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Fluorescent Immunoassay for Phenotypic Detection of Vancomycin Resistance in *Staphylococcus aureus* (Qualitative)

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

This test checks whether certain bacteria, like *Staphylococcus aureus*, may be resistant to vancomycin—a common antibiotic used to treat infections. It helps doctors decide if stronger antibiotics are needed.

Quick summary

["This test helps identify if bacteria might become harder to treat with standard antibiotics."]

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

Key facts at a glance

LOINC
50698-0
Short code
FLUAV ADM resis Islt Ql Phenotyp
Synonyms
FLUAV ADM resis Islt Ql Phenotyp
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
phenotyping
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 Is This Test Done?

Your doctor may order this test if you have a *Staphylococcus aureus* infection (such as bloodstream, skin, or bone infections) and are being treated with vancomycin. It helps assess whether the bacteria could be developing resistance, which could affect your treatment plan.

What Does the Test Involve?

A blood sample is taken to detect specific markers in your body fluids that indicate whether certain bacteria may be resistant to vancomycin. The result is qualitative (yes/no) rather than a measured value.

What Does a Positive Result Mean?

A positive result suggests that the bacteria may be developing resistance to vancomycin, which could mean your infection may require alternative antibiotics. Your doctor will discuss further steps, such as adjusting treatment or trying different medications.

What Does a Negative Result Mean?

A negative result means your body fluids do not show signs of vancomycin resistance markers, so vancomycin is likely still effective against the bacteria causing your infection. Your treatment plan may continue as planned.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Vancomycin Resistance Phenotyping (VISA/VRSA Screen)

Frequently asked questions

What does a 'positive' result mean for my infection?
A positive result means your doctor may need to switch to a different antibiotic or monitor your infection closely. This helps ensure you receive the most effective treatment possible.
How often is this test performed?
This test is usually done once during your treatment to check for resistance markers. If your infection persists or worsens, your doctor may repeat it.
Can I take antibiotics before this test?
Yes, you can take your prescribed antibiotics before the test. However, inform your doctor about any antibiotics you’ve taken recently, as they may affect the test results.
  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