Focal skin and soft tissue infections are often due to bacteria infections, and include conditions like impetigo, folliculitis, cellulitis, erysipelas, furuncles and carbuncles, and necrotizing fasciitis.
The first step is getting a full history.
In impetigo, there’s usually no pain, whereas in necrotizing fasciitis the pain is severe.
Most skin infections tend to be localized and around a particular anatomic structure.
For example, folliculitis, furuncles, and carbuncles involve the hair follicle.
Also, a superficial infection like impetigo or folliculitis causes itchiness.
In erysipelas, the fever is high and abrupt in onset, and in necrotizing fasciitis the fever usually persists.
Some individuals have had contact with other individuals with skin infections, and this is commonly the case with community-acquired methicillin-resistant S. aureus, which causes cellulitis and furuncles.
On physical exam, there may be signs of systemic illness like fever and chills, and signs of toxicity like lethargy, tachycardia, and hypotension.
Additionally, there may be adenopathy, which can occur in non-bullous impetigo and cellulitis, bullae which can be seen in bullous impetigo, and crepitus with edema that exceeds the rash border, which can be seen in necrotizing fasciitis.