Cutaneous anthrax

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    Anthrax is caused by the bacterium Bacillus anthracis that primarily affects herbivores (sheep, goats, cows, camels, horses, etc.). Humans may become infected through contact of broken skin with a dead or sick animal. People at risk include livestock farmers and those that manipulate skins, wool or carcasses of infected animals.

    The disease is found in Eastern Europe, Central Asia, the Mediterranean Basin, Africa and South America.

    Pulmonary (acquired by inhalation) and intestinal (acquired by eating infected meat) forms also exist.

    Clinical features

    • Papule, then pruritic vesicle on uncovered skin surfaces (face, neck, arms, legs). The vesicle ulcerates and becomes a painless black eschar surrounded by oedema, often associated with with lymphangitis and regional lymphadenopathy.
    • The following are criteria of severity:
      • lesion located on the head or neck, or
      • presence of systemic symptoms (fever, malaise, headache, tachycardia, tachypnoea, hypotension, hyper/hypothermia), or
      • presence of extensive oedema, or
      • multiple, extensive or bullous lesions.

    Laboratory

    • From vesicular fluid a Citation a. Samples can be stored (including transport time) for 7 days max. in cold chain (if not available, at a temperature < 30 °C).  : culture and susceptibility testing (rarely available) or Gram stain for microscopic examination.
    • PCR testing (reference laboratory).

    Treatment

    Uncomplicated cutaneous anthrax 

    • Do not excise the eschar; daily dry dressings.
    • Antibiotherapy for 7 to 10 days:
      • If drug susceptibility is not known: 
        ciprofloxacin PO is first-line treatment for all patients including pregnant women and children:
        Children: 15 mg/kg 2 times daily (max. 1 g daily)
        Adults: 500 mg 2 times daily
        Alternatives include:
        doxycycline PO (except in children under 8 years and pregnant or lactating women)
        Children 8 to 12 years: 50 mg 2 times daily
        Children over 12 years and adults: 100 mg 2 times daily
        or
        clindamycin PO (e.g. in pregnant or lactating women and children less than 8 years)
        Children: 10 mg/kg 3 times daily (max. 1800 mg daily)
        Adults: 600 mg 3 times daily
      • If penicillins are effective (documented susceptibility): 
        amoxicillin PO
        Children: 30 mg/kg 3 times daily
        Adults: 1 g 3 times daily

    Severe cutaneous anthrax

    • Combination antibiotherapy for 14 days:
     

    Whatever the protocol used, do not mix the two drugs in the same infusion bag (incompatibility).

    • If drug susceptibility is not known
      ciprofloxacin IV infusion over 60 minutes b Citation b. Dilute each dose of ciprofloxacin or clindamycin in 5 ml/kg of 0.9% sodium chloride or 5% glucose in children less than 20 kg and in a bag of 100 ml of 0.9% sodium chloride or 5% glucose in children above 20 kg and in adults. Administer ciprofloxacin more slowly than clindamycin.
      Children: 10 mg/kg every 8 hours 
      Adults: 400 mg every 8 hours 
      clindamycin IV infusion over 30 minutes b Citation b. Dilute each dose of ciprofloxacin or clindamycin in 5 ml/kg of 0.9% sodium chloride or 5% glucose in children less than 20 kg and in a bag of 100 ml of 0.9% sodium chloride or 5% glucose in children above 20 kg and in adults. Administer ciprofloxacin more slowly than clindamycin.
      Children 1 month and over: 10 to 13 mg/kg every 8 hours (max. 2700 mg daily)
      Adults: 900 mg every 8 hours
    • If penicillins are effective (documented susceptibility):
      ampicillin IV
      Children 1 month and over: 50 mg/kg every 6 to 8 hours
      Adults: 4 g every 8 hours
      clindamycin IV infusion as above.

    Change to oral treatment as soon as possible to complete 14 days of treatment with ciprofloxacin + clindamycin or amoxicillin + clindamycin as for cutaneous anthrax without severity criteria.

    • Intensive care: symptomatic treatment of shock (see Shock, Chapter 1); tracheostomy and ventilatory support may be necessary.

    Prevention

    • Antibiotic prophylaxis in case of known skin exposure: treat for 10 days PO as for cutaneous anthrax without severity criteria.
    • Livestock vaccination; burial or burning of animal carcasses.

     

    Footnotes
    • (a)Samples can be stored (including transport time) for 7 days max. in cold chain (if not available, at a temperature < 30 °C).
    • (b) Dilute each dose of ciprofloxacin or clindamycin in 5 ml/kg of 0.9% sodium chloride or 5% glucose in children less than 20 kg and in a bag of 100 ml of 0.9% sodium chloride or 5% glucose in children above 20 kg and in adults. Administer ciprofloxacin more slowly than clindamycin.