Identification of Probable Urinary Tract Infection in Children Using Low Bacterial Count Thresholds in Urine Culture.

OBJECTIVE: To assess the proportion of children, symptomatic for urinary tract infection (UTI), with urine culture showing single bacterial species >104 CFU/mL, and to compare patient and disease characteristics between children having low counts (from >104-105 CFU/mL) and those with counts >105 CFU/mL.

METHODS: Prospective observational study, enrolling symptomatic children aged 1 month to 12 years. Mid-stream clean-void or catheter collected urine were cultured. Children with single species >104 CFU/mL were scheduled for imaging studies, following age criteria of Indian Society of Pediatric Nephrology guidelines. The main outcome was proportion with single bacterial species >104 CFU/mL in urine culture.

RESULTS: Of 216 children (132 males) with median (IQR) age of 24 (12, 48) months, 38 (17.6%) showed single species growth >104 CFU/mL. Of these, 29 (13.4%) were diagnosed as UTI at cutoff >105 CFU/mL, and an additional 9 (4.2%) were found to have 'probable low-count UTI' (from >104 to 105 CFU/mL). One child in the latter group had bilateral hydroureteronephrosis, vesico-ureteral reflux and renal scarring. There was largely no difference in parameters between children with low counts and those with counts >105 CFU/mL.

CONCLUSION: An additional proportion of symptomatic children with probable urinary tract infection and possible underlying urological abnormalities may be identified by lowering bacterial colony count cutoff to >104 CFU/mL, in clean-voided and catheter-based urine samples.