Skin and soft tissue infections

Question 1

What are the main causative organisms of skin and soft tissue infections?

Answer 1

• streptococcus pyogenes

- staphylococcus aureus

Question 2

What is folliculitis?

Answer 2

• infection of hair follicles on the skin/scalp
• hair follicles can be damaged by friction from clothing, blockage of follicles, shaving
• looks like acne/pimples
• some itch
• common in hot weather
• often occurs in macerated areas eg. wet dressings, heavy sweating, obesity

Question 3

What is the most common organism causing folliculitis?

Answer 3

S. aureus

Question 4

What is impetigo?

Answer 4

• superficial infection of the skin
• mostly in children
• contagious
• 2 types
  > crusted/non bullous - honey coloured and crusts
  > bullous - ballae which rupture easily, erosions yellow/brown (looks like water filled massive chicken pox)

Question 5

What is the most common organism responsible for impetigo?

Answer 5

Affluent communities - Staph. aureus

Remote Australia and Indigenous communities - Strep. Pyogenes

Question 6

What are boiles and carbuncles?

Answer 6

Boiles:

• hair follicle associated cutaneous abscesses that penetrate deep into the skin
• painful pus filled legions

Carbuncles:

• cluster of boiles
• deeper and more severe infection than a single boil
• SMx include fever, extreme pain, increased WBC

Question 7

What are the common causative organisms associated with boiles and carbuncles?

Answer 7

• Staph. aureus usually

- Step. pyrogens occasionally

Question 8

What is the tx of folliculitis and impetigo?

Answer 8

Severe, widespread or recurrent infections:
Di/flucloxacillin 500mg qid (10 days)

Hypersensitivity to penicillin, excluding immediate hypersensitivity:
Cephalexin 1g bd (10 days)

Immediate hypersensitivity:
Roxithromycin 300mg d (10 days)

Question 9

What is the tx of boiles and carbuncles?

Answer 9

Because of the increase in CA-MRSA, microbiology and culture required.

While awaiting culture, if CA-MRSA non suspected:
Di/flucloxacillin 500mg qid (5 days)

Hypersensitivity to penicillin, excluding immediate hypersensitivity:
Cephalexin 1g bd (5 days)

Immediate hypersensitivity OR CA-MRSA suspected:
Clindamycin 450mg tds (5 days)

Question 10

What is erysipelas?

Answer 10

• form of cellulitis but with well defined raised border
• particularly affects infants and the elderly
• unlike cellulitis, almost always caused by Strep. pyogenes
• usually affects lower limps, but on the face has a characteristic butterfly distribution
• can lead to rare complications eg. endocarditis

Question 11

What is cellulitis?

Answer 11

• can occur anywhere in the body
• usually unilateral eg. one leg
• SMx include redness, swelling, warmthn(if warmth not present, unlikely cellulitis), tenderness, maybe fever, chills, increased WBC

Note:
A search for a portal entry should be made to prevent recurrence eg. tinea in the toes (treat)

Question 12

What are the causative organism of cellulitis?

Answer 12

• strep. pyogenes
• staph. aureus
• pseudomonas aeruginosa (rare)
• H. influenza (rare)

Question 13

What is the treatment of erysipelas and cellulitis?

Answer 13

To cover staph. aureus and strep. pyogenes, use:

Di/flucloxacillin 500mg qid (7 - 10 days)