Lecture 24 10/17/24 Flashcards by Danika Boltz

What is foodborne illness?

any illness resulting from the consumption of food contaminated by pathogenic bacteria, viruses, parasites, chemicals, or natural toxins

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What typically results in foodborne illness?

-improper handling
-improper preparation
-improper storage

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What is foodborne intoxication?

ingestion of food containing “preformed” chemical toxicants; the toxins cause illness instead of the bacteria that produced the toxins

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What are examples of foodborne intoxication?

-staphylococcal food poisoning
-botulism

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What is foodborne infection?

pathogens in food survive the digestive processes and overcome the host’s natural defenses

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What is an invasive foodborne infection?

organism penetrates the lining of the GI tract and subsequently multiplies

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What are the characteristic signs of an invasive foodborne infection?

-dysentery/blood in feces
-fecal leukocytes
-fever

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Which pathogens are examples of invasive foodborne infections?

-EIEC
-Salmonella spp.
-Listeria monocytogenes

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What is a non-invasive foodborne infection?

organism multiplies in the GI tract without penetrating the GI tract

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What is the characteristic sign of a non-invasive foodborne infection?

watery diarrhea

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Which pathogens are examples of non-invasive foodborne infections?

-ETEC
-Vibrio cholerae
-Clostridium perfringens

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How does foodborne intoxication differ from foodborne infection?

intoxication:
-usually presents within 1 to 7 hours
-usually lacks a fever
infection:
-requires 8 hours to several weeks to present
-fever occurs due to inflammatory response to pathogens

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What are the typical growth requirements for foodborne pathogenic bacteria?

-temp. between 40-140 deg. F
-pH greater than 4.6
-water activity greater than 0.85
-variable O2 and nutrient requirements

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What are the top 5 foodborne pathogens that result in hospitalization?

-Salmonella spp.
-Norovirus
-Campylobacter spp.
-Toxoplasma gondii
-E. coli (STEC) O157

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What are the characteristics of E. coli?

-gram neg. rod
-found in water and food contaminated with feces
-characterized by varying degrees of diarrhea

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What are the six pathogenic strains of E. coli in humans?

-EHEC
-ETEC
-EIEC
-EPEC
-EAEC
-DAEC

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What are the characteristics of Shiga Toxin E. coli (STEC)?

-E. coli that produces shiga-like toxins or vero toxins
-similar/identical toxin to Shigella dysentariae toxin
-neutralized by shigatoxin antiserum
-cytotoxic
-causes fluid accumulation in GI tract
-causes hemorrhagic colitis
-group of concern is EHEC, which includes O157 and non-O157 STEC

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What are the characteristics of enterohemorrhagic E. coli (EHEC)?

-most virulent, with severe clinical disease
-most common strain is E. coli O157:H7
-cattle is primary reservoir host

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What do the O and H stand for in E. coli serotyping?

O: cell wall antigen
H: flagellar antigen

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What are the characteristics of E. coli distribution and prevalence?

-preferred temp. between 45 and 122 deg. F
-63,000 cases of EHEC in US each year
-world-wide distribution
-low infection rate in cattle and humans

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What is the epidemiology of E. coli in humans?

-all ages susceptible, but most common and severe in children and elderly
-children under the age of 5 have highest overall incidence
-children under the age of 5 have highest incidence of hemolytic uremic syndrome

What are the characteristics of E. coli transmission?

-incubation period of 3-4 days
-adults able to spread disease for 1 week
-children able to spread disease for 3 weeks
-common in summer and fall
-seen in rural pop.

What are the clinical signs of E. coli in humans?

-diarrhea ranging from mild and watery to severe and hemorrhagic
-nausea
-vomiting
-abdominal pain
-possibly asymptomatic

What are the characteristics of hemolytic uremic syndrome?

-thrombocytopenia
-hemolytic anemia
-main cause of acute renal failure in children
-case fatality rate around 3.5%

What are the characteristics of thrombocytopenic purpura?

-neurologic symptoms -thrombocytopenia -hemolytic anemia -mortality rate in elderly around 50%

What are the potential routes of transmission for E. coli?

-indirect fecal-oral route in food -direct fecal oral route between humans or animal and human

What are the common sources of E. coli outbreaks?

-raw/undercooked ground beef/beef products -raw milk -unpasteurized fruit juices -various water sources -petting zoo animals -person-to-person -various produce

What are the prevention steps at the individual level for E. coli?

-wash hands, kitchen surfaces, and utensils -avoid cross-contamination of other foods -do not eat raw/undercooked ground beef/products -cook ground beef to 160 deg. F internal temp. -practice personal and food safety hygiene at petting zoos

What are the prevention steps at the community level for E. coli?

-surveillance -notification of disease to health officials -pasteurization and hygienic slaughter -waste disposal -public education and awareness

What are the prevention steps at the livestock level for E. coli?

-proper animal husbandry -vaccination -probiotics -stress reduction -antemortem inspection

What are the clinical signs of E. coli in animals?

-EHEC: usually asymptomatic -ETEC: colibacillosis

What are the top five foodborne pathogens that result in death?

-Salmonella spp. -Toxoplasma gondii -Listeria monocytogenes -Norovirus -Campylobacter spp.

What are the characteristics of Listeria monocytogenes?

-gram pos. rod -13 serotypes -reportable disease -ubiquitous in environment -found in moist environments, soil, and decaying vegetation -persistent in food manufacturing environments

What makes Listeria monocytogenes hard to kill in food?

-can grow at refrigeration temps -salt tolerant

What is the epidemiology of Listeria monocytogenes?

-reservoirs include domestic and wild mammals, birds, and man -may be free living -can survive in soil for months to years -widely distributed by farming techniques and spreading of manure -can contaminate vegetables, animal feed, and water

What are the characteristics of non-invasive listeriosis?

-fever -muscle aches -nausea -diarrhea -generally resolves in healthy people

What are the characteristics of invasive listeriosis?

-causes septicemia and meningitis -pregnant women more susceptible -mother likely to recover while fetus does not survive

What are the characteristics of listeriosis mortality?

-severe form has a case fatality rate of 15-30% -increases to 70% with meningitis -increases to 50% with septicemia -increases to 80% in perinatal/neonatal infections

What are the incubation periods for listeriosis?

non-invasive: 9-48 hrs invasive: 2-6 weeks

What are the food sources of Listeria?

-raw milk -raw or smoked fish/seafood -meat (including deli meat) -cheese, especially soft -ice cream -raw fruits and vegetables

How is Listeria diagnosed?

-culture from tissue, blood, CSF or sterile site -stool culture not helpful due to intestinal carriers

How is Listeria treated?

antimicrobial therapy consisting of ampicillin +/- gentamicin; cross BBB

How do humans acquire trichinosis?

eating raw/undercooked meat from animals infected with Trichinella cysts

What is the epidemiology of trichinosis?

-Trichinella spiralis is most common cause in humans -worldwide dist. -most cases in US come from eating undercooked wild game rather than pork

What are the clinical signs of trichinosis?

1-2 days: -GI signs 2-8 weeks: -muscle pain -swelling of face -weakness/fatigue -chills -itchy skin/rash -cough -fever -headache -constipation

How are trichinosis and taeniasis prevented and controlled?

-cook whole cuts of meat to 145 deg. F and allow to rest for 3 minutes before consumption -cook poultry to 165 deg. F and allow to rest for 3 minutes before consumption -cook ground meat and all wild game to 160 deg. F

What are the characteristics of Taeniasis?

-Taenia saginata/beef tapeworm -Taenia solium/pork tapeworm -can lead to cysticercosis in humans -infections from eating raw/undercooked beef or pork

What are prions?

family of rare progressive neurodegenerative disorders affecting humans and animals

What are the characteristics of prions?

-long incubation periods -spongiform changes associated with neuronal loss -failure to induce inflammatory response

What is the theory behind bovine spongiform encephalopathy pathogenesis?

agent is a modified form of normal protein that changes into pathogenic form to damage CNS of cattle