++
Anthrax is an acute infectious disease caused by the gram-positive,
encapsulated, nonmotile, spore-forming rod Bacillus anthracis.1,2 The
incubation period is 1 to 7 days after exposure, and no person-to-person
transmission is documented. Its potential as an agent of bioterrorism
should prompt immediate notification of the local or state health
department upon first suspicion of an anthrax-like illness. Human
anthrax cases arise after exposure to infected animals or their
products and rarely occur in the United States. In 2001, B
anthracis spores intentionally delivered through the US
Postal Serviceresulted in 22 cases of bioterrorism-related
anthrax.3
++
Clinical Manifestations
++
Anthrax infections occur as cutaneous, inhaled, and gastrointestinal.
All forms can progress to sepsis and meningitis. Cutaneous
anthrax appears when B anthracis spores
enter through a cutaneous abrasion.4 A small erythematous papule
vesiculates to form a painless eschar with marked edema. Lymphadenopathy
or lymphangitis may occur. Untreated, mortality is as high as 20%.
++
Inhalation anthrax occurs after respiratory
exposure to B anthracis spores.5 Initial symptoms
are nonspecific, mimicking influenza. Symptoms become fulminant
over a few days, often leading to death. Mediastinal widening on
chest radiograph is pathognomonic. Hemorrhagic meningitis and bacteremia
are common.
++
Gastrointestinal anthrax follows ingestion of
contaminated, undercooked meat,6 presenting with
nausea, vomiting, and malaise, progressing to bloody diarrhea, gross ascites,
hemorrhagic lymphadenitis, and sepsis. A pharyngeal form of anthrax
occurs with profound submental swelling, adenopathy, and systemic
symptoms.7 Multiple forms of anthrax have been
described in children.8-15
++
Gram stain and culture of vesicular fluid or blood confirm the
diagnosis of anthrax. B anthracis grows in ordinary
nutrient broth and on blood agar,2 appearing as
large, gram-positive, sporulating bacilli on Gram stain. Rapid diagnostic
tests are available through the Laboratory Response Network.16
++
Treatment and Prevention
++
Antibiotic resistance to penicillins and tetracyclines is assumed
in bioterrorism cases until proven otherwise.1 Empiric
therapy of inhalational or gastrointestinal bioterrorism-mediated
anthrax includes intravenous ciprofloxacin or doxycycline plus 1
or 2 additional agents, including rifampin, vancomycin, penicillin,
ampicillin, chloramphenicol, imipenem, clindamycin, and clarithromycin. Ciprofloxacin
has better central nervous system penetration than doxycycline.
First-line therapy for cutaneous anthrax includes either oral ciprofloxacin
or doxycycline. If cutaneous lesions involve the head and neck or extensive
edema is associated, combination intravenous regimens are recommended. Steroid
therapy is considered for severe edema associated with cutaneous
lesions and for meningitis. As spores may persist in the respiratory
tract, all forms of anthrax are treated for 60 days, and therapy
may be completed orally when clinically appropriate.17,18
++
Treatment recommendations for children include ciprofloxacin
(10 mg/kg/dose intravenously transitioning to
15 mg/kg/dose orally every 12 hours, maximum 500
mg per dose) or doxycycline (2.2 mg/kg/dose intravenously
transitioning to same dose orally every 12 hours, maximum 100 mg
per dose), plus 1 or 2 ...