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Beta-lactamase gene detection (ESBL-specific) in serum/plasma

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

This test checks for the presence of genes that produce extended-spectrum beta-lactamases (ESBLs), enzymes that can make certain antibiotics less effective against certain bacteria, including those causing urinary tract or bloodstream infections.

Quick summary

["Helps identify bacteria resistant to common antibiotics, guiding treatment choices."]

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

Key facts at a glance

LOINC
85837-3
Short code
ESBL blaPER gene Islt/Spm Ql
Synonyms
ESBL blaPER gene Islt/Spm Ql
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
molgen
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

Why This Test Matters for You

ESBLs are enzymes produced by some bacteria that can break down antibiotics like penicillin and cephalosporins. If your doctor suspects an infection caused by bacteria with ESBL genes, this test helps determine if your current antibiotic treatment might be ineffective. It’s particularly important for infections in the urinary tract, bloodstream, or wounds.

How the Test Works

This test analyzes a small sample of your blood (serum or plasma) to detect specific genetic material (DNA) from bacteria that produce ESBLs. It’s not a direct test for the bacteria themselves but confirms the presence of the genes that make certain antibiotics less reliable.

What to Expect Before the Test

No special preparation is needed for this test. You’ll have a small needle inserted into a vein (usually in your arm) to draw blood. The process is quick and usually painless. If you’re concerned about blood draws, let your healthcare provider know.

Possible Results and Next Steps

If the test is positive for ESBL genes, your doctor may recommend a different antibiotic or a combination of treatments to target the infection effectively. If negative, it means the bacteria you’re infected with do not produce ESBLs, and your current antibiotic may still work.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

ESBL Gene Test (Serum/Plasma)

Frequently asked questions

What does a positive result mean?
A positive result indicates that the bacteria causing your infection may produce enzymes that break down certain antibiotics, potentially making them less effective. This can lead to treatment challenges and may require alternative antibiotics or stronger regimens. Your healthcare provider will adjust your treatment plan accordingly.
How often is this test used?
This test is typically used in patients with infections that do not respond to standard antibiotics, or when there is a suspicion of bacterial resistance due to travel, recent hospital stays, or exposure to certain antibiotics. It’s also common in cases of urinary tract infections (UTIs) or bloodstream infections (sepsis) where antibiotic resistance is a concern.
Can I get this test if I’m not sick?
No, this test is generally only performed if you have an active infection or symptoms that suggest bacterial resistance. It’s not a routine screening test for healthy individuals. Your doctor will determine if this test is necessary based on your medical history and symptoms.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

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