Normal Microbiota

Question 1

define colonisation

Answer 1

establishment at a site in the body

Question 2

define microbiota

Answer 2

all the organisms in a given community

Question 3

define microbiom

Answer 3

all the genes present within microbiota

Question 4

what is symbiosis

Answer 4

two or more organisms living or co-existing in close physical association

Question 5

what are the 4 types of symbiosis

Answer 5

mutualism - both organism benefit
neutralism - neither benefit nor harm
commensalism - one organism benefits the other derives no benefit or harm
parasitism - one rogasnim benefits at the expense of the other

Question 6

how can non-sterile environments be contaminated

Answer 6

directly through the skin or indirectly such as through trachea or GI tract

Question 7

how are sterile sites in the body kept that way with examples

Answer 7

surface cleaning - eg lower RT uses sputum to trap MO’s
OR barriers
OR physical operation (pleural cavity)

Question 8

define tropism

Answer 8

propensity for an organism to grow in that particular habitat

Question 9

what does a tropism depend on

Answer 9

moisture, temp, ph, O2, nature of surface

Question 10

which microbes are normally found on the skin

Answer 10

staphylococcus epidermis/aureus and other coagulase negative staphylococcus
propionbacterum such as (acnes)

Question 11

what kind of environment does the skin provide

Answer 11

variable temperature, dry, subject to abrasion, aerobic. nutrient poor

Question 12

what kind of environment is gingival crevice

Answer 12

constant temp, moist, aerobic, lots of nutrients

Question 13

what microbiom are present in gingival crevice

Answer 13

viridian’s streptococci

anaerobes (clostridium)

Question 14

what relationships are there between the bacteria and host in the gingival crevice

Answer 14

mutualistic (both gain) and/or parasitic (one gain other loses)

Question 15

what microbiom are usually present in the nose and pharynx

Answer 15

s. aureus (nose) 
pharynx - streptococcus pyogenes 
haemophilus influenza 
streptococcus pneumonia 
niesserira meningitis 
s.aureus

Question 16

what microbiom are present in the vagina before and after puberty

Answer 16

before - same as skin flora and lower GIT (e.coli)
after - glycogen produced and nutrient rich = lactobacillus (mutualistic)
skin flora
candida albicans (can lead to thrush in higher pH)

Question 17

what microbiom are present in the stomach and small intestine

Answer 17

low gastric pH inhibits bacterial growth

mostly aerobic or acid tolerant such as lactobacilli or h pylori

Question 18

what microbiom are present in the large intestine

Answer 18

95-99% anaerobes (clostridium spp, bacteriedes spp)
aerobic bacteria - gram negative bacilli (escherichia coli)
overgrowth of c. difficile

Question 19

what is toxic megacolon and what is the treatment

Answer 19

infection by clostridium difficile - antibiotic resistant colitis
faecal transplant - introduce normal flora

Question 20

what are the benefits of normal flora

Answer 20

metabolism - synthesis metabolites such as vit K and B12 - eneertic bacteria in the gut

resistance against colonisation

protective effects - cross reactive antibodies

nitric oxide production - vascular health

acetate, propionate production - inhibit growth of enteropathogens

Question 21

which disease is commonly linked with unhealthily gut flora (primary granulomatous disease)

Answer 21

crohns disease

Question 22

what are the three pathological steps of normal flora

Answer 22

overgrowth

translocation - presence at the wrong site (endogenous infection)

Question 23

what is exogenous infection

Answer 23

cross infection from other people

Question 24

what is latent infection

Answer 24

pathological organism is present but doesn’t cause disease