In this video blog, Adam Lipworth, MD, discusses highlights from his lecture, Infectious Disease Dermatology Management Update: Complex Choices For Common Conditions, on July 27, 2024, during the inaugural Elevate-Derm Alliance Summer Conference at the Westin Copley Place in Boston, Massachusetts.

In this video

Dr. Lipworth starts with the common conditions: impetigo can be strep or staph, but bullous impetigo "has to be caused by staph" because only staph makes the exotoxins that split keratinocytes. Since the bullae are superficial and rupture easily, he warns clinicians not to "hang your hat on the bullae themselves" — erosion with golden crusting is often the telltale sign, and HSV can be confused for it, so a low-cost swab is worth doing when unsure. In adults, impetigo is rarely spontaneous; it's usually secondary to an abrasion, eczema, or immunosuppression, so he urges a step further to figure out why. On furuncles, he revisits the old teaching that I&D alone equals I&D plus antibiotics, citing the 2017 New England Journal study by Daum and others — the benefit of antibiotics largely disappears once you remove new lesions from the failure criteria. His approach: I&D and culture everyone, then let the patient's clinical course drive the decision, telling them "what they tell me is more important than what I tell them," with the culture reserved to guide a rescue drug.

He also flags infection mimickers, especially contact dermatitis from over-the-counter triple antibiotic ointment — bacitracin and neomycin are perennial top allergic contact allergens — which produces "a rash that doesn't seem to quit." Finally, he makes the case for recognizing retiform purpura, which he says is oddly not taught in medical school and "almost always missed" outside dermatology. It reflects occlusion of the perforating arterioles, meaning an embolism, hypercoagulable state, or septic or inflammatory vasculitis — "there's nothing good on that differential" — and even a solitary lesion on a finger is a chancre lesion, or embolus, until proven otherwise, potentially in a patient who is about to get very sick.

  • Bullous impetigo is always staph-driven; don't rely on intact bullae — look for erosion with golden crusting, and swab for HSV when the diagnosis is unclear.
  • Adults rarely get impetigo out of the blue — treat it as a secondary diagnosis and hunt for the underlying cause (abrasion, eczema, immunosuppression).
  • For simple furuncles, I&D and culture everyone; let the patient's clinical response, not epidemiology alone, decide whether antibiotics are needed as a targeted rescue.
  • Ask patients exactly what OTC products they're using — triple antibiotic ointment (bacitracin, neomycin) is a common cause of superimposed allergic contact dermatitis mistaken for persistent infection.
  • Learn to recognize retiform purpura: even a single lesion signals embolism, hypercoagulability, or septic/inflammatory vasculitis — nothing benign belongs on that differential.