L19: Food Poisoning Flashcards
What is food poisoning? (definition)
illness (gastroenteritis) caused by contaminated food
What are the symptoms of food poisoning?
- diarrhea
- vomiting
- nausea
- crampy abdominal pain
- ± fever
What investigations/tests can be done if food poisoning is suspected?
- PCR of Faeces
- Blood Culture
- Test Food
Generally, what is the treatment for food poisoning?
- supportive treatment
- antibiotics typically not indicated
Explain the toxin involved and the characteristics of food poisoning caused by S. aureus
- heat stable enterotoxin ingested
- works fast [within 1 to 8 hours]
- lasts 8-24 hours
- vomiting predominates
What is the clinical presentation of food poisoning by S. aureus?
- works fast [within 1 to 8 hours]
- lasts 8-24 hours
- vomiting predominates, occasionally diarrhea
What is Type 1 of Bacillus cereus food poisoning?
Type 1 = Emetic Syndrome
What is Type 2 of Bacillus cereus food poisoning?
Type 2 = Diarrheal Syndrome
How does Bacillus cereus cause type 1 emetic syndrome? (toxin/spore involved?)
- spores germinate in food and release toxin
- ingestion of performed toxin
- e.g. fried rice
What is the clinical presentation of food poisoning by B. cereus type 1?
- works fast [within 1 to 6 hours]
- lasts 2-10 hours
- predominantly vomiting + abdominal cramps
- may have diarrhea
How does Bacillus cereus cause type 2 diarrheal syndrome? (toxin/spore involved?)
- spores ingested in food (not toxin)
- toxin production (in vivo) after spores germinate
What is the clinical presentation of food poisoning by B.cereus type 2?
- incubation period between 6 to 14 hours
- lasts between 8 to 24 hours
- predominantly diarrhea
How does Clostridium perfringens cause food poisoning? (spores/toxin involved?)
- ingestion of heat-resistant spores
- toxin production in-vivo
What is the clinical presentation of food poisoning by C. perfringens?
- incubation period between 8-24 hours
- lasts 1-3 days
- profuse diarrhea, occasionally vomiting
How does Clostridium botulinum cause food poisoning? (spores/toxin involved?)
- ingestion of neurotoxin
- improperly canned/home bottled products
- toxin binds irreversibly to pre-synaptic nerve endings and inhibits ACh release
- get paralysis
What is the clinical presentation of food poisoning by C. botulinum?
- incubation between 12 and 36 hours
- acute descending symmetrical weakness
- paralysis
- high mortality
What is the treatment of food poisoning by C. botulinum?
treat w/ antitoxin
What organism is the most common cause of food poisoning in developed countries?
Campylobacter spp.
What are the 4 types of campylobacter spp. that may cause food poisoning? Which is the most common?
- C. jejuni = most common
- C. coli
- C. fetus
- C. lari
What is the main source of campylobacter spp. which causes food poisoning?
- undercooked meat and meat products*
- – inadequate decontamination
- raw or contaminated milk
*cases peak in summer months/barbecue season
What is the clinical presentation of food poisoning cause by campylobacter spp.?
- incubation period of 2-4 days (can be up to 8-9 days)
- prodromal illness (fever, headache)
- diarrhea (may be bloody)
- abdominal pain
- resolves w/in 5 to 7 days
List the complications after food poisoning by campylobacter spp
- toxic megacolon
- bacteraemia
- Guillain-Barre Syndrome
What investigations can be done to diagnose food poisoning caused by campylobacter spp.
- PCR (of faeces)
- Culture (of faeces or blood)
List all the laboratory features of the campylobacter species
- gram negative (curved) bacilli
- positive oxidase test
- hydrolyses hippurate (makes a blue colour)
- greyish colonies on selective charcoal-containing media incubated in CO2 at 42 degrees
Which organism will produce greyish colonies on selective charcoal-containing media incubated in CO2 at 42 degrees?
Campylobacter spp.
Which organism hydrolyses hippurate?
Campylobacter spp.
What is the treatment of food poisoning caused by Campylobacter spp.?
- typically rehydration
- antibiotics only given if bacteraemic or immunosuppressed (azithromycin or ciprofloxacin)
In specific cases, antibiotics may be given to treat food poisoning caused by Campylobacter spp - what antibiotics may be given?
Azithromycin or Ciprofloxacin
What is another name for enterohaemorrhagic E. coli (EHEC)?
Verotoxigenic E. coli (VTEC)
What is the main reservoir of enterohaemorrhagic E. coli and what are the modes of transmission?
- main reservoir = cattles
- transmitted through beef products, contact w/ animals or faeces and person-to-person
What is the most common serotype of enterohaemorrhagic E. coli?
E. coli O157:H7
Where in the GIT does enterohaemorrhagic E. coli affect?
- colon
- adheres + invades intestinal epithelial cells
- causes cell death and bloody diarrhea
What is the clinical presentation of enterohaemorrhagic E. coli food poisoning?
- incubation b/w 1 to 10 days (median = 3)
- bloody diarrhea
- lasts 3 days
What is the main complication of food poisoning caused by enterohaemorrhagic E. coli?
Haemolytic Uremic Syndrome
What organism causes Traveller’s Diarrhea?
enterotoxigenic E. coli
What is the clinical presentation of food poisoning caused by enterotoxigenic E. coli?
- incubation b/w 1 to 3 days
- watery diarrhea, fever, nausea
- self limiting
- lasts 1-5 days
What 2 toxins are involved in food poisoning caused by enterotoxigenic E. coli?
- Heat Labile Toxin
2. Heat Stabile Toxin
Where in the GIT does enterotoxigenic E. coli affect?
small GIT - does not invade
What organism is the major cause of infantile gastroenteritis?
Enteropathogenic E. coli
Where in the GIT does enteropathogenic E. coli affect?
small GIT
What is the clinical presentation of infantile gastroenteritis caused by enteropathogenic E. coli?
- watery diarrhea
- vomiting
- fever
Which organism that causes food poisoning can also grow in refrigerated foods?
Listeria monocytogenes
Explain how an early-onset neonatal listeria infection is acquired and how it presents
- acquired in utero
- presents w/ BSI
- HIGH mortality (compared to late onset)
Explain how late-onset neonatal listeria infection is acquired and how it presents
- acquired from maternal genital tract during birth
- presents w/ meningitis or meningoencephalitis
- more common than early onset
Is early-onset or late-onset neonatal listeria infection more common?
late-onset
What is the treatment of a listeria monocytogenes infection?
high dose ampicillin/amoxicillin
w/ an aminoglycoside (e.g. gentamicin)
What is the clinical presentation of infection with a cryptospordium spp infection?
- symptoms begin 2-10 days after infection
- watery diarrhea
What is the main mode of transmission of cryptosporidium spp?
- faecal-oral
- faecally contaminated food or WATER sources
- resistant to chlorine-based disinfectants
What special stain is used to detect cryptosporidium spp under a microscope?
modified acid-fast stain or auramine
