Although suprapubic bladder aspiration(SBA) is the most reliable technique for identifying bacteriuria in young infant, no report has been published about the clinical manifestations of urinary tract infection(UTI) diagnosed by aspirated urine in Korea. This study was performed to examine clinical manifestations and related factors of UTI confirmed by a positive urine culture obtained by SBA in young infants.

We reviewed medical records of 159 infants younger than six months of age, who had been admitted for UTI to Korea University Ansan Hospital from January 2002 to June 2005.

The male:female ratio was 5.1 : 1. The most common pathogen in urine culture was Escherichia coli (92.5 percent). Most of the gram-negative pathogens had high sensitivity to amikacin, or third generation cephalosporins and had low sensitivity to ampicillin, trimethoprim-sulfamethoxazole, or gentamicin. Hydronephrosis and vesicoureteral reflux(VUR) were present in 32.7 percent and 27.7 percent respectively. Renal cortical defects observed on DMSA scans were detected in 37.1 percent. Prolonged fever duration and hospital day, high erythrocyte sedimentation rate(ESR) and C-reactive protein(CRP) levels, hydronephrosis and VUR were related to the renal cortical defects( P <0.05). Rates of UTI-associated bacteremia and aseptic meningitis were 8.3 percent and 6.6 percent.

Early differential diagnosis is very important in infants younger than 6 months of age with UTI because the clinical findings are non-specific and UTI-associated bacteremia and aseptic meningitis are concomitantly found. Because prolonged fever and higher ESR and CRP levels are risk factors of the renal cortical defects, radiologic evaluations and nephrologic follow-up were needed in identifying the predisposing congenital abnormalities and chronic renal scarring.