Public - Anthrax - Diagnosis

Anthrax

Author: Sandro Cinti, MD; Barbara Robinson-Dunn, PhD; Niklas Mackler, MD
Editorial changes - 2008-10-10
Author information and module status



		Prevention
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		Diagnosis
		Consultation for Diagnosis
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Diagnosis
Obtain a travel or exposure history in patients with suspected anthrax. Consider cutaneous anthrax in patients with typical lesions and an exposure history. Consider the diagnosis of inhalational anthrax in patients with a febrile illness and respiratory symptoms and an appropriate exposure history. Consider gastrointestinal anthrax in patients with fever, GI symptoms, and an appropriate exposure history. Obtain appropriate laboratory studies in patients with suspected anthrax. Obtain appropriate chest imaging studies in patients with suspected inhalational anthrax. Consider the broad differential diagnosis of lower respiratory tract infections with widening of the mediastinum. Consider the broad differential diagnosis of cutaneous anthrax. Consider the broad differential diagnosis of gastrointestinal anthrax. Consider other infections in the differential diagnosis of anthrax meningitis.
History and Physical Examination Elements for Anthrax (table)
Laboratory and Other Studies for Anthrax (table)
Differential Diagnosis of Anthrax (table)


Obtain a travel or exposure history in patients with suspected anthrax.
Ask about: Travel to the Middle East, Africa, South America, or Asia Exposure to wool, hides, or animal hair from the Middle East, Africa, or Asia Exposure to concentrated forms of anthrax in a laboratory setting or as a result of an intentional release of a bioweapon containing anthrax spores Determine if the patient fits the characteristics of a high-risk exposed group if disease is the result of a bioterrorist attack. See table History and Physical Examination Elements for Anthrax.
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Consider cutaneous anthrax in patients with typical lesions and an exposure history.
Consider the diagnosis of cutaneous anthrax in patients with: Chills, fever, and constitutional symptoms An enlarging, painless lesion with eschar surrounded by edema, usually on the neck, face, hands, or arms Lesions that start as a papule and get progressively larger Vesicular satellite lesions which may or may not be present See table History and Physical Examination Elements for Anthrax. See figure Cutaneous Anthrax Lesion, Day 2. See figure Cutaneous Anthrax Lesion, Day 4. See figure Cutaneous Anthrax Ulcer With Vesicle and Ring. See figure Cutaneous Anthrax Ulcer With Black Eschar.
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Consider the diagnosis of inhalational anthrax in patients with a febrile illness and respiratory symptoms and an appropriate exposure history.
Consider the diagnosis of inhalational anthrax in patients with: Shortness of breath Fever Chest pain Nausea Vomiting Headache Altered mental status Syncope Neck pain Exposure history Suspect inhalational anthrax when the constellation of symptoms is present in a person at high risk for its development. Recognize that meningitis occurs frequently in inhalational anthrax. See table History and Physical Examination Elements for Anthrax.
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Consider gastrointestinal anthrax in patients with fever, GI symptoms, and an appropriate exposure history.
Consider gastrointestinal anthrax in patients with: Nausea Vomiting Malaise Lower GI bleeding Hematochezia Abdominal pain Fever Acute abdomen Bloody diarrhea Sepsis A history of ingestion of poorly cooked infected meat Possible inhalation of anthrax-containing material See table History and Physical Examination Elements for Anthrax.
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Obtain appropriate laboratory studies in patients with suspected anthrax.
For cutaneous anthrax: Perform Gram stain and culture of unroofed vesicle, ulcer base or edge, or eschar Consider doing a punch biopsy for immunohistochemical testing if the patient has received antibiotics or has a negative Gram stain and culture result For inhalational anthrax: Perform blood culture, Gram stain, and culture of sputum and pleural effusion (if present) Consider sending blood and pleural effusion for PCR testing For gastrointestinal anthrax: Perform culture on stool specimen Obtain blood and ascites for Gram stain, culture, and PCR For anthrax meningitis: Obtain blood and CSF for Gram stain, culture, and PCR See table Laboratory and Other Studies for Anthrax.
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Obtain appropriate chest imaging studies in patients with suspected inhalational anthrax.
Obtain chest x-ray films in a patient with fevers who is in a high-risk group during an anthrax outbreak to look for a widened mediastinum with or without pleural effusion Obtain chest CT in: All patients with fevers and a widened mediastinum on chest x-ray film and no history of chest trauma High-risk patients with fevers and pleural effusions or infiltrates on chest x-ray film during an anthrax outbreak High-risk patients with fevers and chest pain during an anthrax attack, even if the chest x-ray film appears normal See table Laboratory and Other Studies for Anthrax. See figure Mediastinal Widening in Inhalational Anthrax. See figure Mediastinal Widening With Pleural Effusion in Inhalational Anthrax.
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Consider the broad differential diagnosis of lower respiratory tract infections with widening of the mediastinum.
Consider other lower respiratory tract infections and pneumonias in the differential diagnosis of inhalational anthrax as well as noninfectious causes such as sarcoidosis, lymphoma, traumatic injury, or aneurysm. Obtain a thorough history and physical examination. Send sputum cultures for bacterial pathogen testing. Send blood cultures for bacterial pathogen testing. Send nasal swab for influenza testing. Perform a thoracentesis on patients with pleural effusions. Perform a chest CT scan if a widened mediastinum is seen on chest x-ray film. See table Differential Diagnosis of Anthrax.
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Consider the broad differential diagnosis of cutaneous anthrax.
Consider spider bites, bacterial and rickettsial infections such as tularemia, scrub typhus, rat bite fever, fungal infection (blastomycosis, histoplasmosis), and mycobacterial infection (M. marinum) in the differential diagnosis of cutaneous anthrax. Send a culture swab of fluid from underneath an eschar for culture and Gram stain if patient has not been on antibiotics. Send biopsy for immunohistochemical staining and culture if the patient has been on antibiotics or the swab Gram stain result is negative. Send serologies or cultures for tularemia and serologies for rickettsial diseases. Ask about a history of a spider bite. See table Differential Diagnosis of Anthrax.
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Consider the broad differential diagnosis of gastrointestinal anthrax.
Consider infectious diarrheas and IBD in the differential diagnosis of gastrointestinal anthrax. Send stool and blood samples for culture and stool samples for ova and parasite exam and C. difficile toxin in patients with bloody diarrhea. Perform a colonoscopy on patients with fever and bloody diarrhea if stool culture and toxin results are negative. Perform colonoscopy immediately in patients with a widened mediastinum and bloody diarrhea. See table Differential Diagnosis of Anthrax.
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Consider other infections in the differential diagnosis of anthrax meningitis.
Consider other bacterial and viral meningoencephalitides in the differential diagnosis of anthrax meningitis. Obtain a lumbar puncture in any patient with suspected anthrax and headache or mental status changes. See table Differential Diagnosis of Anthrax.
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FAQs

Barbara Robinson-Dunn, PhD has no financial relationships with pharmaceutical companies, biomedical device manufacturers, or health-care related organizations. Demetrios N. Kyriacou, MD, PhD, editorial consultant, has no financial relationships with pharmaceutical companies, biomedical device manufacturers, or health-care related organizations. Niklas Mackler, MD has no financial relationships with pharmaceutical companies, biomedical device manufacturers, or health-care related organizations. Sandro Cinti, MD has no financial relationships with pharmaceutical companies, biomedical device manufacturers, or health-care related organizations.

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