Urine Culture and Sensitivity Test
A urine culture is a laboratory test that can identify specific types of germs that cause urinary tract infections. A urinary tract infection occurs when bacteria enter the urinary system through the urethra. Bacteria can rapidly grow and multiply, and cause an infection. This test is done to let healthcare providers prescribe the best medicine to give to their patients. It is usually done for people who are more vulnerable to complicated, repeated, or frequent urinary tract infections. These individuals often have a weakened immune system, kidney disease, or any other disease that affects the kidney such as diabetes and kidney stones.
Generally, urine culture and sensitivity tests do not require special preparations. However, you will be instructed not to urinate at least 1-2 hours before the test. To ensure that enough urine sample is produced for the test, you will be instructed to drink a glass of water 15-20 minutes before collecting the urine sample. You will also be told on how to properly collect the urine sample to avoid any contamination.
Why is the test done?
This test is useful in diagnosing urinary tract infections, especially in patients who have a catheter inserted for an extended period of time and those who have dysuria (painful urination). To find out the specific germs causing the infection and to determine the best medication, a urine culture and sensitivity test is done. To see whether the medications are working or not, a routine urinalysis can be done while you are taking the medicine. Microorganisms, particularly bacteria, can be identified through urine culture tests.
Symptoms of a Urinary Tract Infection
The following are common symptoms of a urinary tract infection:
- Pain and discomfort in the lower back and lower abdominal area
- Burning urination
- Dysuria (painful urination)
- Passing urine in small amounts
- Urinary urgency and frequency
- Cloudy urine
- Hematuria (blood in urine)
- Foul-smelling odor in urine
In severe UTI cases, the following symptoms may be experienced aside from the above symptoms:
How is the test done?
For this test, a midstream clean-catch urine sample is collected. The following is the procedure on how to collect a urine sample for the test:
- Wash your hands properly before collecting the urine sample.
- It is also recommended to clean the external genitalia, especially in women. Men should also wipe the tip of their penis. In women, the folds of the labia should be spread open and cleaned from front to back.
- The initial stream of urine should not be collected.
- Collect around 20-30 mL or urine midway in a sterile screw-top container and then void the rest into the toilet.
- The container should be tightly sealed and labeled.
- Wash your hands after collecting the urine sample.
Other Methods of Urine Collection
- Urine Collection Bag: Another way of collecting urine is through the use of a urine collection bag. This method is commonly used in infants and young children. In this method, a sterile plastic bag is attached to a boy's penis or girl's labia to collect urine. The plastic bag will catch the urine when the child urinates. The collected urine sample will then be sent to the laboratory for analysis.
- Catheter: A urine sample can also be collected with a catheter. In this method, a thin rubber tube is inserted into the urethra and bladder. Once it is in place, a urine sample can be collected by your healthcare provider.
- Suprapubic Aspiration: In a few cases, the doctor needs to collect a urine sample directly from the urinary bladder using a needle. This procedure is called suprapubic aspiration. It is usually done when all other methods have failed in collecting a sterile urine sample.
Urine Culture During Pregnancy
Pregnant women may be recommended to do a urine culture during pregnancy as a safety precaution. If pregnant women develop a urinary tract infection, it is very important to diagnose and treat it as soon as possible to prevent premature labor and other complications. Urinary tract infections are common during pregnancy. Sometimes, UTIs can even go unnoticed.
Urine sample collection is generally an easy and painless process unless you experience dysuria (painful urination) due to a urinary tract infection. There are also no known risks associated with preparing or collecting a urine sample.
In some cases, your healthcare provider may request a urine sample collected with a catheter. In this process, discomfort and pressure may be experienced during the insertion of the tube through the urethra. The tubes used are usually lubricated to make the process easier along with causing lesser pain to the patient. Your healthcare provider will also discuss some ways to effectively lessen the pain during the procedure.
In the laboratory, small amounts of the urine are put in a petri dish with a culture medium and stored at body temperature. In the next few days, yeast or bacteria may grow and multiply in the culture medium. A laboratory scientist will examine the germs under the microscope and will take note of their shape, size, number, and color to specifically identify the microorganisms.
A negative urine culture means no growth of harmful germs. If the result is positive, it means the presence of harmful microorganisms is identified. E. coli is the most common bacteria that cause urinary tract infections. More testing may be done to determine which drugs are the best to get rid of the infection.
The result of a urine culture is usually released within 2-3 days. If the result of the test is positive, your healthcare provider may prescribe an antibiotic. However, there are some cases wherein more than one kind of bacteria are present in the culture medium. In such cases, a repeat urine culture test may be necessary or it might take more days before the results are released.
Most urinary tract infections are caused by E. coli. Other types of bacteria that can cause urinary tract infections are Staphylococcus and Proteus species. Sometimes, Candida may cause an infection. Sexually transmitted diseases may also cause urinary tract infections.