S9) Gastrointestinal Infections

Question 1

Identify the 5-step clinical approach when dealing with GI infections

Answer 1

• History (incl travel and exposure history)
• Physical examination (incl hydration status)
• Investigation (samples, tests)
• Supportive treatment (±antimicrobial treatment)
• Infection prevention & control measures

Question 2

Identify 3 major causes of infective diarrhoea as well as the organisms involved

Answer 2

• Bacteria: salmonella, shigella, campylobacter, enterotoxigenic E. coli, C.diff
• Viruses: norovirus, rotavirus, adenoviruses
• Parasites: cryptosporidium, giardia, entamoeba

Question 3

Which organisms are observed in selective nutrient agars of stool cultures?

Answer 3

• Salmonella
• Shigella
• Campylobacter spp
• E.coli

Question 4

A Campylobacter infection is a major cause of diarrhoea worldwide.

Where is it found?

Answer 4

The Campylobacter organism lives in the GI tract of animal hosts, especially poultry

Question 5

Identify 3 methods of transmission for a Campylobacter infection

Answer 5

• Contaminated food
• Water
• Direct contact with animals/animal products

Question 6

Which organisms usually cause Campylobacter enteritis?

Answer 6

• C. jejuni
• C. coli

Question 7

Identify 5 symptoms of a Campylobacter infection (may mimic appendicitis)

Answer 7

• Abdominal pain & cramps
• Diarrhoea (absent/bloody)
• Nausea
• Prodromal symptoms (fever, rigors, aches, dizziness)
• Colitis

Question 8

Identify 5 acute complications of Campylobacter enteritis

Answer 8

• Cholecystitis
• Peritonitis (patients with peritoneal dialysis)
• Rash (urticaria, erythema nodosum)
• Septic pseudoaneurysm
• Pericarditis & myocarditis

Question 9

Identify 2 late complications of Campylobacter infections

Answer 9

• Reactive arthritis
• Guillain-Barré syndrome

Question 10

Outline the treatment of Camplybacter enteritis

Answer 10

• Supportive treatment
• Antibiotics if severe, pregnant, elderly or immunocompromised (fluoroquinolone / macrolide)

Question 11

What is Cyclospora cayetanensis?

Answer 11

Cyclospora cayetanensis is a coccidian parasite which is associated with travellers diarrhoea

Question 12

Where is Cyclospora cayetanensis usually found?

Answer 12

• 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

Question 13

How does a Cyclospora cayetanensis infection spread?

Answer 13

Faeco-oral transmission (food / waterborne)

Question 14

Identify 6 symptoms of a Cyclospora cayetanensis infection

Answer 14

• Anorexia
• Nausea
• Flatulence
• Fatigue
• Abdominal cramping
• Watery diarrhea

Question 15

Describe the duration of illness for a Cyclospora cayetanensis infection

Answer 15

• Incubation period ~7 days after ingestion
• Average course length of illness ~ 3 weeks

Question 16

Outline the treatment of a Cyclospora cayetanensis infection

Answer 16

• Supportive treatment – fluid rehydration
• Antibiotics – trimethoprim-sulphamethoxazole

Question 17

How can a Cyclospora cayetanensis infection be prevented?

Answer 17

Prevention – attention to food hygiene when travelling to endemic areas

Question 18

What is a norovirus?

Answer 18

A norovirus is the most common cause of epidemic gastroenteritis and its peak incidence is in winter, affecting all ages

Question 19

Where do norovirus outbreaks usually occur?

Answer 19

Outbreaks associated with hospitals, schools, nurseries, restaurants, cruise ships, hotel resorts

Question 20

How is the norovirus transmitted?

Answer 20

• Faeco-oral
• Person-to-person

Question 21

How long is the incubation period for a norovirus?

Answer 21

Incubation period 24-28 hours

Question 22

In detail, explain how the norovirus is transmitted

Answer 22

• <100 viral particles can cause transmission
• Viral particles shed in stool and vomitus
• Fomites can contaminate environment

Question 23

Describe the treatment of a norovirus infection

Answer 23

• Supportive treatment – fluid rehydration
• No antiviral treatment available

Question 24

Infection prevention and control are key in avoiding and managing outbreaks.

Describe the prevention of the norovirus outbreaks

Answer 24

• Hand washing
• PPE
• Isolation
• Environmental cleaning

Question 25

Identify 4 infective causes of bloody diarrhoea

Answer 25

• Campylobacter
• E.Coli
• Salmonella
• Shigella

Question 26

What is the route of transmission for Shigella infection?

Answer 26

Foecal-oral route

Question 27

How do you identify clinically that a child is dehydrated?

Answer 27

• Xerostomia (tongue)
• Skin turgor
• Elevated HR
• Low BP

Question 28

What kind of bacteria is Shigella?

Answer 28

Shigella is a gram-negative rod shaped anaerobic bacteria

Question 29

Identify a virulence factor of shigella

Answer 29

Shiga toxin

Question 30

Describe the 4-step mechanism used by Shigella to cause bacteria

Answer 30

Question 31

What type of organism is cryptosporidium?

Answer 31

Parasite (protozoa)

Question 32

What is the route of transmission for Cryptosporidium?

Answer 32

Foecal-oral route (often through contaminated water)

Question 33

Identify 3 methods used to diagnose parasitic infections of the GI tract

Answer 33

• Stool samples
• Blood tests
• Endoscopy

Question 34

Outline the treatment of Cryptosporidiosis

Answer 34

• Supportive treatment – fluid resuscitation
• Anti-motility agents
• Antiparasitic drugs (azithromycin & paromycin)
• Antiretroviral therapy (HIV patients)

Question 35

Why is antiretroviral therapy necessary for the treatment of Cryptosporidiosis in HIV-infected patients?

Answer 35

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

Question 36

What methods are used to remove cryptosporidium oocytes from a swimming pool?

Answer 36

• Hyperchlorination
• UV Radiation