By the age of 11, approximately 3 percent of girls and 1 percent of boys will have developed at least 1 bacterial urinary tract infection (UTI). As these infections frequently occur in children too young for relating symptoms effectively, these estimates are likely low. Fortunately, lower UTIs may resolve in up to 40 percent of cases without treatment and upper tract "febrile" infections are adequately treated by the antibiotic therapies prescribed for otitis media and other common bacterial infections. Effective intervention in children with bacterial urinary tract infection includes three elements; diagnosis, treatment, and prevention.

There are two types of bacterial UTI; febrile and afebrile. Beyond early infancy, it is reasonable to use the terms upper and lower tract urinary infection, respectively. Lower tract symptoms include abdominal and back pain, dysuria, urgency, frequency, incontinence, and nocturnal enuresis. All of these symptoms can occur in upper tract infections, but the febrile child has an upper tract infection, pyelonephritis, unless proven otherwise. In addition, vaginitis, urethritis, viral cystitis, proctitis, and meatitis can mimic lower UTI symptoms.

• Bacterial UTI is ultimately diagnosed by culture. Spontaneous voiding is an acceptable method for obtaining a urine sample in children who can void on command. A mid-stream sample should be obtained after gentle cleansing with soap and water and drying. Bladder catheterization and suprapubic aspiration (rarely necessary) are the methods of choice in the incontinent patient. Urine collected by attaching a bag to the perineum is frequently contaminated in spite of adequate cleansing and may be used to demonstrate a normal urinalysis and thereby rule out a urinary tract infection in 95 percent of children. Any bacterial growth on culture medium obtained from sterile catheterization or suprapubic aspiration is considered significant. Most children with a UTI will have colony counts of greater than 10⁵/ml but lesser counts in a child with fever or evidence of a WBC response within the urinary tract should be treated as an infection. The likelihood of contamination is low in voided specimens by males, and as a result, all positive cultures must be addressed.

Treatment

• In children without complicating disorders, 80-90 percent of UTIs are caused by E. coli. Other organisms include Klebsiella-Enterobacter sp., Proteus sp., Streptococcus faecalis, Staphylococcus saprophyticus, and Pseudomonas aeruginosa. Antimicrobials that have established efficacy in the treatment of acute, uncomplicated UTIs in children include amoxicillin, trimethoprim-sulfamethoxazole, and cephalexin. Doses are noted in the Pediatric Formulary section. Nitrofurantoin is an effective antibiotic, but its use is limited to lower tract UTI as its tissue penetration is negligible.

• In recurrent infections, antimicrobial choices are similar. However, in such cases bacterial resistance may be a problem, especially if the patient recently has received an antimicrobial, and culture results must be monitored in order to change therapy at the first documentation of a resistant organism. Patients who are toxic, are unable to tolerate P.O. medicine, or have abnormal structure or function of the urinary tract, should initially be managed as inpatients. In such cases, initial broad spectrum therapy intravenous therapy is indicated.

• Post-treatment urine cultures are of questionable benefit in children with symptomatic lower UTIs, as they rarely provide information that would alter therapy. In children with repeated infections, cultures will differentiate bacterial persistence from reinfections. The complexities of these clinical entities warrant referral to a urologist.

• Lower urinary tract infection is not caused by inadequate hydration, improper perineal hygiene, and tight-fitting or irritating undergarments. History in these children should focus on voiding habits, difficulties with constipation or encopresis, and continence. Dysfunctional elimination of urine and stool is causative in lower UTIs. Any UTIs that occur in proximity to sexual activity should be well controlled by post-coital voiding or peri-activity pulse-antibiotic therapy.

• Children with febrile UTIs, or children with lower UTIs and repeated diagnosis of otitis media or URIs, should undergo imaging of the urinary tract that includes a structural study (ultrasound, or intravenous pyelography) and a voiding cystourethrogram. These tests will assess for elements of obstruction, anomalies, or vesicoureteral reflux, all of which require involvement of a specialist, if present.

• Finally, episodes of child abuse have manifested only by frequent UTIs or voiding complaints. This diagnostic consideration must be entertained when clinical evidence dictates.