High incidence of abnormal imaging findings in circumcised boys diagnosed with urinary tract infections.

BACKGROUND

The American Academy of Pediatrics guidelines recommend delaying voiding cystourethrogram (VCUG) until the second febrile urinary tract infection (UTI). Similarly, the NICE Guidelines do not recommend VCUG after the first febrile UTI in infants and children under three years of age. Currently, there is no good clinical indicator to determine which patients would benefit from an earlier cystogram. Here, we sought to identify clinical and bacteriologic findings that are associated with an increased risk of urinary tract anatomic anomalies in pediatric males presenting to the Emergency Department with a UTI.

METHODS

A retrospective review was performed of all urine cultures from the Emergency Department at our institution between 2006 and 2015. Males under 18 years of age with ≥50,000 CFU/mL of Proteus, Klebsiella, Escherichia coli, Staphylococcus, Streptococcus and Enterococcus were included. Clean catch, catheterized and suprapubic aspiration specimens were included. Bagged specimens and specimens from patients on intermittent catheterization were excluded. Ultrasound and cystogram images were reviewed when available. Univariate and multivariable Poisson regression with robust variance was used to calculate and compare prevalence ratios. Statistical analysis was performed with Stata software, version 15.1 MP (Stata Corporation, College Station, Texas, USA).

RESULTS

We reviewed 1585 urine cultures, of which 812 met eligibility criteria including 619 (76.2%) E. coli, 84 (10.3%) Proteus, 55 (6.8%) Klebsiella, 29 (3.6%) Staphylococcus, 13 (1.6%) Enterococcus and 12 (1.5%) Streptococcus. Median age was six months (2.4-36 months IQR). After adjusting for age, ethnicity and bacterial species, the prevalence of dilating vesicoureteral reflux (VUR, defined as grades III-V) was 5.3 times higher in circumcised males compared to uncircumcised males (95% CI: 2.4-11.4, p = 0.001). Circumcised males had a 3.1 times increased prevalence of high-grade hydronephrosis (defined as SFU grades 3 and 4) compared to uncircumcised males (prevalence ratio: 3.1, 95% CI: 1.0-10.0, p = 0.05). Among bacterial pathogens, no patients with Proteus UTI had high-grade hydronephrosis or dilating VUR. In contrast, Staphylococcal infections were associated significantly with dilating VUR (prevalence ratio 10.1, 95% CI: 2.3, 44.8; p = 0.002) and high-grade hydronephrosis (prevalence ratio 8.1, 95% CI: 1.7, 39.7; p = 0.010).

CONCLUSIONS

Circumcision status is an independent predictor of structural urinary anomalies of the bladder and upper tracts in pediatric males with UTI, therefore circumcised males should be considered for early imaging, including VCUG, after their first UTI. Furthermore, Staphylococcal infections were associated with an even higher prevalence of high-grade hydronephrosis and dilating VUR and therefore warrant early investigation with VCUG. In contrast, none of the Proteus infections, which were seen almost exclusively in uncircumcised males, were associated with dilating VUR or hydronephrosis, making initial observation more appropriate in these patients.