session 9- GI infections Flashcards
3 main non bacteria/virus in gut toxins
nematodes, cestodes, trematodes
what are the gi defences
saliva, gastric acid, bile, colonic mucus, anaerobic environment
benefits microbiome
competition for nutrients, produces antimicrobial substances, produce vitamin K
what do bacteria in colon produce
short chain fatty acids such as acetate, butyrate and propinoate
role acetate
cholesterol metabolism
role butyrate
energy source for colonocytes
role propinoate
regulate satiety
what is FMT
transport of faecal better to patients to replenish gut microbiota
how to carry out FMT
NG tube, upper GI endoscope, colonoscopy, transplant to caecum
gram negative bacteria causing infections
salmonella, campylobacter, shigella, Enterotoxic e coli.
gram positive bacteria causing infections
Clostridium difficile
symptoms salmonella
nausea, vomiting and diarrhoea, fever, abdo cramping.
how spread salmonella
ingesting contaminated food and bacteria.
how does salmonella cause symptoms in body
enters enterocytes, then to submucosa. enters macrophage. transferred to RES. multiple causing lymphoid hyperplasia, re-enter gut from liver
shape campylobacter
s shaped.
how campylobacter spread
faecal-oral
symptoms campylobacter
longer incubation period, fever, abdo cramping, diarrhoea.
spread shigella
infected stool, person to person, flies
how does shigella cause disease
small dose invades coloncytes and neighbouring cells. kills colonocytes and forms abscesses in mucosa.
symptoms shigella
bloody diarrhoea with mucus and abdo cramping
E coli spread
faecal oral or water
enterotoxic e coli acryonym
ETEC
symptoms ETEC
watery diarrhoea.
how does ETEC cause symptoms
adheres to enterocytes to cause hypersecretion of chloride ions, and water to leave cells into gut lumen.
which bacteria can cause haemolytic uraemia syndrome
shigella, campylobacter
duration of infection compare
shortest- ETEC, salmonella, shigella, campylobacter -longest
structure C difficile
gram positive anaerobic spore forming bacillus
what are toxins A and B
A- enterotoxin that causes excessive secretion
B- cytotoxin that kills colonocytes
what causes c Diff proliferation
antibiotics
severe consequences of C diff infection
pseudomembranous colitis, toxic megacolon
what is pseudomembranous colitis
elevated yellow plaques join to form a pseudomembrane.
treatment c diff
remove antibiotic, fluid resuscitation, metronidazole or vancomycin, probiotics
viral causes gastroentertiis
rotovirus, norovirus
parasitic causes gastroenteritis
cryptosporidium, giarida.
symptoms rotavirus norovirus
vomiting with fever, diarrhoea
structure rotovirus
double stranded RNA
how does rotavirus cause diarrhoea
chloride secretion, SGLT1 disruption, reduced brush border enzyme function
how is cryptosporidium spread
faecal oral or water
how does cryptosporidium cause disease
ingested oocyst reproduces in distal SI epithelial eels. excreted in faeces.
symptoms cryptosporidium
watery diarrhoea
symptoms giardia
persistent diarrhoea, abdo cramping
life cycle giardia
cyst ingested, damages proximal SI causing symptoms. villous atrophy. parasite excreted to repeat cycle
symptoms entamoeba histolytica
diarrhoea, liver abscess
cause travellers diarrhoea
ETEC
how does rotavirus cause diarrhoea
chloride secretion creates gradient for Na+ and water into lumen, SGLT1 disruption increases osmotic load in gut, brush border dysfunction causes general malabsorption
