Name:
Center for Disease Control
Salmonella Contamination
RFP No. IS7- 400
Evidence Collection Notebook
1.
What organism or chemical is responsible for poisoning? Salmonella Which steps did we take to
determine this information?
a. From Contagion City Case Study
i. Compare symptoms of patients
ii. Research 7 different bacteria to compare what symptoms occur with infection, the
mode of infection or which food can be contaminated, and how long the infection lasts
iii. Compare the diet of all 3 patients
2. What is the impact of the contagion on the human body? (What symptoms occur with this infection?)
a. From Contagion City Case Study:
Salmonella causes
i.
ii.
iii.
diarrhea,
fever, and
abdominal cramps
3. What specific food source was contaminated? Spinach What steps did we take to determine this
information?
a. From Using a Microarray to Test for the Presence of Salmonella
i. We tested which salad ingredient, lettuce, cabbage, spinach or kale had been exposed to
salmonella by testing samples of single stranded (ss) DNA from each of the ingredients
to determine if the salmonella gene was being expressed or turned on.
ii. We compared the 4 ssDNA results to a positive and negative control to see what each
result would look like.
iii. Spinach showed a positive result meaning it was expressing the Salmonella gene.
4. What factory was responsible for packaging and shipping the food? Schneider’s Salads Which steps
did we take to determine this information?
a. From Paper Chromatography Lab
i. Separates ink particles/molecules according to solubility (how well the solute dissolves
in the solvent) and the size of the ink particles (smaller particles will travel further from
the starting point that larger ink particles).
Center for Disease Control
Salmonella Contamination
RFP No. IS7- 400
Evidence Collection Notebook
ii. We then compared the color pattern produced from the 4 factories to the contaminated
salad package found at the restaurant where all three patients dined.
iii. The results were inconclusive so we needed a second, more accurate test
b. From Gel Electrophoresis of Ink from Salad Packaging
i. Separates ink particles according to size (larger molecules remain closer to starting
point, smaller molecules travel further from the starting point) and electrical charge
(positively charged molecules will move towards the negative electrode because
opposite charges attract and vice-versa)
ii. We then compared the color pattern produced from the 4 factories to the contaminated
salad package found at the restaurant where all three patients dined.
iii. The pattern of colors, distance molecules traveled and direction molecules from
Schneider’s Salad matched the contaminated salad packaging ink found at the
restaurant.
Center for Disease Control
Salmonella Contamination
RFP No. IS7- 400
Evidence Collection Notebook
5. What farm produced the food source? Campo’s Cabbage for 1st and 3rd, Shane Spinach for 5th and 6th
Which steps did we take to determine this information?
a. From Find the Farm
i. We conducted a DNA fingerprint using Gel Electrophoresis to match one of the farms
producing spinach to the contaminated spinach found at the restaurant.
ii. DNA is negatively charged so all DNA fragments moved towards the positive
electrode.
iii. DNA fragments separate according to size, smaller fragments travel further from the
starting point, large molecules stay closer to the starting point.
iv. We compared the contaminated spinach DNA fingerprint pattern to the 3 farms in Sligo
Town and matched the number of fragments and distance the fragments travels from
the farm to determine which farm was responsible for growing the contaminated
spinach.
Center for Disease Control
Salmonella Contamination
RFP No. IS7- 400
Evidence Collection Notebook
6. Was the produce farm responsible for the contamination? No
7. Which animal farm was responsible for the contamination? McGill’s Moos (cattle/cow farm) Which
steps did you take to determine this information?
a. From Pig, Horse, or Cattle?
i. We conducted this last test, bacteria streaking, to determine which animal farm was
responsible for contaminating the pond used to irrigate the spinach crops. The animal
waste traveled to the pond through runoff.
ii. We collected samples of animal waste from each of the 3 surround animal farms.
iii. We streaked samples from each farm over a petri dish with nutrient rich gel and
incubated the dishes
iv. We found raised white shiny dots growing in the cattle section of the petri dish showing
the that McGill’s Moss was the source of the contagion or ground zero.
Center for Disease Control
Salmonella Contamination
RFP No. IS7- 400
Evidence Collection Notebook
8. Which steps can Sligo Town take to stop the contamination?
Steps to stop the contamination include:
a. Stop using the pond to irrigate the spinach crops
b. Treating the animals infected with salmonella with antibiotics
c. Creating a filtering plant to filter the water used to irrigate the crops
d. Create a drainage ditch area to divert the runoff from the animal farm so it will not go
into the pond
9. What PREVENTATIVE steps can be taken to ensure this problem does not happen again?
To prevent this problem from happening again we could:
a. Periodically test the irrigation water for contaminates
b. Grow plants hydroponically
c. Put up a fens to divert the flow of runoff from the animal farm
d. Periodically check produce shipping out to factories for contaminates
e. Make sure consumers are educated about the proper handling and preparation of food
items including washing hands before touching food, washing fresh produce prior to
eating, storing food at proper temperature and in proper packaging