Skin infections (bacterial)

Question 1

Name a commensal bacterium which can causes skin infections?

Answer 1

Staphylococcus aureus

Question 2

Where is commensal staph aureus found?

Answer 2

Nose
Armpits
Groin

Question 3

What is the gram stain for staph aureus? Give some characteristics

Answer 3

Gram positive
Stains purple
Encapsulated
Produces toxins

Question 4

Name four toxins produced by staph aureus

Answer 4

Panton Valentine Leucocidin (PVL)
Exfoliative toxin
Toxic shock syndrome toxin 1 (TSST 1)
Enterotoxin

Question 5

What does the Panton Valentine Leucocidin toxin from Staph Aureus cause?

Answer 5

Necrotising soft tissue infection

Question 6

What do exfoliative toxins from staph aureus cause in babies and in young children and adults?

Answer 6

Blistering infections
Babies: scalded skin syndrome
Children and adults: bullous impetigo

Question 7

What do the toxic shock syndrome toxin 1 (TSST 1) from staph aureus cause?

Answer 7

Septicaemia

Question 8

What does the enterotoxin cause?

Answer 8

Diarrhoea if someone infected with it on their hands then touches food

Question 9

What are the other sites of infection by staph aureus, besides skin?

Answer 9

Bone
Joint
Lung (post-flu staph pneumonia)
Blood (sepsis)

Question 10

If the infection is in the top layer of the skin (epidermis), what is this caused?

Answer 10

Impetigo

Question 11

If it is an infection of the hair follicle, what is this caused?

Answer 11

Folliculitis

Question 12

What do you call an infection of the full thickness of the epidermis (often necrotising)?

Answer 12

Ecythma

Question 13

If it’s a puss producing infection of the hair follicle, what do you call it?

Answer 13

Boil

Question 14

If several adjacent abscess producing hair follicles are connected, what do you call this?

Answer 14

Carbuncle

Question 15

Describe the appearance of impetigo

Answer 15

Honey coloured crusty infection of top layer of skin

aureus = golden

Question 16

Where does staph aureus impetigo commonly affect children?

Answer 16

Mouth

Question 17

What do you call it when you get a staph aureus infection secondary to a skin disease e.g. eczema

Answer 17

Impetiginisation

Question 18

Explain the pathophysiology of bullous impetigo

Answer 18

Exfoliative toxin produced by the staph causes splitting of the skin (bullous formation).

The pus is formed by proliferating bacteria

Question 19

Describe the appearance of ecthyma

Answer 19

Thick, crusty, necrotic dead skin

Question 20

What is eschar?

Answer 20

A dry dark scab or falling away of dead skin, typically caused by a burn, insect bite or anthrax infection

Question 21

Who is at risk of ecthyma?

Answer 21

Immunosuppressed individuals

Question 22

What do you call the staph infection of skin in babies?

Answer 22

Scalded skin syndrome

Question 23

Explain the pathophysiology of scalded skin syndrome

Answer 23

Exfoliative toxin causes layers of skin to peel

Question 24

How is scalded skin syndrome usually treated?

Answer 24

Methicillin (except for if it’s MRSA)

Question 25

What is the American name for methicillin?

Answer 25

Flucloxacillin

Question 26

Name a spiral shaped bacteria causing skin infections

Answer 26

Treponema pallidum

Question 27

What is treponema pallidum more commonly known as?

Answer 27

Syphilis

Question 28

What is the gram stain of treponema pallidum? Describe the appearance

Answer 28

Gram negative; spiral shaped

Question 29

What are the stages/classifications of syphilis infection?

Answer 29

``` Primary Secondary Latent Tertiary Congenital ```

Question 30

Describe the time frame and appearance of primary syphilis

Answer 30

3-8w | Painless ulcer at inoculation site (genitals or mouth)

Question 31

What is the serology and swab result of primary syphilis?

Answer 31

Serology - negative | Swab - positive

Question 32

Describe the time frame and appearance and symptoms of secondary syphilis

Answer 32

6-12w Disseminated infection Generalised rash Lymphadenopathy

Question 33

Where do the rashes commonly appear in secondary syphilis?

Answer 33

Palms Soles Peri-anal region

Question 34

What are the appearances of the rashes in secondary syphilis?

Answer 34

Can be a widespread maculopapular rash Or a small red rash Or look like sticky out-y lesions that look like warts

Question 35

What do you call these sticky out-y lesions in secondary syphilis?

Answer 35

Condyloma lata

Question 36

Why is it thought that brothels worked under red lights?

Answer 36

The red rashes wouldn't be visible...

Question 37

What is the serology and swab result in secondary syphilis and what can be seen in biopsies?

Answer 37

Positive blood test Positive swab Teeming with plasma cells

Question 38

Describe the time frame and appearance and symptoms of tertiary syphilis

Answer 38

``` Years later Destructive bone lesions Destructive skin lesions Thoracic aneurysm Neurosyphilis ```

Question 39

Describe the effects of congenital syphilis cause on pregnancy

Answer 39

Miscarriage Still birth Prematurity

Question 40

Describe the time frame of symptom onset in congenital syphilis

Answer 40

Can be early or late manifestations

Question 41

What are the symptoms of congenital syphilis in the baby?

Answer 41

``` Bone disease Rashes Brain and neurological problems Saddle shaped nose Peg like teeth Blindness ```

Question 42

Describe the time frame and appearance and symptoms of latent syphilis

Answer 42

NO CLINICAL SIGNS