Flashcards in All things diarrhoea (but not malabsorption) Deck (18):
What is chronic diarrhoea?
Persistent diarrhoea for > 2 weeks
What are the different types of diarrhoea?
- Due to damaged intestinal epithelial cells
- Mainly due to bacterial toxins
- Stimulates Cl secretion and inhibits neutral copied NaCl absorption
- Continues when enteral feeding is stopped
- Faecal Na > 90mosmol/L
- pH >6
- Reducing substances negative
- Presence of non-absorbed carbohydrate solutes gets fermented by colonic bacterial producing short-chain organic acids resulting in osmotic load
- Ceases when enteral feeding stopped
- Faecal pH < 5
- Faecal Na < 60mosmol/L
- Faecal osmo > 100 (290 - 2(Na+K)) - suggesting extra sugar load
- Reducing substances positive
What is the acid-base disorder related to vomiting, esp with pyloric stenosis ?
Metabolic alkalosis with hypochloraemia and hypokalaemia
- main cation at rest: Na+
- main cation when stimulated: H+
- main anion: chloride
Loss of gastric fluid
- results in chloride and variable H+ loses
- causes metabolic alkalosis, initiated by loss of H+ then sustained by disproportionate loss of Cl- and the kidneys tried to reabsorb an anion (choosing HCO3)
- Loss of ECF --> activates renin-aldosterone system --> retains Na in exchange for K
What is the acid-base disorder related to diarrhoea?
Only occurs when volume of fluid lost is large requiring the kidney's ability to adjust excretion....
- Hypotension, acute renal failure
- Metabolic acidosis with hyperchloraemia and hypokalaemia
Long term laxative ingestion results in chronic loss of potassium so kidneys try to increase absorption of K in exchange of H+ --> metabolic alkalosis
What are the differential diagnoses for acute diarrhoea?
- UTI, pneumonia, OM, meningitis, sepsis
- Appendicitis, intussusception, malrotation, Hirschprung's enterocolitis, partial bowel obstruction
- DM, antibiotic-associated diarrhoea, primary disaccharide deficiency
What are common causes of diarrhoea?
- rotavirus (winter) (dsRNA)
- norovirus (all seasons) (ssRNA)
- adenovirus 40, 41 (summer)
- astrovirus (winter)
EPEC / EAEC / EHEC
What is lactase deficiency a complication of gastroenteritis?
Destruction of epithelial cells --> subvillous atrophy --> brush border enzymes deficiency (lactase is most superficial)
What kinda vaccine is the rotateq?
Live attenuated vaccine
- reduces gastro of any severity by 70%
- reduces severe gastro by 85-100%
- reduces host by 50%
What are complications of viral gastroenteritis?
Febrile convulsions (rotavirus)
Seizures from electrolyte imbalance
- lasts 6-8wks
Why do you need 1:1 sodium: glucose solution for rehydration?
Absorption of glucose is via glu-Na cotransporter....
What are the causes of inflammatory enteritis?
Presents as fever, abode pain, abrupt onset of diarrhoea before vomiting, bloody / mucousy stools
Shigella, E.coli, Salmonella, Campylobacter, C.diff, entamoeba histolytic
What are causes of secretory (enterotoxigenic) diarrhoea?
Stools are watery with no faecal leucocytes.
- S aureus, B cereus, C perfringens
- E.Coli, giardia, cryptosporidium, rotavirus, norovirus
What are the complications of shigella enteritis?
Gram -ve rod
Untreated illness is ~ 2 weeks
Abx can reduce course of illness / duration of pathogen excretion
Isolate untile diarrhoea settles
- Headache / meningism / seizures / encephalopathy
- Septicaemia <5%
- Reiter syndrome (arthritis / urethritis / conjunctivitis)
What are the special features that causes complications related to Salmonella infection?
Gram negative rod (bacilli) of the enterobacteriaceae family
Produces cholera-like endotoxin --> secretory diarrhoea
Also invades mucosa --> inflammatory response
Survives poorly in low pH conditions --> increased in those on PPI
Has special virulence factors to invade blood stream resulting in 1-5% bacteraemia
Risk factors: immunodeficiency (HIV: 50% mortality), < 3m old, sickle cell disease, IBD, malaria, schistosomiasis
- Meningitis and brain abscess
- Reactive arthritis (HLAB27)
Cotrimoxazole / 3rd generation cephalosporin only indicated for <3/12, disseminated infection / severe or protracted course
(abx doesn't shorten clinical course, in fact, may actually increase excretion time)
What are the complications of campylobacter?
Gram -ve rod
9 species assoc with human disease - C. jejuni most common
- reactive arthritis (large migratory arthritis 5-40 days post)
- Guillain Barre syndrome (accounts for 25-40%)
- Ig A nephropathy
Antibiotics not beneficial...
What are the complications with yersinia?
Gram negative coccobacilli
Siderophoric (iron loving)
Can present like appendicitis
What are the complications with C.diff?
Spore-forming gram positive anaerobic rod (lives in soil)
Spectrum of severity
- from mild self-limited diarrhoea to pseudomembranitis colitis
- Discontinue current abx
- Metronidazole or vancomycin