Anthrax laboratory findings
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: João André Alves Silva, M.D. [2]
Overview
Initial evaluation of patients suspected of having anthrax should be similar to the standard evaluation for patients with an acute febrile illness and should have an emphasis on obtaining pre-treatment blood and other appropriate cultures.[1] When systemic anthrax is present, abnormalities in laboratory tests include anemia, thrombocytopenia, and leukocytosis particularly in the latter stages of the disease. Other laboratory findings are hyponatremia, increased BUN, elevated transaminase levels, hypoalbuminemia, and elevated troponin. Cell cultures from the initial skin lesion, blood, CSF, or pleural fluid can identify the organism and possibly the toxins. In injection anthrax, the typical laboratory finding is an inflammatory pattern with a low CRP. A normal PT/PTT at admission does not exclude coagulopathy nor DIC.
Laboratory Findings
Show below is a table depicting the tests are used in the diagnosis and monitoring of systemic anthrax.[2]
| Test | Initial Findings | Serial Monitoring |
|---|---|---|
| CBC | Hemoconcentration Possible thrombocytopenia Leukocyte count commonly normal |
Anemia Thrombocytopenia Leukocytosis (late in disease) |
| Electrolyte Renal Panel |
Decreased sodium level Increased BUN | |
| Liver Enzymes Serum Albumin |
Elevated transaminase levels Hypoalbuminemia | |
| PT PTT D-dimer Fibrinogen |
Normal PT/PTT does not exclude DIC or coagulopathy | Low threshold for hypercoagulability workup: Haptoglobin LDH Fibrin split products ADAMTS 13 if hemolytic anemia |
| C-Reactive Protein | Characterization of inflammatory response Typically low CRP in injection anthrax | |
| Gram stain Cultures Toxic Assays (Blood, serum, CSF, pleural fluid, ascites, wound exudate*, bronchial exudate) |
Cultures usually negative after antibiotics Toxins may be detected | |
| Cardiac Enzymes BNP |
Troponin leak caused by increased cardiac demand from infection (particularly if atrial fibrillation with rapid ventricular response) | |
* Note that topical swabs from skin lesions will not pick up B. anthracis. Detection in smears or by culture requires lifting the edge of the eschar with tweezers (this gives no pain unless there is secondary infection) and obtaining fluid from underneath. The fluid will probably be sterile if the patient has been treated with an antibiotic.
References
- ↑ "Centers for Disease Control and Prevention Expert Panel Meetings on Prevention and Treatment of Anthrax in Adults".
- ↑ Hendricks, Katherine A.; Wright, Mary E.; Shadomy, Sean V.; Bradley, John S.; Morrow, Meredith G.; Pavia, Andy T.; Rubinstein, Ethan; Holty, Jon-Erik C.; Messonnier, Nancy E.; Smith, Theresa L.; Pesik, Nicki; Treadwell, Tracee A.; Bower, William A. (2014). "Centers for Disease Control and Prevention Expert Panel Meetings on Prevention and Treatment of Anthrax in Adults". Emerging Infectious Diseases. 20 (2). doi:10.3201/eid2002.130687. ISSN 1080-6040.