Food Microbiology 1 Unit 3 Food borne Pathogens

Food Microbiology 1 Unit 3 Food borne Pathogens II

Infection

Bacteria That Cause Infection • Campylobacter jejuni • Salmonella • Listeria monocytogenes • Yersinia

Campylobacter jejuni • Gram negative spiral curved rod • Non-spore forming • Microaerophilic (low oxygen) i. e. 3 -8% Oxygen, 15% CO 2 o. C, optimum is Growth Temperature: 32 -45 • 42 o. C (body temperature of chickens)

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

• 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

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

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

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

Foods Implicated • Undercooked poultry and meats • Raw Milk • Contaminated Water • Raw Clams

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

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 PT 4 most pathogenic in chickens and predominated • Temperature for growth 5 -45 o. C (35 -37 o. C) • Min p. H 4. 5 • Min aw 0. 97

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

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

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

Frequent Serotypes Associated with Food borne Illness • Salmonella Typhimurium • Salmonella Enteritidis • Salmonella Dublin

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

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

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!

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

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

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

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