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Urinary tract infection (UTI) is one of the most common bacterial infections in children, with an estimated incidence of 3 to 7 percent in girls and 1 to 2 percent in
boys by age 6.
Diagnosis should be based on the presence of both pyuria on urinalysis and a positive urine culture (>100,000 colony forming units (CFU) of a single organism for clean catch specimen, >50,000 CFU for a catheterized specimen). Both tests are necessary for diagnosis, although the clinical impression should guide initial therapy. Urine specimens collected using an adhesive bag should be avoided, given the high rate of false-positive results. When UTI with fever or other symptoms leads to suspicion of pyelonephritis, dimercaptosuccinic acid (DMSA) renal scintigraphy can help confirm the diagnosis in the acute setting. Although diagnosis in an infant may require a high index of suspicion, the presence of high fever in a child under 2 should prompt consideration of UTI.
Empiric therapy should be initiated if there is reasonable suspicion of UTI, particularly in the setting of fever. Animal studies strongly suggest that timely initiation of effective parenteral antibiotics (within 24 to 48 hours) can prevent development of post-infectious renal scarring, so prompt intervention is essential. Persistent fevers should prompt further work-up or antibiotic change. Oral antibiotic therapy (usually 10 days) is appropriate if the child is non-toxic appearing and the family is reliable.
There is variation in practice with respect to follow-up imaging, used to identify anatomic abnormalities that may predispose children to recurrent infection, renal injury or other genitourinary pathology. In general, a child whose initial UTI presents with fever (or other signs of pyelonephritis) should undergo imaging, including renal and bladder sonography and voiding cystogram. Among school-aged and younger boys with UTI, we recommend similar imaging. Among toilet-trained girls, initial non-febrile UTI generally doesn’t warrant imaging, unless the child develops recurrent infection. Among children for whom cystography is indicated, initiation of antibiotic prophylaxis is appropriate.
Referrals should be based on the comfort level of the primary clinician. Although some pediatricians manage low-grade vesicoureteral reflux (VUR) themselves, patients with higher-grade VUR, or persistent low-grade VUR, should be evaluated by a urologist, as should children with other significant anatomic abnormalities.
- Caleb Nelson, MD, MPH, pediatric urologist
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