Case study #2 Doctor enter his examination room to find a Rob, a...

 

Case study #2

Doctor enter his examination room to find a Rob, a boisterous 2-year old playing with a truck while his pregnant mother, Shelly watches him from the examination table. Shelly has not been feeling well for the last week, she attributes her pregnancy to her not feeling well. However, she has begun having chills, muscle aches, fever, headaches and sore throat. As this is early summer, you do not suspect influenza. Upon examination she has a low grade fever and her cervix has started to dilate even though she is only 28-weeks pregnant. In questioning Shelly, Doctor learned that her husband and co-workers are all healthy; however, Rob complained of mild nausea, diarrhea and low grade fever a week ago after he and his mother visited a dairy farm with his play group. Shelly and the kids ate picnic lunches of peanut butter sandwiches, chips, cookies, and milk. The milk was fresh from the cow and little Rob had been asked to help milk the cow! Shelly and Rob shared a snack of fresh, soft cheese that they purchased from the dairy and crackers. Shelly had been careful to keep the cheese on ice until they ate their snack. That night Shelly was beat, so she and the family ate at the local pizzeria for dinner. Rob awoke during the night with the symptoms, which lasted approximately 2 days, though Shelly and her husband felt fine. None of the other children were sick the next day.

 

1.    What is the likely etiologic agent?

2.    What food is likely to be associated with their illness?

3.    Did you discount any of the foods as the carrier? If so why?

4.    In public interest, specify your recommendations to avoid foodborne illness in each case study.

Case Study #2

1.    What is the likely etiologic agent?
 

The most probable causative agent is a bacterial contaminant of dairy products specifically raw milk and its products, the Listeria monocytogenes.  Listeria monocytogenes is important as a cause of a wide spectrum of disease in animals and humans. And given the symptoms, such as having chills, muscle aches, fever, headaches and sore throat, indicates the most probable cause is Listeria monocytogenes. This bacterium is shed from infected cows through their fecal matter. Poor handling and lack of adequate treatment (pasteurization)  caused the cross contamination of the milk. Listeria monocytogenes is capable of growing and surviving over a wide range of environmental conditions. It can survive at refrigerator temperatures (4°C), under conditions of low pH and high salt conditions.  Therefore, it is able to overcome food preservation and safety barriers, making it an important foodborne pathogen. 
 

Two forms of perinatal human listeriosis. Early-onset syndrome (granulomatosis infantiseptica) is the result of infection in utero and is a disseminated form of the disease characterized by neonatal sepsis, pustular lesions, and granulomas containing L. monocytogenes in multiple organs. Death may occur before or after delivery. The late-onset syndrome causes the development of meningitis between birth and the third week of life; it is often caused by serotype 4b and has a significant mortality rate. Adults can develop Listeria meningoencephalitis, bacteremia, and (rarely) focal infections. Meningoencephalitis and bacteremia occur most commonly in immunosuppressed patients, in whom Listeria is one of the more common causes of meningitis. Clinical presentation of Listeria meningitis in these patients varies from insidious to fulminant and is non-specific. In immunocompetent individuals, illness may not occur after ingestion of contaminated food or patients may develop a symptomatic febrile gastroenteritis. This develops after an incubation period of 6-48 hours. Symptoms include fever, chills, headache, myalgias, abdominal pain, and diarrhea. Illness is usually self-limiting in 1-3 days; most clinical laboratories do not routinely culture for Listeria from routine stool samples. The diagnosis of listeriosis rests on isolation of the organism in cultures of blood and spinal fluid.

2.    What food is likely to be associated with their illness? 

The possible cause of infection is by drinking raw milk and eating fresh cheese which is most probably made from raw, since only both Shelly and Rob were affected after eating and drinking the contaminated milk products. Listeria monocytogenes as mentioned, is important as a causative agent of a wide spectrum of disease in animals and humans. This bacterium is shed from infected cows through their fecal matter. Poor handling and lack of adequate treatment (pasteurization)  caused the cross contamination of the milk.

Both pregnants and children are immunocompromised individuals, that made them at risk. However, Shelly, who is pregnant is experiencing the more severe symptoms. Listeria monocytogenes, can tolerate salty conditions, and low temperatures, that is why the soft cheese though placed in ice did not kill the bacteria, that even Rob who ate it with her mom was infected. In addition, there is also a probability that Rob did not wash his hands after milking the cow and touched the crackers that both she and his mom ate.


3.    Did you discount any of the foods as the carrier? If so why?
 

Yes, we can disregard other foods like pizza nad peanut butter as carrier of pathogen as other people who ate same foods like Shelly's husband and co-workers and presumably other children who went to the park with them did not manifest any symptoms of the infectiom. It means that the pathogen only contaminate those food which got in contact with the infected  cow, and highly put young children, most especially pregnant women at risk. For instance, aside from the poor handling of milk products, Rob who helped in milking the cow, and did not wash hands got infected when he touched and ate the biscuit with cheese which he ate with his mom.
 

4.    In public interest, specify your recommendations to avoid foodborne illness in each case study. 

According to Food and Drug Administration, there are steps to reduce risk from Listeria. First, is to Chill at the Right Temperature. Adequate emperatures slows down the growth of Listeria. The refrigerator should register at 40°F (4°C) or below and your freezer at 0°F (-18°C). It is also important to consume ready to eat foods qucikly, and by the manufacturer's use by date because the longer the food stayed in the refrigerator, the more chance for Listeria to grow. And always keep the refrigerator clean. Second, always choose the right food to eat especially for people who are highly at risk of getting infected. This includes, unpasteurized dajry products, cold cuts, poultry meat and vegetables. Third, food handlers should always practice proper cleaning of food items and adequate preparation  and treatment (e.g. cooking, pasteurization) should always be followed. 

In this particular case study for public safety we can recommend the following:
1. The affected cattles should be isolated and properly treated.
2. Milk products should be properly handled and if possible undergo adequate treatment like pasteurization before public consumption.
3. At risk individuals should avoid  intake of food and drinks that are prone to Listeria contamination.
4. Always observe good personal hygiene. Wash hands before and after touching food. If eating outdoors, if possible it's better not to directly touch the food, use of packaging or cutleries are highly advised.
5. Always properly store, read the package label and consume food and drinks by use date.

 

References: 

Center for Food Safety and Applied Nutrition. "What You Need to Know ABou Preventing Listeria Infections." U.S. Food and Drug Administration, FDA, www.fda.gov/food/buy-store-serve-safe-food/what-you-need-know-about-preventing-listeria-infections#:~:text=Follow%20These%20Steps%20For%20Food,meat%2C%20poultry%2C%20or%20eggs. 

"Listeria Outbreaks." Centers for Disease Control and Prevention, Centers for Disease Control and Prevention, 24 Feb. 2021, www.cdc.gov/listeria/outbreaks/index.html. 

Riedel, Stefan A., and Karen C. Carroll. Jawetz, Melnick & Adelberg's Medical Microbiology(Review Questions). McGraw-Hill Ecucation, 2016. 

Medicine, Center for Veterinary. "Get the Facts about Listeria." U.S. Food and Drug Administration, FDA, www.fda.gov/animal-veterinary/animal-health-literacy/get-facts-about-listeria#:~:text=Symptoms%20of%20listeriosis%20vary%20depending,loss%20of%20balance%2C%20and%20convulsions.