Skip to content

Understanding Your Medical Test: What It Is, Why It Is Done, and What to Expect During the Procedure

Published: August 9, 2026Updated: August 16, 2026

This test detects the DNA of Bacillus anthracis, the bacteria that causes anthrax, in blood that has already shown bacterial growth.

Quick summary

{"This test confirms whether bacteria growing in your blood is anthrax (Bacillus anthracis)","It uses a method called nucleic acid amplification (NAA) to detect specific bacterial DNA","A positive result means you have anthrax, which requires immediate medical treatment","Anthrax is a serious but treatable infection when caught early","Your doctor will determine treatment based on this and other test results"}

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
101369-7
Short code
BANTHPXO1
Synonyms
B anthracis plsmd pXO1 DNA Bld Pos Ql
Category
chemistry
Sample
whole-blood
Container
Positive blood culture bottle (aerobic and/or anaerobic) flagged positive by automated continuous monitoring blood culture system (e.g., BACTEC, BacT/ALERT, VersaTREK). Specimen transferred to sterile screw-cap vial or cryovial for molecular testing.
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
0–120 years
Method
non-probe-amp-tar
CPT
87801
SNOMED
418952002
Specimen volume
1-2 mL aliquot from positive blood culture broth; minimum 0.5 mL required for nucleic acid extraction
Stability
Stable at room temperature (20-25°C) for up to 24 hours from time of blood culture positivity; refrigerated (2-8°C) for up to 7 days; frozen (-70°C or below) for extended storage up to 30 days. Avoid repeated freeze-thaw cycles.
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
2–8 hours
Order
routine

What is this test, and what does it measure or look for in my body?

This test looks for the DNA of Bacillus anthracis, the bacterium that causes anthrax. It is performed on a blood sample that has already been found to contain bacteria growing in culture. The test uses a method called nucleic acid amplification (NAA) to detect specific genetic material (DNA) from the Bacillus anthracis bacterium. Specifically, it detects the pXO1 plasmid, which contains the genes responsible for producing the anthrax toxins.

Why might my doctor recommend this test, and what can the results show?

When a blood culture shows bacterial growth, doctors need to know exactly what type of bacteria is present. This test helps determine if the bacteria is Bacillus anthracis (anthrax) versus other less dangerous bacteria. Anthrax is a serious infection that requires specific treatment, so quick and accurate identification is essential for proper care.

What actually happens during the test, and how should I prepare for it?

This test is performed on a blood sample that has already been collected for a blood culture. The laboratory first detects bacterial growth in the blood culture, then uses the nucleic acid amplification method to look for Bacillus anthracis-specific DNA. The test does not require any additional blood draw beyond what was already collected for the initial culture.

Reference range

Negative (Not Detected) for Bacillus anthracis plasmid pXO1 DNAN/A

Specimen: whole-blood

No special patient preparation required. Specimen should be collected before initiation of antimicrobial therapy whenever possible. Standard blood culture collection protocols apply using aseptic technique.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

This test is critical for diagnosing anthrax sepsis, a life-threatening condition. Early detection of Bacillus anthracis allows doctors to begin appropriate antibiotic treatment promptly, which is essential for survival. Anthrax requires specific antibiotics (often including ciprofloxacin or doxycycline) and may require additional treatments depending on the form of the disease. A positive result confirms anthrax, while a negative result suggests the bacteria is not anthrax and may be a different, less dangerous organism.

Frequently asked questions

Is anthrax contagious from person to person?
Anthrax is generally not contagious from person to person. However, in rare cases, contact with infected bodily fluids or lesions can transmit the bacteria. The main routes of infection are through breathing in spores, eating contaminated food, or skin contact with infected animals or animal products.
What are the symptoms of anthrax?
Symptoms depend on how the infection occurred. Inhalational anthrax (breathing in spores) starts with flu-like symptoms and can progress to severe breathing problems. Cutaneous anthrax causes skin ulcers with a black center. Gastrointestinal anthrax causes nausea, vomiting, and abdominal pain. All forms can progress to a dangerous bloodstream infection (sepsis).
How is anthrax treated?
Anthrax is treated with antibiotics, typically for 60 days. Common antibiotics include ciprofloxacin, doxycycline, and penicillin. Treatment is most effective when started early. In some cases, additional treatments like anthrax immune globulin may be needed.
How long does it take to get results?
The time varies depending on when bacterial growth is detected in the culture and when the specific testing is performed. Your healthcare provider will inform you of the results as soon as they are available.
  1. 1
    Centers for Disease Control and Prevention - AnthraxSource
  2. 2
    Mayo Clinic - AnthraxSource
  3. 3
    LOINC Code 101369-7 ReferenceSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy