1.2 Microbiota and Flora

Question 1

What are the 4 dominant phyla in the human gut?

Answer 1

Firmicutes
Bacteriordetes
Actinobacteria
Proteobacteria

Question 2

Describe the 2 types of transmission

Answer 2

Vertical: acquisition of microbes directly from a parent

Horizontal: acquisition of microbes from environment and non-parental factors (i.e diet and nutrition)

Question 3

Give an example of vertical transmission

Answer 3

exposure to mothers vaginal and gut bacteria are part of the main seeding event for founding microbiome

Question 4

What is GBS?
Where is it commonly found?
How can It cause problems to infants during birth?
Who does it most commonly affect?

Answer 4

Group B streptococcus is caused by Streptococcus agalactiae: Gram (+) beta hemolytic bacteria

Commonly colonizes in GI and genitourinary tract.

During onset of labour when membrane ruptures, GBS can travel upwards into amniotic fluid and affect the infant OR it can be transferred as baby travels down the birth canal and aspirate into lungs

Largely affects infants, pregnant women and older adults

Question 5

What are 4 additional risk factors for early onset GBS disease?

Answer 5

1) Obstetric: preterm delivery, prolonged membrane rupture, infection/fever during labour
2) GBS in mother’s urine during pregnancy
3) Previous infant with GBS disease
4) Low maternal levels of anti-GBS antibodies

Question 6

What is the leading cause of invasive neonatal infections and is a significant pathogen in immunocompromised adults

Answer 6

Group B streptococcus

Question 7

When are the 3 biggest risks to a newborn due to GBS neonatal infection

Answer 7

1) early-onset sepsis
2) pneumonia
3) meningitis

Question 8

What Is specific to all GBS strains

Answer 8

They harbour the Lancefield group B cell-wall specific polysaccharide antigen

Question 9

Give an example of horizontal transmission

Answer 9

Acquisition of microflora through diet

Question 10

What is LD50?

Answer 10

The lethal dose required to to kill 50% of population

Question 11

Define microbiota and microbiome?

Answer 11

Microbiota: community of microorganisms living in a specific environment
Microbiome: a collection of specific microbiota

Question 12

Name the 5 stages of biofilm formation

Answer 12

1. Initial attachment
2. Irreversible attachment
3. Maturation I
4. Maturation II: initial base organisms are protected and can avoid the host immune system
5. Dispersion (to form another biofilm within close proximity)

Question 13

In what situation may biofilm may lead to endocarditis?

Answer 13

When a stent or valve is inserted into the heart, biofilm build up of the wrong bacteria can have serious consequences and lead to endocarditis

Question 14

How may biofilm formation affect patients with cystic fibrosis?

Answer 14

Patients with cystic fibrosis have increase mucus invading

Bacteria may create a biofilm over the mucus leading to increased thinking of mucus

This leads to increased risk of infection due to the inability to clear mucus

Question 15

Define Dysbiosis?

Answer 15

persistent imbalance of guts microbial community as a cause or consequence of disease

Question 16

Name 4 diseases associated with dysbiosis?

Answer 16

1) IBS
2) IBD
3) Coeliac disease
4) Colorectal cancer

Question 17

What are the effects of antibiotics on Microbiota?

Answer 17

Use of antibiotics can remove large amounts of natural flora, which can result in growth of opportunistic bacteria causing harmful effects

Question 18

List 4 harmful effects that antibiotics have on microbiota

Answer 18

1) Alterations In blood metabolism
2) inflammation
3) gut dysbiosis
4) impaired vaccine immunity

Question 19

What might you do if you suspected a patient with an imbalance in their gut flora?

Answer 19

Order a breath test: have individual drink a high glucose drink and measure amount of methane produced over time

Begin them on an antimicrobial program