Infections of the Skin

Question 1

Name the 3 routes of infection

Answer 1

Skin
Wounds
Bites

Question 2

What is the role of commensal microbiota in and on the body ?

Answer 2

Commensal bacteria supply the host with essential nutrients and defend the host against opportunistic pathogens.

Question 3

What skin infection occurs in the ‘keratinised epithelium’ ?

Answer 3

Ringworm

Question 4

What skin infection occurs in the ‘epidermis’ ?

Answer 4

Impetigo

Question 5

What skin infection occurs in the ‘hair follicles’ ?

Answer 5

Folliculitus

Question 6

What skin infection occurs in the ‘subcutaneous fat’ ?

Answer 6

Cellulitis

Question 7

What skin infection occurs in the ‘fascia’ ?

Answer 7

Necrotising fasciitis

Question 8

What skin infection occurs in the ‘muscle’ ?

Answer 8

Gas gangrene

Question 9

What is a skin lesion ?

Answer 9

A skin lesion refers to any skin area that has different characteristics from the surrounding skin, including color, shape, size, and texture.

Question 10

What are the 2 classes of skin lesions ?

Answer 10

Primary
Secondary

Question 11

What are primary skin lesions ?

Answer 11

Primary skin lesions originate on previously healthy skin and are directly associated with a specific cause.

Common examples of primary skin lesions include freckles, moles, and blisters, among others

Question 12

Name the 6 different forms of primary skin lesions

Answer 12

Macule
Papule
Nodule
Vesicle
Bulla
Pustule

Question 13

What are secondary skin lesions ?

Answer 13

Secondary skin lesions develop from the evolution of a primary skin lesion, either due to traumatic manipulation, such as scratching or rubbing, or due to its treatment or progression.

Question 14

Name the 4 examples of secondary skin lesions

Answer 14

Scales
Crust
Fissure
Ulcer

Question 15

Abscess

Answer 15

Collection of pus; pustule

Question 16

Vesicle

Answer 16

Blister; bullae (plural); fluid filled sac

Question 17

Pyoderma

Answer 17

Pus forming skin infection; cutaneous abscess

Question 18

What does the pus in a pyoderma contain ?

Answer 18

Bacteria, White blood cells, Dead tissue and serum

Question 19

Impetigo

Answer 19

Vesicles developing into ruptured pustules then forming dried crusts.

Caused by Gram + bacteria
Highly contagious

Question 20

Ecthyma

Answer 20

Rupturing vesicles leading to erythematous lesions and dried crusts.

Question 21

Folliculitis

Answer 21

Inflammation at hair follicle

Question 22

Furuncle

Answer 22

Boil; deep foliculitis

Question 23

Carbuncle

Answer 23

Collection of boils

Question 24

Erysipelas

Answer 24

Erythema (redness) and inflammation of superficial dermis

Question 25

Cellulitis

Answer 25

Erythematous inflammation affecting deeper dermis and subcutaneous fat

Question 26

Acne

Answer 26

Infection of sebaceous follicles

Question 27

Necrotising fasciitis

Answer 27

Cellulitis with necrosis affecting skin, deeper fascia and sometimes muscle

Question 28

Dehiscence

Answer 28

Wound rupture along surgical suture

Question 29

What are pathogenic bacteria ?

Answer 29

Pathogenic bacteria are bacteria that can cause disease.

Question 30

Name the 5 key bacterial pathogens

Answer 30

Streptococcus pyogenes Staphylococcus aureus Pseudomonas aeruginosa Mycobacterium tuberculosis (Some may be toxin mediated)

Question 31

Streptococcus pyogenes

Answer 31

Coccus Grows in chains Gram + Group A Streptococcus Multiple virulence factors Beta-haemolytic

Question 32

Staphylococcus aureus

Answer 32

Coccus Grows in clusters Gram + Causes a huge range of illnesses Antibiotic resistant strains (MRSA, VRSA) Multiple direct virulence factors Direct infection or effect of toxin

Question 33

Pseudomonas aeruginosa

Answer 33

Coccobacillus Gram - Single flagellum, at one pole Opportunistic Colonises catheters Produces exotoxin A

Question 34

Which pathogenic bacteria colonises catheters ?

Answer 34

Pseudomonas aeruginosa

Question 35

Where is impetigo usually found ?

Answer 35

Superficial - epidermis Note : Ecthyma is a deep form of impetigo (goes into the dermis)

Question 36

Management of spread of impetigo

Answer 36

Wash affected areas with soap and water Wash hands regularly Avoid scratching affected areas Avoid sharing towels

Question 37

What causes staphylococcal scalded skin syndrome ?

Answer 37

Severe, superficial blistering skin disorder. Detachment of the epidermis

Question 38

What is Staphylococcal Scalded Skin Syndrome also known as ?

Answer 38

Ritters disease

Question 39

What is SSSS ?

Answer 39

Localised Staph A infection of the skin or upper respiratory tract.

Question 40

Skin infections associated with the epidermis ?

Answer 40

Impetigo Erysipelas (dermis as well- mainly)

Question 41

Skin infections associated with the dermis ?

Answer 41

Necrotising fasciitis Cellulitis Erysipelas

Question 42

Skin infections associated with the hypo-dermis ?

Answer 42

Necrotising fasciitis

Question 43

Why are diabetics particularly susceptible to infections ?

Answer 43

High blood glucose can alter the normal microbiota Reduced blood flow in the vasculature may result in problems in mobilising the immune system effectively Neuropathy, particularly in the extremities, may result in increased injury Injection with insulin provides a portal of entry