Lab Exercise - The Senior Picnic: An Investigation into Foodborne Illnesses

Objectives:

Create a table of the key bacterial agents associated with foodborne illnesses.
Identify relevant symptoms, onset, and food sources to evaluate potential agents.
Determine and justify the causative agent for your table’s food source using the appropriate laboratory tests.
Report the identification, transmission, treatment, and method of control for their etiologic agent.

On Oct 11 thirty-five Nursing students from Prokaryote University attended a picnic at Pasteur Park. It was a relatively warm day. The food was prepared by individuals at home and brought to the park at 10:00AM. There were a variety of activities including volleyball, three legged races, and frisbee golf. The food was set out on serving tables at 11:00AM and students partook of the food all day long between events. The picnic ended at 7:00PM when it became dark. The food was covered and the picnic organizers took the leftovers home.
Following the picnic, participants began to complain of gastrointestinal problems of varying severity. The county Public Health officials were notified and an investigation began. Samples of the various leftovers were recovered and cultured for pathogens. You have received a sample of each of the following dishes:

Food	Method of Preparation
1) Three bean salad	Fresh cold salad made of canned green beans, kidney beans, garbanzos, onions and spices marinated in a vinegar and oil dressing and refrigerated overnight
2) Fresh vegie salad	Fresh marinated salad made of fresh cucumbers, zucchini, bean sprouts, onions and Tzatziki sauce. Tzatziki is a Greek sauce made of cucumber, strained yogurt, fresh parsley, lemon juice and mint.
3) Deviled eggs	eggs boiled, peeled, and stuffed with yolks that were removed mashed mayonnaise, mustard and spices two days prior to the picnic. Stored in the fridge until the day of the picnic.
4) Buffalo wings (chicken wings)	Marinated raw chicken in sauce over night and barbecued, basted with sauce from pan
5) Ceviche	A dip of raw shrimp, crab and shellfish mixed with celery, onions, jalapeno chili and tomatoes as a dip for tortilla chips
6) Chicken Fried Rice	Rice was prepared and left to cool at room temperature for several hours, the refrigerated. The next day, left over chicken, the cooked rice and veges (celery, onions, peas, carrots) were stir fried with the rice and soy sauce was added.
7 Punch	prepared from fresh squeezed fruit had been served in a large thermos sliced and placed on crackers
8) Jalapeno Monterey jack cheese	This is a special cheese made with unpasteurized milk at a local dairy famous for the spicy chees. It was cut and served on crackers.

Lab period 1

1. Apply your PPE.

2. Subculturing each of your food sources to enriched and selective agar (TSA, EMB, MSA).This should be done aseptically, being careful to mix the specimen and use a method of inoculation that will help you to isolate possible pathogens and rule out normal, harmless environmental bacteria.

3. Incubate your subcultures. Incubate the original food specimens as a back up in case a subculture was hot looped.

4. Investigate the potential causes of GI problems. Research information on the following pathogens. Each team member can select three potential pathogens to research from the master list, but this information must be shared in detail with the other lab partners.

Potential Pathogens of Food borne Infections and Intoxications

Bacillus cereus

Cambylobacter jejuni

Clostridium botulinum

E. coli 0157:H7

Listeria monocytogenes

Salmonella enteridis

Shigella flexneri

Staph aureus

Vibrio cholera

CDC has excellent resource material available

http://www.cdc.gov/ncidod/dbmd/diseaseinfo/foodborneinfections_g.htm#foodbornedisease

Include the following information on each pathogen:

Gram stain
Determine whether the organism is aerobic, anaerobic, or a facultative anaerobe
Indicate key or characteristic chemical reactions
Describe typical symptoms and timing of onset
Explain the mode of transmission
Identify the typical food sources infected with this organism
Indicate whether this organism causes food intoxications or food infections
Evaluate the appropriate treatment and prevention

Lab 2

Observe subcultures and Gram stain the isolates.
Rule out any flora that may be normal skin or environmental organisms.
Narrow down potential pathogen possibilities, develop a differential list.
Refer to past labs and the biochemical chart to suggest further tests to identify and rule out pathogens.
Set up any additional tests after you have checked them with the instructor.
Compare your results with the potential pathogens you have researched.

Lab 3

Identify specific pathogens
Determine transmission route, public health measures and treatment.

Lab 4

Write up report of the outbreak and give oral explanation of the etiologic agent covering the details listed above. Refer to the CDC foodborne outbreak questionnaire and be sure that you have covered the relevant information concerning your pathogen.

Senior Picnic Grading Criteria

Criteria	Possible	Earned	Comments
Research on potential food pathogens	5
Proper Testing · only appropriate tests used · testing done in a timely manner · log or records of testing complete	2
Agent Identification · correct identification · justification of pathogen · reasoning for ruling out non-pathogens · reasoning for ruling out other pathogens	3
Explanation of treatment and plan to curtail outbreak · treatment (if any) of the patients · tracking of the source (if necessary) · prevention of any further possible outbreaks (if possible).	3
Grammar and Write up	2
Teamwork and oral report · Evidence of teamwork · 5 minute max · organized	5
Total Possible	20