12- Normal Microbiota And The Host

Question 1

Transient microbiota?

Answer 1

Microbiota that may be present for days, weeks, or months

Question 2

Symbiosis?

Answer 2

• the relationship between normal microbiota and the host

- an association of two or more different species of organisms

Question 3

Commensalism?

Answer 3

When one organism benefits and the other is unaffected

Question 4

Mutualism?

Answer 4

When both organisms benefit

Question 5

Parasitism?

Answer 5

When one organism benefits at the expense of the other

Question 6

Microbial antagonism?

Answer 6

Competition between microbes

Question 7

How do normal microbiota protect the host?

Answer 7

• occupying niches that pathogens might occupy
• producing acids
• producing bacterocins

Question 8

Probiotics?

Answer 8

Live microbes applied to or ingested into the body, intended to exert a beneficial effect

Question 9

Normal microbiota?

Answer 9

Microbiota that permanently colonize the host

Question 10

What are opportunistic pathogens?

Answer 10

Members of normal microbiota that produce disease under certain circumstances

Question 11

What is a compromised host?

Answer 11

A debilitated host with lowered resistance to infection

Question 12

These oral bacteria are responsible for dental caries?

Answer 12

• S. mutans and Lactobacillus

Question 13

What is the goal of the Human Microbiome project?

Answer 13

To attempt to define ‘normal’ populations of microbes in and on human beings

Question 14

Name some reasons it would be beneficial to study normal microbiota (3).

Answer 14

• to gain insight into possible infections resulting from injury
• to understand causes and consequences of overgrowth of microbes normally absent from a body site
• to increase awareness of role played by indigenous microbe(s) in stimulating immune response

Question 15

Sebum?

Answer 15

Fluid secreted by oil glands

Question 16

Comedo?

Answer 16

• plug of sebum and keratin in duct of oil gland

- results from inflammatory response to sebum accumulation

Question 17

Acne vulgaris is caused in part by the activity of what bacteria?

Answer 17

Propionibacterium acnes

Question 18

These gram-positive, salt-tolerant bacteria are part of the normal microbiota of the skin?

Answer 18

• staphylococci (S. epidermis)
• Micrococci (M. luteus)
• Diptheroids – aerobes on surface (Corynebacterium xeroxis)– anaerobes in hair follicles (Propionibacterium acnes)

Question 19

These are predominant bacteria found just inside the nostrils?

Answer 19

Staphylococcus aureus and S. epidermis

Question 20

These gram-positive bacteria are found in the pharynx and trachea?

Answer 20

• Staphylococci (S. Epidermis)
• Micro cocci (M. luteus)
• Diptheroids
• Streptococci (both alpha- and beta-hemolytic)

Question 21

These potentially pathogenic microbes may be present in the pharynx?

Answer 21

• streptococcus pneumoniae
• Neisseria meningitidis
• Haemophilus influenzae
• mycoplasmas

Question 22

Why is there normal microbiota in the lower respiratory tract?

Answer 22

Microbes are moved by:

• continuous stream of mucous generated by ciliated epithelial cells (ciliary escalator)
• phagocytic activation of alveolar macrophages
• lysozyme in mucus

Question 23

Are there many or few microbes present in the stomach?

Answer 23

Few. Most microbes are killed by acidic conditions

• some survive if they pass through the stomach very quickly
• some can survive if ingested in food particles

Question 24

Where is the largest microbial population of the body found?

Answer 24

In the large intestine (Colon)

Question 25

List some characteristics regarding the microbiota of the large intestine (Colon).

Answer 25

Largest microbial population now the body

• microbes are eliminated from the body by peristalsis, desquamation, and movement of mucus
• microbes are replaced rapidly because of their high reproductive rate
• most of the microbes present are anaerobes

Question 26

List some of the normal microbiota found in the large intestine (colon).

Answer 26

• E. Coli
• Bacteroides
• Fusobacterium
• Lactobacillus
• Enterococcus
• Bifidobacterium
• Enterobacter
• Citrobacter
• Proteus
• Klebsiella
• Candida (fungus)

Question 27

These bacteria are predominant in the vagina?

Answer 27

Lactobacilli

Question 28

These areas of the genitourinary tract are normally free of microbes?

Answer 28

• Kidneys
• Ureters
• Bladder

Question 29

You may find a few microbes normal present in this area of the genitourinary tract?

Answer 29

The distal portions of the urethra

Question 30

The ______ the urethra, the more likely to develop infections?

Answer 30

Shorter