The kidneys, ureters, bladder and urethra filter and expel wastes from the body. The most common sites for a urinary tract infection (UTI) are the bladder and the urethra. Bladder infections and urethritis (infection of the urethra) are more common in females but can occur in men as a result of prostate gland problems or sexual activity. Risk factors include dehydration, pregnancy, diabetes, past infections, use of some personal care products or medications, and structural abnormalities. Symptoms of a UTI are frequent trips to the bathroom with little urination, a burning sensation during or after voiding, and abdominal pain. Tests can diagnose a UTI and determine treatment.
Specimen Collection
A sample of urine is collected and may be dipped with a test strip to confirm infection and the need for further analysis. Urine collection is usually done via a clean-catch, in which the patient washes herself with disinfectant wipes and voids a small amount before catching the specimen in midstream. The goal of the clean-catch technique is to eliminate contamination and avoid false results. For small children, a special bag with adhesive can be attached over the genitals and worn under a diaper. If necessary, sterile collection may be done with the insertion of a urinary catheter, or small, flexible tube, into the bladder. Urine should be collected at least one hour after the last void and, preferably, first thing in the morning, when it is more concentrated. False negatives may be due to diluted urine or a low bacteria count.
Urinalysis
Inspection of the urine specimen will reveal probable signs of infection, such as a strong ammonia odor (created by the action of the bacteria) and a cloudy appearance. Test strips dipped in the urine will change color if it contains blood cells, leukocyte esterase (pus) and nitrites (the result of pathogens metabolizing dietary nitrates). Protein in the urine is usually explained by fever. These substances are absent in normal urine. In her 2002 Medscape article, "Urinary Tract Infection: Providing the Best Care," Margaret Fitzgerald, MS, states that alkaline urinary pH is also associated with infection. Positive findings should trigger treatment with a broad-spectrum antibiotic. Microscopic analysis can count bacteria and rule out specimen contamination.
Culture and Sensitivity
Antibiotics interfere with the accuracy of culture and sensitivity tests; urine must be collected and sent to a laboratory prior to treatment. A sample placed in a medium will grow bacterial colonies within a few days. According to Fitzgerald, Escherichia coli (E. coli), a bacteria normally found in the intestines, is the most common cause of a UTI. Chlamydia, group B streptococcus (GBS), Pneumococci or staphylococci might also be isolated.
Once cultures are established, the laboratory can test medications to determine sensitivity. The final report provides a list of antibiotics and the degree to which they are able to kill the cultured bacteria. This information will prove valuable should initial treatment fail to clear up the infection.
