Bacteria
Anthrax
search
Anthrax
, Bacillus anthracis, Anthrax Vaccine
See Also
Biological Weapon
(
Bioterrorism
)
History
Bioterrorism
attack with Anthrax spores sent via mail in 2001
Resulted in 11 cutaneous cases, 11 inhalation cases (with 5 deaths)
Postexposure Prophylaxis
recommended for 10,000 exposures
Cost >$300 Million for
Decontamination
Schmitt (2012) Biosecur Bioterror 10(1): 98-107 [PubMed]
Pathophysiology
Organism: Bacillus anthracis
Gram Positive
rod
Spore forming aerobic
Bacteria
Pulmonary
Macrophage
s transfer spores from the lung to the mediastinal
Lymph Node
s
Necrotizing
Lymphadenitis
results, followed by
Septic Shock
Transmission
No transmission person to person
Contrast with other
Bioterrorism
agents such as
Plague
, which do involve person-to-person spread
Reservoir is in herbivores, with occasional human cases
Cutaneous contact with hides of infected animals (wild and domestic herbivores)
Cattle
Sheep
Camels
Antelopes
Ingestion of undercooked and contaminated meat
Anthrax invades intestinal mucosa resulting in necrotic ulcers
Maddah (2013) Caspian J Intern Med 4(2): 672-6 [PubMed]
Inhalation of spores (most lethal)
Infective aerosol dose: 8,000-50,000 spores
Spores may remain viable in soil for >40 years
Course
Incubation: 4-6 days (range as broad as 1 to 42 days)
Duration of illness: 3-5 days
Findings
Cutaneous ("Malignant
Pustule
")
Inoculation at site of broken skin
Painless pruritic
Pustule
s develop at inoculation site
Begins as erythematous
Papule
on exposed skin
Vesiculates and then ulcerates within 1-2 days
Surrounded by a ring of non-tender
Brawny Edema
Black eschar may form
Findings
Inhalation Anthrax
Malaise
Regional Lymphadenopathy
Two phases
Initial Phase (
Influenza
-like illness) for 1-2 days
Fever
Headache
Viral upper respiratory symptoms
Cough
No
Pharyngitis
or
Rhinorrhea
(contrast with typical URI)
Middle Phase
Transient improvement for 1-2 days
Later Phase: Rapid Deterioration
High fever
Drenching sweats
Nausea
and
Vomiting
Dyspnea
and
Hemoptysis
during dissemination
Cyanosis
Shock
Hemorrhagic mediastinitis
Thoracic
Lymphadenitis
Hemorrhagic
Meningitis
Findings
Intestinal Anthrax
Acute Gastroenteritis
type symptoms
Hematemesis
Severe
Diarrhea
Differential Diagnosis
Cutaneous Anthrax
Spider Bite
Ecthyma
gangrenosum
Ulceroglandular
Tularemia
Plague
Staphylococcus
or
Streptococcus
Cellulitis
Inhalational Anthrax
Community Acquired Pneumonia
(late phase Anthrax)
Mycoplasma pneumonia
(early phase Anthrax)
Influenza
(early phase Anthrax)
Covid19
Legionnaires' Disease
Psittacosis
Tularemia
Q Fever
Viral Pneumonia
Histoplasmosis
(fibrous mediastinitis)
Coccidioidomycosis
Labs
Rapid
ELISA
tests, PCR are now available
Cultures
Blood Culture
(high sensitivity)
Cultures of Vomitus or feces (Intestinal Anthrax)
CSF Culture
(Inhalational Anthrax)
Nasal Swab (Epidemiologic tool to identify outbreak)
Sputum Culture
(Inhalational Anthrax)
Vesicular fluid (Cutaneous Anthrax)
Gram Stain
of blood or vesicular fluid from lesion
Large,
Gram Positive
bacilli
Complete Blood Count
Neutrophil
ic
Leukocytosis
in severe cases
Imaging
Chest XRay
Widened Mediastinum (hemorrhagic mediastinitis)
Management
Suspected Anthrax Contact
Suspicious item management
See
Biological and Chemical Weapon Exposure in Mail
Decontamination
Careful
Hand Washing
with soap and water
No special
Decontamination
procedures
See
Post-exposure Prophylaxis
below
Probability of exposure should be assessed
See resources below to address probability
Lab test all patients treated with prophylaxis
Hospitalized Patients with possible Anthrax findings
Public Health to start epidemiologic evaluation
Confirm diagnosis with lab testing (see above)
Management
Antibiotics for inhalational Anthrax
Gene
ral
Combine antibiotic regimen with either
Monoclonal Antibody
(e.g. Rxibacumab) or Anthrax IgG
Initial IV management
Start with IV preparations and then transition to oral when stable
Meningitis
(confirmed or suspected)
Ciprofloxacin
(or
Levofloxacin
or
Moxifloxacin
) AND
Meropenem (or Imipenem or doripenem, or if
Penicillin
sensitive,
Penicillin
G or
Ampicillin
) AND
Linezolid
(or
Clindamycin
or
Rifampin
or Chloramphenicol)
Without
Meningitis
Ciprofloxacin
AND
Clindamycin
(or
Linezolid
)
Oral antibiotics (after initial IV) to complete a total of 60 days of antibiotics
Ciprofloxacin
or
Doxycycline
Antibiotic Dosing
Ciprofloxacin
IV: 7.6 mg/kg up to 400 mg every 8 hours
PO: 15 mg/kg up to 500 mg orally twice daily
Clindamycin
IV: 7.6 mg/kg up to 900 mg every 8 hours
Meropenem
IV: 40 mg/kg up to 2 g every 8 hours
Linezolid
IV: 15 mg/kg up to 600 mg every 12 hours (or 30 mg/kg/day divided q8h if <12 years old)
Doxycycline
IV: 200 mg IV, then 100 mg IV every 12 hours
PO: 4.4 mg/kg up to 200 mg orally once, then 2.2 mg/kg up to 100 mg twice daily
Monoclonal Antibody
or IgG Dosing (used with antibiotic regimen)
Obiltoxaximab (Anthim)
Raxibacumab (coadminister with
Diphenhydramine
)
Weight >50 kg: Give 40 mg/kg IV over 2 hours
Weight >15-50 kg: Give 60 mg/kg IV over 2 hours
Weight <15 kg: Give 80 mg/kg IV over 2 hours
Anthrax
Immunoglobulin
(Anthrasil)
Dosing in number of vials (2-7 each with 60 units) based on weight (10-60 kg)
Management
Gastrointestinal Anthrax (Ingested)
Same antibiotics as for inhalational Anthrax, but total duration of treatment is 7-14 days (21 days for
Meningitis
)
Contrast with 60 days for inhalational Anthrax
Management
Post-exposure Prophylaxis
Regimen
Anthrax Vaccine (BioThrax) at 0, 2 and 4 weeks post-exposure AND
Approved for ages 18 to 65 years
Emergency authorization for children, pregnancy, elderly
Antibiotic course for 60 days
Start with
Ciprofloxacin
or
Levofloxacin
(or
Doxycycline
)
In pregnancy and children, if Anthrax tested as susceptible, may switch to
Amoxicillin
after 14 days
Antibiotic Dosing
Ciprofloxacin
Adults: 500 mg orally twice daily
Children: 10-15 mg/kg up to 500 mg orally twice daily
Doxycycline
Adults: 100 mg orally twice daily
Children over age 8 years: 2.5 mg/kg up to 100 mg orally every 12 hours
Amoxicillin
(only if susceptible)
Adults: 500 mg orally three times daily
Children: 40 mg/kg up to 500 mg orally three times daily
Prognosis
Inhalation Anthrax (inhaled spores)
Bioterrorism
(refined spores): 95% mortality (80% if treated)
Naturally occurring: 30-45% mortality
Cutaneous Anthrax (skin contact)
Untreated: 20% mortality
Treated: Rare mortality
Intestinal Anthrax (ingested contaminated meat)
Mortality 25 to 60%
Prevention
Anthrax Vaccine
Anthrax Vaccine (preexposure) 93% effective
Indications
Deployed military to specific regions
Lab personnel at risk for exposure
Risk of infected animal handling (e.g. farmers, veterinarians)
Contraindications
Pregnancy (unless risk outweighs benefit)
Dosing
Initial: 0, 1 and 6 months
Next Booster: 12 and 18 months
Maintenance: Annually if high high risk
Postexposure Prophylaxis
as above
Empiric prophylaxis for any suspected exposure
Best prognosis with antibiotics prior to symptoms
Resources
Department of Defense Anthrax Vaccine Program
http://www.anthrax.osd.mil
Phone: 877-GETVACC
CDC
Bacteria
l and Mycotic Disease Information
http://www.cdc.gov/ncidod/dbmd/diseaseinfo/
CDC
Bioterrorism
Preparedness and Response
http://www.bt.cdc.gov
References
Gary Malet, Correspondence
(1998) Medical Management Biological Casualties, Army
(2016) Sanford Guide Antimicrobial
Seeyave (2015) Crit Dec Emerg Med 29(5): 13-21
Hendricks (2014) Emerg Infect Dis 20(2) +PMID:24447897 [PubMed]
Inglesby (1999) JAMA 281(18):1735-45 [PubMed]
Rathjen (2021) Am Fam Physician 104(4): 376-85 [PubMed]
Sweeney (2011) Am J Respir Crit Care Med 184(12):1333-41 [PubMed]
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