal (Mary’s)

Cold Cereal (Jake’s)

Lunch 1

Pizza (Mike’s)

Pizza (Mike’s)

Dinner 1

Chicken Breast and Salad (Mary’s)

Salad (Mary’s)

Breakfast 2

Poached eggs (Jake’s)

Poached eggs (Jake’s)

Lunch 2

Peanut butter Sandwich (Jake’s)

Peanut butter Sandwich (Jake’s)

Dinner 3

Spaghetti (Jake’s)

Spaghetti (Jake’s)




Do you know the answer?
To find out the solution, please submit your email address below.
The solution will be emailed to you right away.


Email Address: *
 

Learn more about Food Forensics:
Using Genetic Fingerprinting to Trace Foodborne Illness