Treat ACA skin manifestations with extended antibiotics

Acrodermatitis chronica atrophicans (ACA) is a late-stage skin manifestation caused almost exclusively by B. afzelii. It requires longer antibiotic courses than other Lyme manifestations: doxycycline 200 mg daily or amoxicillin 500 mg three times daily for 21-28 days. ACA presents as bluish-red discoloration and progressive skin atrophy, typically on the extremities.

Why It Works

B. afzelii is dermatotropic and persists in skin tissue for years if untreated. The longer treatment course is needed because the organism is deeply embedded in skin connective tissue. Antibiotic treatment halts progression and resolves the inflammatory component, though established skin atrophy may not fully reverse.

Tips

• ACA is essentially pathognomonic for B. afzelii infection and is rarely seen in North America
• Pruritus (itching) is a common symptom that typically resolves with treatment
• A skin biopsy showing characteristic lymphocytic infiltration supports the diagnosis
• Associated peripheral neuropathy in the affected limb often improves with antibiotic treatment