Urine Cultivation: What Is It And What Is It Used For?

You’ve probably had a urine test someday and wondered what happened to the sample after you took it to an expert. Urine culture is one of the methods used to isolate pathogens.
Urine culture: what is it and what is it used for?

Urinary tract infections are very common. Scientific studies estimate that 50-60% of women get one during their lifetime. Urinary tract infections can be caused by many bacteria. Fortunately, urine culture is a way to accurately identify the factor that caused the infection.

Identifying the pathogen that caused the infection is very important, of course, because it allows the patient to recover quickly.

What is urine cultivation used for?

First, it should be emphasized that urine culture and urine testing are not the same thing. The latter consists of a number of different tests, including macroscopic and microscopic tests, physico-chemical tests and, if necessary, urine culture.

Therefore, not all urine tests require urine culture for diagnostic purposes. According to the U.S. National Library of Medicine, it is considered when urinary tract infection is suspected in adults and children.

How is the sample taken?

Most often, the  patient takes a urine sample at home and then takes it to a sampling center. The Clinical Microbiology Committee of the Chilean Infectious Diseases Association has mentioned each of its stages in its scientific paper.

Urine culture is a means of isolating pathogens from urine
Medical professionals process urine samples in laboratories.

How to take a sample

This is a crucial step in the urine collection process, as fluid can become contaminated with commensal bacteria on the skin and urinary and genital organs. According to the American Society of Microbiology,  all samples contaminated with less than 5% are eligible.

The sample can be collected in several different ways, but we are now going to focus on the most common way. In it, the patient urinates into a container at home and takes it to a sampling center. This procedure should take into account the following guidelines:

  • Collect the first urine of the morning,  as it is the most concentrated.
  • Do not drink too much fluid before collecting the sample as it will dilute the urine.
  • Experts recommend collecting 25 to 50 milliliters of urine. At least three milliliters are needed for urine culture.

According to the Annals of Pediatrics , the sample can also be taken by other methods, such as aspiration above the pubic bone or bladder catheterization. Although they are more aseptic than urinating in a jar, they are also much more intrusive procedures that are used only in exceptional cases.

What happens to the sample?

According to the medical sources mentioned above, several analyzes are performed on urine culture. The most common is bacterial culture. We report it below:

  • The urine sample is applied by means of a culture loop to a culture medium leading to bacterial growth, usually based on an agar medium mixture in a petri dish.
  • The cultured sample is grown for 16 to 18 hours at 35 to 37 ° C.
  • The expert then counts the number of bacterial communities grown in the dish.

The premise is simple:  if there are bacteria in a patient’s urine, they multiply in the urine culture. This is how medical professionals find out if a patient has an infection or not. Additional tests, or in the case of a culture medium specifically for a specific pathogen, will reveal the exact cause of the infection.

Symptoms of urinary tract infection

It can be difficult to know if urine culture is needed to solve your own ailment. Here are the most common symptoms of urinary tract infection according to the Mayo Clinic:

  • Strong and constant need to urinate.
  • Burning sensation when urinating.
  • Red, pink or cola-colored urine – a sign of blood in the urine.
  • Pelvic pain in women – especially in the middle of the pelvis and in the area around the pubic bone.

Symptoms vary depending on where in the urinary tract the bacterial infection is. Nevertheless, the symptoms already described, as well as fever and abdominal discomfort, are very common.

Urine culture: results

The results of urine culture are very easy to interpret. Normal values ​​mean that everything is fine, which rules out the patient’s bacterial infection. Instead, a positive test result indicates the presence of bacteria or fungus in some part of the urinary tract.

In these situations, the  attending physician will prescribe the correct antibiotic or antifungal to the patient. Be sure to follow your doctor’s instructions carefully, as stopping treatment too soon can lead to complications.

The urine culture sampling process is an important step as the sample must not be contaminated.

Is urine culture important during pregnancy?

According to the website of the non-profit organization Inatal,  urine culture during pregnancy is very important. Pregnant women are more susceptible to bacterial infections due to physiological changes during pregnancy.

In addition, many are asymptomatic. Even if a urinary tract infection does not cause clinical signs in the mother, it can still lead to adverse complications such as an increased risk of preterm birth.

Why urine culture is important

As you can see, urine culture is an important part of a urine test when a patient is suspected of having an infection. This simple laboratory method can be used to isolate and identify the pathogen in question in each case.

It is easy for patients to collect a sample at home. However, in some exceptional cases, aspiration and catheters above the pubic bone are required. Negative urine culture indicates the absence of bacteria in the urinary tract,  while positive culture requires antibiotics or antifungals.

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