Skin & Soft Tissue Infections

Question 1

What are SSTIs and how are they organized into categories?

Answer 1

Skin and soft tissue infections

Often divided into purulent (pus) and non-purulent

Question 2

What are some purulent SSTIs?

Answer 2

Bullous impetigo, carbuncles, cutaneous abscess, folliculitis, purulent cellulitis

Question 3

What are some non-purulent SSTIs?

Answer 3

Non-bullous impetigo, non-purulent cellulitis

Question 4

What is cellulitis?

Answer 4

It is the infection of the epidermis and dermis; and it can spread within the superficial fascia

It can also spread through lymphatic tissue and bloodstream

Question 5

What is the presentation of cellulitis?

Answer 5

The infected area tends to be hot and painful. It also involves erythema and edema of skin. The skin does not show signs of necrosis, it is inflamed instead.

Fever, chills, malaise are also found in cellulitis

Cellulitis often follows minor trauma, abrasion, ulcer or surgery

Question 6

How to differentiate between cellulitis on the lower limbs and venous stasis?

Answer 6

Venous stasis has similar presentation, but it is slightly different. Venous stasis affects bilaterally, while cellulitis is a unilaterally presenting condition

Question 7

What are some symptoms associated with severe cellulitis?

Answer 7

Hypotension, dehydration, and an altered mental status

Question 8

What microorganisms are known to cause cellulitis?

Answer 8

Group A Streptococcus

Staphylococcus aureus

Question 9

What are CA-MRSA and HCA-MRSA?

Answer 9

CA-MRSA (Community associated MRSA): Onset of infections in community without health-care associated risk factors

HCA-MRSA (Healthcare associated MRSA): Onset of infection occurs in the hospital or other healthcare institutions.

The drugs used in both are different because we assume resistance is higher in microorganisms in medical facilities (HCA-MRSA).

Question 10

What is the association between purulent/non-purulent vs. Strep and Staph?

Answer 10

Non-purulent (think Strep)

Purulent (Staph)

Question 11

What are some risk factors for community associated MRSA?

Answer 11

Crowding, frequent skin contact, compromised skin, sharing contaminated person items and lack of cleanliness

Extreme of ages

Gay male sex

Prisons

Antibiotic use in the last 6 months

Question 12

When should cellulitis drug therapy cover for MRSA?

Answer 12

Patient is from a highly endemic area for CA-MRSA

Lack of improvement on beta-lactam (signs of resistance)

Patient has a serious illness, immmunocomprimised, etc.

Question 13

What are some non-purulent cellulitis antibiotic choices?

Answer 13

Cephalexin 500 mg QID (adult)/50-100mg/kg/day divided QID)

This antibiotic will not cover MRSA, but 100% of Group A Strep are susceptible to Cephalexin

Question 14

What are some antibiotic choice for cellulitis in people with penicillin allergy?

Answer 14

Clindamycin 300mg QID(adults)

20-40mg/kg/day divided QID (paediatric)

Question 15

What are some good antibiotic choices for purulent cellulitis?

Answer 15

Cephalexin 500mg QID

Cloxacillin 500mg QID (adults)
50mg/kg/day divided QID

Question 16

What are some antibiotic choices for purulent cellulitis in MRSA or penicillin allergy?

Answer 16

TMP/SMX:
1-2 double dose BID

Doxycycline:
100mg BID (adult)

Clindamycin (seen as a drug for Streptococcus, but significant proportion (15-30%) of microorganisms are resistant

Question 17

Are the microorganisms that cause purulent cellulitis susceptible to ciprofloxacin?

Answer 17

Not really, less than 50% of these microorganisms are susceptible to ciprofloxacin

Question 18

What is are some empiric therapy for cellulitis with unknown microorganisms?

Answer 18

Provide antibiotics that cover both Group A Strep and Staph. Aureus

Cephalexin + TMP/SMX

Cephalexin + doxycycline

Question 19

How long does cellulitis therapy usually last?

Answer 19

In uncomplicated cellulitis, 5 days of therapy is effective

During therapy, the condition may worsen in the first few days; it is a part of the healing process

Full skin healing (inflammation and symptoms) may take 1-2 weeks after antibiotics are stopped

Question 20

What are some non-pharmacological therapy options in cellulitis treatment?

Answer 20

Incision and drainage:
This is key to successful treatment, especially in purulent cases

For abscesses smaller than 5 cm, incision and drainage are sufficient

Elevation of affected limb:
Helps drain fluid away from the affected area