LG 5.3 - Normal Microbiota

Question 1

What is normal microbiota?

Answer 1

• Microorganisms frequently found on or in the body of healthy people. (being colonized during, shortly after birth).

Question 2

What is the difference between commensalism and mutualism?

Answer 2

• Commensalism: one member benefits while the other is relatively unaffected.
• Mutualism: both members benefit.

Question 3

(1) Is it likely that a normally colonized area on your body will be colonized with something new, why why not?

Answer 3

• No, because it must outcompete the host and current microbial defenses.

Question 4

(1) What is the significance of microbes at normally sterile places? Why?

Answer 4

• Usually diagnostically significant.

- No microbial competition

Question 5

(1) What is the difference between resident and transient microbiota?

Answer 5

• Resident: relatively fixed, given area, given age. Washing, sweating doesn’t significantly alter. If disturbed, reestablishes.
• Transient: from environment, food, water. Nonpathogenic to potentially pathogenic. Usually excluded by normal microbiota, host’s innate defenses. Hrs, days, weeks.

Question 6

(1) What causes our normal microbiota to be in constant flux?

Answer 6

• Age, diet, hormonal state, health, personal hygiene, geography, neighbors.

Question 7

(1) What are the roles of normal microbiota?

Answer 7

• Participate in end stages food digestion.
• Provide some vitamins
• Help protect against pathogens. (contribute to maturation of immune system, stimulate immune response, competition for binding sites, space).

Question 8

(1) How do microbiota prevent colonization of pathogens?

Answer 8

• Using up: space, nutrients, oxygen.

- Producing: bacteriocins, metabolic products.

Question 9

(1) What is dysbiosis?

Answer 9

• balance microbes shifts in unhealthful direction.

- When the dynamic equilibrium with normal microbiota tips in favor of disease.

Question 10

(1) What is the difference between strict pathogens and opportunistic pathogens?

Answer 10

• Strict: always associated with disease.
• Opportunistic: don’t produce disease in their normal environment, but can cause disease when introduced into unprotected sites, or when overgrow their normal environment.

Question 11

(1) What is the difference between colonization and infection?

Answer 11

• Colonization differentiated from infection by evidence of pathological process in host.

Question 12

(1) Why is CDAD an example of dysbiosis?

Answer 12

• GI tract, opportunity for colonization with new bugs occurs daily with ingestion food, water; inhalation aerosols, spores.
• Population remains relatively constant unless exogenous factors like acid neutralizers, antibiotic treatment disrupt balance.