Bacterial urine culture - analysis interpretation
Bacteriological culture (bacteriological culture) of urine is a common and high-precision type of laboratory examination of urine. It is aimed at detecting infection in the urinary tract and identifying the pathogen. Urine analysis for bacterial culture involves an assessment of the level of bacteriuria, that is, the concentration of microorganisms. The urine excreted by the body is not a sterile fluid. Most bacteria end up in the discharge in the lower part of the urethra (urethra). A healthy microflora of the urethra is streptococci, some staphylococci and diphtheroids. These bacteria are normally non-pathogenic and harmless to humans. And the concentration of microorganisms in the urine is quite low. More bacteria can be detected with an incorrect test or urinary tract infection.
How is bacteriuria determined
The study is quite lengthy and requires high-quality sampling of material. For bacterial urine culture, an average morning urine portion (3-10 ml) is used, collected in a sterile disposable container. Collecting urine for analysis for bacterial culture is carried out after a thorough toilet of the genitals. The collected urine should be delivered to the laboratory within the next 2 hours. There, biological material is placed in special containers containing nutrients for bacteria (sugar broth, agar-agar). If colonies of microorganisms do not appear after a certain time, then the result of the urine culture is considered negative. If a large number of bacteria or fungi multiply in the environment, then the result is positive. The concentration of microorganisms is estimated in colony forming units (CFU). Most often, when an infection is detected, an antibioticogram is performed (determining the sensitivity of microorganisms to drugs). The results of urine analysis for bacterial culture are ready in 5-7 days.
Indications for urine culture
The analysis is prescribed by the attending physician (therapist, nephrologist, endocrinologist). Indications may include urinary tract infection, control of treatment, pregnancy, diabetes mellitus, immunodeficiency states, flora insensitivity to conventional treatment regimens.
Urine culture during pregnancy
Bacterial urine culture is taken twice during pregnancy. The first time when registering, and the second - at 36 weeks of gestation. If there are indications (protein and leukocytes in the general urine analysis, urinary tract diseases), then the analysis may be prescribed more often. Even if a woman has no complaints, urine culture during pregnancy sometimes reveals the presence of pathogenic flora - asymptomatic bacteriuria. This condition must be treated to avoid complications for the mother and baby.
Decoding of urine culture
A colony-forming unit is a single living microbial cell (or group of cells) that causes the growth of a visible colony of microorganisms. If the detected number of bacteria is up to 1000 CFU / ml, then this indicates an accidental ingress of microbes into the urine sample from the external genital organs. No treatment required. If the number of microorganisms is equal to or exceeds 100,000 CFU / ml, then we can talk about the connection of inflammation with this particular infection. It is necessary to carry out treatment with a course of antibiotics. With an intermediate result of 1000-10,000 CFU / ml, urinalysis for bacterial culture is questionable, and a second study is required. If the test is positive, the report lists specific microorganisms. These can be bacteria, fungi, protozoa. If an antibioticogram was performed, then the results of the sensitivity of microorganisms to specific drugs are given. The sensitivity of microorganisms is important when choosing a rational antibiotic therapy. Decoding of urine culture is carried out by the attending physician. Based on the results, further examination and treatment is prescribed.
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