Normal microbiota

Question 1

define normal flora

Answer 1

Organisms found in a given location in a state of health.

Question 2

define colonisation

Answer 2

Establishment at a site in the body

Question 3

define symbiosis

Answer 3

Two or more organisms co-exist in close physical association

Question 4

There are 4 types of symbiosis

Answer 4

Mutalism
Neutralism
Commensalism
Parasitism.

Question 5

define mutalism

Answer 5

both organisms benefit from symbiosis.

Question 6

define neutralism

Answer 6

neither organism derives benefit or harm

Question 7

define commenalism

Answer 7

one organism benefits and the other derives neither benefit or harm.

Question 8

define parasitism

Answer 8

One organism (parasite) benefits at the expense of the other (host)

Question 9

define non sterile

Answer 9

have normal flora

Question 10

define sterile

Answer 10

no normal flora

Question 11

where are non sterile sites found

Answer 11

where the body is exposed to the environment either directly or indirectly.

Question 12

examples of non sterile sites

Answer 12

skin, conjunctiva, vagina, GI tract, Nasopharynx.

Question 13

name 3 mechanisms which help to maintain sterile sites

Answer 13

surface cleaning
barriers that allow unidirectional flow- when adjacent to a non sterile site.
physical separation from non-sterile sites (closed sites)

Question 14

example of a sterile site which is maintained by cleaning

Answer 14

lower respiratory tract.

Question 15

example of a sterile site maintained by a barrier

Answer 15

upper genitals-cervix
Urinary tract- urethra
Middle ear- eustachian tube

Question 16

example of a sterile site maintained by physical separation

Answer 16

pleural cavity
peritoneal cavity
spinal cord and meninges.

Question 17

what are the physical variable which determine where an organism grows

Answer 17

moisture, temperature, pH, O2 availability and nature of surface.

Question 18

what are the factors in skin which are relevant to which organism grow here.

Answer 18

variable temperature
dry
subject to abrasion
aerobic environment
nutrient-poor
skin surface components.

Question 19

what are the factors in Gingival crevice (gum) which are relevant to which organism grow here.

Answer 19

constant temperature
moist
few physical challenges
anaerobic environment
bathed in nutrients
muocosal surface components.

Question 20

what are the main organisms which affect the skin (skin flora)

Answer 20

coagulase negative staphylococci (staphylococcus epidermis)
staphylococcus aureus
Propionbacterium species

Question 21

what are the main organisms which are found in the mouth

Answer 21

Viridans/oral streptococci

Anaerobes

Question 22

what are the main flora found in the nostrils

Answer 22

skin flora- S. aureus.

Question 23

what is the main flora found in the pharynx

Answer 23

Streptococcus pyogenes (group A) 
Haemophilus influenzae
Streptococcus pneumoniae
Neisseria meningitidis
S. Aureus.

Question 24

what are the main flora found in the vagina prepuberty

Answer 24

Skin flora

Lower GI flora- mainly E.coli.

Question 25

what are the main flora found in the vagina post puberty

Answer 25

glycogen produced due to circulating oestrogens
– Lactobacillus spp. Lactobacillus acidophilus (ferment glycogen maintain pH 3)
Skin lora
C albicans

Question 26

what are the main flora found in the stomach and small intestines.

Answer 26

Low gastric pH inhibits bacterial growth
Predominantly aerobic bacteria
H pylori.

Question 27

what 99% of the bacteria found in GI anaerobes or aerobes

Answer 27

anaerobes

bacteroides, clostridium, bifidobacteria.

Question 28

what aerobic bacteria is found in the large intestines

Answer 28

Escherichia coli, Klebsiella spp., Enterobacter spp., Proteus spp., Citrobacter spp. etc.

Question 29

benefits of normal flora

Answer 29

synthesis excretion of vitamins- K and B12.
colonisation resistance- environmental manipulation
antibacterial agents
Induce cross reactive antibodies.

Question 30

what is the main cause of c difficile

Answer 30

antibiotic treatment.

Question 31

what are the consequences and symptoms of c difficile infection

Answer 31

toxin is produced

diahorrhea and pseudomembranous colitis

Question 32

what is the most effective treatment for C difficile

Answer 32

faecal transplants.

Question 33

how does faceal treatment treat c difficult

Answer 33

increased diversity in colonic mocroflora, similar to that of healthy donor

Question 34

what other conditions might faceal transplants be useful for.

Answer 34

MS, chronic fatigue syndrome, idiopathic thrombotic purpura, ulcerative colitis, irratible bowel syndrome, diabetes mellitus.

Question 35

what problems can cause pathology at the site of normal flora

Answer 35

1.	Overgrowth
•	Excessive growth at normal site
2.	Translocation
•	Presence at the wrong site
•	Spread from one surface to another
•	Inoculation into a normally sterile site
3.	Cross-infection

Question 36

what is the most common cause of Inoculation into a normally sterile site (medical equipment)

Answer 36

catheter.