Bacterial Skin Infections

1.  Impetigo

• Very common
• Characteristics
  • Crusty honey colored lesions found on arms, face and legs
• Usually associated with crowded living situations (nursery) and poor hygiene (but not always)
• Most worried about Cavernous Sinus Thrombosis (remember the triangle of danger from anatomy):  the central facial region drains into the cavernous sinus and any bacterial infection can spread into the brain and cause a life threatening situation

2.  Bullous infections

• Fungal:  bullous dermatophytosis
• Bacterial:  bullous impetigo
• Staphylococcal Scalded Skin Syndrome:  a staph infection can cause bullous impetigo with exotoxin leading to shallow blisters (simulates a thermal burn).  Cultures may not be positive so you have to be careful diagnosing
• Viral:  chickenpox

3.  Erythrasma

• Caused by Cornyebacterium minutissimum
• Usually found in the groin area
• Can resemble a dermatophyte infection but with fluoresce red with a Wood’s light

• Caused by Bartonella henselae and B. Quintana (from body lice and flea infected cats)
• Can be confused with vascular neoplasms
• Part of the difficulty in diagnosis is that the bacteria are extremely difficult to culture
• This skin finding can be indicative of a serious systemic disease
• We HAVE to know this

5.  Lyme Borreliosis

• Caused by Borrelia burdorferi
• Endemic to the tropical locations of New Jersy, New York and Connecticut
• First stage is called erythema chronicum migrans with a enlarging red patch 1-2 weeks after the tick bite
• Second stage (in US):  characterized by arthritis, neuritis and carditis
• Third stage occurs in Europe (because it is caused by a different species)

6. Necrotizing Fascitis

• Have to know because it could be life threatening

• 4 types (which he will never ask us about)
  • polymicrobial
  • group A Strep
  • gas gangrene (clostridium)
  • saltwater containing a Vibrio species
• Characteristics
  • Begins with a fever and chills
  • After 2 or 3 days the patient will start to see erythema, vesiculation or bullae form (serosanguineous may drain from the infected site)
  • Insidiously advancing soft tissue infection with widespread fascial necrosis
• Places of infections:  skin biopsy, needle puncture, frostbite, and insect bites
• Can occur with diabetes, surgery (one of the most life threatening complications of surgery) and trauma

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