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Understanding Urine Culture

    • A urine culture may be ordered when symptoms indicate the possibility of a urinary tract infection, such as pain and burning when urinating and frequent urge to urinate.
    • A urine sample is kept under conditions that allow bacteria and other organisms to grow. If few or no organisms grow, the test is negative. If organisms grow in numbers large enough to indicate an infection, the culture is positive. The type of organisms causing the infection are identified with a microscope or by chemical tests. 
    • Urinary tract infections are more common in women and girls than in men. This may be partly because the female urethra is shorter and closer to the anus, which allows bacteria from the intestines to come into contact more easily with the urethra. Men also have an antibacterial substance in their prostate gland that reduces their risk. 
    •  If the urine culture is positive, other tests may be done to help choose which antibiotic will do the best job treating the infection. This is called sensitivity testing.

Requirement for urine culture


A urine culture may be done to:

1. Find the cause of a urinary tract infection (UTI).
2. Make decisions about the best treatment for a UTI based on sensitivity testing.
3. Find out whether treatment for a UTI worked.

Antibiotic therapy may be prescribed without requiring a urine culture for symptomatic young women who have an uncomplicated lower urinary tract infection. If there is suspicion of a complicated infection or symptoms do not respond to initial therapy, then a culture of the urine is recommended. Pregnant women without any symptoms may be screened for bacteria in their urine, which could affect the health and development of the fetus.

A urine culture may be ordered with a urinalysis or as follow up to abnormal results on a urinalysis.

Conventional method of urine culture

Typically, the presence of a single type of bacteria growing at high colony counts is considered a positive urine culture. For clean catch samples that have been properly collected, cultures with greater than 100,000 colony forming units (CFU)/mL of one type of bacteria usually indicate infection. In some cases, however, there may not be a significantly high number of bacteria even though an infection is present. Sometimes lower numbers (1,000 up to 100,000 CFU/mL) may indicate infection, especially if symptoms are present. Likewise, for samples collected using a technique that minimizes contamination, such as a sample collected with a catheter, results of 1,000 to 100,000 CFU/mL may be considered significant.

A culture that is reported as "no growth in 24 or 48 hours" usually indicates that there is no infection. If the symptoms persist, however, a urine culture may be repeated on another sample to look for the presence of bacteria at lower colony counts or other microo rganisms that may cause these symptoms.

If a culture is positive, susceptibility testing is done. The specimen to a laboratory, where it will be spread on a special growing surface or culture. Bacteria in the culture will grow and multiply. The bacteria will form colonies (large groups of bacteria) that will each be exposed to different antibiotics. The colonies show up as susceptible, resistant or intermediate.


means they can't grow if the drug is present. This indicates an effective antibiotic.


means they can grow even if the drug is present. This indicates an ineffective antibiotic.


means a higher dose of the antibiotic is needed to prevent growth.

Interpretation of Urine Culture Test Results

Urine Culture Normal

No bacteria or other organisms (such as fungi) grow in the culture. The culture result is negative.

Urine culture Abnormal:

Organisms (usually bacteria) grow in the culture. The culture result is positive.A count of 100,000 or more bacteria per milliliter (mL) of urine may be caused by an infection. A count ranging from 100 to 100,000 could be either caused by infection or by contamination of the sample (you may need a repeat urine culture). If the count is 100 or less, infection is unlikely; however, a count of 100 or less may also be seen if you are already taking antibiotics. If test results are positive, sensitivity testing may be done to help make decisions about treatment.

Time required in conventional test for sensitivity and treatment

A urine culture is a test to detect and identify organisms (usually bacteria) that may be causing a urinary tract infection (UTI). Urine culture results are usually ready in 1 to 3 days. Some organisms take longer to grow in the culture; for this reason, results may not be available for several days.
RightBiotic is a method for rapid urine cuture testing. It can give the sensitivity results in 4hrs.

Procedure adopted by RightBiotic

RightBiotic is designed to test for presence of bacteria and sensitivity together. It works by reducing the time for culture assay which is 24-48hrs to 4 hrs and gives a sensitivity report at the end of test is sample is found positive for bacteria.

Reliability of RightBiotic as culture and sensitivity tests

RightBiotic is as reliable as conventional culture and sensitivity tests. It is developed at Birla Institute of Technology and Sciences with funding support from DRDO under its National Programme on Micro and Smart Systems (NPMASS) and has been tested at All India Insititute of Medical Sciences, New Delhi and Medicity Insitiute of Medical Sciences, Hyderabad among other locations. The assay has shown a specificity of 100% when compared to conventional methods which means no cases of UTI are missed with this method.

Cost of RightBiotic test

The test does not cost more than standard culture and sensitivity test.

Why test with RightBiotic?

RightBiotic does the same test with the same sample for the same cost in only 4 hours compared to 48 hours of the current testing methods. Thus treatment can start sooner saving both time and money. In addition it does away with the possibility of lower bacterial counts during UTI as seen in cases where patients are already on antibiotics before the results of culture test due to the duration taken to complete the test. This often leads to retesting as symptoms persist despite normal culture reports and to a longer duration antibiotic treatment. Since RightBiotic is completed in a matter of a few hours as opposed to a few days, sensitivity test based antibiotics can be prescribed from day one and the need for longer treatment and repeat testing are considerably minimized.