Gastrointestinal Diseases

Question 0

Acute gastroenteritis causes

Answer 0

Viral-> rotavirus, adenovirus, norovirus
Bacterial-> E.coli, salmonella, shigella, cholera, campylobacter, yersina
Toxin mediated-> c.diff, s.aures, b.cereus, c.perfingens
Parasitic-> cryptosporidium parvum, giardia lambia, entamoeba histolytica

Question 1

Host defence against GI infection

Answer 1

Enzymes in saliva and small bowel
Acidic environment of stomach
Unspecific antibodies in stomach-> IgA, peyers patches
Bile
Physical movement prevents close approximation with intestinal wall
Mucin and mucus act as a barrier

Question 2

Food associated diarrhoea causes

Answer 2

Spread from contaminated food
Viral-> rotavirus, adenovirus, rotavirus
Bacterial-> compylobacter, e.coli, salmonella, shigella, cholera, yersina
Toxin mediated-> s.aureus, b.cereus, c.perfringens

Question 3

Travel associated diarrhoea causes

Answer 3

Spread from contaminated food or water
Viral-> rotavirus, adenovirus, norovirus
Bacterial-> e.coli, salmonella, shigella, cholera, compylobacter, yersina
Parasitic-> cryptosporidium parvum, giardia lambia, entamoeba histolytica

Question 4

Investigations of gastroenteritis

Answer 4

History and examination
Blood cultures
Stool
-> microscopy-> ova, cysts, parasites
-> culture-> salmonella, shigella
-> antigen detection-> rotavirus, adenovirus
-> toxin testing-> c.diff

Question 5

Symptoms of viral gastroenteritis

Answer 5

Faecal-oral spread, incredibly infectious
Explosive diarrhoea often with vomiting
Incubation of 24-48hrs
Supportive management

Question 6

E.coli and E.coli 0157

Answer 6

Enterotoxigenic-> heat labile and heat stable toxins
-> abdo pain, cramping,diarrhoea 
->12hr intubation
-> oral rehydration
Enterohaemorrhagic-> e.coli 0157.H7
->Variable presentation-> mild diarrhoea to haemolytic uraemia syndrome
-> mediated by verocytotoxin
-> 2-19 days intubation
-> do not give antibiotics 
Enteroinvasive
Enteropathogenic
Enteroaggregative

Question 7

Diagnosis of E.coli

Answer 7

Culture
-> sorbitol no fermenter
-> biochemistry to confirm E.coli
Toxin detection 
-> PCR stool

Question 8

Salmonella

Answer 8

Multiple sub species
-> s.enteritidis-> most common->usually self limiting diarrhoea
-> s.typhi and s.paratyphi-> most severe-> life threatening sepsis with possible secondary seeding
Occasional carrier state in gall bladder
Servere infections-> ciproflaxacin or ceftriaxone

Question 9

Diagnosis of salmonella

Answer 9

Stool culture 
-> XLA, DCA agar
-> black colonies 
-> s.enteritidis 
Blood cultures
-> typhi and paratyphi
-> special lab as high risk infections

Question 10

Shigella

Answer 10

Different sub species
Dysentery-> most server disease
Haemorrhagic colitis, fluid loss and shock-> potentially life threatening-> bowel perforation
Incubation 1-3 days
Supportive therapy with good fluid rehydration
Faecal- oral

Question 11

Diagnosis of shigella

Answer 11

Stool cultures
-> XLD, DCA agar
-> pink colonies
Subtype to species level

Question 12

Campylobacter

Answer 12

Zoonotic bacterial infection with c.jejuni, c.coli
Malaise, abdo pain, fever, nausea, vomiting
Contaminated food or water-> raw chicken
Incubation 3-5 days
Supportive therapy
Usually self limiting
Diagnosis-> selective agar and microaerophillic conditions 45*c

Question 13

Clostridium difficile

Answer 13

Spectrum of antibiotics associated diseases produced by toxin from c.diff
-> diarrhoea, pseudomembranous colitis, bowel perforation and death
Broad spectrum antibiotics are a major risk factor
Treat with -> metrondiazole or vancomycin and stop offending antibiotics

Question 14

Pathophysiology of c.diff

Answer 14

Spores which survive for a long time in the environment
2 toxins
-> A enterotoxin
-> B cytotoxin
Both penetrate epithelial cells leading to cell death
ELISA to look for toxin and stool culture

Question 15

Toxin mediated food poisoning

Answer 15

Mainly s.aureus, clostridium perfingens, b.cereus
Incubation of a few hours
Enterotoxin induced
-> s.aureus-> sudden onset abdo pain and vomiting
-> clostridium-> occasional necrotising enteritis

Question 16

Parasites

Answer 16

Cryp. Parvum, giardia lambia, entamoeba histolytica
Faecaly contaminated water
Incubation 7-10 days
Cryp-> self limiting
Giardia and entamoeba-> metrondiazole
Stool analysis-> cyst and Protozoa in stool

Question 17

Infection control

Answer 17

Single room
Own toilet
Damp dust daily 
Minimum, specific equipment 
Patient must be 48 hours healthy
Or 72 hours if going to another health care facility or c.diff

Question 18

H.pylori

Answer 18

Bacterial infection that causes-> chronic gastritis and duodenal ulcers
Initiation and continuation of inflammatory response
Eventually atrophy and metaplasia
Associated with gastric adenocarcinoma
2 antibiotics and a PPI

Question 19

Clinical features of H.pylori

Answer 19

Epigastic pain
Nausea
Vomiting
Haematemesis 
Blood in poo
Symptoms usually resolve despite continuing infection

Question 20

Diagnosis of H.pylori

Answer 20

Gram negative spiral curved bacillus 
Strict growth requirements
Motile
Urease positive great test 
Serology-> presence of antibody