Urinary Tract Infection

James K. Todd, M.D.
Professor of Pediatrics, Microbiology, and Preventive Medicine
University of Colorado School of Medicine
Denver, Colorado

What is a urinary tract infection?

A urinary tract infection, also called UTI, refers to a bacterial infection of the bladder ("cystitis") or the kidneys ("pyelonephritis").


What causes a urinary tract infection?

A urinary tract infection is caused by bacteria that get into the bladder from the skin surface surrounding the urethra (the opening that urine comes out of). Because of the proximity of the urethra to the colon, organisms like E. coli are common causes of UTI.


How does it cause disease?

Once the bacteria get into the bladder, they can grow in the urine, especially if the child does not empty the bladder frequently, or if there are structural abnormalities of the urinary tract. If the infection of the bladder is not recognized and treated, it can move up the ureters (the tubes that connect the bladder to the kidney) and cause an infection of the kidneys.


Who gets a urinary tract infections?

In the newborn period, both boys and girls get UTI. Boys seem to be at an increased risk if they are uncircumcised with a tight foreskin. Thereafter, UTI is much more common in girls, presumably because they have shorter urethras, leading to more frequent bacterial contamination of the bladder. In girls, itching caused by pinworms, sitting in bathwater for an extended time period, bubble bath, wiping from back to front, and sexual activity increase the likelihood of such bacterial contamination, and thereby increase the risk of UTI. In addition, the bacteria more readily cause infection in those girls who urinate infrequently or incompletely.


What are the common findings?

The symptoms of a urinary tract infection are dependent upon the age of the child. In older children and adults, the symptoms may include a fever and back pain (i.e., a kidney infection), or increased frequency, urgency, or burning on urination (i.e., a bladder infection). Younger children may have enuresis (bed or clothes wetting) or strong smelling urine. Babies and infants often have less specific symptoms, such as a fever, poor feeding, and/or failure to gain weight.


How is a urinary tract infection diagnosed?

Most importantly, a urine specimen must be analyzed to diagnose UTI. The way the specimen is obtained is critical to interpretation. When the child is sick, it is recommended to get a urine specimen by catheter (inserting a thin tube up the urethra into the bladder). Especially in younger children, bag urines, or those obtained by having the child urinate into a cup, often are contaminated, and may confuse the correct diagnosis.

"Clean catch" urine specimens may be useful in boys and older girls who do not have a fever, if obtained by a health professional. The urine should be analyzed immediately or held in the refrigerator. A preliminary "urine analysis" can be performed by dipping a special test strip into the urine; however, it also should be cultured. These results take 24 to 48 hours. Treatment may be started based on the urine analysis.


How is a urinary tract infection treated?

Oral antibiotics, taken for 10 to 14 days, are very effective in the treatment of UTI. Antibiotics can be given at home, unless the child is very young, vomiting, and/or very sick. Once the culture result is known, antibiotics may be changed. Fluids should be encouraged to promote urine flow.

Often, physicians will obtain imaging (e.g., x-rays, ultrasound, or scanning) of the urinary tract in children with UTI. This imaging may help to determine which children require a closer follow-up, or need to see the urologist (a surgeon who specializes in diseases of the urinary tract). Most children with UTI can be cared for very effectively by the primary physician.


What are the complications?

The bacteria that cause a urinary tract infection rarely enter into the bloodstream ("sepsis"). Recurrent kidney infections may cause scarring of the kidneys. However, these complications are more common in children who have significant structural abnormalities of the urinary tract.


How can a urinary tract infection be prevented?

Preventive measures are useful to reduce the recurrence of UTI. Children should be treated for pinworms or constipation, if determined to be present, by a primary physician. Girls should take showers rather than baths, and be taught to wipe from the front to the back (to decrease fecal contamination). Little girls often tend to "hold" their urine, which should be actively discouraged. All children should be encouraged to drink fluids frequently and to urinate every three to four hours (an alarm watch and/or a discussion with the child's teacher often helps).

The primary physician may suggest follow-up appointments for urine testing, or home follow-up using urine testing strips and urine specimens collected first thing in the morning. Any child with a positive home test (if done) or the symptoms of UTI should see a physician. Some children (especially the very young, those with complications, and those with recurrences) may be put on long-term antibiotic therapy to prevent recurrent infections, but this may result in the development of more resistant organisms.


What research is being done?

Current research is focused on better ways to treat and prevent UTI at home. Physicians also are trying to identify how imaging tests can better guide the management of UTI.


Links to other information

For more information on urinary tract infections, visit: National Kidney and Urologic Diseases Information Clearing House.



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Todd JK. Office laboratory diagnosis of urinary tract infection. Pediatr Infect Dis 1982;1:126-131.

Hoberman A, Wald ER. Urinary tract infections in young febrile children. Pediatr Infect Dis J 1997;16(1):11-7.

Hoberman A, Wald ER, Hickey RW, Baskin M, Charron M, Majd M, Kearney DH, Reynolds EA, Ruley J, Janosky JE. Oral versus initial intravenous therapy for urinary tract infections in young febrile children. Pediatrics 1999;104:79-86.

Copyright 2012 James K. Todd, M.D., All Rights Reserved