Gut Flora

Question 1

Composition of the Normal Flora

1. most animals are …….. ……… in the uterus
2. colonised by dozens of species at …….. which remain with the organism until ……… (……………..)
3. Normal flora are only normal when ………. ……… e.g. in th gut not the bloodstream
4. May be required for the maintainence of ……….
5. Some times have ……….. microbiota, inhibit the organism for brief period of time

Answer 1

1. germ free
2. birth, death, microbiota
3. appropriately situated
4. health
5. transient

Question 2

Symbiosis

• define parasitism
• define commensalism
• define mutualism

Answer 2

parasitism - unilateral benefit
commensialisem - one benefits, one is not harmed\
mutualism - reciprocal benefit

Question 3

Describe the mechanism by which normal flora compete and how this is altered in disease.

Answer 3

Normal flora layer of mucosal surface as a barrier to pathogens. Responsible for immune stimulation. Produce protective waste products

This can become disrupted after large inoculum, antimicrobial drugs, reduced peristalsis, immune suppression, irradiation, chemicals, burns. This allows access for opportunistic pathogens

Question 4

Why are the normal flora located in particular locales?

Answer 4

TISSUE TROPISM
adapted to that location
most bacteria able to colonise particular tissues using own surface components as specific ligand for attachment to specific receptors located at colonisation site

Question 5

Major source of endogenous infection via reduced host defence and traumatic spillage. Give examples

Answer 5

Oesophageal perforation –> polymicrobial mediastinitus

faecel flora –> urethra –> UTI