Infectious Diarrhoea Flashcards
Infective gastroenteritis
Inflammation of the stomach and intestines, resulting from bacterial toxins or viral infection.
3+ stools in 24 hours plus at least one of:
- Fever
- Vomiting
- Abdominal pain
- Blood/mucus
Diarrhoea
- Subjective
- Change in fluidity/frequency of stool from normal
Dysentery
Type of gastroenteritis caused by microorganisms: large bowel inflammation, abdominal pain and bloody stools
Host’s natural defences
- Gastric acid
- Gut motility
- Normal gut flora
- Gut immunity
- Age
Mechanism of diarrhoea
- Toxin
- Invasion
- Others
Non-inflammatory infective gastroenteritis
Secretory enterotoxin- mediated
- Does not invade intestinal mucosa
Non-inflammatory infective gastroenteritis: organisms
- Enterotoxigenic E. coli (traveller’s diarrhoea)
- Bacillus cereus
- Staph aureus
- Vibrio cholera
- Rotavirus
- Noravirus
- Giardia
- Cryptosporidium
Inflammatory infective gastroenteritis
Toxin-mediated damage and mucosal destruction
Inflammatory infective gastroenteritis: organisms
- E. coli
- Campylobacter
- Salmonella
- Staph aureus
- Shigella
- Entamoeba histolytica
Infective gastroenteritis epidemiology
- Contaminated foodstuffs
- Poor storage of produce
- Travel-related
- Person-to-person spread
Bacteria causes of infective gastroenteritis
- Campylobacter (most common)
- Salmonella
- E. coli O157
- Cholera
- Shigella
- Clostridiodes (Clostridium) difficile
Food poisoning outbreaks
- Staph aureus (toxin)
- Bacillus cereus (re-fried rice)
- Clostridium perfringens (undercooked meat)
Most common cause of infective gastroenteritis
Viral
Viral causes of infective gastroenteritis
- Rotavirus (most common)
- Norovirus
- Adenovirus
Parasitic causes of infective gastroenteritis
- Giardia
- Cryptosporidium parvum
- Entamoeba histolytica
Bristol Stool Chart
Improving/worsening
- Frequency
- Fluidity
- Timeframe
- Infective gastroenteritis: Type 6/7
Non-inflammatory infective gastroenteritis: symptoms
- Frequent watery stools
- Little abdominal pain
Inflammatory infective gastroenteritis: symptoms
- SIRS: pain, fever
- Bloody stools
Infective gastroenteritis: history
- Symptom duration
- Food poisoning risk: dietary, contact, travel
Infective gastroenteritis: differential diagnosis
- IBD (>2 weeks)
- Spurious diarrhoea
- Carcinoma
- Extra-intestinal sepsis
Hydration assessment
- Postural BP
- Skin turgor
- Pulse
- Urine flow
- Muscle cramps
Inflammatory features of infective gastroenteritis
- Fever
- Bloods: raised WCC, culture
Infective gastroenteritis: investigations
- Stool culture
- Blood culture: immune deficiency
- Renal function
- Blood count: neutrophilia, haemolysis
- AXR/CT
Routine stool culture organisms
- Campylobacter
- Salmonella
- Shigella
- E. coli O157
Additional bacterial stool culture
- Specific bacteria not routine
- Toxin detection
Infective gastroenteritis: viral diagnosis
PCR
Infective gastroenteritis: parasite diagnosis
Stool microscopy (PCO)
- Parasites
- Cysts
- Ova
Infective gastroenteritis: Prevention
- Hygiene
important for viral
Non-inflammatory Infective gastroenteritis: Management
- Rehydration
IV (saline), oral (salt/glucose)
Antibody therapy not beneficial
Inflammatory Infective gastroenteritis: Management
- Rehydration
- Antimicrobials may be appropriate
Antimicrobial indications
- Immunocompromised
- Severe sepsis
- Invasive infection
- Chronic illness
Complication of E. Coli O157
Haemolytic uraemic syndrome
- Blood disorder
- Largely children, adults, compromised
1. Acute renal failure
2. Haemolytic anaemia
3. Thrombocytopenia - 5-9 days after diarrhoea
- Symptoms: bloody diarrhoea, fever, vomiting, weakness
Campylobacter gastroenteritis
Commonest bacterial gastroenteritis
- Gram negative spiral bacteria
- C-jejuni (90%), C. coli
- Inflammatory
- Food poisoning
- up to 7 days incubation, severe abdominal pain, diarrhoea (bloody)
- Routine stool culture
- Post-infective: polyneuritis, reactive arthritis
- Infections clears in 3/52
Salmonella gastroenteritis
- Gram negative rod
- Inflammatory
- S. enterica, bongori
- Food poisoning, travel
- <48 hours after exposure
- Diarrhoea <10 days
- Routine stool culture (lactose non-fermenters)
- Post-infectious IBS common (1/4)
E. coli O157 gastroenteritis
- Gram negative rod stays in gut
- Shiva-Like toxin in blood
- Contaminated meat
- Person-to-person spread
- Frequent bloody stools
- Complication: HUS
- Routine stool culture: lactose fermenter
- Excretion after 3/52 NO ANTIBIOTICS
Vibrio cholera
- Gram negative comma
- Non-inflammatory
- Increased cAMP/Cl/Na/K secretion
- Food/water contamination
- Watery diarrhoea
- Antimicrobial resistance, vaccine
Shigella
- Gram negative rod
- 4 species: S. sonnei, flexneri, boydii, dysenteriae
- Produces SLT (inflammatory)
- Food/water contamination, travel
- Bloody diarrhoea
- Severe: antibiotics
Clostridiodes (Clostridium) difficile
- Gram positive rod
- C. diff produces Enterotoxin and Cytotoxin
- Inflammatory
- Previous antibiotics (4C’s), institution
- Mild diarrhoea to severe colitis, fever, nausea, vomiting
- Not routine, bloods, imaging
4C’s
- Cephalosporin’s
- Co-amoxiclav
- Clindamycin
- Ciprofloxacin
C. diff: Management
Stop precipitating antibiotic
- Oral metronidazole (if no severity markers)
- Oral vancomycin (if 2 or more severity markers)
- Fidaxomicin
- Stool transplants
- Surgery
Prevention
- Reduce broad spectrum antibiotics
- Avoid 4C’s
- Antimicrobial Management Team
- Isolate symptomatic patients
- Wash hands (not alcohol)
- Cleaning environment
Giardia duodenalis
- Non-inflammatory
- 2 forms: cysts, trophozoites
- Contaminated water (cysts)
- Giardiasis: abdominal cramps, bloating, nausea, watery diarrhoea, malabsorption, failure to thrive
- Stool microscopy: cyst
- Diarrhoea specimen, duodenal biopsy, string test: trophozoites
- Metronidazole
Cryptosporidium parvum
- Non-inflammatory
- 2 forms: oocysts, trophozoites
- Water contamination (oocysts)
- Cryptosporidiosis: watery diarrhoea, nausea/vomiting, abdominal cramps, low grade fever
- Stool microscopy
- No specific treatment
Entamoeba histolytica
- Inflammatory
- Water/food contamination
- Bloody diarrhoea
- Complications: amoebic liver abscess
- Stool microscopy
- Serum antibody
- 10/7 Metronidazole (symptomatic), Diloxanide furoate (asymptomatic)
Rotavirus
Most common virus
- Infects mature enterocytes (villous body, tip), cell death and lactose intolerance
- Non-inflammatory (watery diarrhoea)
- Faecal-oral transmission
- Antigen detection in stool
- Vaccine at 8+12 weeks
Adenovirus
- Diarrhoea, fever, vomiting, abdominal pain, respiratory symptoms
- 10 days
Norovirus
- Highly contagious (infection dose: 18 particles)
- Non-Inflammatory
- Institutions: hospital, community, cruise ships
- Watery diarrhoea, vomiting
- PCR testing
- Ward closures, strict infection control
