1. Listeria monocytogenes and listeriosis
Megan Antosik, RD

2. Agenda History Microbiology Related foods Infection Pathogenesis
At-Risk Populations
Diagnosis & Treatment
Outbreak History
Current Outbreaks
Prevention

3. Objectives After this presentation, audience members will be able to:
Identify at-risk populations for contracting Listeria monocytogenes.
List 3 foods highly susceptible to contamination of Listeria monocytogenes
Describe the clinical characteristics used to diagnose and identify listeriosis.

4. History Hayem (France, 1891) & Henle (Germany, 1893)
Hulphers (Sweden, 1911) assigned the name Bacillus hepatitis
French clinicians preserved a diphtheroid isolated form of spinal fluid cultures of a patient with meningitis
Bacterium monocytogenes, named for the monocytosis it produced in rabbits
Gellin et al 1989

5. History Lord Joseph Lister (1925) – Listerella hepatolytica
Nyfeldt (1929)
Listeria monocytogenes (1940)
Gellin et al 1989

6. Listeria Seven species of Listeria Listeria monocytogenes
Listeria ivanovii
Listeria seeligeria
Listeria welshimeri
Gellin et al 1989

7. Listeria monocytogenes
Facultative anaerobe
ß-hemolytic
Gram-positive
Non-acid fast
Non-sporulating linear rod
Can grow at temperatures as low as 4°C
Incubation period of 5-70 days
Gellin et al 1989

8. L. monocytogenes Sixteen serotypes
Only 3 responsible for more than 90% of human disease
Serotype 4b
Serotype 1/2b
Serotype 1/2a
Gellin et al 1989

9. L. monocytogenes Ubiquitous in nature: Dust Soil Water Sewage
Decaying vegetation
Animals can carry bacterium and transmit to food
Gellin et al 1989

10. As a dietitian, what can we do?
How would you protect against an invader of this magnitude??

11. Susceptible Foods Ready-to-Eat (RTE) foods Raw foods
Hot dogs
Delicatessen meats
Soft cheeses
Raw foods
Meat
Fruits
Vegetables
Unpasteurized foods
Milk and milk products
static.howstuffworks.com/gif/hot-dog-km.

12. +   Transmission Etiologic agent Reservoir Leads to…
Susceptible food
Consumption of contaminated food

13. Listeriosis Severe infection
Consumption of foods contaminated by L. monocytogenes
Symptoms
Chills
Fever
Muscle aches
Diarrhea
Other GI symptoms

14. Pathogenesis
&feature=related
Intracellular pathogen
Entry, growth, movement and spread in a macrophage
Phagocytosis
Actin filaments “comet tail”
Bypasses humoral immune system
Tilney et al 1989

15. Pathogenesis

16. At Risk?
In the United States, an estimated 1,600 persons become seriously ill with listeriosis each year. Of these, 260 die.
Older adults
Pregnant women
Newborns
Immunocompromised
General public

17. Manifestations Diagnosis of “invasive” listeriosis Symptoms include:
Headache
Stiff neck
Confusion
Loss of balance
Convulsions

18. Listeriosis in Older Adults and the Immunocompromised
Host-dependent
Septicemia
Meningitis
Death
Persons with AIDS: They are almost 300 times more likely to get listeriosis than people with normal immune systems.

19. Listeriosis in Pregnant Women
Twenty times more likely to get listeriosis. About one in six (17%) cases occurs during pregnancy
Commonly experience mild “flu-like” symptoms
Infections:
Still birth
Miscarriage
Premature delivery
Life-threatening Infection of the newborn

20. Diagnosis Blood Cerebrospinal fluid (CSF) Amniotic fluid
No stool or serological tests available

21. Treatment Most cases can spontaneously be cleared within 7 days
Otherwise - treated with IV antibiotics
Ampicillin
Bactrim

22. Outbreak History

23. Outbreak History

24. What can we do? Activate Listeria Initiative USDA FSIS & FDA
“Zero Tolerance” policy
Initiate the Healthy People objective
Achieve a 50% reduction in listeriosis incidence by 2010
2.5 cases per 1 million people
Voetsch et al 2007

25. How do we evaluate efficacy?
Active surveillance studies
Foodborne Disease Active Surveillance Network (FoodNet)
Assess consumer practices
Determine the burden of foodborne illness in the United States
Monitor trends in the burden of specific foodborne illness over time
Attribute the burden of foodborne illness to specific foods and settings
Disseminate information that can lead to improvements in public health practice and the development of interventions to reduce the burden of foodborne illness.
The network was established in July 1995 and is a collaborative program among CDC, 10 state health departments, the U.S. Department of Agriculture's Food Safety and Inspection Service (USDA-FSIS), and the Food and Drug Administration (FDA). FoodNet personnel located at state health departments regularly contact the clinical laboratories in Connecticut,Georgia, Maryland, Minnesota, New Mexico,Oregon, Tennessee and selected counties inCalifornia, Colorado, and New York to get reports of infections diagnosed in residents of these areas.  The surveillance area includes 15% of the United States population (46 million persons).
FoodNet accomplishes its work through active surveillance; surveys of laboratories, physicians, and the general population; and population-based epidemiologic studies. Information from FoodNet is used to assess the impact of food safety initiatives on the burden of foodborne illness
Voetsch et al 2007

28. What did we find? N=766 isolates from 1996-2003 670 hospitalizations
153 fatalities
122 pregnant-associated cases
Voetsch et al 2007

29. Demographics

30. Crude Incidence

31. Did we achieve our goals?
Incidence of invasive listeriosis decreased by 24%
Pregnancy-associated decreased by 37%
Decrease of 23% in patients > 50 years old
Crude incidence in 2003 was 3.1 cases per 1 million
Voetsch et al 2007

32. Are we in the clear?

33. Cantaloupe Outbreak 2011 Jensen Farms 146 affected 28 states
4 different strains
30 deaths
1 miscarriage
Outbreak has officially ended

36. What Went Wrong? Inspectors ignored federal regulators
FDA cited “serious design flaws” and “lack of awareness”
Bio Food Safety Auditing gave Jensen Farms near perfect marks
Jensen Farms did not have proper chlorine or anti- bacterial wash
Improper equipment

38. As dietitians, what can we do?
Prevention methods
Food Safety
Cook foods thoroughly
Prevent cross-contamination
Buy pasteurized foods
Proper sanitation
Know where your food comes from
Keep up-to-date on foodborne illness outbreaks
Regulation of food safety policies

39. Questions? Don’t be afraid of food! Just play it safe!