Infective diarrhea Flashcards
(18 cards)
Watery diarrhoea
- possible microbes
Release of toxin
- increased water & electrolyte secretion by enterocyte w
- Vibrio cholerae
- Enterotoxigenic E. coli
- Clostridium perfringens
- Staphylococcus aureus
- Bacillus cereus
Diarrhea with mucus, blood, pus, fever, abdominal cramps
- possible microbes
Shigella sp.
Enterohaemorrhagic E coli – E coli O157 (VTEC/STEC)
Entamoeba histolytica
Dissemination beyond the GI tract
- possible microbes
Enterocyte invaded, multiplication in macrophages/ mesenteric lymph nodes → dissemination → fever +/- bacteraemia
Salmonella sp.
Campylobacter sp.
most common causes of infective diarrhoea
Campylobacter > Noro > Non-typhoidal Salmonella
> Rota > Verocytotoxigenic E coli > Shigella sp
> Listeria > Yersinia
Antibiotics to use in infective diarrhoea
fluoroquinolones - ciprofloxacin
azithromycin (clarithromycin for campylobacter)
AVOID anti-peristaltic drugs like loperamide
Campylobacter jejuni
- how can you catch it?
- incubation period
- presentation
- treatment
- complications
Undercooked poultry
Incubation: 1-3 days
Bloody stool, abdominal cramps, fever
Complications: bacteraemia, Gullian-barre syndrome (ascending paralysis)
Treatment: Macrolides
Salmonella
- how can you catch it?
- incubation period
- presentation
- treatment
- complications
Non typhoidal Salmonella
Eggs (imported) / poultry/ meats/ pets (reptiles; tropical fish)
Incubation: 6- 72 hours
Diarrhoea, vomiting / high fever (no blood)
Complications: bacteraemia; aortitis; osteomyelitis; meningitis; splenic cyst
Typhoid usually presents with fever and constipation
Verocytotoxigenic E coli (VTEC/STEC)
- how can you catch it?
- incubation period
- presentation
- treatment
- complications
Serious clinical & Public Health problem- E coli O157:H7 & non-O157 VTEC
- Very low infective dose
Cattle and other animals = reservoir
Food (minced beef/ raw vegetables/ imported salad), contaminated water/ environment
Diarrhoea frequent, initially non-bloody then bloody
- Acute bloody diarrhoea
Symptoms before HUS develops 81% diarrhea 74% bloody diarrhoea 60% vomiting 56% abdominal pain 23% fever 7% neurological (baby – may then get long-term cerebral palsy) 3% cardiomyopathy
Haemolytic uraemic syndrome (HUS) - 10-15%, usually <16 years or >60 years → blood haemolysis & renal failure
Diagnosis: Culture or molecular tests (PCR)
Symptoms more severe in pregnancy & risk to baby
Shigella sp
- how can you catch it?
- presentation
- who is at risk?
- treatment
Shigella sonnei; flexneri; dysenteriae; boydii
Important Public Health problem - developing countries
- Low infectious dose
- Causes dysentery & bloody diarrhoea
- Fever/ vomiting/ abdo pain
- Travellers (India/ Pakistan); Young children; gay men (Shigella flexneri)
Increased resistance to antibiotics esp. ampicillin & cotrimoxazole
Treatment: Cephalosporins/ ciprofloxacin/ azithromycin
Entero-toxigenic E. Coli
Leading cause: (1) bacterial diarrhoea in tropical areas (2) diarrhoea in returning traveller
Watery diarrhea/ vomiting / abdominal cramps/ mild or no fever
Resolves in 2-4 days
Diagnosis based on PCR detection of the toxins (not routinely done)
Staphylococcus aureus
- presentation
- how is it transmitted?
Short incubation < 4 hours
Heat-stable enterotoxin
S. aureus transmitted by asymptomatic carrier or skin lesion
Contaminated ready to eat food e g cream
Vomiting / diarrhoea no fever
Clostridium perfringens
Toxin generated in gut after ingestion
Short incubation: 6-24 hours
Abdominal cramps & diarrhoea, no vomiting
Contaminated meat / sauce ++
Contaminated food → clusters of cases - schools/ institutions/ gatherings
Bacillus cereus
Produces 2 toxins- emetic type and diarrhoeal
Vomiting presents very soon after ingestion, watery diarrhoea slightly later
In food and multiplies quickly at room temp. - rice/ leftovers/ sauce/ soups
Self limiting- usually around 24 hours
Toxigenic Vibrio cholera
- what kind of bacteria is it?
- where is it endemic?
- reservoir?
- symptoms
- treatment
Gram negative bacillus - 2 serogroups involved: O1 and O139
Endemic/ epidemic in tropical areas
- India/ Central America/ Africa
- 3-5,000,000 cases / year à 150,000 deaths
Reservoir = people & aquatic sources - brackish waters and estuaries
Non-O1 strains cause gastro- enteritis in returning travellers, not cholera
Cholera
- Clinical presentation in endemic areas
- No symptoms: 75%
Among symptomatic cases
- Mild diarrhoea = 80%
- Profuse watery diarrhoea causing dehydration
Vaccination confers partial protection
Antibiotic treatment (tetracyclines) and rehydration
Rotavirus
- who does it affect?
- what is the seasonality?
Children
Spring / summer
High risk of dehydration if < 2 years
Reduced since UK vaccination programme 2013
Amoebiasis
Protozoan parasite (division in host)
Orofaecal infection: cysts eliminated in stool; ingested; trophozoites invade mucosal lining
Entamoeba histolytica histolytica
Tropical areas with poor sanitary conditions
Human reservoir
Clinical presentation
- Asymptomatic - 80%
- Loose stool and abdominal cramps
- +++ Bloody stools and abdominal cramps, no fever, colitis
Extradigestive infection
- Liver +++
- Fever, enlarged and tender liver
- Unique 2/3 → multiple abscesses
- 80% right lobe
Diagnosis
- Stool sample for colitis
Entamoeba histolytica = ingested erythrocytes in trophozoite
Urgent examination of pus and stools for trophozoites within 2 hours
Serology for liver disease
- False negative <7 days of fever
- No parasites in pus/stool
- Treat: metronidazole followed by diloxanide
Cryptosporidiosis
- what kind of pathogen is this?
- which ones causes human infection
- how can you catch it?
- who is at risk?
- presentation?
- duration?
- treatment
Protozoal parasite
Cryptosporidium hominis & Cryptosporidium parvum cause human infection
Resistant to chlorine; acquired from swimming pools/ contaminated water; contact with lambs or calves
Often children age 1-5, vet students
Watery diarrhoea, stomach cramps
Duration- 1-2 weeks, but may have relapse before resolving, up to 30 days
More severe in immunocompromised patients - HIV
Fluid replacement important
Giardiasis
- presentation
- diagnosis
- treatment
Stomach cramps; Abdominal cramps; prolonged non-bloody diarrhoea
- GAS, BLOATING, BELCHING, FLATULENCE
Asymptomatic
Examination of stool for parasites – but under-diagnosed
Treatment - metronidazole or albendazole
