Foodborne diseases Flashcards
(62 cards)
- 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
