Beta-Lactamase Production (Screening for Extended-Spectrum Beta-Lactamase, ESBL) in Serum/Plasma
This test checks whether your blood contains enzymes that can make certain antibiotics less effective. These enzymes, called beta-lactamases, may help bacteria resist antibiotics like cephalosporins.
["Helps determine if certain antibiotics may not work well against your infection."]
Key facts at a glance
- LOINC
- 73470-7
- Short code
- Cefepime ind plt IgM SerPl Ql FC
- Synonyms
- Cefepime ind plt IgM SerPl Ql FC
- Category
- hematology
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- flow-cytometry
- CPT
- 82784
- 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 Might Be Ordered
Your doctor may order this test if you’ve been treated with antibiotics like cefepime (a type of cephalosporin) and your infection doesn’t improve, or if you’ve had recent exposure to bacteria that produce these enzymes. It’s also used in settings where infections are common in hospitals or nursing homes.
What to Expect Before the Test
No special preparation is needed. You’ll have a small needle inserted into your arm to draw a blood sample. The process is quick and usually painless. If you’re on blood thinners, let your doctor know before the test.
What the Test Results Mean
A positive result means your blood contains beta-lactamases that could make cephalosporins less effective against certain bacteria. This doesn’t mean you have an infection—it’s a test for the enzyme’s presence. Your doctor will discuss next steps, such as changing antibiotics or further testing.
Common Causes of a Positive Result
Bacteria like *Escherichia coli*, *Klebsiella*, or *Enterobacter* species sometimes produce these enzymes. A positive result doesn’t always mean you’re infected—it’s about the bacteria’s potential to resist antibiotics.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
This test is critical in guiding antibiotic treatment decisions. If bacteria produce beta-lactamases, your doctor may choose different antibiotics or use combinations that target the enzyme. Early detection helps prevent antibiotic resistance and improves infection outcomes.
Short name
ESBL Screen (Serum/Plasma)
Frequently asked questions
What does a positive result mean for my health?
Will I need to take any special medicine if my test is positive?
Can I still have antibiotics if my test is positive?
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