13.2

Question 0

In places where moisture content of the skin is high (armpit, groin) relatively high population densities of bacterial cells can be

Answer 0

Found

Question 1

The skin surface is relatively dry and slightly acidic, and the main food sources for microorganisms living on the skin are

Answer 1

Dead cells

Sebum (an oily secretion from the sebaceous glands)

Question 2

Human skin supports a community of many microorganisms, including:

Answer 2

Staphylococci
Micrococci
Corynebacterium
Fungi

Question 3

These microorganisms that are supported by the human skin are called

Answer 3

Commensals

Question 4

Microorganisms supported by the skin are called commensals because they

Answer 4

live harmlessly on the skin, helping to prevent infection by out-competing potential pathogenic microorganisms

Question 5

A number of skin conditions are caused when populations of commensal skin bacteria begin to

Answer 5

Grow rapidly in response to a change in their environment

Question 6

An example of a skin condition is

Answer 6

Acne vulgaris

Question 7

Acne is caused by

Answer 7

Over-activity if the sebaceous glands

Question 8

The sebaceous glands release

Answer 8

Sebum into hair follicles

Question 9

Once sebum is released into hair follicles it can reach the surface of the skin, helping to keep the skin

Answer 9

Supple and waterproof

Question 10

The sebaceous glands of people with acne are especially sensitive to

Answer 10

Normal blood levels of testosterone

Question 11

The levels of testosterone begin to increase during puberty and this stimulates the

Answer 11

Sebaceous glands on the face chest and back to produce excess sebum

Question 12

If the excess sebum can’t leave the hair follicles because they are blocked by dead skin cells, the sebum builds up inside the follicles, causing

Answer 12

Blackheads and whiteheads (spots)

Question 13

The build up of sebum inside the hair follicles provides an ideal environment for a normally harmless skin bacterium called propionibacterium scenes to

Answer 13

Multiply rapidly in and near sebaceous glands in the skin

Question 14

This increased bacterial population of propionibacterium acnes produces an immune response that

Answer 14

Inflames the skin and creates the redness associated with spots

Question 15

Sometimes the inflammatory acne can become severe and cysts (cavities filled with dead skin cells, sebum and pus that form when the sebaceous glands rupture) can develop beneath the skin’s surface that produce

Answer 15

Scarring on the skin

Question 16

There are a number of treatments that can be used to control the populations of the bacteria that can cause Acne vulgaris:

Answer 16

Soaps and cleansers
Over-the-counter remedies
Prescriptions (topical - creams and lotions - systemic - tablets)

Question 17

Examples of soaps and cleansers

Answer 17

Mild soap

Mild antiseptic cleanser

Question 18

Example of over-the-counter remedies:

Answer 18

Benzoyl peroxide

Question 19

Example if topical prescriptions:

Answer 19

Retinoids
Antibiotic lotions (clindamycin)

Question 20

Examples of systemic prescriptions:

Answer 20

Antibiotics (tetracycline)
Oral contraceptive (women)
Isotretinoin

Question 21

How soaps and cleansers work;

Answer 21

Remove some of the surface oil and reduce the size of populations of some bacteria living on the skin

Antiseptics may kill the bacteria (bacteriacidal) or they may inhibit further growth of bacterial population (bacteriostatic)

Question 22

How over-the-counter remedies work:

Answer 22

Antibacterial cream or lotion - dries out skin and encouraged it to shed the surface layer of dead skin making it harder for follicles to become blocked and for infection to develop

Question 23

How retinoids work

Answer 23

Medicines based on vitamin A
Run into skin daily
Work by encouraging the outer layer of skin to flake off

Question 24

How antibiotic lotions (clindamycin) work:

Answer 24

Applied to skin
Can be used to control the P.acnes bacteria
Need to continue for at least 6 months

Question 25

How antibiotics work:

Answer 25

Prescribed for inflammatory acne
Taken daily for around 3 months
Success limited - strains of bacteria at often resistant

Question 26

How oral contraceptive works:

Answer 26

Suppresses testosterone activity

Shown to reduce sebum production

Question 27

Now isotretinoin works:

Answer 27

Inhibits secretion of sebum

Tends to be prescribed to people with severe forms of acne that have proved resistant to other treatments