The American Academy of Pediatrics (AAP) has released guidelines for the diagnosis, treatment and follow-up evaluation of urinary tract infections in infants and toddlers. Published in the April 1999 issue of Pediatrics, the recommendations apply specifically to children two months to two years of age who present with fever and their first urinary tract infection. This age group is the focus of the recommendations because (1) these children may present with few recognizable signs or symptoms other than fever, and (2) these children are more likely than older children to sustain renal damage if the urinary tract infection remains undetected and untreated. The recommendations do not apply to other age groups. Children older than two years are excluded because they are more likely than younger children to have urinary tract symptoms.

The recommendations were developed after a comprehensive literature review was conducted to formulate evidence-based recommendations. Each of the 11 recommendations in the guidelines is given a designation according to the strength of the evidence for that particular recommendation. The following information summarizes the recommendations.

Recommendation 1:The presence of urinary tract infection should be considered in infants and young children two months to two years of age with unexplained fever. Strength of evidence: strong.

The literature review revealed that the prevalence of a urinary tract infection as the etiology of fever is high (approximately 5 percent) among infants from two months to two years of age who have no obvious source of infection on physical examination. In this age group, the prevalence of urinary tract infection in febrile girls is more than twice that in boys with fever.

According to the guidelines, infants and young children are at higher risk than older children for acute renal injury from a urinary tract infection, and the risk of renal damage increases as the number of infections increases. In addition, identification of a urinary tract infection may bring to attention a child with an obstructive anomaly or severe vesicoureteral reflux.

Recommendation 2:In the setting of unexplained fever, the degree of toxicity, dehydration and ability to retain oral intake must be carefully assessed. Strength of evidence: strong.

If the degree of illness warrants initiation of antimicrobial therapy, a urine specimen should be obtained for culture before antimicrobial therapy is administered. In this situation, a urine specimen must be obtained by invasive means. However, if the degree of illness does not mandate initiation of antimicrobial therapy, immediate urine culture is not required. In such a situation, the clinician may choose to obtain a urine specimen by non-invasive means.

Recommendation 3:If the illness is severe enough to warrant immediate antimicrobial therapy, a urine specimen should be obtained by suprapubic aspiration or transurethral bladder catheterization. The diagnosis of urinary tract infection cannot be established by culture of urine collected in a bag. Strength of evidence: good.

The recommendations state that urine obtained by suprapubic aspiration is the least likely to be contaminated; the next best method for obtaining urine is transurethral bladder catheterization.

Recommendation 4: There are two options if the degree of illness does not signal the need for immediate antimicrobial therapy. Strength of evidence: good.

Option 1—Perform culture on a urine specimen obtained by suprapubic aspiration or transurethral bladder catheterization.

Option 2—Obtain a urine specimen by the most convenient means and perform a urinalysis. If urinalysis suggests urinary tract infection, obtain and culture a urine specimen collected by suprapubic aspiration or transurethral bladder catheterization. If urinalysis does not suggest a urinary tract infection, it is reasonable to follow the clinical course without initiating antimicrobial therapy, recognizing that a negative urinalysis does not exclude urinary tract infection.

Recommendation 5:The diagnosis of a urinary tract infection requires a culture of the urine. Strength of evidence: strong.

What constitutes a significant colony count depends on the collection method and the patient's clinical status. In addition, significance also depends on the identification of the pathogen.

Recommendation 6:If the patient is toxic, dehydrated or unable to retain oral intake, initial antimicrobial therapy should be administered parenterally and hospitalization should be considered. Strength of evidence: opinion/consensus.

The recommendations state that careful monitoring and repeated clinical examinations are required in children with clinical urosepsis or bacteremia. In most patients, the clinical condition improves in 24 to 48 hours, allowing a switch to oral administration.

Recommendation 7:Parenteral or oral antimicrobial therapy should be initiated if the patient does not appear ill but culture confirms the presence of urinary tract infection. Strength of evidence: good.

The usual choices include amoxicillin, a sulfonamide-containing antimicrobial or a cephalosporin. According to the recommendations, emerging resistance of Escherichia coli to ampicillin have rendered ampicillin and amoxicillin less effective than alternative agents.

Recommendation 8:If the expected clinical response does not occur with two days of antimicrobial therapy, reevaluation should be conducted and another urine specimen should be cultured. Strength of evidence: good.

Routine urine culture after two days of therapy is generally not required if the patient has responded to therapy and the uropathogen is sensitive to the antimicrobial drug. If the sensitivity of the organism is found to be intermediate or resistant, or if sensitivity testing is not performed, a culture for proof of bacteriologic cure should be performed after 48 hours of treatment.

Recommendation 9:A seven- to 14-day course of oral antimicrobial therapy should be completed. Strength of evidence: strong.

The medical literature shows that treatment results are better with seven to 10 days of treatment than with one dose or up to three days of treatment. The recommendations note that many experts prefer 14 days of treatment in children who appear ill and have evidence of pyelonephritis.

Recommendation 10:After a seven- to 14-day course of antimicrobial therapy and sterilization of the urine, the antimicrobial drug in a therapeutic or prophylactic dosage should be continued until imaging studies are completed. Strength of evidence: good.

The risk of renal scarring increases with an increasing number of urinary tract infections. With three infections, the risk of scarring is approximately 15 percent; with four infections, it approaches 40 percent; with five infections, the risk of renal scarring is approximately 60 percent.

Recommendation 11:Ultrasonography should be promptly performed in patients who do not demonstrate the expected clinical response within two days of initiation of antimicrobial therapy. In addition, voiding cystourethrography or radionuclide cystography should be performed at the earliest convenient time. If the response to therapy is as expected, ultrasonography and voiding cystourethrography or radionuclide cystography should be performed at the earliest convenient time. Strength of evidence: fair.

Imaging of the urinary tract is recommended for every febrile infant or young child with a first urinary tract infection to identify abnormalities that predispose the patient to renal damage. Ultrasonography is performed to detect dilatation secondary to obstruction, and voiding cystourethrography or radionuclide cystography is performed to detect vesicoureteral reflux.

Areas for Future Research

The recommendations conclude with a section that discusses some of the unanswered questions with regard to urinary tract infections in infants and toddlers. One component of urinalysis that warrants study is the significance of white blood cells in the urine. While bacteriuria can occur without pyuria, it is not clear whether pyuria is a specific marker for renal inflammation. Another question pertains to the duration and route of therapy.

With regard to the need for ultrasonography in the evaluation, the report states that current data do not allow determination of whether ultrasonography can be reasonably omitted. Data on the yield of positive findings with this imaging study were obtained before widespread use of fetal ultrasonography. Also unknown is the role of cortical scintigraphy and other techniques for identifying decreased perfusion. Noninvasive techniques such as power Doppler ultrasonography may be useful for demonstrating hypoperfusion.