Bacteria Culture Test Understand the Test & Your Results (2024)

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What is a bacteria culture test?
Bacteria are a large group of one-celled organisms. They can live on different places in the body. Some types of bacteria are harmless or even beneficial. Others can cause infections and disease. A bacteria culture test can help find harmful bacteria in your body. During a bacteria culture test, a sample will be taken from your blood, urine, skin, or other part of your body. The type of sample depends on the location of the suspected infection. The cells in your sample will be taken to a lab and put in a special environment in a lab to encourage cell growth. Results are often available within a few days. But some types of bacteria grow slowly, and it may take several days or longer.
What is it used for?
Bacteria culture tests are used to help diagnose certain types of infections. The most common types of bacteria tests and their uses are listed below.
Throat Culture
Used to diagnose or rule out strep throat
Test procedure:
Your health care provider will insert a special swab into your mouth to take a sample from the back of the throat and tonsils.
Urine Culture
Used to diagnose a urinary tract infection and identify the bacteria causing the infection
Test procedure:
You will provide a sterile sample of urine in a cup, as instructed by your health care provider.
Sputum Culture
Sputum is a thick mucus that is coughed up from the lungs. It is different from spit or saliva.
Used to help diagnose bacterial infections in the respiratory tract. These include bacterial pneumonia and bronchitis .
Test procedure:
You may be asked to cough up sputum into a special cup as instructed by your provider; or a special swab may be used to take a sample from your nose.
Blood Culture
Used to detect the presence of bacteria or fungi in the blood
Test procedure:
A health care professional will need a blood sample. The sample is most often taken from a vein in your arm.
Stool Culture
Another name for stool is feces.
Used to detect infections caused by bacteria or parasites in the digestive system. These include food poisoning and other digestive illnesses.
Test procedure:
You will provide a sample of your feces in a clean container as instructed by your health care provider.
Wound Culture
Used to detect infections on open wounds or on burn injuries
Test procedure:
Your health care provider will use a special swab to collect a sample from the site of your wound.
See Also
Principles of Diagnosis
Why do I need a bacteria culture test?
Your health care provider may order a bacteria culture test if you have symptoms of a bacterial infection . The symptoms vary depending on the type of infection.
Why do I have to wait so long for my results?
Your test sample doesn't contain enough cells for your health care provider to detect an infection. So your sample will be sent to a lab to allow the cells to grow. If there is an infection, the infected cells will multiply. Most disease-causing bacteria will grow enough to be seen within one to two days, but it can take some organisms five days or longer.
Will I need to do anything to prepare for the test?
There are many different types of bacteria culture tests. Ask your health care provider if you need to do anything to prepare for your test.
Are there any risks to the test?
There are no known risks to having a swab or blood test or to providing a urine or stool sample.
What do the results mean?
If enough bacteria is found in your sample, it likely means you have a bacterial infection. Your health care provider may order additional tests to confirm a diagnosis or determine the severity of the infection. Your provider may also order a "susceptibility test" on your sample. A susceptibility test is used to help determine which antibiotic will be most effective in treating your infection. If you have questions about your results, talk to your health care provider.
Learn more about laboratory tests, reference ranges, and understanding results .
Is there anything else I should know about a bacteria culture?
If your results show you don’t have a bacterial infection, you should not take antibiotics. Antibiotics only treat bacterial infections. Taking antibiotics when you don’t need them won’t help you feel better and may lead a serious problem known as antibiotic resistance . Antibiotic resistance allows harmful bacteria to change in a way makes antibiotics less effective or not effective at all. This can be dangerous to you and to the community at large, as this bacteria can be spread to others.
References
FDA: US Food and Drug Administration [Internet]. Silver Spring (MD): U.S. Department of Health and Human Services; Combating Antibiotic Resistance; [updated 2018 Sep 10; cited 2019 Mar 31]; [about 3 screens]. Available from: https://www.fda.gov/ForConsumers/ConsumerUpdates/ucm092810.htm
Lab Tests Online [Internet]. Washington D.C.: American Association for Clinical Chemistry; c2001–2017. Bacterial Sputum Culture: The Test; [updated 2014 Dec 16; cited 2017 Mar 4]; [about 3 screens]. Available from: https://labtestsonline.org/understanding/analytes/sputum-culture/tab/test/
Lab Tests Online [Internet]. Washington D.C.: American Association for Clinical Chemistry; c2001–2017. Bacterial Sputum Culture: The Test Sample; [updated 2014 Dec 16; cited 2017 Mar 4]; [about 2 screens]. Available from: https://labtestsonline.org/understanding/analytes/sputum-culture/tab/sample/
Lab Tests Online [Internet]. Washington D.C.: American Association for Clinical Chemistry; c2001–2017. Bacterial Wound Culture: The Test; [updated 2016 Sep 21; cited 2017 Mar 4]; [about 3 screens]. Available from: https://labtestsonline.org/understanding/analytes/wound-culture/tab/test/
Lab Tests Online [Internet]. Washington D.C.: American Association for Clinical Chemistry; c2001–2017. Bacterial Wound Culture: The Test Sample; [updated 2016 Sep 21; cited 2017 Mar 4]; [about 2 screens]. Available from: https://labtestsonline.org/understanding/analytes/wound-culture/tab/sample/
Lab Tests Online [Internet]. Washington D.C.: American Association for Clinical Chemistry; c2001–2017. Blood Culture: At a Glance; [updated 2015 Nov 9; cited 2017 Mar 4]; [about 1 screen]. Available from: https://labtestsonline.org/tests/blood-culture
Lab Tests Online [Internet]. Washington D.C.: American Association for Clinical Chemistry; c2001–2017. Blood Culture: The Test; [updated 2015 Nov 9; cited 2017 Mar 4]; [about 3 screens]. Available from: https://labtestsonline.org/understanding/analytes/blood-culture/tab/test
Lab Tests Online [Internet]. Washington D.C.: American Association for Clinical Chemistry; c2001–2017. Blood Culture: The Test Sample; [updated 2015 Nov 9; cited 2017 Mar 4]; [about 2 screens]. Available from: https://labtestsonline.org/understanding/analytes/blood-culture/tab/sample/
Lab Tests Online [Internet]. American Association for Clinical Chemistry; c2001–2017. Glossary: Culture; [cited 2017 May 1]; [about 3 screens]. Available from: https://labtestsonline.org/glossary/culture
Lab Tests Online [Internet]. Washington D.C.: American Association for Clinical Chemistry; c2001–2017. Stool Culture: The Test; [updated 2016 Mar 31; cited 2017 Mar 4]; [about 3 screens]. Available from: https://labtestsonline.org/understanding/analytes/stool-culture/tab/test
Lab Tests Online [Internet]. Washington D.C.: American Association for Clinical Chemistry; c2001–2017. Stool Culture: The Test Sample; [updated 2016 Mar 31; cited 2017 Mar 4]; [about 2 screens]. Available from: https://labtestsonline.org/understanding/analytes/stool-culture/tab/sample/
Lab Tests Online [Internet]. Washington D.C.: American Association for Clinical Chemistry; c2001–2017. Strep Throat Test: The Test Sample; [updated 2016 Jul 18; cited 2017 Mar 4]; [about 2 screens]. Available from: https://labtestsonline.org/understanding/analytes/strep/tab/sample/
Lab Tests Online [Internet]. American Association for Clinical Chemistry; c2001–2017. Susceptibility Testing: The Test; [updated 2013 Oct 1; cited 2017 May 1]; [about 4 screens]. Available from: https://labtestsonline.org/understanding/analytes/fungal/tab/test/
Lab Tests Online [Internet]. Washington D.C.: American Association for Clinical Chemistry; c2001–2017. Urine Culture: The Test; [updated 2016 Feb 16; cited 2017 Mar 4]; [about 3 screens]. Available from: https://labtestsonline.org/understanding/analytes/urine-culture/tab/test
Lab Tests Online [Internet]. Washington D.C.: American Association for Clinical Chemistry; c2001–2017. Urine Culture: The Test Sample; [updated 2016 Feb 16; cited 2017 Mar 4]; [about 2 screens]. Available from: https://labtestsonline.org/understanding/analytes/urine-culture/tab/sample/
Lagier J, Edouard S, Pagnier I, Mediannikov O, Drancourt M, Raolt D. Current and Past Strategies for Bacterial Culture in Clinical Biology. Clin Microbiol Rev [Internet]. 2015 Jan 1 [cited 2017 Mar 4]; 28(1): 208–236. Available from: http://cmr.asm.org/content/28/1/208.full
Merck Manuals: Professional Version [Internet]. Kenilworth (NJ): Merck & Co., Inc.; c2017. Culture; [updated 2016 Oct; cited 2017 Mar 4]; [about 2 screens]. Available from: http://www.merckmanuals.com/professional/infectious-diseases/laboratory-diagnosis-of-infectious-disease/culture
Merck Manuals: Professional Version [Internet]. Kenilworth (NJ): Merck & Co., Inc.; c2017. Overview of Bacteria; [updated 2015 Jan; cited 2017 Mar 4]; [about 2 screens]. Available from: http://www.merckmanuals.com/professional/infectious-diseases/bacteria-and-antibacterial-drugs/overview-of-bacteria
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FAQs

Bacteria Culture Test Understand the Test & Your Results? ›

A bacteria culture is a test to identify whether you have a bacterial infection. It can be performed on a sample of blood, stool, urine, skin, mucus or spinal fluid. Using this type of test, a healthcare provider can identify what caused an infection and determine the most effective treatment.

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How to read culture test results? ›

The results of a blood culture test are based on whether any germs were detected. The test report may list the blood culture test as either negative or positive. A negative test result means that no germs grew in the culture. A positive test result means that one or more germs developed in the dish.

What does culture mean in test results? ›

A urine culture is a test that checks your pee (urine) for bacterial or fungal (yeast) infections. “Culture” is the medical term for growing microorganisms (germs) from body fluids in a lab. Your healthcare provider will collect a sample of your pee and send it to a lab to be cultured.

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Does positive culture mean infection? ›

An abnormal (positive) result means that germs were identified in your blood. If the germs are bacteria, the medical term for this is bacteremia. This can cause sepsis. Sepsis is a medical emergency and you will be admitted to a hospital for treatment.

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How long does it take to diagnose bacteria in culture? ›

Most test samples don't include enough cells for that. So your sample is sent to a lab to allow the cells to grow until there are enough to test. Most disease-causing bacteria will be ready for testing within one to two days, but some types of bacteria take five days or longer to grow enough cells.

What is the normal range for bacteria culture? ›

In the urine culture, the number of colony-forming units (CFUs) per ml is an estimate of the number of bacteria in the sample. More than 10³ CFUs per ml in the urine culture is associated with infection. However, true infection may occur in patients with lower CFUs in the presence of symptoms and urinary leukocytes.

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How to identify bacterial infection? ›

There are some general signs of bacterial infection:

fever.
feeling tired.
swollen lymph nodes in your neck, armpits, groin or elsewhere.
headache.
nausea or vomiting.

What does a bacterial culture test for? ›

A bacteria culture is a test to confirm whether you have a bacterial infection. The test can also identify what type of bacteria caused the infection, which helps guide treatment decisions. For a bacteria culture test, a healthcare provider takes a sample of blood, stool, urine, skin, mucus or spinal fluid.

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What are five common symptoms of a bacterial infection? ›

Eight Types of Bacterial Infections and Their Symptoms

Redness around the wound, especially if it spreads or streaks.
Swelling or warmth.
Pain or tenderness.
Pus oozing or around the wound.
Swollen lymph nodes in neck, armpits or groin.
Delayed healing.

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What can a culture tell you? ›

A blood culture test helps your doctor figure out if you have a kind of infection that is in your bloodstream and can affect your entire body. Doctors call this a systemic infection. The test checks a sample of your blood for bacteria or yeast that might be causing the infection.

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How do you treat a bacterial infection? ›

Antibiotics are used to treat or prevent some types of bacterial infection. They kill bacteria or prevent them from reproducing and spreading.

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What is considered a positive culture? ›

What is a positive work culture? Simply put, a positive work culture is one that prioritizes the well-being of employees, offers support at all levels within the organization, and has policies in place that encourage respect, trust, empathy, and support.

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How to read a bacterial culture report? ›

A culture and susceptibility report from a microbiology laboratory identifies the bacterial pathogen and lists antimicrobials labeled with an S, R, or I, designating Susceptible, Resistant, or Intermediate, respectively. These labels indicate the likelihood of a clinical response to antimicrobial treatment.

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How long can a bacterial culture last? ›

Table 1. Approximate time bacterial cultures remain viable in different storage conditions.
Condition	Temp (°C)	Time (approx.)
Standard freezer	-20	1 - 3 years
Super-cooled freezer	-80	1 - 10 years
Freeze dried	≤4	15 years+

2 more rows

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Is bacterial infection infectious? ›

Many bacterial infections are contagious, meaning that they can be transmitted from person to person. There are many ways this can occur, including: close contact with a person who has a bacterial infection, including touching and kissing.

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How do I read my urine culture? ›

Interpreting test results

Positive urine culture: Typically, the presence of a single type of bacteria growing at high colony counts is considered a positive urine culture.
Negative urine culture: A culture reported as “no growth in 24 or 48 hours” usually indicates no evidence of infection.

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Sep 29, 2022

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How do you interpret wound culture results? ›

A negative result means that no organisms grew in the culture from your wound. A positive result means that bacteria or other organisms did grow and that your wound is infected. From your test results, your healthcare provider can figure out the best antibiotic to treat it.

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How do I read my strep culture results? ›

If the throat culture is positive, it means you or your child has strep throat or other strep infection. If the throat culture is negative, it means your symptoms are not being caused by strep A bacteria. Your provider will probably order more tests to help make a diagnosis.

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