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A urine culture is a test to find germs (such as bacteria) in the urine that can cause an infection. Urine in the bladder is normally sterile. This means it does not contain any bacteria or other organisms (such as fungi). But bacteria can enter the urethra and cause a urinary tract infection (UTI).
A sample of urine is added to a substance that promotes the growth of germs. If no germs grow, the culture is negative. If germs grow, the culture is positive. The type of germ may be identified using a microscope or chemical tests. Sometimes other tests are done to find the right medicine for treating the infection. This is called sensitivity testing.
UTIs are more common in women and girls than in men. This may be partly because the female urethra is shorter and closer to the anus. This allows bacteria from the intestines to come into contact more easily with the urethra. Men also have an antibacterial substance in their prostate gland that reduces their risk.
A urine culture may be done to:
You do not need to do anything before you have this test. If you are taking or have recently taken antibiotics, tell your doctor.
You will need to collect a urine sample. Avoid urinating just before having this test.
Talk to your doctor if you have any concerns about the need for the test, its risks, how it will be done, or what the results will mean. To help you understand the importance of this test, fill out the medical test information form .
You may be asked to collect a clean-catch midstream urine sample for testing. The first urine of the day is preferred because bacterial levels will be higher.
This method helps protect the urine sample from germs that are normally found on the penis or vagina.
A health professional may collect a urine sample by placing a urinary catheter into the bladder. This method is sometimes used to collect urine from a person in the hospital who is very ill or unable to provide a clean-catch sample. Using a catheter to collect a urine sample reduces the chance of getting bacteria from the skin or genital area in the urine sample.
Collecting a urine sample from a small child or baby may be done by using a special plastic bag with tape around its opening (a U bag). The bag is attached around the child's genitals until he or she urinates (usually within an hour). Then the bag is carefully removed. To collect a urine sample from a very sick baby, a doctor may insert a needle through the baby's belly directly into the bladder. (This is called suprapubic tap).
Collecting a urine sample is not painful.
Collecting a urine sample does not cause problems.
A urine culture is a test to find germs (usually bacteria) in the urine that can cause an infection. Urine culture results are usually ready in 1 to 3 days. Some germs take longer to grow in the culture. So results may not be available for several days.
No bacteria or other organisms (such as fungi) grow in the culture. The culture result is negative.
Organisms (usually bacteria) grow in the culture. The culture result is positive.
A count of 100,000 or more bacteria per millilitre (mL) of urine may be caused by an infection. A count ranging from 100 to 100,000 could be caused either by infection or by contamination of the sample. If the count is 100 or less, infection is unlikely. But you may have a count of 100 or less if you are already taking antibiotics.
If test results are positive, sensitivity testing may be done to help make decisions about treatment.
You may not be able to have the test, or the results may not be helpful, if:
Current as of: September 23, 2020
Author: Healthwise StaffMedical Review: E. Gregory Thompson MD - Internal MedicineAnne C. Poinier MD - Internal MedicineAdam Husney MD - Family MedicineKathleen Romito MD - Family MedicineW. David Colby IV MSc, MD, FRCPC - Infectious DiseaseElizabeth T. Russo MD - Internal Medicine
Current as of: September 23, 2020
Author: Healthwise Staff
Medical Review:E. Gregory Thompson MD - Internal Medicine & Anne C. Poinier MD - Internal Medicine & Adam Husney MD - Family Medicine & Kathleen Romito MD - Family Medicine & W. David Colby IV MSc, MD, FRCPC - Infectious Disease & Elizabeth T. Russo MD - Internal Medicine
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