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Introduction
Types of Clinical Anthrax
Inhalational anthrax (Lethal Dose [10-50
spores] LD50 believed to be 10,000-20,000
spores in the human with intact immune system) follows
deposition of spore-bearing particles into the alveolar
spaces. Macrophages ingest the spores, some of which
undergo lysis and destruction. Surviving spores are transported
by macrophages to mediastinal lymph nodes, germinate
into vegetative cells en route and intensively multiply
once in the lymph nodes. Once multiplication has begun,
disease follows rapidly. The infection rapidly progresses
through the following pathogenetic stages:
- Accumulation of vegetative cells in the lymphatic
system and lymphoid tissue-containing organs (spleen,
liver, and lymph nodes). This stage is characterized
by low bacteremia and low toxemia
- Increasing bacteremia, toxemia, and rapidly accumulating
organisms of bacilli in the lymphatic system and
organs
- Rapidly accumulating organisms of anthrax toxins
in blood and lymph
- Increasing massive mediastinal edema, hemorrhagic
thoracic lymphadenitis, hemorrhagic mediastinitis,
and sometimes hemorrhagic meningitis
- Increasing respiratory dysfunction and increased
vascular permeability induced by anthrax toxins
- Mediastinitis
- Sepsis
- Septic shock and death
Cutaneous anthrax (LD50 is
about 10-50 spores) occurs following the deposition
of anthrax spores into the skin through cuts or abrasions.
After the spores germinate in skin tissues, toxin production
results in local edema. This route of infection has
the following stages of development:
- Initial pruritic macule or papule
- Spherical ulcer, sometimes with 1- to 3-mm vesicles
around periphery
- Black, painless, depressed eschar, usually associated
with extensive local edema
- Lymphadenitis and painful lymphadenopathy can occur
with associated systemic symptoms
Gastrointestinal (GI) anthrax (LD50 several
hundreds of thousands of spores) occurs as a result
of germination of anthrax spores deposited in the upper
or lower gastrointestinal tract. Depending on the focus
of infection, this can result in either the oropharyngeal
(upper GI tract) or ileocecal form (lower GI tract).
In the oropharyngeal form, an oral or esophageal ulcer
leads to the development of regional lymphadenopathy,
edema, and sepsis. The ileocecal form leads to partial
necrosis of the intestinal tract, resulting in bloody
diarrhea, acute abdomen, ascites, or sepsis.
Diagnosis and Treatment
Presenting Syndromes
- Influenza
- Pulmonary
- Meningitis
- Stridor
- Pleural effusions
- Mediastinitis
- Respiratory Distress
- Septic Shock
- Cyanosis
- Elevated White Blood Cells (WBC)
- Edema
Diagnostic Samples : Blood, Cerebral Spinal Fluid
(CSF)
Differential Diagnosis : Tularemia, Plague, Diphtheria
Isolation/Decon Precautions : Standard precautions
Therapy for Inhalational Anthrax: From CDC
guidelines published in the MMWR,
10/26/2001; 50(42), 909-919
For mass-casualty settings, ciprofloxacin or doxycycline
may be used.
Ciprofloxacin 400 mg Intravenous (IV) q 12h (Peds:
10-15mg/kg q 12h dosing up to 1 Gm/day)
OR
Doxycycline 100 mg IV q 12h (Peds: >8 yrs and > 45
kg, 100 mg IV q 12h; >8 yrs and
<45 kg, 2.2mg/kg IV q 12h;
<8yrs, 2.2mg/kg IV q 12h)
Plus
One or two additional antimicrobials : Rifampin,
Vancomycin, Penicillin, Ampicillin, Chloramphenicol,
Imipenem, Clindamycin, or Clarithromycin
Begin IV treatment initially. Change to oral antibiotic
therapy when clinically appropriate: Ciprofloxacin
500 mg orally (po) twice a day (BID) OR Doxycycline
100 mg po BID. (Peds: Ciprofloxacin 10-15 mg/kg po
q 12, OR Doxycycline as follows: >8 yrs and >45
kg, 100 mg po BID; >8 yrs and
<45 kg, 2.2mg/kg po BID;
<8yrs, 2.2mg/kg po BID). Therapy should continue
for 60 days IV and po combined.
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