A urine culture can show if there are any bacteria present in the urine.
The results of the analysis can be used to help diagnose a disease and thus choose an appropriate treatment.
A urine culture or urine culture is a urine test that is done to detect the presence of bacteria, viruses, or fungi in the urine . This test is used to diagnose urinary tract infections such as cystitis, pyelonephritis, and urethritis. The most common agent is the Escherichia coli bacterium .
The results of the analysis can be used to help diagnose a disease and thus choose an appropriate treatment. It is a highly requested test and performed in clinical laboratories. Also, sometimes a urine culture can reveal the presence of other medical conditions such as diabetes insipidus, kidney stones , or primary glomerulone-phritis.
What is a urine culture used for?
It is recommended to perform it when a person presents symptoms of urinary tract infection such as pain or burning when urinating, frequent urination, blood in the urine, pain in the lower back or abdomen, fever or chills. These symptoms can be caused by a urinary infection, so it is important to do this test to confirm the diagnosis.
In addition, a urine culture is also recommended for people who have a chronic disease such as diabetes , kidney disease, or heart disease , as these people are at higher risk of developing UTIs.
Finally, it is also recommended for those who have a sexually transmitted disease , such as gonorrhea or chlamydia , since these diseases can cause urinary infections.
There are two types of urine culture; the standard is done to detect bacteria in the urine and the selective is done to find out if there are specific bacteria in the urine.
How is a urine culture done?
The test consists of a urine sample that is analyzed to determine which microorganisms are present , which must be alive and in optimal condition. The procedure to do it is relatively simple. First, a patient’s urine sample is collected and then transported to the laboratory for culture to identify the microorganisms present .
In the processing of the urine sample, microorganisms are isolated from the urine and it is determined what type of bacteria appears. It is done using a technique known as light microscopy , with the aid of a microscope.
Once the sample is analyzed, the doctor receives information about the type of bacteria, virus or parasite and its response to certain antibiotics. This information is used to aid in diagnosis and to initiate treatment .
What is seen in a urine culture?
A urine culture can show if there are any bacteria present in the urine , the amount of bacteria present, and what type of bacteria it is. This helps the doctor determine if there is an infection and how to treat it.
How long do the results of a urine culture take?
Usually, the results of a urine culture can take 24 to 48 hours to get back . This depends on the number of bacteria present in the urine sample, as well as the number of tests that are performed, the quality of the urine sample, the laboratory methods used to examine it, and the organism that is being looked for. If there are a large number of bacteria or additional tests are performed, the results may take longer to obtain.
Interpretation of results in a urine culture
Interpretation is important for medical decision making. Knowledge of how to interpret urine culture results can help improve patient care and therapy planning.
The results of a urine culture are presented in the report based on the standard colony density (CFU/mL). This is a mathematical expression that locates the density of the reported pathogen (identified bacteria) in relation to the density of total microorganisms found in the urine.
Negative results . When no bacteria are detected, the report shows a “not detected” result. This means that no bacteria were identified in the sample.
Positive results . When a number of bacteria below 1500 bacteria per cm3 is identified, this is considered a weak positive result, and the result is reported as “isolated”. A number of 1,500-155,000 bacteria per cm3 is considered moderately positive (and a number greater than 155,000 bacteria per cm3 is considered highly positive).
Ambiguous results . There are positive results, even if they are atypical bacteria, such as viruses, fungi, etc., that cannot be identified as bacteria. These results are indicated as ‘other’. This helps the doctor to plan the correct treatment.
It is important to correctly interpret the results of the urine culture to ensure adequate treatment and avoid future complications. The laboratory that performs it offers a detailed description of the results, explaining the density reference values and the amount of bacteria present. In this way, the doctor can correctly interpret the diagnosis of the patient.
Can there be a urinary infection with a negative urine culture?
Although the test helps to identify the infection, it is not always accurate. A negative result is usually a good indication that there is no infection . But, in some cases, a negative result doesn’t necessarily mean that. If the doctor still suspects a UTI, he or she may order other tests to rule out any infection.
contaminated urine culture
Can the results of a urine culture be contaminated? Although this test provides accurate results, they can be contaminated or result in a false positive if certain precautions are not taken. Some of the reasons why it can occur are:
Improper placement of the urine sample.
Presence of bacteria on the skin around the opening of the urethra.
Excess of intimate hygiene.
Patient with previous infections in the urine.
The proper technique is not used when collecting the urine sample.
Exposure to external sources of bacteria, such as urinating in a public restroom.