Clinical infections - Gastrointestinal 2

Question 1

Foodborne gastroenteritis

Answer 1

• Can be Intoxication or infection

Question 2

Intoxication =

Answer 2

• Toxin ingested = infection
• Minutes to hours
• Neurological affects – sensory, motor
• Non-communicable
• Inadequate cooking, improper handling of food

Question 3

Infection =

Answer 3

• Pathogen ingested = infection
• Hours to days
• No neurological defects
• Transmissible
• Inadequate cooking, cross contamination, poor hygiene and handwashing procedures

Question 4

S.aureus food intoxication

Answer 4

• No fever - not an infection
• Heat stable enterotoxin
• 1-4hrs after ingestion
• Nausea and often projectile vomiting

Question 5

Bacillus cereus food intoxication

Answer 5

• Forms 2 enterotoxins
• Heat stable emetic form associated with cooked rice and starchy foods - Vomiting
• Heat labile diarrhoeal form produce profuse diarrhoea - 12-14hrs after ingestion

Question 6

Clostridium perfringens food intoxication

Answer 6

• Enterotoxin formed when organism sporulates
• Heat labile – toxin breaks down on heat
• Abdominal cramping
• Watery diarrhoea
• No fever
• 8-24 hrs after ingestion
• Associated with meat/meat products

Question 7

Clostridium botulinum food intoxication

Answer 7

• Neurotoxin formed when organism sporulates - large AB toxin - B portion protects A toxin from stomach acid
• A blocks neurotransmission, causing blurred vision, constipation, Descending flaccid paralysis – leading to respiratory failure
• No fever
• 1-2 days after ingestion of improperly canned food

Question 8

Infant botulism

Answer 8

• C. Botulinum spores in honey can colonise infant (<1yr) GI tract and produce toxin
• Constipation
• Neurological symptoms
• Milder disease than adults

Question 9

Salmonella gastroenteritis (infection)

Answer 9

• Killed by gastric acid → high numbers needed to infect
• Found in guts of chickens, reptiles, birds and humans
• Usually self-limiting – symptoms last 2 days to 1 week
• 6-8h after contaminated food or water

Question 10

Salmonella gastroenteritis (infection) treatment

Answer 10

• Antibiotic treatment not necessary, but consider for:
• Are older than 50 years of age.
• Are immunocompromised.
• Have cardiac valve disease or endovascular abnormalities
• Prescribe ciprofloxacin twice a day for 1 day only

Question 11

Dysentery - Shigella

Answer 11

• Fairly resistant to killing by gastric acid → low numbers needed to infect
• Some produce an enterotoxin and Shiga toxin
• 36-72h incubation period
• Causes Dysentery (bloody mucoid stool)

Question 12

Dysentery - Shigella treatment

Answer 12

• Stop use of ammodium (further lowers gastric acid)

- Ciprofloxacin 500 mg twice a day for 1 day only

Question 13

Antibiotic-associated diarrhoea

Answer 13

• Develops in ~30% patients on antibiotics
• Clostridium difficile most common infectious cause
• Antibiotics deplete normal gut flora
• C. difficile spores ingested, germinate produce toxins (A &B)

Question 14

Antibiotic-associated diarrhoea complications

Answer 14

Symptoms: Watery diarrhoea, abdominal cramps, low grade fever
- Can lead to fulminant colitis, pseudomembranous colitis, toxic megacolon, death

Question 15

Antibiotic-associated diarrhoea treatment

Answer 15

• Stop antibiotic and start treatment with metronidazole, vancomycin, or fidaxomicin
• Other treatments include immunoglobulin, bezlotoxumab and faecal transplants

Question 16

Antibiotic-associated diarrhoea tests

Answer 16

• Must demonstrate toxin (EIA, CCNA) as well as organism (GDH, NAAT) to prove disease