Enteric pathogens Flashcards
What is the Reservoir for cholera?
Acquatic environments and humans
How is cholera transmitted?
Food and water borne
What type of organism is vibrio cholerae and what sub species that cause disease?
Gram negative bacilli
Serogroup O1 and non O1 (O139)
What are the biotypes causing cholera?
Classical (Bangladesh) and El Tor
Classical - causes more severe dehydration
El Tor - can survive better in the environment
Pathophysiology of cholera
cholera toxin A and B subunits
A subunit binds to gut and promotes secretion of chloride and sodium
What type of diarrhoea in cholera?
Fishy smelling, rice water diarrhoea
How does WHO classify diarrhoea?
Some signs of dehydration (loss of 5-9% body weight)
Severe signs of dehydration (>9% loss of body weight)
How do you rehydrate patients with cholera?
Rehydration phase - IV 100ml/kg in severe dehydration for 4 hrs , can use oral in some dehydration
Maintenance phase - match ongoing losses
What criteria would you discharge a patient with cholera?
Oral intake
Stool output
Urine output
What is the value of antimicrobials in cholera?
Decrease length of dehydration
Treatment of cholera?
Single dose 300mg doxycycline
(alternatives azithromycin, ciprofloxacin, Cotrim)
Who should be vaccinated against cholera?
Endemic areas, prevention of outbreak, children/pregnant/HIV
What is the classic presentation of shigellosis?
Bloody diarrhoea, multiple episodes, small volume, tenesmus and abdo pain in left iliac fossa.
Not same as cholera - large volumes
Transmission of shigella?
Faecal oral, can also be flies contaminating food and direct contact
What is the incubation period for shigella/cholera?
hrs for cholera
Days for shigella
What is the organism causing shigellosis?
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.
Diagnosis of shigella?
Stool culture
Will also see lots of PMNs in stool
Management of shigella?
Ciprofloxacin 500mg BD for 3 days
Alternatives: azithromycin single dose
Treatment of Campylobacter?
3-5 days of azithromycin
Prevents complications such as GBS
What are the most common viral pathogens causing gastroenteritis in children?
Rotavirus - most common in children <5 and in developing countries
Norovirus - most common worldwide
Sapovirus
Enteric adenovirus - milder, less vomiting/fever
Astrovirusin
What is the triad of symptoms in rotavirus?
Explosive watery diarrhoea, fever, vomiting
Incubation period 1-3 days
Diarrhoea 2-8 days and worst day 4-5
How do you test for rotavirus?
Stool PCR or rapid test (ELISA)
How does norovirus classically present?
Short duration vomiting and diarrhoea of sudden onset, no blood/mucous or leucs in stool.
Vomiting key - 90% have this
How is norovirus transmitted?
Faecal oral, aerosolised vomit, contaminated food - oysters
