1. Food borne Pathogens II
Food Microbiology 1
Unit 3
Food borne Pathogens II

2. Infection

3. Bacteria That Cause Infection
Campylobacter jejuni
Salmonella
Listeria monocytogenes
Yersinia

4. Microaerophilic (low oxygen) i.e. 3-8% Oxygen, 15% CO2
Campylobacter jejuni
Gram negative spiral curved rod
Non-spore forming
Microaerophilic (low oxygen) i.e. 3-8% Oxygen, 15% CO2
Growth Temperature: 32-45oC, optimum is 42oC (body temperature of chickens)

5. Campylobacter jejuni
In the intestinal tract of warm-blooded animals
Does not survive well outside the host and does not grow well in food
Initial contamination levels are more important than storage conditions
Fastidious nutrient requirements
Sensitive to oxidative stress
Normally present in low numbers in foods
Can be isolated from patients diarrhea at relatively high levels

6. Less than 500 organisms are thought to be enough to cause illness in humans
Colonizes the mucosal surface of the lower intestinal tract
Motility permits access through mucus to epithelial cells
Invasion of epithelial cells results in inflammatory enteritis

7. Symptoms Incubation period (from ingestion till first sign) 2-5 days
Abdominal pain/cramps
Headache, Diarrhea (sometimes bloody)
Nausea and sometimes vomiting
Fever, chills
Case fatality rate is 0.1 to 0.2 %
Duration is approximately 1 week

8. Further complications
Meningitis
Guilian- Barré syndrome
- ascending paralysis leading to respiratory muscle paralysis and death
The number one bacteria causing food borne illness

9. Sources Found in foods of animal origin, water and sewage
Commonly found in birds (chicken)
80% of poultry carry Campylobacter
90-100% of organic poultry produced carry Campylobacter
Birds, cattle and pigs show no symptoms
Humans can be symptomless carriers

10. Foods Implicated Undercooked poultry and meats Raw Milk
Contaminated Water
Raw Clams

11. Prevention Adequate cooking of poultry
Minimize cross-contamination between cooked and raw foods
Wash hands and work surfaces after handling raw foods
Pasteurize milk
Chlorinate water

12. Salmonella
Facultative anaerobes, Gram-negative, motile rods with peritrichous flagella, highly invasive and spread easily
Salmonellosis: disease caused by bacteria in this genus
Salmonella Enteritidis PT4 most pathogenic in chickens and predominated
Temperature for growth 5-45oC (35-37oC)
Min pH 4.5
Min aw 0.97

13. Contamination from eggs and broiler meats
Trans-ovarian: before eggs formed.
Trans-shell: infection invade the egg through
the shell after eggs laid
Estimated 1% of the population diagnosed with Salmonella yearly
Infected birds are symptomless, eggs laid appear normal
They may survive the hard-cooking process (Hard-cooked eggs associated with two recent outbreaks)
Infective dose for Salmonellae is believed to be less than 103 CFU/ml

14. Colonization in intestinal tract
Salmonella Cycle
Contaminated feed, environment, insects, rodents, spread from infected birds, etc
Colonization in intestinal tract
Invasion into internal organs
Fecal Shedding
Breeders
Broilers
Layers
Hatching eggs
Poultry Meat
Infected chicks
Table Eggs
Infected pullets
Contaminated eggs or meat
Human enteritis

15. Invades small intestine and colon by entering absorptive mucosal cells and mucosa associated macrophages
Grow inside fixed macrophages of liver and spleen

16. Salmonella Enteritidis Salmonella Dublin
Frequent Serotypes Associated with Food borne Illness
Salmonella Typhimurium
Salmonella Enteritidis
Salmonella Dublin

17. Symptoms
Typhoid or paratyphoid fever from Salmonella typhi and Salmonella paratyphi
Salmonellosis
Headache
Fever and chills
Diarrhea, cramps
Nausea
Vomiting

18. Salmonella
Symptoms usually occur 12 to 24 hours after ingestion of the contaminated food
Period of illness is 1-3 days
Infected individuals can carry and shed Salmonella for months
Infected persons can show no symptoms but carry and spread the organism. E.g. Typhoid Mary

19. A house cook in 1906 in New York
Typhoid Mary
Mary Mellon
A house cook in 1906 in New York
She was a symptomless carrier of Salmonella
Infected 33 people
Eventually she was sent to jail to protect the public!

20. Garden soil survives for 250 days Liquid manure for 27-286 days
Sources of Salmonella
Inhabitant of intestinal tract of animals, birds, reptiles, insects
Garden soil survives for 250 days
Liquid manure for days
Slurry for 84 to 250days
Infected feces stored in cans for 159 days

21. Factors Contributing to outbreaks
Improper cooling
lapse of a day or more between preparation and serving
Inadequate cooking or heat processing
Ingestion of contaminated raw ingredients
Cross-contamination

22. Associated Foods
Poultry
Eggs and Egg products
Meat and meat products
Un-pasteurized milk and dairy products
Vegetables and sprouted seeds

23. Prevention
Vaccine programs and screening significantly reduce numbers in poultry and eggs
Cook food products sufficiently (no sunny side-up eggs)
Avoid cross-contamination between raw and cooked foods