Gastrointestinal Infections Flashcards
What is the source/resevoir of infection?
The original source of the infection
What is the vehicle of infection?
The means by whch the infection is transmitted from one person to another.
Is campylobacter a gram negative or gram positive organism?
Gram negative
Campylobacter is a curved gram negative bacillus
What is the incubation period of campylobacter?
3-10 days
What does campylobacter cause inflammation of?
Colon and rectum
Why does campylobacter cause bloody diarrhoea
Campylobacter causes inlfammation of the colon and rectum which causes bloody diarrhoea
What are the sources and vehicles of infection of campylobacter?
Farm animals
Undercooked poultry
Water and unpasteurised milk
What is the management of a campylobacter infection?
(Usually self-limiting)
Give erythromicin or ciprofloxacin for 5 days if patient develops systemic illness
Is person-person spread of campylobacter common?
No
What is the incubation period of salmonella enterica?
12-48 hours
What does salmonella enterica cause inflammation of?
Ileum and colon
What is the management of a salmonella infection?
(Usually self-limiting)
Give ciprofloxacin for 5 days if patient develops systemic illness
What is the incubation period of shigella?
1-9 days
What does Shigella invade?
Shigella invades the intestinal mucosa, causing severe inflammation.
Does not invade further (never seen in blood cultures).
How is Shigella spread?
Person-person
What is the treatment for shigella sonnei?
Symptomatic treatment only
How are more severe species of shigella (e.g. dysenteriae) treated?
Ciprofloxacin
What does the “O” in E. coli O157 stand for?
The surface antigen
What does the “H” in E. coli O157:H7 stand for?
The flagellar antigen
What toxin does the O157:H7 strain of E. coli produce?
Verotoxin
What does Verotoxin do?
Damages red cells and the kidney, causing haemolytic-uraemic syndro (HUS)
Increases blood urea, red cell haemolysis and thrombocytopenia.
Verotoxin binds to receptors found on renal cells, RBC and others, inhibits protein synthesis and causes cell death.
What is the source of E. coli O157 infection?
Cattle (part of the normal gut flora in cattle)
Beef becomes contaminated on outside at slaughter
Is risk of getting E coli O157 higher from mince and hamburgers or steak.
Higher risk in mince and hamburgers, lower risk in steak.
What is the appropriate management of an E. coli O157 infection?
Symptomatic and supportive treatment only
Antibiotics contraindicated as may increase release of toxin
When should you check bloods of patient for HUS1?
1 week after onset of symptoms
What would blodd tests show for patient with HUS?
High white cells Low platelets Low HB Red cell fragments Lactate dehydrogenase increased (increased more than 1.5 x normal)
Is shigella gram neg or gram pos?
Gram neg
Is e coli gram neg or gram pos?
Gram neg
Is salmonella gram neg or gram pos?
Gram neg
