GI Lower Bacterial Infections I Flashcards
Difference between food poisoning and food infections?
Timing. Poisoning is with pre-formed toxins. Infections are can cause both
What is an “enterotoxin”?
Exotoxin that targets intestine
What are three common bacteria generate pre-formed toxins in food?
Staphylococcus aureus
Bacillus cereus
Clostridium botulinum
What other skin infection does staph aureus cause?
Scalded skin syndrome
How long after food ingestion do S. aureus symptoms appear?
1-7 hrs
How long does food poisoning from S. aureus last?
1-3 days
How do you diagnose S. aureus food poisoning?
Toxin producing S aureus identified in stool and vomit
Linked with food
What are common S. aureus food reservoirs?
Ham, eggs, custard
What do Bacillus cereus look like?
Box-car shaped G+ rods
Which of the three toxin producing bacteria produce spores?
Bacillus cereus
Clostridium botulinum
What is the reservoir for Bacillus cereus?
Rice (spores survive cooking process)
How does Bacillus cereus food poisoning present?
Vomiting 1-6 hrs after ingestion
Watery Diarrhea 6-15 hrs after ingestion
For 24 hours
What causes vomiting in B cereus infection?
Enterotoxin Cereulide forms holes in membranes
What causes diarrhea in B cereus infection?
Large amounts of bacteria cause it to generate toxins in small intestine
What is drug of first choice for B cereus?
Vancomycin
Does B cereus presence on incubation plate rule in its cause for diarrhea?
No because it’s ubiquitous
What does Clostridium botulinum look like?
G+ spore forming rod
How is food borne botulism treated?
Vent if in resp failure
Antitoxin if paralysis is incomplete
Remove contaminated food in gut
How do you diagnose botulism?
Organism or toxin in stool sample
Symptoms and history
Tests to exclude
What is botulinum toxin?
Irreversibly blocks acetylcholine release from motor end plate
What are symptoms of botulism?
Blurred, double vision Slurred speech Difficulty swallowing Drooping eyelids Muscle weakness
What are some food reservoirs for botulinum?
Toxin is in food, spores are in honey (don’t give honey to infants)
What does Clostridium perfringens look like?
G+ spore forming rod
What does C. perfringens enterotoxin do?
Binds to receptors in endothelial cell junctions, generating pores
What skin disease is C perfringens responsible for?
Gas gangrene
What are symptoms of C perfringens infection?
Diarrhea, abd cramps
After 6-24 hours of eating
Smx less than 24 hours
No fever or vomiting
How do you diagnose C perfringens?
Detection of TOXIN or high amounts of bacteria in feces
What does campylobacter jejuni look like?
Gram - spirilli, motile
What is C jejuni reservoir?
Poultry
How do you culture C. jejuni?
Karmali agar (cold sensitive) Oftentimes killed before cultured
What are the symptoms of C jejuni
FEVER
Diarrhea, cramping, abd pain
Sx last a week
Can be bloody diarrhea
Mechanism of disease for C jejuni?
Cell invasion, inflammatory response
What are possible complications of C jejuni?
Guillain Barre syndrome
Reactive arthritis
Which serotypes of salmonella cause typhoid (not food-related)?
Paratyphi A
Typhi
Which serotypes of Salmonella cause gastroenteritis?
S. Enteritidis
S. Typhimurium (more common in US)
What do salmonella look like?
Motile, gram negative bacilli
What molecules are sought out on culture to find out if something is salmonella?
Lactose fermenting negative
H2S production positive
What are symptoms of Salmonellosis?
Diarrhea
Sx typically last 4-7 days
12 hr to 3 day incubation
REACTIVE ARTHRITIS
What is a major complication of salmonella?
Reactive arthritis, systemic infection
What are typical reservoirs for Salmonella?
Unwashed produce Raw milk Raw eggs Food service (if ill) Apparently turtles
