Medical Laboratory Test: What It Is, How It Is Done, and How to Get Ready
A laboratory test that identifies and grows bacteria from a sputum sample to diagnose respiratory infections.
{"This test detects harmful bacteria causing lung or airway infections","A sputum sample is collected and sent to a laboratory for analysis","Results help doctors choose the right antibiotics for treatment"}
Key facts at a glance
- LOINC
- 17893-9
- Short code
- SPCBC2
- Synonyms
- Bacteria Spt Aerobe Cult org #2
- Category
- chemistry
- Sample
- sputum
- Container
- Sterile, leak-proof, wide-mouth container with screw-cap lid (e.g., 50 mL centrifuge tube); sterile sputum collection cup
- Units
- N/A
- Ref low
- 0.8
- Ref high
- 1.2
- Critical range
- — – 5 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 0–120 years
- Method
- aerobic-culture
- CPT
- 87077
- SNOMED
- 408841000000100
- Specimen volume
- 1-2 mL of sputum (minimum); 5-10 mL preferred for adequate analysis
- Stability
- Room temperature: 2 hours; Refrigerated (2-8°C): 24 hours. Do not freeze. Transport to laboratory as soon as possible after collection for optimal organism viability.
- TAT
- 48–168 hours
- Order
- routine
This test is a laboratory procedure that helps your doctor measure specific substances in your body to check how well your organs are working, screen for certain medical conditions, or monitor a treatment you are already receiving.
The Sputum Bacteria Culture test is a laboratory procedure that identifies specific bacteria present in your sputum (mucus from your lungs and airways). When you have a respiratory infection, bacteria can be present in your sputum. This test helps doctors find out exactly which type of bacteria is causing your infection by allowing the bacteria to grow in a special environment and then identifying them.
During the test, a trained healthcare professional collects a small sample, usually a blood draw from a vein in your arm or a urine specimen, and sends it to a laboratory where specialized equipment analyzes the sample and reports the results to your doctor.
You will be asked to cough deeply to produce sputum from your lungs (not saliva). The sample is collected in a sterile container and sent to a laboratory. In the lab, the sputum is placed on growth media that allows bacteria to multiply. After the bacteria grow, specialists identify the specific type using various techniques. This process typically takes 2-5 days.
Your doctor will give you specific instructions before the test, which may include fasting for several hours, drinking plenty of water, avoiding certain foods or medications, and telling the staff about any prescriptions or supplements you take.
Before the test, rinse your mouth with water to reduce contamination from mouth bacteria. Do not eat or drink anything except water for at least 30 minutes before collecting the sample. Collect the sample in the morning when sputum is most plentiful. If you have difficulty producing sputum, your doctor may use a procedure to obtain samples from your airways.
Reference range
INR: 0.8-1.2 (warfarin: 2.0-3.0)N/A
Patient should rinse mouth with water prior to collection to reduce oral contamination. Avoid eating, drinking, or using mouthwash for at least 1 hour before specimen collection. Collect specimen before starting antibiotic therapy whenever possible. If patient is on antibiotics, note medication and last dose time on requisition.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
This test is crucial for diagnosing bacterial respiratory infections such as pneumonia, bronchitis, and lung abscesses. By identifying the specific bacteria causing your infection, doctors can prescribe targeted antibiotics rather than using broad-spectrum medications. This personalized approach is more effective and helps prevent antibiotic resistance. The test also determines which antibiotics will work best against the identified bacteria (antibiotic susceptibility testing).
Frequently asked questions
Does this test hurt?
How long does it take to get results?
What do the results mean?
Do I need to stop taking antibiotics before the test?
Sources
- 1
- 2
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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