Urine culture is an exam carried out to identify the presence of bacteria in the urinary system, being useful to confirm urinary infection and identify which microorganism is responsible for the infection, which helps to determine the most appropriate treatment.
To perform urine culture, also called urine culture or urine culture, it is recommended that the first urine of the morning be collected, eliminating the first stream, however the urine culture test can be carried out using urine collected during the day.
Normally, along with the urine culture, an antibiogram is requested, which is only performed by the laboratory when the urine culture result is positive, which is indicative of infection in the urinary system. Through this examination, it is possible to know which antibiotics the bacteria are most sensitive or resistant to, helping to define the best treatment. Find out more about urine culture with antibiogram.
What is it for
The urine culture test is used to investigate the existence of an infection in the urinary system, such as cystitis, urethritis or pyelonephritis, for example, as it allows the microorganism responsible for the infection to be identified.
The urine culture test can be performed by anyone, and is especially performed during pregnancy, as untreated urinary infection during this period can increase the risk of miscarriage.
When is indicated
The urine culture test is recommended by the doctor when the person presents some symptoms, such as:
- Pain and burning when urinating;
- Vaginal or penile discharge;
- Very dark urine;
- Little amount of urine;
- Feeling of heaviness in the bladder;
- Itching and/or redness in the genital region;
- Strong-smelling urine.
Thus, based on the test results, it is possible to verify the infectious agent responsible for the symptoms and, thus, initiate the most appropriate treatment, which may involve the use of antimicrobials in accordance with the doctor’s instructions.
How urine culture is collected
To collect urine, you must follow the following steps:
- Wash the intimate area with soap and water;
- Move the lips away from the vagina, in women, and retract the foreskin, in men;
- Reject the first jet of urine;
- Collect the remaining urine into the appropriate container.
Urine can remain at room temperature for up to 2 hours, however, the container must be delivered to the laboratory as quickly as possible, so that the results are more reliable. The container where the urine is placed must be sterile and can be purchased at a pharmacy, but it can also be provided by the laboratory or hospital where the test will be carried out and, preferably, it must be quickly closed and taken within a short time for laboratory analysis. , to avoid contamination.
Another way to collect the urine culture test can be with the use of a probe, also called bladder catheterization, as a way of ensuring the most contamination-free collection possible, but generally, this type of collection is done on people who are hospitalized. .
In cases where the urine culture is positive, that is, the growth of an infectious agent is verified, an antibiogram is performed with the aim of identifying the antimicrobials, such as antifungals and antibiotics, that are most suitable for treatment.
Urine culture in babies
As they have a developing immune system, as well as the urinary system, it is common for babies to have urinary infections more frequently, which is also influenced by the fact that babies are frequently in contact with urine or feces present in the diaper.
Therefore, urine culture can also be indicated for babies, and can be done using some methods according to the baby’s age and general health, such as the perineal adhesive bag, bladder stimulation technique or suprapubic puncture, this method being more invasive and painful for the baby.
How to understand the result
The result of the urine culture test may be:
- Negative or normal: when there is no growth of bacteria colonies in the urine at worrying levels;
- Positive: when it is possible to identify more than 100,000 colonies of bacteria, and which bacteria were identified in the exam.
In case of a positive urine culture result, a urine culture is also performed to identify which bacteria is responsible for the symptoms that the person presents and the sensitivity and resistance profile of the bacteria. See more about urine culture with antibiogram.
In some cases, when sample collection or storage is not done properly, other results may be verified:
- False positive: occurs in situations where there is contamination of urine by other microorganisms, blood or medications;
- False negative: it can happen when the urine pH is very acidic, below 6, or when you are taking an antibiotic or diuretic.
The result may still be doubtful if the number of colonies is less than 100,000 cfu/mL, and it may be necessary to repeat the test. Normally, when there is an infection, more than 1,000,000 cfu/mL is detected.
However, it is necessary for the doctor to also evaluate other signs and symptoms that indicate a urinary tract infection, to assess what type of treatment is necessary, according to each case. Know how to identify the symptoms that indicate a urinary tract infection.
Other tests to detect urinary tract infections
Although urine culture is the main test to diagnose urinary infection, the common urine test, also called type 1 urine, EAS or routine urine, can also provide some signs of urinary infection, such as the presence of bacteria, leukocytes, epithelial cells and/or blood in the urine, positive nitrite or the presence of hyphae, in addition to changes in the color and smell of the urine, for example.
Therefore, the doctor will be able to evaluate the result of this test and observe the patient’s symptoms and physical examination to identify the infection, without necessarily requesting a urine culture, as it is a simpler test and the result is faster, as urine culture can take a long time. up to 3 days to be ready. Understand what the urine test is for and how to do it.
However, urine culture is necessary, mainly, to assess whether the antibiotic used is the most appropriate, to identify the bacteria in cases of repeated infections, pregnant women, the elderly, people who will undergo urinary tract surgery, or when there are doubts about that it is a urinary infection, for example.
