Skin + soft tissue infections

Question 1

What is impetigo?

Answer 1

Skin infection of the epidermis, commonly caused by Staphylococcal

Question 2

What is erysipelas?

Answer 2

Skin infection of the epidermis, commonly caused by Streptococcal

Question 3

What is cellulitis?

Answer 3

Skin infection of the dermis (+/- subcutaneous fat), commonly caused by either Staphylococcal or Streptococcal

Question 4

What is furuncle?

Answer 4

A deep infection of a hair follicle causing a ‘boil’ - commonly caused by Staphylococcal

Question 5

What is carbuncle?

Answer 5

Connecting collections of furuncles, commonly caused by Staphylococcal

Question 6

What is necrotising fasciitis?

Answer 6

A deep infection of the fascia (+/- muscle), commonly caused by Streptococcal or mixed bacterias

Question 7

What viruses commonly affect the skin?

Answer 7

Viral warts
Herpes
Viral exanthems (e.g. chickenpox, shingles)

Question 8

What bacteria commonly affect the skin?

Answer 8

Streptococcus species
Staphylococcus aureus
Opportunistic bacterias (e.g. in diabetic foot ulcers)

Question 9

What is a commensal host-microbe interaction?

Answer 9

Symbiotic relationship between two different species where one derives some benefit and the other is unaffected

Question 10

What is colonisation?

Answer 10

When a microbe grows on (or in) another organism without causing any disease

Question 11

What is a pathogen?

Answer 11

Microbe that is able to cause disease

Question 12

Define infection

Answer 12

The invasion and multiplication of microbes in an area of the body where they are not normally present, usually leading to disease

Question 13

What bacteria dominates the normal flora of the skin?

Answer 13

Gram positive bacteria species

Question 14

What areas of the body are normally sterile from bacteria?

Answer 14

Lungs
Internal tissue
Urinary tract (except distal region of urethra)

Question 15

What bacteria dominates the normal flora of the vagina?

Answer 15

Lactobacilli

Question 16

What are the risk factors for SSTIs?

Answer 16

Direct inoculation (trauma, medical procedures, skin ulcers etc.) 
Previous colonisation (poor hygiene, MRSA etc.) 
Immunosuppression (e.g. DM, renal failure)

Question 17

What characteristics should be used to describe a skin lesion or rash?

Answer 17

Shape
Size
Edge
Colour
Surface 
Distribution

Question 18

What is the diagnostic process for SSTIs?

Answer 18

1. History
2. Examination
3. Differentials
4. Investigations
5. Diagnosis
6. Treatment

Question 19

What microbiology samples can be used to aid diagnosis of SSTIs?

Answer 19

Swabs (e.g. pus or skin) 
Body fluids (e.g. pus, vesicle fluid, blood) 
Body tissues (biopsies)

Question 20

How should viral SSTIs be treated?

Answer 20

Generally self-limiting and therefore do not require treatment.
Antivirals (e.g. aciclovir) can be used to treat herpes, chickenpox and shingles

Question 21

How is impetigo normally treated?

Answer 21

Topical Fuscidin

Question 22

How is Staphylococcus Aureus usually treated?

Answer 22

Sampling recommended + Flucloxacillin initially

[These types of infection are often abx resistant e.g. MRSA]

Question 23

How are Streptococcus species skin infections usually treated?

Answer 23

Penicillin recommended

Question 24

How are opportunistic bacterial skin infections (e.g. diabetic ulcers) usually treated?

Answer 24

Often polymicrobial so sampling is recommended and Co-Amoxiclav used initially

Question 25

How are fungal skin infections usually treated?

Answer 25

Topical Terbinafine often used

Question 26

What factors need to be taken into account when deciding how to treat an SSTI?

Answer 26

Allergy/ intolerance
Renal/ liver function 
Severity of infection 
Immunocompromised? 
Risk of antibiotic-associated infections 
Route of administration
Drug interactions 
Age/ ethnic group
Pregnancy/ breast-feeding/ contraception

Question 27

Is Staph Epidermis usually a pathogen?

Answer 27

No, normally considered a commensal bacteria

Only causes infection only if reaching internal prosthetic material

Question 28

Which type of Staphylococcus bacteria is normally considered a pathogen?

Answer 28

Staph. Aureus