Diarrhoea Flashcards
Describe campylobacter
Curved gram negative bacillus
Name the commonest cause of bacterial GI infection
Campylobacter
What is the incubation period of campylobacter
3-10 days
Describe the mechanism of campylobacter
Inflammation of the colon and rectum causing bloody diarrhoea.
Can campylobacter infect the blood stream
Yes (occasionally)
What is the vehicle of campylobacter?
Farm animals especially undercooked poultry
What is the management of campylobacter?
Usually self limiting- if systemic effects occur offer citrofloxacin or erythromycin for 5 days
What is the mechanism of Salmonella Enterica?
Causes inflammation of the ileum and colon. The bacteria multiply in the gut causing mucosal damage. This means there is decreased absorption and increased fluid secretion
Can salmonella enterica invade the blood steam?
Yes (occasionally)
Symptoms of campylobacter
Abdominal pain, diarrhoea (could be with or without blood)
What is the incubation period of salmonella enterica?
12-48 hours
What is the vehicle for salmonella infection?
Farm animals especially undercooked poultry
Symptoms of salmonella enterica
Abdominal pain, diarrhoea (occasionally bloody), vomiting
Management of salmonella enterica
Generally self limiting
Systemic- use ciprafloxacin for 5 days
What is the only species of Shigella spp seen in the UK?
Shigella sonnei
Mechanism of shigella
Invades intestinal mucosa causing severe inflammation but does not invade further.
What would be seen in stools of a person with shigella?
Blood and pus cells
What is the incubation period of shigella?
1-9 days
How is shigella spread?
Human contact- common amongst young children at school.
Management of shigella
Self limiting
Why is Escherichia Coli O157 called ‘O157’?
O antigen on the surface
What does E.coli do to the body?
They produce a toxin (verotoxin or VTEC) that damages red blood cells and the kidney. There is an increase in blood urea, red cell haemolysis and thrombocytopenia.
Who are most effected by E coli?
The elderly and young children.
Symptoms of E.coli?
Abdominal pain, bloody diarrhoea
Vehicle of E.coli
Part of the normal gut flora of cattle.
There is an increased risk when eating meat or visiting farms
Management of E.coli
Symptomatic and supportive treatment- antibiotics are contraindicated.
What makes E.coli so high in prevalence?
It has a low infectious dose.
What is haemolytic uraemic syndrome?
Associated with progressive renal failure and red blood cell lysis (prematurely)
Symptoms of haemolytic uraemic syndrome
Abdominal pain Fever Pallor Petechiae (haemorrhaged skin) Oliguria Bloody diarrhoea
When will HUS present?
7-10 days after an E-coli infection.
What will HUS blood tests show?
Increased WCC
Decreased platelets
Decreased Hb
Increased lactate dehydrogenase
What is typhoid/paratyphoid fever caused by?
Caused by salmonella typhi or salmonella paratyphi A or B
What is the incubation period for typhoid/paratyphoid fever?
14-21 days
What is the mechanism of typhoid/paratyphoid fever
Organism invades from the gut lumen. Goes into the lymphatic system, back into the blood stream and into the Peyers patches in the gut.
Management of typhoid/paratyphoid
antibiotics
Which organism causes cholera?
Vibrio cholera
Where is cholera likely to present
Outbreaks present in recent disaster zones
Describe the mechanism of cholera
Causes outputting of fluid from cells in the gut due to an exotoxin.
Symptoms of cholera?
Watery, constant diarrhoea. Rice water stools
Vehicle of cholera
Human
Management of cholera
Fluid and electrolyte replacement
Describe the mechanism of staph aureus
Some strains produce enterotoxins. Toxin is absorbed quickly which affects the vagus nerve and vomiting centre.
Symptoms of staph aureus
Vomiting within 1-2 hours
Describe the mechanism of clostridium perfingens
Belongs in the normal gut flora of humans and animals. Some spores survive cooking then turn into vegetative organisms. Also some strains produce enterotoxins
How can you be infected by clostridium perfingens
Inadequately refrigerated meat gravy
Describe the mechanism of bacillus cereus.
Can muiltiply in the intestine producing a toxin that is absorbed by the gut.
How can you be infected by bacillus cereus
Inadequately cooked re-heated rice.
Describe the mechanism of a protozoal infection.
Cysts are ingested. They hatch into trophozoites that invade the cells in the small intestine.
Source of protozoal infection
Domestic animals.
Person-person
Swimming pools
Contaminated water.
Symptoms of protozoal infection
Diarrhoea
Treatment of protozoal infection
Symptomatic treatment
Describe the mechanism of giardia lamblia
Protozoal infection (single celled parasite) Cysts hatch into trophozoites
How is giardia lamblia spread?
Human to human
What are the symptoms of giardia lamblia
Diarrhoea, malabsorption syndrome, anorexia, abdominal pain, flatulence
Treatment of giardia lamblia
Oral metronidazole
Mechanism of enterobius vermicularis (threadworms)
Ova ingested
Hatch in the small intestine and live in the caecum and colon. Adult females come out of the perianal skin at nigt to lay ova causing perianal itchiness.
How are threadworms spread?
Human to human
Symptoms of threadworms
Perianal itch
Worms in stool
Treatment of threadworms
Oral metronidazole
How is norovirus spread?
Faecal oral- common on cruise ships
Symptoms of norovirus?
Abrupt vomiting, nausea, myalgia, cramps
Incubation period of norovirus
24-48 hours
Investigations into norovirus
PCR
Treatment of norovirus
Self limiting
