Low bacterial count urinary tract infections in infants and young children.

UNLABELLED: The purpose of the study was to compare bacterial species, clinical, laboratory and imaging findings ((99m )Tc-dimercaptosuccinic acid renal scan and voiding cystogram) in infants and children with high (>/=10(5) colony forming units (CFU)/ml, group A patients) and low (</=5 x 10(4) CFU/ml, group C patients) bacterial count in urine cultures during first episode of urinary tract infection. Group B included patients with intermediate CFU/ml. Included were 419 symptomatic patients with: (a) no previous antibiotic treatment, (b) urine samples for quantitative cultures taken by bladder catheterisation or suprapubic bladder aspiration, (c) growth of only one microorganism, and (d) age </=54 months (age of the oldest patient of group C). Out of 419 cultures, Escherichia coli grew in 315 (75.2%), gram-negative bacteria except E. coli in 91 (21.7%) and gram-positive in 13 (3.1%). Group C patients were significantly ( P <0.0001) more often affected with gram-negative pathogens except E. coli than group A patients (21/44 versus 67/360). Most of group C patients were younger than 24 months of age; none was older than 54 months. Comparison of the prevalence of clinical and laboratory (leucocyte count, CRP, ESR) findings between groups A and C showed no significant differences. There was no statistically significant difference in the prevalence of pyelonephritis, reflux and urological malformations (except reflux) between groups A and C.

CONCLUSION: Low bacterial count urinary tract infections mainly affect infants and young children and are often due to gram-negative bacteria other than E. coli. Clinical and laboratory findings, prevalence of pyelonephritis, reflux and urological malformations are similar in high and low bacterial count urinary tract infections.