Lecture 1.2: Microbiota

Question 1

What is the Microbiota?

Answer 1

Community of microorganisms living in a specific environment

Question 2

What is the ‘Normal Flora’?

Answer 2

Microorganisms regularly found at an anatomical site in healthy humans & not causing infection or disease

Question 3

What is the Microbiome?

Answer 3

The term “microbiome” refers to the collective genomes of the microorganisms in a given environment, meaning the collection of all their genetic material (DNA and RNA)

Question 4

What are the 4 dominant phyla in the human gut?

Answer 4

• Firmicutes
• Bacteroidetes
• Actinobacteria
• Proteobacteria

Question 5

Acquisition of Microbiota: Vertical Transmission

Answer 5

Acquisition of microbes directly from an organism’s parents

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

GBS bacteria can travel up from vagina to amniotic fluid, in birth canal through lung aspiration

Exposed to GBS from contact with mothers faecal matter during birth process

Question 6

Acquisition of Microbiota: Horizontal Transmission

Answer 6

Acquisition of microbes from sources other than an organism’s direct parents

Such as the environment or from non-parental conspecifics

Question 7

What is Group B Streptococcus? Where is it found?

Answer 7

• Gram positive, beta haemolytic bacteria
• Common coloniser of human gastrointestinal and genitourinary tracts
• Recognised as causing disease in humans in the 1930s

Question 8

Problems related to Group B Streptococcus

Answer 8

Causes serious disease in young infants, pregnant women and older adults

Emerged as most common cause of sepsis and meningitis in infants <3 months in the 1970s

Question 9

Obstetric Risk Factors for Early-Onset GBS Disease

Answer 9

• Preterm delivery
• Prolonged rupture of membranes
• Infection of the placental tissues or amniotic fluid/fever during labour
• GBS in the mother’s urine during pregnancy (marker for heavy colonisation)
• Previous infant with GBS disease
• Low maternal levels of anti-GBS antibodies

Question 10

Demographic Risk Factors for Early-Onset GBS Disease

Answer 10

• African American
• Young Maternal Age

Question 11

Horizontal Transmission: Diet Effects

Answer 11

Diet is one of the major factors involved in shaping the gut microbiota composition

Question 12

What is the gut microbiome of humans comprised of?

Answer 12

• Diverse group of trillions of microorganisms including
• Symbiotic organisms
• Opportunistic pathogens
• Commensal organisms

Question 13

What does microbiota plays a major role in?

Answer 13

• Digesting food
• Absorbing and synthesizing some nutrients and releases their metabolites
• Deliver a variety of growth-promoting and growth-inhibiting factors that
influence human health either directly or indirectly

Question 14

What are Biofilms?

Answer 14

• Microbial community enclosed by an extracellular materials such as mineral
crystals, blood & other substances
• Form on tissue, medical devices & surfaces
• Biofilms environment for genetic exchange

Question 15

Problems with Biofilms

Answer 15

• >80% of microbial infections are related to biofilms -National Institute of
Health
• Bacteria within Biofilms have increased resistance to antimicrobial drugs

Question 16

What is Dysbiosis?

Answer 16

Disturbance to microbiota homeostasis due to an imbalance in the flora itself, changes in their functional composition and metabolic activities, or changes in their local distribution

Question 17

Effects of Dysbiosis (3)

Answer 17

1) Loss of beneficial organisms
2) Excessive growth of potentially harmful
organisms
3) Loss of overall microbial diversity

Question 18

Effects of Microbiota on Adiposity

Answer 18

Gut microbiota increases energy production from food, provides low-grade inflammation, and impacts fatty acid tissue composition

These mechanisms may link the gut microbiota with obesity

Question 19

What is included in Symbiotic Intervention? (4)

Answer 19

• Probiotics
• Prebiotics
• Synbiotics
• Faecal Matter/Bacteriotherapy

Question 20

What are Probiotics?

Answer 20

They are live microorganisms that are intended to have health benefits when consumed or applied to the body

Question 21

What are Prebiotics

Answer 21

They are non-digestible food components that selectively stimulate the growth or activity of desirable microorganisms

Question 22

What are Synbiotics?

Answer 22

They are products that combine probiotics and prebiotics

Question 23

What is Faecal Transplantation (FMT)/Bacteriotherapy?

Answer 23

It is the transfer of stool from a healthy donor into the gastrointestinal tract for the purpose of treating recurrent

Question 24

Probiotics: Pros vs Cons

Answer 24

PROS:
• Oral Application
• Restoration of good bacteria and gut barrier

CONS:
• Oral dose that reached gut is variable
• Potential loss of adaptation of culture-derived
probiotics in the gut

Question 25

FMT: Pros vs Cons

Answer 25

PROS:
• Safe Application
• Simple Procedure

CONS:
• Variable Imapact
• Not effective in IBD (Inflammatory Bowl Disease)
• Quality of donor stool is important

Question 26

Effect of Symbiotic Intervention

Answer 26

Changing the environment microbial status can either promote disease or confer protection

Question 27

Effects of Antibiotics on Microbiota (2)

Answer 27

Antibiotics can alter the population structure of the microbiome

While the overall structure of such microbiomes is recovered after some time, the genomic structure is not fully equivalent