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

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.

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.

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.

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.