Foodborne diseases Flashcards
- illness occurring in two or more individuals showing similar symptoms after ingestion of the same food, meal, or water
- illness caused in the consumer due to the consumption of food containing pathogenic microorganisms or toxins
- caused by ingesting bacteria, parasites, viruses, or toxic metabolites through contaminated food or water
Foodborne diseases
Foodborne diseases 2 groups according to their causative agent and its manifestation:
- foodborne infection
a. invasive infection
b. toxicoinfection - foodborne intoxication
- results from ingestion of viable bacterial cells in sufficient numbers with food, their survival in stomach acidity, and their in vivo multiplication with colonization in the intestinal lumen
- pathogen attaches to and colonizes on the epithelial cell surface
- attachment is provided by adhesions (such as fimbriae) on the bacterial cell surface recognize and attach to the specific receptor sites on the microvilli
Foodborne invasive infection
- once attached, bacterial cells spread through cells of intestine, multiply, and produce protein _______ in the intestinal tract
enterotoxin
EIEC invades the colonic epithelial cell, lyses the phagosome and moves through the cell by nucleating actin microfilaments. The bacteria might move laterally through the epithelium by direct cell-to-cell spread or might exit and re-enter the baso-lateral plasma membrane
- Adherence
- Internalization
- Lysis of vacuole
- Multiplication
- Invasion
- Cytoplasmic movement
- Damage epithelial cells/bloody diarrhea
- results from ingestion of viable bacterial cells together with food and their multiplication in the intestine
- do not spread much beyond the epithelial cells
- some bacterial cells either sporulate or die and release toxin(s) to produce symptoms in gut system causing fluid production and diarrhea
Toxicoinfection
Types of disease in invasive infection
Brucellosis
Campylobacteriosis
EHEC
E. coli
Listeriosis
Salmonellosis
Types of disease in toxicoinfection
Aeromonas
Bacillus (diarrhea)
Clostridium gastroenteritis
Plesiomonas
E. coli
Cholera
- caused by consumption of food containing toxins (previously produced by microorganisms)
- toxigenic microorganisms multiply in foods and produce toxins under suitable conditions
- toxins can cause disorders in gastrointestinal tract and system
- viable microorganisms may not be present in the food at the point of consumption
- microbial toxins may not alter the appearance, odor, or flavor of food.
Intoxication
Types of diseases in intoxication
B. cereus (emetic)
Botulism
Staphylococcal
Mycotoxicosis
___________ can happen by eating foods that have been contaminated with botulinum toxin. Common sources of ———- are homemade foods that have been improperly canned, preserved, or fermented. Though uncommon, store-bought foods also can be contaminated with botulinum toxin.
foodborne botulism
is an anaerobic bacterium, meaning it can only grow in the absence of oxygen. Foodborne botulism occurs when ___________ grows and produces toxins in food prior to consumption. ——– produces spores and they exist widely in the environment including soil, river and sea water.
C. botulinum
The growth of the bacteria and the formation of toxin occur in products with low oxygen content and certain combinations of storage temperature and preservative parameters. This happens most often in lightly preserved foods and in inadequately processed, home canned or home-bottled foods.
C. botulinum will not grow in acidic conditions (pH less than 4.6), and therefore the toxin will not be formed in acidic foods (however, a low pH will not degrade any preformed toxin). Combinations of low storage temperature and salt contents and/or pH are also used to prevent the growth of the bacteria or the formation of the toxin.
Mechanism of action of botulinum toxin
Release of acetylcholine at the neuromuscular junction is mediated by the assembly of a synaptic fusion complex that allows the membrane of the synaptic vesicle containing acetylcholine to fuse with the neuronal cell membrane. The synaptic fusion complex is a set of SNARE proteins, which includes synaptobrevin, SNAP-25, and syntaxin. After membrane fusion, acetylcholine is released into the synaptic cleft and then bound by the receptors of the muscle cell.
Botulinum toxin binds to the neuronal cell membrane at the nerve terminus and enters the neurons by endocytosis. The light chain of botulinum toxin cleaves specific sites on the SNARE proteins, preventing complete assembly of the synaptic fusion complex and thereby blocking acetylcholine release. Botulinum toxins types B, D, F, and G cleave synaptobrevin; types A, C, and E cleave SNAP-25; type C also cleaves syntaxin. Without acetylcholine release, the muscle is unable to contract.
Key symptoms of botulism
Dry mouth
Slurred speech
Blurred vision
Descending flaccid paralysis
Respiratory failure
Death
Modes of transmission
- Direct
- Indirect - vectors, vehicles
Other non-bacterial toxins that cause illness include:
- Paralytic shellfish toxin
- Ciguatera toxins
- Scombroid toxins
- Fungal toxins
caused by the consumption of mussels, clams and scallops which have ingested toxic dinoflagellates)
Paralytic shellfish toxin
associated with certain tropical fish
Ciguatera toxins
results from the production of histamine due to bacteria spoilage of fish
Scombroid toxins
________ or mycotoxins that can be of long-term carcinogenic concern with consumption of mold contaminated foods (e.g., aflatoxins in contaminated corn, peanuts, or other foods and patulin from contaminated apple or other fruit products).
Fungal toxins
Paralytic Shellfish Poisoning (PSP)
Alexandrium
Gymnodinium
- after consumption of shellfish contaminated with _______
saxitoxin
neurotoxin; lethal dose when ingested by humans, is ____________
5.7 micrograms per kilogram
- ingestion of fish with ciguatoxin (CTx)
- gastrointestinal, neurological and sometimes cardiovascular (in cases of severe intoxication) symptoms
Ciguatera poisoning
what microorganism produces CTX
Gambierdiscus spp.
barracuda (Sphyraena barracuda)
- ingestion of fish with high levels of histamine
- histamine is produced by bacterial decarboxylation of the generally large quantities of histidine in the muscles of fish
- sufficient levels of histamine may be produced without the product being organoleptically unacceptable (fresh and spoiled fish)
Scombroid poisoning/histamine poisoning
Scombroid dark-meat fish
Tuna
Mackerel
Bonito
Marlin
Skipjack
Nonscombroid fish
Mahi mahi
Sardine
Herring
Blue fish
Yellowtail
*Histamine is heat-stable and remains present after cooking, freezing, canning, or smoking
- a potent marine neurotoxin, named after the order Tetraodontiformes
- from the skin, viscera, ovaries, and liver of the pufferfish
- fatal respiratory diseases
Tetrodotoxin (TTX)
TTX producing marine bacteria
Vibrio alginolyticus
Shewanella alga
Shewanella putrefaciens
Alteromonas tetradonis
tetrodotoxin of puffer fish is not endogenous (produced by the puffer fish itself), but exogenous (taken from outside and accumulated) via the food chain
a disease caused by the consumption of food or feed contaminated with mycotoxins, poisonous substances produced by fungi (molds).
Mycotoxisos
Microorganisms that produce aflatoxins
Aspergillus flavus, A.parasiticus, A. nomius
- by eating contaminated plant products; by consuming meat or dairy products from animals that ate contaminated feed; by inhaling dust generated during the handling and processing of contaminated crops and feeds
- cereals (corn, sorghum, wheat and rice), oilseeds (soybean, peanut, sunflower and cotton seeds), spices (chili peppers, black pepper, coriander, turmeric and ginger) and tree nuts (pistachio, almond, walnut, coconut and Brazil nut); in milk, meat, eggs of animals fed with contaminated feed
- large doses of aflatoxins can lead to acute poisoning (aflatoxicosis)
- damage to the liver; genotoxic
Fungal toxins (mycotoxins)
- cereals and cereal products, coffee beans, dry vine fruits, wine and grape juice, spices and licorice
- formed during the storage of crops
- kidney damage, but the toxin may also have effects on fetal development and on the immune system
Ochratoxin A (OTA)
Microorganisms that produce Ochratoxin A
species of Aspergillus and
Penicillium
Microorganisms that produce patulin (PAT)
- Aspergillus, Penicillium and
Byssochlamys
- often in rotting apples and apple products, various mouldy and rotten fruits (pears, blueberries, cherries, peaches, plums, strawberries, and mulberries), grains and other foods
- liver, spleen and kidney damage and toxicity to the immune system
- genotoxic however a carcinogenic potential has not been demonstrated yet
Patulin (PAT)
Mycotoxins produced by Fusarium spp:
- deoxynivalenol (DON)
- nivalenol (NIV)
- T-2 and HT-2 toxins
- zearalenone (ZEN)
- fumonisins
Sequence of events leading to foodborne disease by pathogenic bacteria and viruses
Reservoir of a pathogen -> Contamination of a food -> (For viral infection) Consumption of the food -> Long storage of food at growth temperature -> Growth of pathogens to sufficient level -> (For intoxication) Consumption of food containing toxin -> (For bacterial infection) Consumption of food containing live cells -> (For toxicoinfection) Consumption of live cells in sufficient numbers
The epidemiological triad
Agent
Environment
Host
Vulnerable population
YOPI
Young
Old
Pregnant
Immuno-compromised
Vulnerable population - Young
Younger than 5 years
Young children’s immune systems are still developing, so their body’s ability to fight germs and sickness isn’t as strong. Food poisoning can be particularly dangerous for them because illness can lead to diarrhea and dehydration. Children younger than 5 are 3 times more likely to be hospitalized if they get a Salmonella infection. Kidney failure strikes 1 out of 7 children under age 5 who are diagnosed with E. coli O157 infection.
Vulnerable population - Old
Age 65 and older
As people age, their immune systems and organs don’t recognize and get rid of harmful germs as well as they once did. This increases the chance they’ll get sick from food poisoning. Nearly half of people aged 65 and older who have a lab-confirmed foodborne illness from Salmonella, Campylobacter, Listeria, or E. coli are hospitalized.
Vulnerable population - Pregnant
If you are pregnant, you are more likely than other people to get sick from certain germs. For example, pregnant women are 10 times more likely to get a Listeria infection.
Vulnerable population - Immuno-compromised
Having a weakened immune system may make it harder to fight germs and sickness effectively. Weakened immune systems may be due to diabetes, liver disease, kidney disease, alcoholism, HIV, autoimmune disorders such as lupus, or receiving chemotherapy or radiation therapy. For example, people on dialysis are 50 times more likely to get a Listeria infection.
Site of pathogenesis and Related organism in humans:
Skeletal muscles
Trichinella spiralis
Site of pathogenesis and Related organism in humans:
Stomach
Helicobacter pylori
Site of pathogenesis and Related organism in humans:
Liver
Clonorchis - liver flukes
Hepatitis A and E
Site of pathogenesis and Related organism in humans:
Small intestine
Astroviruses
Bacillus cereus
Site of pathogenesis and Related organism in humans:
Large intestine/colon
Campylobacter
E. coli
Also referred to stomach flu, is the inflammation of the stomach and intestinal lining, which causes diarrhea and vomiting
Gastroenteritis
Microorganisms that cause gastroenteritis
Campylobacter
Rotavirus
E. coli
Norwalk virus
5 signs of severe food poisoning
- Bloody diarrhea
- Fever higher than 102F
- Vomiting so often you can’t keep liquids down
- Dehydration
- Diarrhea for more than 3 days
5 keys in food safety to prevent foodborne diseases
- Keep clean
- Cook food thoroughly
- Use safe water and raw materials
- Separate raw from cooked food
- Keep food at safe temperatures
4 steps to food safety
Clean
Separate
Cook
Chill
is the assurance/guarantee that food will not cause harm to consumers when it is prepared and/or eaten according to its intended use
Food safety
When do we celebrate food safety awareness week
4th week of October
