GI tract

Question 1

what are coliforms?

Answer 1

sub group within enterobacteriaceae
- species of gram -ve bacillli that look like e.coli on gram film & when cultured on blood agar

Question 2

what condition do coliforms grow best in?

Answer 2

aerobically

Question 3

where in GI tract is highly colonised?

Answer 3

heavily colonised in colon & ileum
- sparsely colonised in stomach

Question 4

what is the habitat of GI tract like?

Answer 4

includes a diverse range of habitats for microbes

Question 5

how is GI tract colonised?

Answer 5

via ingestion of nutrients & includes organisms found in mouth & pharynx (some move down)

Question 6

what types of pathogens colonise in GI tract?

Answer 6

viral, protozoan & parasitic pathogens
(some are normal gut flora)

Question 7

where is secretory IgA lymphoid tisssue?

Answer 7

small intestine

Question 8

what is peristalsis?

Answer 8

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

Question 9

what influeneces where colonies in gut?

Answer 9

different factors like pH & flow etc
we’re mostly interested in bile in small intestine

Question 10

what are 2 main viral diseases to GI tract?

Answer 10

norovirus (winter vomiting bug)
rotavirus (common under 2 year olds)

Question 11

what does self limiting viral disease mean and how does that link to GI diseases?

Answer 11

mean a disease that will resolve itself without treatment (normally GI tract diseases are but are highly transmissable)

Question 12

what are 3 key examples of prokaryotic infections of GI tract?

Answer 12

e.coli
c.difficile
campylobacter (common cause of food poisining)

Question 13

what are common symptoms of prokaryotic infections in GI tract?

Answer 13

diarrhoea
gastroenteritis (another disease causing vomiting & diarrhoea)
dysentery (disease causing diarrhoea, vomiting etc)
enterocolitis (inflammation of small intestine & colon)

Question 14

what are some different variants of e.coli?

Answer 14

enteropathogenic
enterotoxigenic
eneteroinvasive
enteroaggregative

important one = shiga toxin-producing S(V)TEC

Question 15

whay are pilli, fimbriaea & flagella important on e.coli?

Answer 15

they offer opportunities for therapy or screening

Question 16

what is shiga toxin producing strain of e.coli?

Answer 16

it’s a toxin producing strain that delivers toxin into lining of gut which means loss of mucosal integrity and causes blood in stools

Question 17

what can e.coli strains do with each other?

Answer 17

they can potentially swap genetic material

Question 18

what are some key facts about growth/presence of c.difficile?

Answer 18

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

Question 19

what has driven variation in virulence factors in e.coli?

Answer 19

horizontal gene transfer
(virulence factors like key toxins, adhesins etc)

Question 20

how does c.difficile toxins work?

Answer 20

toxin A enterotoxin and toxin B enterotoxin break down cell junctions and binary toxin alters cell surface for increased binding (of the bacteria)

Question 21

what antibiotics can induce c.diff proliferation?

Answer 21

Co-Amoxyclav, Cephalosporins Ciprofloxacin & Clindamycin

Question 22

what is the clear preventative/treatment to control c.difficile?

Answer 22

control of antibiotic prescription, especially in over 65 year olds

• fluid replacement & vancomycin orally

Question 23

what is dysbiosis?

Answer 23

there are global changes in gut biome
- when imbalance in gut microbial community = disease like IBD

Question 24

how is dysbiosis linked to age, health etc?

Answer 24

dysbiosis has impact on ageing & mechanisms are being discovered linking dysbiosis to ageing, cancer, autism etc

Question 25

what is one of the reasons CPE organisms reside in the gut?

Answer 25

horizontal gene transfer can occur efficiently