Culture or just a dipstick? UPMC Children’s study aims to settle debate on testing for UTIs in kids

By: Andrea Kunicky

In recent years, pediatricians who suspect a urinary tract infection (UTI) in feverish children who can’t yet verbalize their symptoms have been moving away from culturing urine samples, instead opting to only do a less-sensitive dipstick test. This has led doctors to wonder: Is the dipstick good enough or should culturing continue?

Dr. Nader Shaikh, professor of pediatrics at the University of Pittsburgh and UPMC Children’s Hospital of Pittsburgh, analyzed more than a dozen studies on nearly 50,000 children to find out. His research team’s results are published today in the Journal of Pediatrics.

The answer came down to how often children have “asymptomatic bacteriuria,” a relatively common condition where bacteria is present in the urine, but it isn’t causing the child to be sick. It is not normally treated with antibiotics because that can unnecessarily kill off good bacteria and allow bad bacteria to flourish. But if a child actually has a UTI and is not given antibiotics, permanent scarring of the kidneys could result.

Q: Why did the testing protocol start to change? 

A: This change can be traced back to changes to the definition of UTI Guidelines in 2011. There, it was argued that, because asymptomatic bacteriuria is relatively common and can be confused with a UTI, an additional test would be needed to differentiate the two conditions. Since then, the presence of leukocyte esterase [a type of enzyme produced in the presence of infections] on dipstick is required for the diagnosis of UTI.  Over time, this has led to fewer cultures being sent in children with suspected UTI.

Q: What did you find out in your analysis?

A: We found out that the prevalence of asymptomatic bacteriuria was considerably less that 0.5% in most subgroups examined.

Q: Did that surprise you?

A: Yes. For years, we have assumed that the prevalence of asymptomatic bacteriuria is somewhere between 1 and 2%. This was based on screening programs in the 1950s and 60s which reported that approximately 1% to 2% of the children screened had bacteriuria. Even though many of these screening programs were aimed at detecting urinary tract infection, and thus included symptomatic children, those with bacteriuria detected in these studies came to be referred to as children with “asymptomatic bacteriuria.”

Q: Based on your findings, what would you encourage fellow clinicians to do?

A: Given that asymptomatic bacteriuria is rare, relatively little is gained by not ordering a urine culture. Our calculations suggest that many UTIs may be missed if we continue not to order urine cultures. We suggest that, for children in whom urine is difficult to obtain and the risk of renal involvement is high (i.e., preverbal febrile children), a urine culture should be ordered.

Q: What should parents take away from your analysis?

A: The urine culture is for now the best test we have for a UTI. Parents should ask about what their child’s urine culture showed.