Enteric pathogens

Question 1

What is the Reservoir for cholera?

Answer 1

Acquatic environments and humans

Question 2

How is cholera transmitted?

Answer 2

Food and water borne

Question 3

What type of organism is vibrio cholerae and what sub species that cause disease?

Answer 3

Gram negative bacilli
Serogroup O1 and non O1 (O139)

Question 4

What are the biotypes causing cholera?

Answer 4

Classical (Bangladesh) and El Tor
Classical - causes more severe dehydration
El Tor - can survive better in the environment

Question 5

Pathophysiology of cholera

Answer 5

cholera toxin A and B subunits
A subunit binds to gut and promotes secretion of chloride and sodium

Question 6

What type of diarrhoea in cholera?

Answer 6

Fishy smelling, rice water diarrhoea

Question 7

How does WHO classify diarrhoea?

Answer 7

Some signs of dehydration (loss of 5-9% body weight)
Severe signs of dehydration (>9% loss of body weight)

Question 8

How do you rehydrate patients with cholera?

Answer 8

Rehydration phase - IV 100ml/kg in severe dehydration for 4 hrs , can use oral in some dehydration
Maintenance phase - match ongoing losses

Question 9

What criteria would you discharge a patient with cholera?

Answer 9

Oral intake
Stool output
Urine output

Question 10

What is the value of antimicrobials in cholera?

Answer 10

Decrease length of dehydration

Question 11

Treatment of cholera?

Answer 11

Single dose 300mg doxycycline
(alternatives azithromycin, ciprofloxacin, Cotrim)

Question 12

Who should be vaccinated against cholera?

Answer 12

Endemic areas, prevention of outbreak, children/pregnant/HIV

Question 13

What is the classic presentation of shigellosis?

Answer 13

Bloody diarrhoea, multiple episodes, small volume, tenesmus and abdo pain in left iliac fossa.

Not same as cholera - large volumes

Question 14

Transmission of shigella?

Answer 14

Faecal oral, can also be flies contaminating food and direct contact

Question 15

What is the incubation period for shigella/cholera?

Answer 15

hrs for cholera
Days for shigella

Question 16

What is the organism causing shigellosis?

Answer 16

S.flexneri - developing world most common - causes milder illness (second most common is sonneri and this is the most common In developed countries)

S.dysenteriae type 1 most severe and responsible for outbreaks. Toxin producing - can cause HUS in children.

Question 17

Diagnosis of shigella?

Answer 17

Stool culture
Will also see lots of PMNs in stool

Question 18

Management of shigella?

Answer 18

Ciprofloxacin 500mg BD for 3 days

Alternatives: azithromycin single dose

Question 19

Treatment of Campylobacter?

Answer 19

3-5 days of azithromycin
Prevents complications such as GBS

Question 20

What are the most common viral pathogens causing gastroenteritis in children?

Answer 20

Rotavirus - most common in children <5 and in developing countries
Norovirus - most common worldwide
Sapovirus
Enteric adenovirus - milder, less vomiting/fever
Astrovirusin

Question 21

What is the triad of symptoms in rotavirus?

Answer 21

Explosive watery diarrhoea, fever, vomiting
Incubation period 1-3 days
Diarrhoea 2-8 days and worst day 4-5

Question 22

How do you test for rotavirus?

Answer 22

Stool PCR or rapid test (ELISA)

Question 23

How does norovirus classically present?

Answer 23

Short duration vomiting and diarrhoea of sudden onset, no blood/mucous or leucs in stool.
Vomiting key - 90% have this

Question 24

How is norovirus transmitted?

Answer 24

Faecal oral, aerosolised vomit, contaminated food - oysters

Question 25

How do you manage viral gastroenteritis?

Answer 25

Establish degree of dehydration
Oral rehydration with low osmolality ORS
IV ringers lactate if needed

Question 26

Causes of bloody vs watery vs persistent diarrhoea?

Answer 26

Watery: Cholera, ETEC, rotavirus, noravirus, EPEC

Bloody: Salmonella, shigella, Campylobacteur, EHEC, EIEC, E.histolytica, Cdiff

Persistent: Giardia, Cyclospora, Cysisospora, Cryptosporridium, EAEC, EPEC (campy and salmonella can)