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The Presence of Bacteria in a Urinalysis Sample

written by: Teresa Martin•edited by: lrohner•updated: 2/28/2011

Pain, pressure and frequency of urination can indicate an infection. Diagnosis of the presence of bacteria in urinalysis requires examination of a urine specimen as well as a culture and sensitivity for best treatment with antibiotics.

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    The Urinary Tract System

    The urinary tract system includes the urethra, the bladder and the kidneys. Urine is formed in the kidneys which remove substances that can be reused by the body such as salts, and other chemicals. The waste then flows along ureters to the bladder which is a holding area for urine. It is finally eliminated through the urethra. The urinary tract system is sterile, however bacteria or other microorganisms can accumulate in the urinary tract system.

    Should there be difficulty in urinating, greater frequency or pain upon urination laboratory testing may be required. The presence of bacteria in urinalysis is a signal to a physician of the possibility of a urinary tract infection, or UTI.

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    Common Bacteria Found in UTIs

    One of the most common bacteria in urinalysis is Escherichia coli, better known as E. coli. E coli is one of the most predominant bacteria in the colon that can cause a UTI. Most urinary tract infections begins with a single bacteria making its way into the urethra and beginning to grow and multiply. A bacterial infection in the urethra is called urethritis. If the bacteria travels up the urethra to the bladder, it causes an infection of the bladder called cystitis. Bacteria that travels up to the kidneys via the ureters causes an infection in the kidneys called pyelonephritis.

    Early detection of bacteria in urinalysis requires a collection of a urine sample. The sample should be a clean catch specimen to eliminate the possibility of bacteria residing on the skin contaminating the specimen. A clean catch specimen is obtained by washing the genital area and beginning to urinate. The collection cup in then positioned to collect the urine midway through urination. This prevents confusion as to whether bacteria present are simply contaminants or need to be treated medically.

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    Laboratory Testing of Urine for Bacteria

    Once a urine sample has been collected a technician will test the urine for the presence of bacteria, white blood cells and red blood cells. The sample is examined with both a dipstick or chemical analysis and microscopically. If the presence of bacteria in urinalysis indicates it, a culture can be required to identify both the quantity and kind of bacteria. The culture uses a calibrated loop to inoculate the agar which has nutritional components to enhance bacterial growth. The number of colonies growing on the agar in a 24-hour period of time aids in determining the severity of the infection.

    Sensitivity to antibiotics follow to ensure that antibiotic treatment will be effective against the infecting organism. Antibiotic therapy generally is very effective and symptoms usually clear up within a few days.

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    Reoccuring Infections

    A urinary tract infection is more common in females than males. Females develop a greater tendency to have UTI as they age. Once a female has experienced a UTI there is a high likelihood of having another infection at some point in life. If the same kind of bacteria in urinalysis occurs, followup tests may include examination of the urinary tract system for abnormalities in the structure. These tests might include injection of dye to view the outline of the urinary tract system, an ultrasound or cytoscopy to view the bladder.

    Drinking plenty of water throughout the day can aid in preventing other infections. It is also important to empty the bladder as soon as the need to urinate arises. Water and frequent urination can help to flush out bacteria preventing colonization of bacteria along any part of the urinary tract system.

    Some physicians recommend drinking cranberry juice as a preventative measure. Unsweetened cranberry juice is recommended as bacteria tend to thrive in the presence of sugar.