Human flora

Question 1

what are commensals?

Answer 1

aerobic and anaerobic genera and species that do no harm to the host when confined to their proper site

Question 2

What are:
Transients
Opportunists
Pathogens

Answer 2

T: Micro - organisms which reside for a short time (eg 1 day, 1 week) in a particular site, without damage to the host
O:incapable of invading or damaging normal host; capable of invading or damaging when immunity compromised
P:capable of invading or damaging normal host by toxigenic action or invasion, to cause disease

Question 3

Examples of commensals of nose, mouth? Pathogens?

Answer 3

nose
staph.aureus 
mouth:
oralstreptococci
neisseria
anaerobic bacteria
fungi

pathogens: strep.pneumoniae
neisseria
meningitidis

Question 4

Commensals of large bowel?

Answer 4

bacteroides spp
clostridia

enterococci and e.coli (enterobacteria)

fungi
lactobacilli
helminths - protozoa

Question 5

Commensals of female lower genital tract?

Answer 5

bacteroides spp
enterobacteria
fungi
lacobacilli

Question 6

how can antibiotics cause Candidiasis?

Answer 6

Mouth: Antibiotics reduce normal flora and allow overgrowth of Candida albicans. This invades the mucosa to cause thrush.

Question 7

4 factors leading to opportunistic infection

Answer 7

compromised immunity
antibiotics or normal flora loss
breach of physical barriers
impaired normal clearance mechanisms (e.g. smoking)