Toxicoinfections Flashcards
What is a toxico infection?
Toxico infection= toxin released from bacterial growth in body.- either due to bacterial death or sporulation (that releases the toxin)
What are some key characteristics of these food borne toxicoinfections?
Spore formers:
Ingestion of large numbers of live vegetative cells is necessary
Vegeatative cells of sporeformers do not multiply in digestive tract, sporulate and release toxin
Gram-negative bacteria
Live cells can be ingested in moderate numbers
Gram neg cells multiply rapidly in GI
Many cells also die to release toxin
Both cause gastroenteritis
What are some microbiological aspects of Clostridium perfringens?
Vegetative cells are sensitive to heat, spores are very sensitive to heat
Lack amino acid synthesis (better in high protein foods)
What factors make outbreaks more common?
Cooking large volumes in advance
Allowing food to cool slowly
Holding food for a long period of time
Serving food without reheating
While the most of Clostridium is harmless GI commensals, what are soem fo the gastrointestinal infections of other strains?
Necrotic tissue infections
Food poisoning
antibiotic -associated diarrhea
Necrotizing enteritis
What are the symptoms of Clostridium Perifingens?
Quick *8-24hours)
Diarrhea, abdominal pain, nausea, vomiting, fever
Symptoms generally resolve in 24h
What is the virulence factors of Clostridium perifigens (Cp)?
15 different toxins
Extracellular hydrolytic enzyme (exoenzymes)
How are Cp strains classified?
5 toxinotypes (A,B,C,D,E) 4 major toxins (alpha, betta,epsilon ,lamda)
What is the function of toxins n Cp?
To make conditions that favor infection
Disrupt cell membranes to release nutrients for cell
Hydrolytic enzymes break down the complex nutrients into smaller units that can be imported into the cells, and utilized by bacteria
What is the cellular mechanism of Clostridium perfringens Enterotoxin?
Produced during sporulation
CPE binds enterocytes via transmembrane tight junctions, preparing to make complex.
Joins other CPE by N-terminal cytotoxicity region to form a highly stable complex
A pore is formed through transmembrane stem domain being inserted into membrane → influx of CA2+ → stops cAMP pathways leading to cell death
How do you prevent Cp?
Keep numbers of viable cells low (spores are okay)
Proper sanitation
Cooking food to highest temperature possible
Quickly cooling (uniformly
If stored for a long time, reheat quickly and uniformly
What are some microbiological aspects of Bacillus cereus?
Spores can survive milk pasteurization, creates off flavours in milk
Unable to grow in refrigeration, but psychrotolerant can
What are the two toxins that Bacillus cereus is able to produce?
Emetic Toxin (Vomitng) → from rice Heat stable Acts rapidly Produced by cells growing in food Stimulates vagus nerve → vomiting Diarrheal Enterotoxin → from meats Heat labile toxins Slower action Produced by veg cell growth in SI Mode of action not well understood - induces diarrhea (cAMP) like vibrio
How do you prevent Bc?
Cooking does not destroy the spore- so make sure that spore do not germinate and cells dont rgow
Chilling food to 4C or holding >60C
Can grow at 4C, don’t refrigerate for long periods of time
Compare the toxins produced by the 3 bacillus species studied.
Thurigiensis- biological control for insects
Anthracis- anthrax (lethal and acute)
Cereus- food borne illness, supresses fungal and crop disease
