Gastrointestinal Infections Flashcards
What is the epidemiology surrounding GI infections?
- Under-reported
- Self-limiting
- Young and old particularly at risk
Give some examples of notifiable GI infections in the UK
- Campylobacter
- Salmonella
- Shigella
- E. coli 0157
- Listeria
- Norovirus
Give some examples of anaerobic GI infections, their symptoms and their treatments.
Clostridium:
Botulinum
- Canned/vacuum packed foods, honey (children)
- Ingestion of preformed antigen (not cooking)
- Blocks ACh release, causing descending paralysis
- Treated with antitoxin
Perfringens
- Reheated meats
- Acts on small bowel, with an 8-16 hour incubation
- Watery diarrhoea, cramps, can cause GI infarction
- Usually self limiting
Difficile
- Hospital acquired, usually as a result of use of cephalosporins
- Causes pseudomembranous colitis
- Isolate the patient, highly infectious
- Treated with PO metronidazole + vancomycin
Give some examples of aerobic GI infections, their symptoms, and their treatments.
Staphylococcus aureus
- Carried by up to a third of the population, on the skin
- beta haemolytic, and appears in clusters on gram stain
- Vomiting, watery non-bloody diarrhoea
- Self-limiting
Bacillus cereus
- Reheated rice
- A result of heat-stable emetic
- Watery, non-bloody diarrhoea
- Self-limiting
Give some examples of lactose fermenting GI infections, their symptoms and their treatments.
Gram negative enterobacteriacae (E. coli). While all are self-limiting, they can be treated with ciprofloxacin. The main source is contaminated food with human faeces.
ETEC:
- Toxigenic, traveller’s diarrhoea
- Acts on jejunum and ileum, not colon
- Self-limiting
EIEC:
- Invasive dysentery
- Self limiting
EHEC:
- Haemorrhagic diarrhoea
- Can cause HUS (E. coli 0157)
- Self-limiting
EPEC:
- Infantile diarrhoea
- Self-limiting
Give some examples of non-lactose fermenting GI infections, their symptoms and their treatments.
Salmonella: O, H and Vi factors used to determine the type. H2S producers
Typhi/paratyphi:
- Only transmitted by humans
- Multiplies in Peyer’s patches, and leaves 3% as carriers (in gallbladder)
- Positive blood cultures
- Slow onset fever, constipation, bradycardia, splenomegaly, rose spots, anaemia, leukopaenia
- Treated with ceftriaxone or ciprofloxacin
Enteritides:
- Found in poultry, eggs or meat
- Stool culture positive
- Non-bloody diarrhoea
- Usually self-limiting
Shigella:
- Mainly affects ileum and colon
- Very low ID (50 organisms)
- Fever, pain, bloody diarrhoea
- Avoid antibiotics, usually self-limiting
Yersinia enterocolitis
- Prefers cold enrichment at 4 degrees
- Causes enterocolitis, mesenteric adenitis +/- necrotising granulomas
- Consider mycobacterium
Describe the GI infections caused by vibriosis, campylobacter and listeria infections, their symptoms and their treatments.
Vibrosis: comma shaped organism
Cholera:
- Transferred by human faeces
- Increased cAMP open chloride channels causing massive water and chloride loss
- Rice-water stool
- Treatment is by replacing losses
Parahaemolyticus:
- Ingestion of raw/undercooked foods
- Treated with doxycycline
Vulnificus:
- Skin infection by shellfish handlers
- Can cause fatal sepsis in the immunocompromised
- Treated with doxycycline
Campylobacter:
- From poultry or unpasteurised milk
- Curved organism, microaerophilic and oxidase positive
- Long prodrome of headache and fever, abdominal cramps, bloody diarrhoea, can last up to 3 weeks
- Associated with Guillian-barre syndrome
- Treated with erythromycin if needed
Listeria
- Beta haemolytic and aesculin positive
- Can infect pregnant women, the young or old (immunocompromised)
- Found in refrigerated foods (cheeses, vegetables)
- Causes watery diarrhoea, cramps, headache, fever
- Treat with amoxicillin
Give some examples of protozoal GI infections, their symptoms and their treatments.
Entamoeba histolytica:
- Found in food, water soil
- 4 nuclei organism
- Killed by boiling
- Stool microscopy important
- Flask-shaped ulcer on histology
- Causes dysentery, wind, tenesmus, RUQ pain, weight loss
- Treat with metronidazole + paromomycin (if luminal)
Giardia lambia
- Usually in travellers, hikers, MSM or mental hospitals
- Pear shaped, with 2 nuclei
- Faecally contaminated water
- Causes malabsorption of protein and fat, causing foul smelling non-bloody diarrhoea
- Treated with metronidazole
Cryptosporidium parvum:
- Infects the jejenum
- Stool culture positive
- Severe diarrhoea
- Treat with paromomycin
Give examples of viral GI infections, their symptoms and their treatments
Viral infections are usually self limiting
Rotavirus:
- Under 6 year olds
- Will be immune afterwards
Adenovirus:
- For under 2 years
- Bloody diarrhoea
Norovirus:
- Adult outbreaks
- Vomiting and diarrhoea
- Low ID of 18 organisms
- Poliovirus
- Enteroviruses (coxsackie)
- Hepatitis A
