Enteric Infection and Diarrhoeal Disease Flashcards
Define diarrhoea?
3+ watery or loose stools per day.
Outline the pathogenic mechanisms of enteric infection?
- Toxin mediated: Can be produced before (S. aureus) or after consumption (E. coli)
- Damage to intestinal epithelium.
- Invasion across epithelial barrier (Salmonella).
What kind of diarrhoea would indicate infection of the small bowel?
Large volume, watery, cramps, bloating, wind, weight loss.
What kind of diarrhoea would indicate large bowel infection?
Frequent, small volume, painful stool, may have fever or blood.
Give examples of some enteric infection causing bacterial, viruses and parasites?
Bacteria: Campylobacter, salmonella, E. coli 0157, C. Difficele.
Viral: Norovirus, Sappovirus, Rotavirus, Adenovirus.
Parasitic: Cryptosporidium, Giardia.
List important things to ask about in a patients history with enteric infection?
Food/diet Onset Occupation Travel Pets/hobbies Recent hospitalisation/antibiotics Co-morbidities.
What tests could be used to diagnose enteric infection?
Faecal Leukocytes: may indicate an inflammatory cause. Poor sensitivity and specificity.
Faecal Occult blood: Checks for hidden blood in stool. Too sensitive.
Faecal Calprotein: Tests calprotein in stool. Can be used but not specific for infection.
Stool Culture: Difficult to grow due to difficult conditions to replicate gut in lab. Need to isolate specific bacteria.
Can use microscopy to see ova and cysts.
Documenting pathogens is beneficial in public health.
How are enteric infections treated?
Oral rehydration solutions.
Drinking water.
IV fluid replacement.
Antibiotics: Only reduce illness by around 1 day. Only give to very ill patients (sepsis or bacteraemia), or with significant co-morbidity.
Where is campylobacter commonly found and roughly whats the infective dose?
What is its incubation period?
Chicken
9000 organisms.
3 days.
What normally prevents campylobacter infection?
Stomach acid - therefore infection may occur when taking things to reduce stomach acidity.
List clinical features of campylobacter infection?
How is it treated?
Frequent, high volume diarrhoea often with blood. Abdominal pain. Fever.
May get late complications such as reactive arthritis and Gullian-Barre.
Self-limiting for 7 days. Don’t treat with antibiotics - bacteria often become resistant during course.
Where is salmonella commonly found? What is the infective dose?
Chickens, reptile skin.
Can be typhoidal (travellers to asia), or non-typhoidal.
10000 organisms.
What normally protects against salmonella?
stomach acid and gut flora.
What are the clinical features of salmonella infction?
Invades enterocytes with inflammatory response. Can cause systemic infection.
Illness usually begins around 72h after ingestion. Higher innoculum = more rapid onset.
Nausea, diarrhoea, cramp, fever.
Can invade and cause bacteraemia (<5) or secondary infection such as endocardidtis or osteomyelitits.
How is salmonella infection treated?
No reduction with antibiotics.
Self limiting for 10 days.
