Lecture 23: Diarrhoea and acute gastrointestinal illness Flashcards Preview

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Flashcards in Lecture 23: Diarrhoea and acute gastrointestinal illness Deck (18):

Signs and symptoms AGI

-Diarrhoea: Acute, watery, bloody(dysentery), severe (6 x a day)
-Abdo pain and cramping


Causes of AGI? differences between them:

Onset; diarrhoea; vomiting; fever/pain; rehydration; antibiotics

Virus: Faster(hrs/days); probably; YES; fever, likely pain; yes; no

Bacteria: range; yes; probaby; abdo pain; yes; sometimes

Protozoa: slower; yes; possibly; abdo pain; yes; prob


Viral AGI

-Small intestine
-Norovirus (+ve strand ssRNA) , Rotavirus (dsRNA)
-Self limiting generally, over in 48 hours
-Effective vaccines for rotavirus


Ways Bacteria cause AGI?

Colonisation of intestines and toxin production
Invasion of intestinal tissue
Toxin produced in food but not ingested, food poisoning


Bacterial agents that colonise and invade intestinal tissue

Campylobacter jejuni
non typhoid salmonella
yersinia enterocolitica
enteroinvasive E coli

May cause blood in faeces, abdo cramping


What is injestion of bacterial toxins?

-No infection. Food poisoning.
-Staph aureus
-Clostridium perfringens
-Bacillus cereus
-Vomiting withing 2-7 hours, symptoms cleared 1-2 days


Protozoa information

_____ and ______

______ contaminated by human faeces e.g _____ _______
incubation of 1 week
symptoms 4-6 weeks
diarrhoea, flatulence, foul stools
mostly self limiting, giardia might need _______

Giardia and Cryptosporidium

food/water contaminated by human faeces e.g farmer, tramper, pet owner
incubation of 1 week
symptoms 4-6 weeks
diarrhoea, flatulence, foul stools
mostly self limiting, giardia might need metronidazole


New Zealand most common agenst of AGI

Worldwide AGI

Campylobacter, Salmonella, Giardia
Most serious, listeria

Diarrhoeal disease really bad, a lot of cholera. Mostly children. E coli, cholera, norovirus an rotavirus


NZ outbreaks (2 or more cases with common source)



Sources of AGI

-Human/animal GI -tract/faeces: Faceal oral route direct or indirect
-Animals, infected people and carriers
-Contaminated food and water


Contaminated food route

means to stop

Animal faces- contaminated carcass(can eat these) and fertilised vegetables
These become food items, which we eat and causes the AGI.
Human Faeces can then be transferred to food product

Slaughter, farming practice, cooking, storage, hygiene


AGI risk factors

Consume retail food; consme at risk foods (soft cheese listeria); farm animal contact; consume untreated water; faecal matter contact; symptomatic people contact; recreational water; sick animals; overseas travel within incubation period


Contaminated water route

means to stop

Human and animal faeces contaminate water source
Drinking and irrigation water into our food and drink

Farming and sewerage, supply, more sewerage


Stool culture types

note food worker would have 3 negative tests to see if clear

-Sheep blood: grow most pathogens, including listeria that won't grow elsewhere
-MacConkey agar with lactose: E coli will ferment lactose, Salmonella, Shigella, yersinia do not
-Maconkey agar with sorbitol: most E coli ferment sorbitol, STEC do not
-XLD: slamonella and shigella grow
-Campy plate: campylobacter

Antibody or PCR for viral
Antigen test for protozoa


AGI complications

Dehydration, bactaraemia (salmonella, campylobacter); haemolytic uremic syndrome (STEC on kidney); Guillan barre and campylobacter; reactive arthritis campy, yersinia


AGI treatment

Fluid and electrolyte replacement: very important. clean water, sugar and salt
Easily digestible food
Anti-motility drugs? Reduce stool rate but concentrate toxins



usually not required
Not recommend for STEC

Use when: clostridium difficile (vancomycin, metronidazole)
Salmonella/Campylobacter if risk of systemic infection


Severe diarrhoea bacteria to have in mind

Shigella, campylobacter, salmonella, yersinia, vibrio if rice water stool (possibly seafood), STEC if bloody, C difficile in hosp

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