Flashcards in Gastroenteritis Deck (27)
What are the most common commensal bacteria type in the gut?
Outnumber facultative anaerobic by 100 to one
What are the ebenficial effects of commensal bacteria in the guy>
What are the main commensal bacteria in the gut?
- E coli
- Enterococcus faecalis
What are the key bacterial causes of gastroenteritis?
What are the main causes of gastroenteritis outbreaks in UK?
Foodbourne infections e.g. salmonella
Recreational water, e.g. swimming pools
What are the clinical presentation of gastroenteritis?
- Acute onset
- Vomiting and diarrhoea (freq, mucous, bloody)
- systemic effects e.g. fever
- Abdo pain
- Complications e.g. dehydration, renal failure, salmonella, toxic megacolon etc
What investigations are carried out in gastroenteritis?
Blood - FBC, U&E, CPR, cultures
- Stools - parasite/oocytes, microscopy, toxin e.g. C diff toxin, PCR - virus
Why are investigations in gastroenteritis difficult?
So many commensal bacteria, difficult to tease out causative bacteria
Whats the most common cause of viral gastroenteritis?
Why is norovirus a very successful pathogen?
Low infective dose, last on surfaces for long time, long excretion (faecal/oral route)
How is viral gastroenteritis spread?
Aerosols - vomiting and diarrhoea
What are the main parasites that cause gastroenteritis?
How is cryptosporidium transmitted mostly and what adaptation does it have which makes it very resistant
Oocyte - resists chlorine
What are the two main routes by which bacteria cause infection?
Production of toxin
Adhesion/invasion of cell
What is the name for E. coli 0157?
How does E coli 0157 cause symptoms?
TOXIN - Shiga toxin
Why is E coli 0157 particularly dangerous?
Can cause haemolytic uraemic syndrome (HUS) - can cause renal failure
What is the mechanism by which E coli causes diarrhoea?
Activates G protein which increase cAMP levels. This activates ion channels which causes an increased efflux of Cl ion. Osmotic gradient produced - diarrhoea/dehydration
How does salmonella cause infection?
Causes infection ITSELF (not toxin)
How is gastroenteritis treated?
Antibiotics avoided (wait it out/rehydration) can worsen symptoms/prolong carriage
How does antibiotic associated diarrhoea occur?
Disrupt normal microflora
- change in metabolism (CHO/bile acid)
- overgrowth of pathogenic bacteria
What conditions can antibiotic cause?
What is the main cause of pseudomembranous colitis?
What C diff strain is associated with deaths in younger individuals
What antibiotics are more associated with C diff infection?
co-amoxiclav (broad spectrum penicllins,)
cephalosporins (3rd generation).
Fluroquinolones (CD027 strain)
What are the main antibiotics used for C. Diff?