[First urinary tract infection in healthy infants: epidemiology, diagnosis and treatment]

Urinary tract infection (UTI) is one of the most common infections in infants. It presents certain peculiarities compared with other pediatric age groups in terms of symptomatology, diagnosis and the therapeutic approach employed to prevent sequels.

To analyze the epidemiology, clinical and laboratory findings, etiology, diagnosis and treatment of first-time UTI in healthy infants.

Between January and December 1999, we performed a retrospective study of 131 previously healthy infants admitted to our hospital with a diagnosis of first-time UTI. Demographic data, clinical characteristics, urine dipstick, urinalysis and urine culture (vesical catheterization), blood cell count and PCR, kidney ultrasonography, voiding cystourethrogram and DMSA scintigraphy were reviewed.

We studied 131 patients (median age: 90 days). In infants younger than 30 days, UTI was more prevalent in males. The most frequent symptom was fever (73.3 %). Seventy-one patients fulfilled the criteria for acute pyelonephritis. The presence of nitrituria was low. Escherichia coli was isolated in 90.1 % of the patients. Voiding cystourethrogram detected vesicoureteric reflux in 18.4 % of the patients. Scintigraphy revealed renal scarring in 15.1 %. No significant correlations were found between renal scarring in late scintigraphy and a diagnosis of acute pyelonephritis and/or alterations in the cystourethrogram.

Fever was the main symptom. E. coli was the most commonly isolated microorganism. Nitrituria had low sensitivity in infants. Ultrasonography had low specificity. Scintigraphy showed the highest sensitivity and specificity in the detection of renal scarring. Predictability improved when scintigraphy was performed a few months after acute infection.