Bacterial Culture with Antimicrobial Susceptibility Testing (Serum/Plasma)
This test checks for bacteria in your blood or plasma and determines how your body might respond to antibiotics.
["Helps identify infections and guide antibiotic treatment choices."]
Key facts at a glance
- LOINC
- 85835-7
- Short code
- ESBL-CTXM8-25
- Synonyms
- blaCTX-M-8+blaCTX-M-25 Gr Islt/Spm Ql
- Category
- chemistry
- Sample
- serum
- Container
- Sterile transport container or appropriate bacterial culture transport medium; for serum, use serum separator tube (SST) or red-top vacutainer tube
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 0–120 years
- Method
- molgen
- CPT
- 87798 (unlisted infectious agent detection by nucleic acid; may vary by lab)
- SNOMED
- 122450008 | Microbial culture AND sensitivity (procedure)
- Specimen volume
- 1-2 mL serum or appropriate clinical specimen for bacterial isolation
- Stability
- Serum: Room temperature 8 hours, Refrigerated (2-8°C) 7 days, Frozen (-20°C or below) 30 days. Bacterial isolates: Refrigerated (2-8°C) for up to 48 hours prior to molecular testing
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 24–72 hours
- Order
- routine
Why This Test Is Done
Your doctor may order this test if you have signs of a serious blood infection (sepsis), fever without an obvious cause, or other symptoms like chills, rapid breathing, or confusion. It’s also used to confirm infections in people with weakened immune systems or those receiving chemotherapy.
How the Test Works
A blood sample is taken and placed in a special medium where bacteria can grow. After incubation, the lab checks for bacterial growth and tests how different antibiotics affect them.
Sample Collection
A needle is used to draw blood from a vein in your arm. You may feel a brief pinch, but it usually doesn’t cause discomfort. The blood is then sent to the lab for testing.
Results and Follow-Up
Results take several days to a week. If bacteria are found, your doctor will use the antibiotic sensitivity results to choose the best treatment. Follow-up tests may be needed to ensure the infection is fully cleared.
Reference range
Negative (Target resistance genes blaCTX-M-8 and blaCTX-M-25 not detected)N/A
No special patient preparation required. Specimen should be collected prior to administration of antibiotics when possible for optimal recovery of resistance determinants.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical Significance
Short name
Bacterial Culture & Sensitivity
Frequently asked questions
This test is critical for diagnosing bloodstream infections, guiding antibiotic therapy to prevent resistance, and ensuring effective treatment for severe infections that could be life-threatening.
How long does it take to get results? Results can take days to a week, depending on the lab’s processing time and whether additional testing is needed for antibiotic sensitivity.
Is there any preparation needed? No special preparation is required, but inform your doctor about any medications you’re taking, including over-the-counter drugs.
Sources
- 1
- 2Lab Tests OnlineSource
- 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