Microbiota and health

Question 1

what is the Microbiome

what are some different types

Answer 1

the total of all the microbes living on and in the body

examples: skin, Vagina, oral cavity, digestive tract

Question 2

genetic composition for microbes

Answer 2

for every human gene there are 350 microbial genes in our body

Question 3

skin Microflora

gram +?

gram -?

oily?

moist?

dry?

Answer 3

varies depending on oiliness, sweatiness, hairiness and environmental exposure

Gram positive: Actinobacteria and Firmicutes

Gram negative: Proteobacteria and bacteriodes

oily skin: Phylum Actinobacteria, Major family Propionibacteriaceae e.g. Propioniobacterium acnes

moist areas: staphylococcaceae and corynebacteriaceae

drier areas: more diverse

skin microbial variation (phyla and family levels) dependent on ecological site rather than on the individual

Question 4

Vaginal microflora
transient 4
colonizers 1

composition dependent on

Answer 4

transient (few in numbers):
staphylococcus epidermidis 
candida 
enteroccocus faecalis 
E. coli 

colonizers (can colonize if imbalance):
Lactobacillus acidophilus

composition dependent on sexual practices, diabetes, antibiotic treatment, Age, hormone levels

Question 5

Oral Microflora

tongue?
tooth?

Answer 5

heavily colonized
tongue: lactobacilli
exposed tooth: streptococci
plaque formation and cavities

Fusobacterium nucleatum is a major bacterium that adheres to other bacteria

Question 6

helicobacter pylori and asthma/allergies

Answer 6

astham/allergies, more common in western world

H. pylori present in all populations

colonization with H. pylori inversely related to allergy and asthma, more pronounced in younger individuals (<43 y)

proposed mechanism:
H. pylori cagA* -> enhanced host cellular responses affect early life equilibria of Th1 and Th2 type immune responses ->prevention of immune hyperactivity states

hygiene hypothesis: Th1 and Th2 type immune imbalances due to modern lifestyle -> allergic reactions

Question 7

Microflora and obesity

Answer 7

increased administration of antibiotics

• Therapeutics and growth promoters
• changes in the population structure of the microbiome

obesity -> variation in gut microbiome

mice fed with antibiotics gained more fat mass and higher percentage of fat

ratio of bacteriodetes/fermicutes changed with different antibiotics as well as increase in fat chains in the body

Question 8

summary of mouse study

Answer 8

control mice burned more calories due to microbiota with increased metabolic activity that extracted dietary complex carbohydrates that were relatively indigestible for the control mice

the mice fed antibiotics had increase in SCFA concentrations and when delivered through portal circulation to the liver it enhanced lipogenesis

Question 9

how could household disinfectants increase kids weight?

Answer 9

postnatal exposure to household disinfectants possibly destroyed the gut microbiome of children. The imbalance can change the body mass index

Question 10

microbiota and height

Answer 10

humans are getting taller

more common in developed world, not prevalent in developing

e.g. japanese men born in california were taller than those> hawaii>japan

exposure to microbes: Guatemalan children were ill less than 5% of the time of diarrheal illness and were 3.5 cm taller and 1.5 kg heavier than children who had diarrheal more

rural bangladesh, each episode of diarrhea costs 0.56cm in height

Endogenous organisms: antibiotic administration (-growth promotion in livestock)
-germ-free and antibiotic fed animals -thinner intestinal walls (more nutrient transfer so more nutrients when feeding on these animals)