What is a urine culture?
A urine culture test checks urine for germs (microorganisms) that cause infections. Urine is your body’s liquid waste (pee). Culture is the medical term for growing microorganisms like bacteria and yeast in a laboratory setting.
A lab adds growth-promoting substances to a urine sample. If bacteria or yeast (a fungus) are present, they start multiplying. This growth indicates an infection in your urinary system.
What is the purpose of a urine culture?
Healthcare providers order urine cultures to check for urinary tract infections (UTIs). A UTI can occur when bacteria enter your urethra, the tube that carries urine out of your body. UTIs typically start in your bladder (the organ that holds urine). They can spread to your kidneys (the organs that make urine) or your prostate.
A urine culture test also:
- Identifies the bacteria or yeast causing the infection so your healthcare provider can select the most effective treatment and determine if the bacteria is resistant to any antibiotics.
Who needs a urine culture?
Your healthcare provider may order a urine culture test if you get frequent or hard-to-treat UTIs. Generally, only people who have symptoms of a UTI need a urine culture. UTIs can affect all genders, but women tend to get them more often than men do.
Risk factors for frequent UTIs include:
- Frequent intercourse, especially with new partners or if you use spermicides.
- Kidney disease, including kidney stones.
- Problems draining your bladder fully, especially if you use a urinary catheter to drain urine.
- Weakened immune system due to autoimmune diseases, organ transplant or cancer treatments.
What is the difference between a urine culture test and urinalysis?
A urinalysis and urine culture both require a urine sample. Your healthcare provider may first do a urinalysis. This quicker test screens urine for the presence of red and white blood cells and bacteria that can indicate an infection.
A urinalysis can’t identify the specific bacteria causing a UTI. For that information, you need a urine culture.
Can a urine culture detect a sexually transmitted infection (STI)?
At one time, healthcare providers used bacterial culture tests to diagnose STIs like chlamydia and gonorrhea. This test wasn’t a urine culture test. Instead, healthcare providers grew (cultured) cells from inside the urethra.
Today, a urinalysis may detect signs of these STIs. But to diagnose an STI, healthcare providers tend to use more accurate methods like testing fluid from the vagina or penis.
Can a urine culture detect E. coli?
A urine culture test can identify Escherichia coli (E. coli) bacteria. E. coli is the cause of most UTIs. E. coli bacteria live in the digestive tract and are found in poop. If fecal matter makes its way from your anus to your vulva or penis, the bacteria can enter your urethra and cause a UTI.
Your vulva (the outer part of your female genitals, where your vagina and urethra open) is close to your anus. That’s one reason why women are more prone to UTIs. To prevent this kind of infection, everyone should wipe from front to back after using the toilet, regardless of gender.
Can a urine culture detect Streptococcus (strep) infections?
Group B strep bacteria are a less common cause of UTIs. A urine culture can detect these bacteria, which live in the urinary and digestive systems.
Group B strep is more likely to cause UTIs in women who are pregnant. Treating the infection with antibiotics before childbirth is critical. Treatment prevents someone who is pregnant from passing the bacteria to their newborn. Babies with a strep B infection also need antibiotics.
How should I prepare for a urine culture?
Your healthcare provider will let you know if you need to take any special steps before providing a urine sample.
Your healthcare provider may ask you to:
- Not pee for at least an hour before giving a urine sample.
- Drink at least 8 ounces of water 20 minutes before the sample collection to ensure there’s enough urine to test.
- Collect a urine sample first thing in the morning.
What happens during a urine culture?
A urine culture requires a clean catch urine sample. This term means a urine sample as free of outside contaminants as possible, such as normal bacteria that live on your skin. You might provide this sample at your healthcare provider’s office or a lab testing facility. In certain situations, you might collect the urine sample at home.
- Wash your hands with soap and warm water.
- Use an antiseptic wipe to thoroughly clean the opening of the urethra (the vulva and vaginal area or the head of the penis).
- Let out a small amount of urine into the toilet and then stop midstream.
- Place a sterile cup under the vulva or penis before you resume peeing. Don’t let the cup touch your skin.
- Collect the designated amount of urine in the cup (usually 1 to 2 ounces). Most people fill the cup before they finish peeing.
- Stop midstream again (if possible) and hold the cup out of the way until you’re done urinating.
- Set the cup down, place a lid on it (if provided) and put it in the designated collection area. Don’t forget to wash your hands again.
What are other ways to collect a urine sample?
For infants and young children, and adults who are ill, hospitalized or elderly, a healthcare provider may use one of these methods:
- Catheterization: Your healthcare provider inserts a catheter (thin, flexible tube) through your urethra to reach your bladder. Urine flows out of the catheter into a sterile collection bag.
- Aspiration: Your healthcare provider inserts a thin needle through numbed abdominal skin into your bladder to draw urine into a collection bag.
- Urine bag (U bag): For infants and young children, you might attach a urine collection bag with sticky adhesive directly to their penis or over their vulva. After your child urinates, you empty their urine into a lidded container. Keep the container refrigerated until you drop it off at your healthcare provider’s office or lab.
How long does a urine culture take?
It takes just a few minutes to give a clean urine sample. Peeing into the cup shouldn’t take very long. Do spend the time to clean your vulva or penis before you pee to ensure a clean catch urine sample.
After the lab receives your urine sample, they grow the culture in an incubator for 24 to 48 hours. The incubator is set at the average temperature for the human body: 98.6 degrees Fahrenheit (37 degrees Celsius).
What are the risks of a urine culture?
It’s very safe to provide a urine sample through the clean catch method. There is a slight risk of infection with the catheter or needle method.
Results and Follow-Up
When will I get the urine culture results?
It may take up to three days for the lab to complete the test and send back the results. Your healthcare provider will call you or have you come into the office to review the results.
What does a positive urine culture test result mean?
If bacteria grow in the urine culture test and you have symptoms of an infection or bladder irritation, it means you have a UTI. This result is a positive urine culture test or abnormal test result.
The lab conducts an antibiotic sensitivity test on the bacteria in the cultured sample. Also called an antibiotic susceptibility test, this test identifies the type of bacteria causing the infection and which antibiotics the bacteria is sensitive to, meaning which antibiotics will kill the bacteria. This information helps your healthcare provider select the most effective antibiotic medicine.
Certain antibiotics only work against certain bacteria. And some bacteria have antibiotic resistance. This means the antibiotic no longer can stop that type of bacteria from growing. Antibiotic-resistant infections are harder to treat.
What does a negative urine culture test result mean?
A negative, or normal, urine culture test result means the urine sample showed no signs of bacteria or yeast. You don’t have a UTI. The range for normal test results can vary depending on the lab doing the test.
If you still have symptoms like painful urination (dysuria) or blood in the urine (hematuria), your healthcare provider may order imaging scans or other tests. In rare instances, these symptoms may indicate bladder cancer.
What should I ask my healthcare provider?
You may want to ask your healthcare provider:
- Why do I need a urine culture test?
- Do I need to fast (not eat or drink), stop smoking or stop medicines before the test?
- When will I get the test results?
- Should I be concerned about the test results?
- Will I need additional tests?
- How can I prevent a UTI?
A note from Cleveland Clinic
A urine culture looks for bacteria that cause UTIs. If you have a UTI, an antibiotic sensitivity test can pinpoint the bacteria. This information helps your healthcare provider choose the best medicine to clear up your infection. A urine culture test may also take place after treatment to ensure your infection is gone. For most people, a simple clean catch urine sample is all a lab needs for the test. More rarely, a healthcare provider might use a catheter to collect your urine sample. If you’re prone to UTIs, talk to your healthcare provider about steps you can take to lower your risk of getting them.
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