Infectious Diarrhoea Flashcards
Definitions of diarrhoea, gastroenteritis, dysentery.
Diarrhoea - fluidity, frequency
Gastroenteritis - three or more loose stools a day
Dysentery - large bowel inflammation, bloody stools
Non-inflammatory/secretory diarrhoea
- secretory toxin-mediated
- cholera - increases cAMP levels and Cl secretion
- enterotoxigenic E. coli (travellers’ diarrhoea)
Presentation of non-inflammatory diarrhoea
Frequent watery stools with little abdominal pain
Treatment of non-inflammatory/secretory diarrhoea
Rehydration mainstay of therapy
Inflammatory diarrhoea
- inflammatory toxin damage and mucosal destruction
- bacterial infection / amoebic dysentery
Inflammatory diarrhoea presentation
Pain and fever
Treatment of inflammatory diarrhoea
Antimicrobials may be appropriate but rehydration alone is often sufficient
Assessing patient with diarrhoea
-Symptoms and their duration
–>2/52 unlikely to be infective gastro-enteritis
-Risk of food poisoning
-Dietary, contact, travel history
-Assess hydration
–postural BP, skin turgor, pulse
-Features of inflammation (SIRS)
-fever, raised WCCFluid and electrolyte losses
Can be severe with secretory diarrhoea
- 1-7 l fluid per day containing 80-100 mmol Na - Hyponatraemia due to sodium loss - Hypokalaemia due to K loss in stool
Investigations for patients with diarrhoea
- stool culture +/- molecular or Ag testing
- blood culture
- Renal function
- blood count - neutrophilia, haemolysis (E. Coli O157)
- abdominal X-Ray/CT if abdomen distended, tender
Differential diagnosis of diarrhoea
- Inflammatory bowel disease
- Spurious diarrhoea -secondary to constipation
- Carcinoma
- Sepsis outside the gut
Sepsis outside the gut presentation
-Diarrhoea and fever
–Lack of abdo pain/tenderness goes against gastroenteritis
–No blood/mucus in stools
Gastroenteritis treatment
- rehydration
- oral rehydration with salt/sugar solution
- IV saline
Campylobacter gastroenteritis
-Campylobacter is the most common food born pathogen
-Up to 7 days incubation so dietary history may be unreliable
-Stools negative within 6 weeks
-abdominal pain can be severe
-<1% invasive
–Post-infection sequelae
-Guillain-Barre syndrome, Reactive arthritis
Salmonella gastroenteritis
- symptom onset usually <48 hrs after exposure
- diarrhoea usually lasts <10 days
- post-infectious irritable bowel is common
- prolonged carriage may be associated with gallstones
Salmonella gastroenteritis investigation results
- <5% positive blood cultures
- 20% patients still have positive stools at 20/52
Commonest salmonella isolates in the UK
- Salmonella enteritidis
- Salmonella typhimurium
E. coli O157
- produces Shiga toxin
- stays in the gut but the toxin gets into the blood
- toxin can cause hemolytic-uraemic (HUS) syndrome
E. coli O157 presentation
frequent bloody stools
Hemolytic-uraemic syndrome (HUS)
HUS characterised by renal failure, haemolytic anaemia and thrombocytopenia
Hemolytic-uraemic syndrome (HUS) treatment
Treatment supportive – antibiotics NOT indicated
Indication for antibiotics in gastroenteritis
- immunocompromised
- severe sepsis or invasive infection
- chronic illness e.g. malignancy
Clostridiodes difficile diarrhoea
- Patient usually gives history of previous antibiotic treatment – the “4 C antibiotics”
- Severity ranges from mild diarrhoea to severe colitis
- C. Diff produces enterotoxin (A) and cytotoxin (B) (inflammatory)
Clostridiodes difficile diarrhoea treatment
- metronidazole
- oral vancomycin
- Fidaxomicin (new and expensive)
- stool transplants
- surgery may be required
