GI tract Flashcards
what are coliforms?
sub group within enterobacteriaceae
- species of gram -ve bacillli that look like e.coli on gram film & when cultured on blood agar
what condition do coliforms grow best in?
aerobically
where in GI tract is highly colonised?
heavily colonised in colon & ileum
- sparsely colonised in stomach
what is the habitat of GI tract like?
includes a diverse range of habitats for microbes
how is GI tract colonised?
via ingestion of nutrients & includes organisms found in mouth & pharynx (some move down)
what types of pathogens colonise in GI tract?
viral, protozoan & parasitic pathogens
(some are normal gut flora)
where is secretory IgA lymphoid tisssue?
small intestine
what is peristalsis?
the involuntary constriction and relaxation of the muscles of the intestine or another canal, creating wave-like movements that push the contents of the canal forward
what influeneces where colonies in gut?
different factors like pH & flow etc
we’re mostly interested in bile in small intestine
what are 2 main viral diseases to GI tract?
norovirus (winter vomiting bug)
rotavirus (common under 2 year olds)
what does self limiting viral disease mean and how does that link to GI diseases?
mean a disease that will resolve itself without treatment (normally GI tract diseases are but are highly transmissable)
what are 3 key examples of prokaryotic infections of GI tract?
e.coli
c.difficile
campylobacter (common cause of food poisining)
what are common symptoms of prokaryotic infections in GI tract?
diarrhoea
gastroenteritis (another disease causing vomiting & diarrhoea)
dysentery (disease causing diarrhoea, vomiting etc)
enterocolitis (inflammation of small intestine & colon)
what are some different variants of e.coli?
enteropathogenic
enterotoxigenic
eneteroinvasive
enteroaggregative
important one = shiga toxin-producing S(V)TEC
whay are pilli, fimbriaea & flagella important on e.coli?
they offer opportunities for therapy or screening
what is shiga toxin producing strain of e.coli?
it’s a toxin producing strain that delivers toxin into lining of gut which means loss of mucosal integrity and causes blood in stools
what can e.coli strains do with each other?
they can potentially swap genetic material
what are some key facts about growth/presence of c.difficile?
low levels of inactive in a few people
as people get older, GI tract gets simpler and you start to see organisms that produce spores
- pseudomembraneous colitis
what has driven variation in virulence factors in e.coli?
horizontal gene transfer
(virulence factors like key toxins, adhesins etc)
how does c.difficile toxins work?
toxin A enterotoxin and toxin B enterotoxin break down cell junctions and binary toxin alters cell surface for increased binding (of the bacteria)
what antibiotics can induce c.diff proliferation?
Co-Amoxyclav, Cephalosporins Ciprofloxacin & Clindamycin
what is the clear preventative/treatment to control c.difficile?
control of antibiotic prescription, especially in over 65 year olds
- fluid replacement & vancomycin orally
what is dysbiosis?
there are global changes in gut biome
- when imbalance in gut microbial community = disease like IBD
how is dysbiosis linked to age, health etc?
dysbiosis has impact on ageing & mechanisms are being discovered linking dysbiosis to ageing, cancer, autism etc
