W25 - Gastroenteritis

Question 1

What is gastroenteritis?

Answer 1

A rapid onset diarrheal illness, lasting less than 2 weeks with diarrhoea (loose and unformed stool) three or more times a day or at least 200 g of stool which is either viral or bacterial in aetiology

Question 2

What is acute, persistent, and chronic diarrhoea?

Answer 2

Acute = less than 14 days (viral or bacterial usually)

Persistent = between 14-29 days

Chronic = >30 days (non-infectious or parasites usually)

Question 3

Smll bowel diarrhoea is usually ….

Large bowel diarrhoea is usually ….

Answer 3

Smll bowel diarrhoea = watery, associated with crampy abdominal pain, bloating, gas. Usually no blood or fever.

Large bowel diarrhoea = small volume, painful stool which occurs often with blood, mucus, fever, and accompanying inflammatory cells found in stool.

Question 4

3 RF categories for gastroenteritis

Answer 4

1. Foodborne
2. Exposure related (travel, occupation, animal contact, childcare facility, outbreak)
3. Host related (immunosuppressed, MSM, young, elderly, anal-genital, oral-anal, or digital-anal contact, haemochromatosis)

Question 5

What is the definition of gastroenteritis?

A) more than 2 weeks of symptoms

B) more than 1 week of symptoms

C) more than 3 weeks of symptoms

Answer 5

B) more than 1 week of symptoms

Question 6

Gastroenteritis - extra-intestinal manifestations:

Aortitis, osteomyelitis, deep tissue infection

Which pathogens are mostly responsible for these?

Answer 6

salmonella

yersinia

Question 7

Gastroenteritis - extra-intestinal manifestations:

haemolytic anaemia

Which pathogens are mostly responsible for these?

Answer 7

campylobacter

yersinia

Question 9

Gastroenteritis - extra-intestinal manifestations:

glomerulonephritis

Which pathogens are mostly responsible for these?

Answer 9

shigella

campylobacter

yersinia

Question 10

Gastroenteritis - extra-intestinal manifestations:

haemolytic uraemic syndrome (HUS)

Which pathogens are mostly responsible for these?

Answer 10

STEC (shiga-toxin producing e coli)

shigella dysenteriae serotype 1

Question 11

Gastroenteritis - extra-intestinal manifestations:

erythema nodosum

Which pathogens are mostly responsible for these?

Answer 11

Yersinia

campylobacter

salmonella

shigella

Question 12

Gastroenteritis - extra-intestinal manifestations:

Reactive arthritis

Which pathogens are mostly responsible for these?

Answer 12

Salmonella

shigella

campylobacter

yersinia

rarely giardia

Question 13

Gastroenteritis - extra-intestinal manifestations:

meningitis

Which pathogens are mostly responsible for these?

Answer 13

listeria

salmonella (infants <3m of age are at high risk)

Question 14

staphylococci gastroenteritis:

• spread by?
• catalase? cogulase? G stain features
• blood agar features
• clinical picture

Answer 14

staphylococci gastroenteritis:

• spread by skin lesions on food handlers
• catalase +, coagulase + G+ cocci clusters
• yellow colonies on blood agar
• clinical picture = prominent vomiting + watery, non-bloody diarrhoea

(self limiting)

Question 15

What is the bacteria associated with chinese fried rice?

Answer 15

Bacillus Cereus

Question 16

Why is bacillus cereus problematic in chinese fried rice?

Answer 16

B/c spores of bacilus cereus germinate in reheated fried rice

Question 17

Bacillus cereus:

• Gram properties?
• types of toxin?
• Clinical picture of gastroenteritis?

Answer 17

Bacillus cereus:

• Gram properties = G+ rod spores
• types of toxin = 2 types, 1) heat stable emetic toxin and 2) heat labile diarrhoeal toxin
• Clinical picture of gastroenteritis = watery, non-bloody diarrhoea, self-limited

Question 18

Clostridia are a gram positive/negative aerobe/anaerobe group

Answer 18

Clostridia are a gram positive anaerobe group

Question 19

2 groups of clostridium and what they each cause?

Answer 19

1. Clostridium botulinum = botulism
2. Clostridium pefringens = food poisoning

Question 20

Clostridium botulinum:

• Source:
• Pathophysiology:
• Clinical picture:

Answer 20

Clostridium botulinum:

• Source: canned or vacuum packed food (honey)
• Pathophysiology: ingestion of preformed toxin (inctivated by cooking)
• Clinical picture: botulism via blocked Ach release from PNS

Question 21

Clostridium pefringens

• Source:
• Pathophysiology:
• Clinical picture:

Answer 21

Clostridium pefringens

• Source: reheated food (meat)
• Pathophysiology: superantigen (enteroxin affects small bowel)
• Clinical picture: food poisoning with watery diarrhoea, cramps, litte vomiting lasting 24h

Question 22

Clostridium difficile can cause ___ ____

Answer 22

Clostridium difficile can cause Pseudomembranous colitis

Question 23

Clostridium difficile:

• 2 toxins?
• when does it usually occur?
• Treatment?

Answer 23

Clostridium difficile:

• 2 toxins = toxin A (endotoxin), toxin B (cytotoxin)
• when does it usually occur = after/during abx course
• Treatment = vancomycin (PO), stop abx where possible

Question 24

Listeria monocytogenes:

• bacterial properties?
• growth temp?
• type of infection?
• treatment?

Answer 24

Listeria monocytogenes:

• bacterial properties = G+, B haemolytic, tumbling motility
• growth temp = 4 degrees celcius (refrigeration causes cold enhancement)
• type of infection = watery diarrhoea, cramps, fever, little vomiting
• treatment = amoxicillin

Question 25

Travellers diarrhoea is caused by...

Answer 25

E coli (mainly ETEC - enterotoxigenic E coli)

Question 26

salmonella enterocolitis: - transmission? - bacteraemia? - clinical picture? - treatment?

Answer 26

salmonella enterocolitis: - transmission = **poultry, eggs, meat** - bacteraemia = **infrequent (\<5%)** - clinical picture = **inflammatory diarrhoea, fever, mucus, or bloody stools** - treatment = **usually none, resolves in 7 days**

Question 27

salmonella typhi (typhoid fever): - transmission? - bacteraemia? - clinical picture? - treatment?

Answer 27

salmonella typhi (typhoid fever): - transmission = **only by humans** - bacteraemia = **blood culture + in 40-80%** - clinical picture = **slow onset fever and constipation, splenomegaly, rose spots, anaemia, bradycardia, hemorrhage, perforation, BM involvement in some cases. first constipated, then diarrhoea a few weeks later.** - treatment = **abx course**

Question 28

Shigella: - Transmission? - Toxin? - Clinical picture? - Treatment?

Answer 28

Shigella: - Transmission = **contaminated food, animal contact, MSM population high risk** - Toxin = **shiga toxin** - Clinical picture = **abdo pain + diarrhoea, bloody in 50%, fever, vomiting** - Treatment = **self-limiting to about 7 days. abx if persistent.**

Question 29

Vibrio cholerae: - transmission? - toxins? - Clinical picture?

Answer 29

Vibrio cholerae: - transmission = **contamination of water and food from human faeces (shellfish, oyster, shrimp)** - toxins = **enterotoxin A and B** **(causes stimulation of small bowel)** - Clinical picture = **massive diarrhoea (rice water stool) without inflammatory cells**

Question 30

Most common cause of gastroenteritis when cruising in the Carribean or when in Japan? - source?

Answer 30

vibrio parahaemolyticus - source: ingestion of raw or undecooked seafood (oysters)

Question 31

Campylobacter: - transmission? - clinical picture? - treatment? - complications?

Answer 31

Campylobacter: - transmission = **via contaminated food and water with animal faeces** - clinical picture = **watery, foul-smelling diarrhoea + blood, fever, severe abdo pain. loos stools \>10xday** - treatment = **often** **self-limiting, lasts 7d. only treat if prolonged.**

Question 32

3 complications from campylobacter gastroenteritis?

Answer 32

1. GBS syndrome 2. reactive arthritis 3. Reiter's

Question 33

Name 3 protoza that cause gastroenteritis?

Answer 33

1. Giardia lamblia 2. Entamoeba histolytica 3. Cryptosporidium parvum

Question 34

Entamoeba histolytica - pathophysiology - Clinical picture - Treatment -

Answer 34

Entamoeba histolytica - pathophysiology = **ingestion of cysts =\> trophozoites in ileum =\> colonise cecum, colon =\> flask shaped ulcers** - Clinical picture = no symptoms to severe symptoms = **Amoebiasis** **= dysentery, flatulence, tenesmus, weight loss, diarrhoea (chronic), liver abscess** - Treatment = **metronidazole + paromomycin** -

Question 35

Giardia lamblia: - Transmission? - Clinical picture? - Treatment?

Answer 35

Giardia lamblia: - Transmission = **ingestion of cyst from faecally contaminated water/food, common in travellers, hikers, day care, MSM** - Clinical picture = **foul-smelling non-bloody dairrhoea, cramps, flatulence, no fever** - Treatment = **metronidazole**

Question 36

Cryptosporidium parvum: - Transmission? - Clinical picture? - Treatment?

Answer 36

Cryptosporidium parvum: - Transmission = **contact with contaminated water** - Clinical picture = **watery diarrhoea, severe in immunocompromised** - Treatment = **reconstitution of immune system**

Question 37

Noravirus: - ID? - Transmission? - Clinical picture?

Answer 37

Noravirus: - ID = **very low (hence causes outbreaks)** - Transmission = **faeco-oral route** - Clinical picture = **watery diarrhoea for 2-3 days**

Question 38

Rotavirus: - Where does it replicate? - Who is affected? - Clinical picture?

Answer 38

Rotavirus: - where does it replicate = **mcosa of small intestine** - Who is affected = **children 6m to 2 years usually. sometimes elderly** - Clinical picture = **3-8 d of** **watery diarrhoea, vomiting less prominent than in norovirus**

Question 39

Which extra-intestinal manifestations are associated with salmonella infection? A) erythema nodosum B) abscess formation C) aortitis

Answer 39

C) aortitis

Question 40

Which virus is commonly associated with gastroenteritis outbreaks? A) Adenovirus B) Noravirus C) Rotavirus

Answer 40

B) Noravirus