L23: Diarrhoea and acute GI illness Flashcards
Signs and symptoms of acute GI illnesses
Vomiting
Diarrhoea: acute, watery, bloody/dysentery, severe (>6/day)
Abdominal pain
Fever
Viruses - onset, symptoms, management
Onset: fast (hrs/day)
Probably diarrhoea, always vomiting, fever
Management: rehydration, no antibiotics
Bacteria - onset, symptoms, management
Onset: range
Always diarrhoea, probably vomiting, abdominal pain
Management: rehydration and sometimes antibiotics
Protozoa - onset, symptoms, management
Onset: slower (days/weeks)
Always diarrhoea, possibly vomiting, abdominal pain
Management: rehydration, probably antibiotics
Viruses
- Norovirus, rotavirus
- Fast onset
- Nausea and vomiting, watery diarrhoea, abdo cramps, muscle aches, low fever, headache
- Colonise small intestine
- Generally self-limiting (over in 48hrs)
- Supportive treatment with fluid replacement
- Be aware of outbreaks and potential for outbreaks
Bacteria mechanisms of action (3)
- Colonisation of intestine and production of toxins
- Colonisation of intestines and invasion of intestinal tissue
- Toxin produced in food and ingested (food poisoning)
Which bacteria colonise the intestine and produce toxins?
Clostridium difficile Shiga toxin producing E. coli* Shigella dysenteriae* Enterotoxigenic E. coli Vibrio cholerae (Often dysentery*, all begin with acute watery diarrhoea)
Which bacteria colonise the intestine and invade the tissue?
Campylobacter jejuni Non-typhoid salmonella Yersinia enterocolitica Enteroinvasive E. coli (may see blood in stool, abdo cramping common)
Which bacteria can produce toxins in food and be ingested?
S. aureus, Clostridium perfringens, Bacillus cereus
Vomiting within 2-7hrs of consumption
Symptoms cleared in 1-2 days
Protozoa
- Colonisation of small intestine
- Giardia lamblia, Cryptosporidium
- Food/water contaminated by human or animal faeces
- Incubation period of 1+ weeks, symptoms may last 4-6weeks
- Diarrhoea, flatulence, foul smelling stools, abdominal cramps
- Mostly self-limiting but may need antibiotics (metronidazole for giardia)
- Can cause serious illness in immunocompromised (esp. cryptosporidium)
- Chemical agents do not kill cysts (e.g. Cl tablets do not kill giardia, instead boil water)
Common causative agents in NZ
- Campylobacter
- Giardia lamblia
- Gastroenteritis (unknown cause)
- Salmonella
- Yersinia enterocolitica
Diarrhoeal disease in developing countries
- 2nd leading cause of death in children <5yrs
- Mainly affects children <2yrs
- Mainly: cholera, E. coli, rotavirus, norovirus
Transmission and outbreaks
Found in animal or human GI tract/faeces -> spread by oral/faecal route (direct or indirect)
Outbreak = 2 or more cases linked to common source
- Can be community-wide or person-to-person spread
- Norovirus outbreaks common
- Salmonella relatively high
Risk factors for acute GI illness
- Consume food from retail premises
- Consume at risk produce (soft cheese for listeria) or untreated water
- Contact with farm animals, faecal matter, symptomatic people, recreational water, sick animals
- Overseas travel with incubation period
Diagnostic tests for severe bacterial diarrhoea
Shigella, Campylobacter, Salmonella, Yersinia enterocolitica, Vibrio cholera (rice water stool, possibly seafood involved)
Stool sample (1 sample unless to confirm not a carrier - 3 tests required e.g. for a food worker Microscopy of limited value as large numbers of bacteria in faeces (wet mount can be helpful for motile bacteria e.g. campylobacter, vibrio
Diagnostic tests for toxigenic bacterial diarrhoea
STEC (shiga toxin-producing E. coli), Clostridium difficile (hospital)
Toxin test - antibody or PCR of toxin gene
Stool culture for bacteria
- Sheep blood agar (grows most pathogens, including Listeria)
- MacConkey agar with lactose (E. coli ferment lactose while Shigella, Salmonella, Yersinia do not)
- MacConkey agar with sorbitol (most E. coli ferment sorbitol, STEC do not)
- XLD (salmonella, shigella grow)
- Campy plate (antibiotics to prevent growth of other bacteria)
- TCBS agar (vibrio cholera grow)
Diagnostic tests for protozoa and viruses
(Protozoa and viruses cannot grow on agar)
Viruses:
- Test for norovirus, rotavirus
- Use antibody or PCR based test
Protozoa:
- 4 wks of diarrhoea, not bacterial (giardia or cryptosporidium)
- Antigen test
Complications of acute GI illness
- Dehydration (main complication)
- Bacteraemia (salmonella, campylobacter)
- Haemolytic uremic syndrome (STEC toxin effects on kidney)
- Gullian-Barre syndrome (autoimmune attack of motor neurone sheath, campylobacter)
- Reactive arthritis (autoimmune attack from campylobacter, yersinia enterocolitica)
Symptomatic treatment
- Fluid and electrolyte replacement (clean water, salt and sugar - absorbed in S. intestine and replaces water lost in faeces)
- Easily digestible foods
- Anti-motility drugs (reduce stool rate, however concentrate toxins in GI tract: useful for watery diarrhoea, sometimes useful for dysentery with effective antibiotics
Treatment with antibiotics
- Usually not required
- Small effect on duration and severity of symptoms
- May reduce numbers shed (impt consideration for cholera or outbreaks)
Recommended for: C. difficile (vancomycin, metranidazole), salmonella/campylobacter (if at risk of systemic infection e.g. immunodeficiency)
Not recommended for: STEC as some antibiotics increased toxin production
Prevention of AGI
- Vaccines not routine, limited efficacy, used for outbreak control (available - rotavirus, cholera)
- Sanitation, hygiene
- Effective cooking
- Food safety regulation for retail food outlets
- Avoid risky food, drinking water
