S9) Gastrointestinal Infections Flashcards
Identify the 5-step clinical approach when dealing with GI infections
- History (incl travel and exposure history)
- Physical examination (incl hydration status)
- Investigation (samples, tests)
- Supportive treatment (±antimicrobial treatment)
- Infection prevention & control measures
Identify 3 major causes of infective diarrhoea as well as the organisms involved
- Bacteria: salmonella, shigella, campylobacter, enterotoxigenic E. coli, C.diff
- Viruses: norovirus, rotavirus, adenoviruses
- Parasites: cryptosporidium, giardia, entamoeba
Which organisms are observed in selective nutrient agars of stool cultures?
- Salmonella
- Shigella
- Campylobacter spp
- E.coli
A Campylobacter infection is a major cause of diarrhoea worldwide.
Where is it found?
The Campylobacter organism lives in the GI tract of animal hosts, especially poultry
Identify 3 methods of transmission for a Campylobacter infection
- Contaminated food
- Water
- Direct contact with animals/animal products
Which organisms usually cause Campylobacter enteritis?
- C. jejuni
- C. coli
Identify 5 symptoms of a Campylobacter infection (may mimic appendicitis)
- Abdominal pain & cramps
- Diarrhoea (absent/bloody)
- Nausea
- Prodromal symptoms (fever, rigors, aches, dizziness)
- Colitis
Identify 5 acute complications of Campylobacter enteritis
- Cholecystitis
- Peritonitis (patients with peritoneal dialysis)
- Rash (urticaria, erythema nodosum)
- Septic pseudoaneurysm
- Pericarditis & myocarditis
Identify 2 late complications of Campylobacter infections
- Reactive arthritis
- Guillain-Barré syndrome
Outline the treatment of Camplybacter enteritis
- Supportive treatment
- Antibiotics if severe, pregnant, elderly or immunocompromised (fluoroquinolone / macrolide)
What is Cyclospora cayetanensis?
Cyclospora cayetanensis is a coccidian parasite which is associated with travellers diarrhoea
Where is Cyclospora cayetanensis usually found?
- Endemic in South and Central America, South Asia, South-east Asia, the Middle East and Africa
- Outbreaks in Europe and North America associated with food contamination
How does a Cyclospora cayetanensis infection spread?
Faeco-oral transmission (food / waterborne)
Identify 6 symptoms of a Cyclospora cayetanensis infection
- Anorexia
- Nausea
- Flatulence
- Fatigue
- Abdominal cramping
- Watery diarrhea
Describe the duration of illness for a Cyclospora cayetanensis infection
- Incubation period ~7 days after ingestion
- Average course length of illness ~ 3 weeks
Outline the treatment of a Cyclospora cayetanensis infection
- Supportive treatment – fluid rehydration
- Antibiotics – trimethoprim-sulphamethoxazole
How can a Cyclospora cayetanensis infection be prevented?
Prevention – attention to food hygiene when travelling to endemic areas
What is a norovirus?
A norovirus is the most common cause of epidemic gastroenteritis and its peak incidence is in winter, affecting all ages
Where do norovirus outbreaks usually occur?
Outbreaks associated with hospitals, schools, nurseries, restaurants, cruise ships, hotel resorts
How is the norovirus transmitted?
- Faeco-oral
- Person-to-person
How long is the incubation period for a norovirus?
Incubation period 24-28 hours
In detail, explain how the norovirus is transmitted
- <100 viral particles can cause transmission
- Viral particles shed in stool and vomitus
- Fomites can contaminate environment
Describe the treatment of a norovirus infection
- Supportive treatment – fluid rehydration
- No antiviral treatment available
Infection prevention and control are key in avoiding and managing outbreaks.
Describe the prevention of the norovirus outbreaks
- Hand washing
- PPE
- Isolation
- Environmental cleaning
Identify 4 infective causes of bloody diarrhoea
- Campylobacter
- E.Coli
- Salmonella
- Shigella
What is the route of transmission for Shigella infection?
Foecal-oral route
How do you identify clinically that a child is dehydrated?
- Xerostomia (tongue)
- Skin turgor
- Elevated HR
- Low BP
What kind of bacteria is Shigella?
Shigella is a gram-negative rod shaped anaerobic bacteria
Identify a virulence factor of shigella
Shiga toxin
Describe the 4-step mechanism used by Shigella to cause bacteria
What type of organism is cryptosporidium?
Parasite (protozoa)
What is the route of transmission for Cryptosporidium?
Foecal-oral route (often through contaminated water)
Identify 3 methods used to diagnose parasitic infections of the GI tract
- Stool samples
- Blood tests
- Endoscopy
Outline the treatment of Cryptosporidiosis
- Supportive treatment – fluid resuscitation
- Anti-motility agents
- Antiparasitic drugs (azithromycin & paromycin)
- Antiretroviral therapy (HIV patients)
Why is antiretroviral therapy necessary for the treatment of Cryptosporidiosis in HIV-infected patients?
Highly active antiretroviral therapy (HAART) can reduce the patient’s viral load to restore their immune response to a certain level so that the symptoms of cryptosporidiosis are resolved
What methods are used to remove cryptosporidium oocytes from a swimming pool?
- Hyperchlorination
- UV Radiation
