Infectious Diarrhoea Flashcards
Define Diarrhoea?
Fluidity and Frequency
Define Gastro-enteritis?
Three or more loose stools/day
Accompanying features
Define Dysentry?
Large bowel inflammation w/ bloody stools
What causes gastroenteritis ?
Contaminated foodstuffs (intensively farmed chicken and campylobacter), poor storage of produce, salmonella or norovirus
What is the commonest bacterial pathogen that causes gastroenteritis?
Campylobacter
What pathogen causes the most hospital admissions?
Salmonella
What are the best defences against enteric infections?
Hygeine, stomach acidity, normal gut flora and immunity
What are clinical features of diarrhoeal illnesses?
Secretory toxin mediated secretion (cholera and enterotoxic E.coli (travellers diarrhoea))
Frequent watery stools with little abdominal pain
How do you treat non inflammatory diarrhoea?
Rehydration
What is the mechanism behind cholera?
Increased cAMP levels = loss of Cl from cells along with Na and K loss
Osmotic effect leads to massive loss of water from gut
What are the clinical features of inflammatory diarrhoea?
Inflammatory toxin damage and mucosal destruction
Pain and fever
What is the main treatment of inflammatory diarrhoeal illness?
Rehydration therapy and perhaps antimicrobials
What is the typical presentation of gastroenteritis in an infant?
Sunken fontanelle, sunken eyes and cheeks, decreased skin turgor, dry mouth/tongue, sunken abdomen
What electrolyte imbalances are seen in gastroenteritis?
Hyponatremia due to sodium loss with fluid replacement by hypotonic solutions
Hypokalaemia due to K loss in stools
How much fluid can be lost with secretory diarrhoea?
1-7l fluid per day
What investigations should be done if gastroenteritis is suspected?
Stool culture, Ag testing, blood culture, renal function, blood count, abdominal x-ray if abdomen distended
What are the differentials for infectious diarrhoea?
IBD, Spurious diarrhoea, carcinoma, sepsis outwith the gut
What are the two most common causative campylobacter organisms ?
C. Jejuni and C. Coli
What are the characteristics of salmonella gastroenteritis?
Symptom onset usually <48 hours after exposure
Diarrhoea lasts less than ten days
20% of patients still have positive stools at 20 weeks post infection
What are the two species of salmonella?
S. Enterica and S. Bongori
What are the most common isolates of salmonella in the UK?
Salmonella Enteritidis and Salmonella Typhimurium
How is E.Coli spread?
Contaminated meat or person-to-person
How is E.Coli characterised?
Frequent bloody stools
What does E.Coli O157 produce?
Shiga toxin
