Master the board step 3

Master the Boards: USMLE Step 3
it becomes a small collection of infected material known as a furuncle. When
several furuncles become confluent into a single lesion, it becomes known as a
carbuncle, essentially a localized skin abscess that must be drained. Folliculitis
is rarely tender, while furuncles and carbuncles are often extremely tender.
Treatment is as follows:
··
Folliculitis can be treated with topical mupirocin.
··
Furuncles and carbuncles must be treated with systemic antistaphylococcal
antibiotics, such as dicloxacillin or cefadroxil.
Necrotizing Fasciitis
This is an extremely severe, life-threatening infection of the skin. It starts as
a cellulitis that dissects into the fascial planes of the skin. Streptococcus and
Clostridia are the most common organisms involved, because they produce
a toxin that worsens the damage to the fascia. Diabetes increases the risk of
developing fasciitis.
Necrotizing fasciitis presents as follows:
··
Very high fever
··
Portal of entry into the skin
··
Pain out of proportion to the superficial appearance
··
Bullae
··
Palpable crepitus
Diagnostic Testing
The following diagnostic tests can be used:
··
Elevated CPK
··
X-ray, CT scan, or MRI that shows air in the tissue or necrosis
If presented with an
obvious clinical case with
crepitus, pain, high fever,
and a portal of entry,
answer surgery, not a test,
such as x-ray, as the best
initial step.
All of these laboratory methods of establishing a diagnosis lack both sensitivity
and specificity. Surgical debridement is both the best way to confirm the diagnosis,
as well as being the mainstay of therapy.
Treatment
Treat with beta lactam/beta lactamase combination medications:
··
Ampicillin/sulbactam (Unasyn)
··
Ticarcillin/clavulanate (Timentin)
··
Piperacillin/tazobactam (Zosyn)
If there is a definite diagnosis of group A Streptococcus (pyogenes), then the
treatment is with clindamycin and penicillin.
Without adequate therapy, necrotizing fasciitis has an 80 percent mortality.
298