Azithromycin Resistance Mutation Screening in *S. pneumoniae* (Pneumococcal) via 16S rRNA Gene Sequencing
This test checks for genetic mutations in *Streptococcus pneumoniae* (pneumococcus) bacteria that may make them resistant to azithromycin, a common antibiotic. It helps healthcare providers determine the best treatment for infections caused by these bacteria.
["This test helps guide antibiotic choices to improve infection outcomes."]
Key facts at a glance
- LOINC
- 89314-9
- Short code
- AZMRES
- Synonyms
- Bact 23S rRNA azith res mut Islt/Spm Ql
- Category
- chemistry
- Sample
- serum
- Container
- Sterile specimen container or appropriate transport medium; serum separator tube (SST) for serum specimens
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- molgen
- CPT
- 87507
- SNOMED
- 397428000
- Specimen volume
- 1-2 mL serum or appropriate sample volume per specimen type
- Stability
- Refrigerate at 2-8°C for up to 7 days; freeze at -70°C or below for long-term storage. Avoid repeated freeze-thaw cycles
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 24–72 hours
- Order
- routine
Why Is This Test Done?
Your doctor may order this test if you have symptoms of pneumonia, sinusitis, or ear infections and are being treated with azithromycin. It helps identify if the bacteria causing your infection might be resistant to this antibiotic, ensuring more effective treatment.
What Does the Test Involve?
A sample of your respiratory secretions (such as sputum or nasal swab) is collected and analyzed for genetic material from *S. pneumoniae*. The test looks for specific mutations in the 16S rRNA gene that could indicate resistance to azithromycin.
How Is the Result Used?
If mutations are found, your doctor may adjust your treatment plan to use a different antibiotic that is more likely to work against resistant bacteria. If no mutations are detected, azithromycin may still be appropriate.
What Are Possible Results?
Results may show either the presence or absence of resistance-associated mutations. Your doctor will interpret the results in the context of your symptoms and medical history to guide treatment decisions.
Reference range
Negative (No azithromycin resistance mutation detected in the bacterial 23S rRNA gene)N/A
No special patient preparation required. Specimen should be collected prior to initiation of antibiotic therapy when possible for optimal bacterial DNA detection
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Short name
Pneumococcal 16S rRNA Mutation Screen
Frequently asked questions
What does a positive result mean for my health?
How often should I get this test?
Can I take antibiotics before the test?
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