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Culture Urine

Interpreting Results
Culture Urine

Overview of Culture Urine

What is Culture Urine?

Culture Urine is a urine test which is used to detect and diagnose a microbial infection of the urinary tract.The waste products are excreted out of the blood by the kidneys in the form of a light straw colored liquid called urine. The path taken by the urine from the kidneys to the outside is called the urinary tract. The urinary tract gets sometimes infected by microorganisms. The culture urine test is performed to detect and diagnose a microbial infection of the urinary tract.

Why is Culture Urine done?

·       To detect and diagnose a urinary tract infection (UTI) 

·        To screen for urinary tract infections in the first trimester of pregnancy

·         As a part of routine health checkups

What does Culture Urine Measure?

The culture urine test is performed to detect and diagnose a microbial infection of the urinary tract. The metabolic processes in the body produce products called metabolites which are present in the blood. Some of them are utilized by cells, while others are wastes which are filtered out of the blood by the kidneys in urine. Urine produced by the kidneys pass through ureters into the urinary bladder where it is stored until the urinary bladder is full. Once full, the urinary bladder releases the urine through another tube called urethra to the outside of the body. The pathway followed by urine from the kidneys to the outside is called the urinary tract. The urinary tract may be infected by some microorganisms causing various conditions. Urine is normally sterile, but if urinary tract infection occurs, the pathogenic microorganism may be found in urine. A urine sample is collected and cultured to detect such an infection and to identify the microorganism causing it.

The collected urine sample is placed on an agar medium (nutrient solution mixed with agarose gel) and incubated at body temperature for 24 to 48 hours. This allows growth of the microorganisms in the sample if any. Growing microorganisms form different types of colonies on the agar which are studied further in a laboratory to determine the exact microbe causing the UTI.

Once the pathogen is identified, antibiotic susceptibility test is performed to guide treatment for the UTI being tested for. This may be done by two ways. The conventional method involves the use of small filter paper discs with antibiotic of known concentration and placing them on agar plate where the pathogen is cultured. The antibiotic creates a small area around the discs where the microorganisms do not form colonies. The radius of this zone is measured to estimate the efficacy and strength of that antibiotic in treating the UTI. The other method involves an automated machine to detect the sensitivity pattern to find out which antibiotic can be used to treat the infection.

Preparation for Culture Urine

  • Collect the Urine Sample in a sterile container available from the lab or any pharmacy. Allow a small stream of urine to flow by and then carefully hold the cup under urine. Make sure the cup doesn’t come in contact with your skin.

Sample Type for Culture Urine

The sample type collected for Culture Urine is: Urine

Interpreting Culture Urine results


Negative result: No colonies to less than 1,00,000 CFU/ml (Colony Forming Units)

Positive result:

·         Usually more than 1,00,000 CFU/ml

·         Patient undergoing antibiotic treatment: More than 1,000 CFU/ml

·         For gram-positive bacteria like Staphylococcus aureus: Single colony

The negative result indicates no infection of the urinary tract.

The positive result indicates an infection of the urinary tract. The positive result is accompanied by an antibiotic susceptibility test.

In an uncontaminated sample, only a single type of colony is found and indicates a clinically significant positive result. However, if multiple colonies of different types are found, a sample contamination is indicated and the sample may need to be collected again.

Answers to Patient Concerns & Frequently Asked Questions (FAQs) about Culture Urine

Frequently Asked Questions about Culture Urine

Q. Is there any preparation required before the Urine culture test?
It may be advised to collect an early morning urine sample (during the first urination after waking up). Inform the doctor of any medications you may be taking. No other specific preparations are usually required before the Urine Culture Test.
Q. How is Urine culture test performed?
The test is performed on the urine sample. It is essential to prevent contamination of the sample with microorganisms naturally present on the skin. During urine collection, women should spread the labia (outer lips of the vagina) while men should retract or pull back the foreskin (fold of skin covering the glans or head of the penis). Start urinating normally and let some urine flow before collecting 20 to 30 ml urine the sterilized container available from the lab or any pharmacy. After collecting the sample, finish urinating into the toilet or urinal. This process is called midstream clean catch method. The urine sample may also be collected using a catheter inserted through the urethra directly into the urinary bladder. Sample collected through a catheter usually has no contamination.
Q. Is there any risk associated with Urine Culture test?
There is no risk associated with the Urine Culture test.
Q. What additional tests can be prescribed by your doctor in case of abnormal Urine culture test result?
Additional tests that may be prescribed are: · Urinalysis · Blood Test to detect advanced infections · Imaging tests to detect blockages in the UTI · Kidney Function Tests
Q. What can affect the Urine culture test results?
The Urine Culture Test can get affected if the patient has recently taken antibiotics before the sample collection. It may also be affected if the urine sample is not collected properly.
Q. What are the common UTI causing microorganisms?
Common microorganisms that may cause an UTI are: · Escherichia coli · Klebsiella spp. · Proteus spp. · Pseudomonas aeruginosa · Staphylococcus aureus · Enterococcus faecalis · Acinetobacter spp. · Streptococcus agalactiae · Candida spp.
Q. What are the common symptoms of UTI?
Common symptoms of UTI that may need to be tested with a Urine Culture Test are: · Frequent need for urination · Burning sensation while urinating · Clouded or strongly smelly urine · Fever and chills · Pain in the abdomen or back · Blood in urine
Q. What are the risk factors for development of UTI?
Risk factors for development of urinary tract infection include: · Gender (UTIs are more common in females than males) · Sexual intercourse · Use of diaphragms or spermicides as contraceptives · History of UTIs in first degree female relatives (mother, sister) · Recurrent urinary tract infections · Diabetes · Use of Antibiotics
Q. What are Upper UTI and Lower UTI?
The upper urinary tract refers to the portion of the urinary tract that includes the kidneys and ureters. The lower urinary tract refers to the portion of the urinary tract including the urinary bladder and the urethra. Thus, Upper UTI refers to an infection of the kidneys or ureters, while Lower UTI refers to infection of the urethra or urinary bladder. Lower UTIs are more common and indicate the preliminary stage of an infection, while Upper UTIs are rarer and indicates a much advanced stage of urinary tract infection. Upper UTIs are more severe.
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About SRL Limited

For over a hundred years, human pathology has been one of the keystones of medicine and rightly so at SRL, we offer our patients world-class Pathology services because their well-being is of the utmost importance to us. Pathology is quite simply the scientific study of the overall response of your body to any foreign influence, i.e., disease. Actually, we use this knowledge to diagnose & subsequently treat your ailment. What we basically do is carefully compare the normal structure and function of a human body (anatomy and physiology) to the abnormal structure and function we witness in an unwell human. Doing this is the most crucial phase & we take note of even the minutest details while adjudging the extent of your ailment because one slip can lead to an incorrect diagnosis, posing serious threat to your health. Our experts ensure that they are extremely careful while analyzing the samples. This is where our advanced technology chips in. SRL is proud to host state-of-the-art equipments based on the latest technology for a speedy and accurate result. We do not take any chances whatsoever with your health & well-being. Avail our Pathology services with no hesitation. You are always in good hands with SRL.

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