Uroculture: What Is It And What Is It Used For?
Urinary tract infections (UTIs) are very common pathologies. Scientific studies estimate that between 50% and 60% of women will have an episode during their lives. Many germs can cause it, but fortunately urine culture is used to detect the specific causative agent.
In 1995, the direct and indirect cost of these infections in the United States reached 2,000 million dollars annually. Of course, knowing how to identify the pathogen that causes each case is essential for the speedy recovery of the patient.
What is a urine culture used for?
First of all, it is necessary to emphasize that a urine culture and a urinalysis are not the same. The second consists of a series of tests applied to the patient sample, including macroscopic and microscopic, physicochemical tests and, if necessary, a urine culture at the end.
Therefore, not all urinalysis requires a urine culture to diagnose the patient. These are considered when the professional suspects a urinary infection in adults and children, as indicated by the United States National Library of Medicine.
How is the sample taken?
Most of the time, the urine sample will be taken at home and then taken to the trusted health center of the patient. In any case, the clinical microbiology committee of the Chilean Society of Infectology establishes each of the steps in detail in a document.
Obtaining the sample
This is a crucial stage in the urine collection process, as the fluid can become contaminated with commensal bacteria from the skin and genitourinary ducts of the patient. According to the American Society for Microbiology, any sample with less than 5% contamination is considered valid.
There are several types of sample collection, but we are going to focus our attention on the most typical of all: the patient must urinate on a pot at home and then take it to the health center. The following guidelines should be taken into account in this procedure:
- The patient should collect the first urine in the morning, as it is the most concentrated.
- It is not necessary to force the ingestion of liquids before collecting the sample, as the urine is diluted.
- It is recommended to collect a volume of 25 to 50 milliliters. The minimum quantity with which a urine culture can be performed is 3 milliliters.
It should be noted that, according to the journal Anales de Pediatría, the sample can also be obtained using other techniques, such as bladder puncture or temporary bladder catheterization. These are more aseptic than urination, but they are much more invasive procedures that are only applied in exceptional cases.
What about the sample?
According to medical portals already mentioned, there are several analyzes that are made on a urine culture, although the most common is microbiological seeding. We tell you its peculiarities in the following lines:
- A seeding loop is used and the urine sample is spread on a medium conducive to bacterial growth, usually consisting of a mixture of nutrient agar as a base on a Petri dish.
- The seeded sample is incubated for 16 or 18 hours at 35-37 ºC.
- Once incubated, the bacterial colonies that have grown – or not – on the plate are counted.
The premise is simple: if bacteria are present in the patient’s urine, they will multiply in the urine culture. This allows us to know if the person is infected or not and, through further tests – or if it is the specific means for that pathogen – the exact agent causing the infection will be determined.
Symptoms of a urinary infection
Knowing whether or not you need a urine culture to solve a discomfort that lasts over time can be a problem. Therefore, here are the most common symptoms of a urinary tract infection. The Mayo Clinic shows us the following:
- Urgent and constant urge to urinate.
- Burning sensation when urinating.
- Urine that is cloudy, red, or has a strong odor.
- Pelvic pain in women.
Depending on the section of the genitourinary system in which the bacterial colonies have settled, the symptoms will be different. Even so, the presence of the signs already described plus episodes of fever and abdominal discomfort are very common.
Urine culture results
The results of the examination are easy to interpret: the normal proliferation value implies that everything is in order, thus ruling out a bacterial infection in the patient. On the other hand, a positive test result implies the presence of bacteria or fungi in some area of the urinary tract.
In these situations, the professional who handles your case will determine the relevant antibiotic or antifungal for each occasion. Remember to strictly follow the doctor’s recommendations, as treatment stopped before its time can complicate the evolution.
Urine culture in pregnancy: is it important?
According to the Inatal organization, urine culture during pregnancy is especially important. Pregnant women are more prone to bacterial infections, due to the physiological changes that occur during the gestation period.
Furthermore, many are asymptomatic. A urine infection, even if it does not cause clinical signs in the mother, can lead to unwanted complications, such as an increased risk of preterm delivery.
The importance of urine culture
As you may have read in these lines, urine culture is one of the tests included in the urinalysis if the medical professional suspects an infection in the patient. This simple laboratory technique allows scientists to isolate and identify the pathogen in each case.
The collection of the sample is very simple and can be done at home, although there are exceptional cases that require punctures and catheters. A negative culture indicates the absence of the bacteria in the genitourinary tract of the patient, while a positive culture requires the use of antibiotics or antifungals.
