Infectious Diarrhoea (bj) Flashcards
Define diarrhoea vs dysentery vs gastro-enteritis?
Diarrhoea is increased frequency/fluidity of stool
Dysentery is colonic inflammation due to infection leading to bloody diarrhoea
Gastro-enteritis is 3 or more loose stools/day along with accompanying features of infection such as fever, vomiting, pain and blood/mucous in stool.
What are the two different types of gastro-enteritis and example of each/
Inflammatory e.g. Shigella
Non-inflammatory e.g. Cholera or E. Coli
Whats the main difference between inflammatory & non-inflammatory gastro-enteritis?
Non-inflammatory involves fluid secretions from the small intestine –> Frequent watery stools with little pain
Inflammatory involves invasion or toxin induced inflammation of the gut –> Pain, systemic upset e.g fever and bloody stools
How is gastro-enteritis transmitted?
Contaminated food e.g. campylobacter in chicken
Bad food storage
Travel
Person-person
Risk factors for gastro-enteritis?
- Food history (unreliable)
- Contacts
- Travel
- antimicrobials
- Occupation
How do you test for gastro-enteritis?
Assess the patient:
- timing? >2wks it’s unlikely
- Risk Factors?
- Hydration? postural BP/Skin turgor/tachycardia/urine flow/muscle cramp
- Inflammation? Fever And WCC
- Electrolytes
- Stool/blood cultures
- Serology
- FBC, U&E + Creatinine
- AXR
- Sigmoidoscopy
How is gastroenteritis treated?
Oral rehydration - Sodium chloride + glucose + AAs
Antimicrobials if:
- Traveller’s
- Severe
- Immunocompromised
- Co-morbidities e.g. renal/resp disease
What are the major Gastroenteritis pathogens?
Campylobacter (Jejuni) Salmonella E. Coli Shigella cholera C. Difficile
Giardia Lamblia
Cryptosporidium Parvum
Entamoeba Histolytica
Noravirus
Rotavirus
Where does campylobacter infection come from?
Undercooked chicken
How does Campylobacter Gastroenteritis present?
7 day incubation and clears within 3 wks
Abdo pain can be severe
Can have post-infective syndromes such as guillain barre or Reactive Arthritis
how does Salmonella Gastroenteritis present?
<48hr incubation & lasts >10days (so shorter than campylobacter)
Can cause post-infective IBS
What is the most dangerous form of E. Coli?
E. Coli O157:H7 aka enterohaemorrhagic E. coli
Where do you get E. Coli O157:H7?
Cattle Reservoir;
- Contaminated Meat
- Stepping in Slurry
- Person-person
How does E. Coli O157:H7 present
Haemolytic Uraemic Syndrome (HUS)
The toxin gets into the blood and causes platelet aggregation –> RBC & renal capillary damage –> Renal failure & anaemia
What are the other forms of E.Coli other than O157:H7?
Enterotoxigenic - traveller’s Diarrhoea
Enteroinvasive
Enteropathogenic
Describe Traveller’s Diarrhoea and the most common causes?
How is the treatment of travellers diarrhoea different to other Gastroenteritises
Diarrhoea usually <1wk, can be treated with Abx.
Mostly Enterotoxigenic E. Coli but also Campylobacter and Shigella
What type of infectious diarrhoea can cause HUS & Seizures?
Shigella
E. Coli O157 causes HUS but not seizures
Whats the main form of Antibiotic Associated DIarrhoea and what causes it?
Clostridium Difficile, it produces 2 toxins (A & B)
Mainly caused by the 4Cs:
- Cephalosporins
- Ceftriaxone (& other quinalones)
- Co-amoxiclav
- Clindamycin
How do we detect C. Diff?
Stool Culture and C.diff Toxin (CDT) Detection
Sigmoidoscopy
How do we treat C. Diff?
- Metronidazole
- Oral Vancomycin (If severe)
- Fidaxomicin (For relapses)
- Stool Transplant
- Surgery
We’d also isolate symptomatic patients & follow hygiene
List some parasites that can cause Diarrhoea?
- Giardia Lamblia
- Cryptosporidium Parvum
- Entamoeba Histolytica aka amoebic dysentery
Where do we get Giardia Lamblia and how does it present?
Contaminated Water
Causes diarrhoea, malabsorption & Failure to thrive
How do we detect Giardia Lamblia?
Sick patients - Vegetative form found on a duodenal biopsy
Asymptomatic patients have inactive cysts that can be detected on stool microscopy
How do we treat Giardia Lamblia?
Metronidazole
Tinidazole
How do we get Cryptosporidium Parvum?
Cattle Reservoir via infected water e.g. private water supplies out of cattle fields
How do we detect and treat cryptosporium Parvum?
With stool microscopy looking for cysts
Usually its self-limiting
How do we test for and treat Entamoebic Histolytica?
Duodenal biospy - Vegetative form in symptomatic patients
Stool Microscopy - Cysts in asymptomatic patients
Treated with metronidazole (Symptomatically) or furamide if asymptomatic
What are the main viruses causing diarrhoea?
Rotavirus
Noravirus
How do you test for Noravirus?
With Serum PCR
How do we get & test for rotavirus?
Faecal-oral Route
Antigen Testing
What are the main pathogens behind Food Poisoning?
1) Staph Aureus Toxins - survive cooking
2) Bacillus Cereus - re-heated rice
3) Clostridium Perfringens - Undercooked Meat
