Understanding Your Medical Test: What It Is, How It Is Done, and Why Your Doctor May Order It
A laboratory test that reads the complete genetic code of bacteria to identify the specific type of bacteria and detect genes that may cause antibiotic resistance.
{"This test reads the entire genetic makeup of bacteria from a blood sample","It helps doctors identify exactly what kind of bacteria is causing an infection","The test can detect genes that make bacteria resistant to antibiotics","Results help doctors choose the most effective treatment","The test is performed on bacteria isolated from a patient's blood sample"}
Key facts at a glance
- LOINC
- 90246-0
- Short code
- BACWGS
- Synonyms
- Bacterial whole genome Islt-Seq
- Category
- chemistry
- Sample
- whole-blood
- Container
- Pure culture isolate on solid agar plate (e.g., blood agar, chocolate agar, MacConkey agar, tryptic soy agar) or in liquid broth (e.g., thioglycollate, brain heart infusion). Isolates should be submitted on appropriate transport medium in leak-proof, biohazard-compliant container (Category B shipping per IATA regulations).
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 0–120 years
- Method
- sequencing
- CPT
- 87900
- SNOMED
- 44750004
- Specimen volume
- A visible pure colony or loopful of organism (approximately 10^6 to 10^8 CFU) from a fresh culture (18-24 hours growth); minimum one isolated colony required. For liquid media, minimum 1 mL of turbid broth culture.
- Stability
- Room temperature: viable for up to 7 days on appropriate solid media. Refrigerated (2-8°C): up to 14 days. Frozen at -80°C in glycerol stock: long-term storage up to 2 years. Purified DNA: stable at -20°C for 1 year or -80°C indefinitely.
- Hemolysis max
- 0
- Lipemia max
- 0
- Icterus max
- 0
- TAT
- 48–168 hours
- Order
- routine
What is this test and what does it check for?
Bacterial Whole Genome Sequencing (WGS) is a sophisticated laboratory test that reads the complete genetic blueprint of bacteria. Instead of looking at just a small part of the bacteria's DNA, this test maps out the entire genome - all the genetic information that makes up the bacteria. This gives doctors a complete picture of what they are dealing with.
How is this test performed, and do I need to prepare for it?
First, bacteria are grown from your blood sample in a laboratory to obtain enough material. Then, specialized equipment reads the entire genetic sequence of the bacteria. Advanced computer programs analyze this genetic code to identify the specific bacterial species and look for any genes that might cause antibiotic resistance. The entire process may take several days to complete.
Why might my doctor order this test for me?
Your doctor may order this test if you have a serious bacterial infection that is not responding to standard antibiotics, if there is concern about antibiotic-resistant bacteria, or to track outbreaks of infection in hospitals or communities. The test provides detailed information that helps doctors select the most appropriate treatment for your infection.
What should I expect before, during, and after the test?
The test requires a blood sample, which is drawn from a vein in your arm. The blood is then sent to a laboratory where bacteria are grown and their entire genetic code is sequenced. Results typically take longer than standard bacterial tests - often 3-7 days or more - because of the detailed analysis involved.
Reference range
Interpretive report provided. Results expressed as identified organism(s), sequence type, resistance genes, virulence factors, and phylogenetic relationship when applicable. No quantitative reference range applies; qualitative interpretation only.N/A
No special patient preparation required. Specimen collection should occur prior to initiation of antimicrobial therapy whenever possible to maximize recovery of viable organisms and sequence yield.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
This test plays a critical role in modern infectious disease management. By reading the complete bacterial genome, it can identify the exact species and strain of bacteria causing infection, detect antibiotic resistance genes before treatment begins, guide selection of effective antibiotics, track how infections spread between patients, and help investigate outbreaks in healthcare settings. This information is especially valuable for treating serious infections like sepsis, bloodstream infections, and infections caused by antibiotic-resistant bacteria such as MRSA or drug-resistant tuberculosis.
Frequently asked questions
Is this test painful?
How long does it take to get results?
Do I need to prepare for the test?
What happens after I get the results?
Is this test different from a standard bacterial culture?
Sources
- 1
- 2
- 3
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.
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