Snapshot A 40-year-old farmer from rural China presents to a local hospital for fever and cough. He reports to have had a nonproductive cough for a few days and feels more short of breath and lightheaded this morning. He works frequently with sheep on the countryside. On physical exam, his temperature is 102.2°F (39.0°C), blood pressure is 100/70 mm Hg, pulse is 96/min, and respirations are 22/min. On physical exam, there is bilateral rhonchi in the lung bases. Chest radiograph reveals a widened mediastinum and bilateral infiltrates. Introduction Classification Bacillus anthracis spore-forming and exotoxin-forming gram + rod capsule protects against phagocytosis the only bacterial with polypeptide capsule (poly-D-glutamate) transmission inhalation of spores direct contact of spores to a skin break ingestion of spores Associated conditions cutaneous anthrax most common pulmonary anthrax “woolsorter’s disease” gastrointestinal anthrax Prevention post-exposure prophylaxis 3 doses of anthrax vaccine 60 days of a single antibiotic ciprofloxacin or doxycycline are first line Epidemiology Incidence more common in areas where animal vaccination rates are low bioterrorism Risk factors intravenous drug use (e.g., heroin) occupational exposure to unvaccinated animals occupational exposure to animal hides ETIOLOGY Pathogenesis edema toxin performs the same function as adenylate cyclase, ↑ cAMP and results in black eschar with edematous borders vasodilation and hypotension infection may spread via lymphatics Presentation Symptoms pulmonary anthrax flu-like syndrome with non-productive cough nausea and vomiting hemoptysis chest pain gastrointestinal anthrax nausea and vomiting dysentery abdominal pain Physical exam cutaneous anthrax initial lesion is a painless and pruritic papule with central vesicle or bulla this progresses to painless and necrotic black eschar surrounded by edema eschar sloughs off at day 14 pulmonary anthrax mediastinitis shock hypoxia dyspnea lymphadenopathy Imaging Chest radiography indication pulmonary anthrax findings pleural effusion pulmonary consolidation widened mediastinum Studies Labs multiple methods of detection “medusa head” appearance on microscopy halo of projections culture of blood, pleural fluid, or eschar positive Gram stain of affected tissue box-car like appearance polymerase chain reaction anti-protective antigen immunoglobulin G on enzyme-linked immunosorbent assay biopsy with immunohistochemistry staining marked hemoconcentration Making the diagnosis most cases are diagnosed clinically and confirmed with positive culture, serology, or immunohistochemistry detection of Bacillus anthracis DNA in tissue Differential Community-acquired pneumonia distinguishing factor less likely to have nausea, vomiting, pallor, or unexplained mediastinal widening on chest radiography Treatment Management approach antibiotics should be given in the prodromal phase of the disease cutaneous anthrax can be treated with 1 antibiotic systemic anthrax can be treated with 2 antibiotics Medical ciprofloxacin or doxycycline indication all patients doxycycline adverse effects gastrointestinal upset, photosensitivity, teeth discoloration, and inhibition of bone growth in children photosensitivity ciprofloxacin adverse effects gastrointestinal upset, risk of tendon rupture, and QT prolongation protein synthesis inhibitor indications systemic anthrax combination therapy with fluoroquinolone or doxycycline mechanism reduces toxin production drugs clindamycin linezolid antitoxins indication all patients drugs monoclonal antibodies raxibacumab anthrax immunoglobulin Complications Bacteremia from cutaneous anthrax Death Prognosis Biphasic nature of pulmonary anthrax prodromal symptoms fulminant bactermic phase often leads to death within days