When we obtain a urinalysis in a young patient and find there is no evidence of pyuria, do we instantly assume there is no infection? We would bet that is the case for the vast majority of us who see a negative dipstick or better yet a negative urinalysis for pyuria on a daily basis. But is that a good assumption to make? Shaikh et al. (peds.2016-0087) report on their study of 6 years’ worth of urinary tract infections (UTIs) for which they paired a positive culture result with the urinalysis for catheterized specimens in children who did not have major genitourinary or immunocompromised conditions and whose cultures did not represent contaminants (meaning multiple organisms were grown).
Pyuria was defined as more than 5 white blood cells per high-powered field or more than 10 white cells per cubic millimeter and was absent in 13% of the pure positive cultures. What’s even more interesting are the organisms that grew in the absence of white cells which included predominantly enterococcus, klebsiella, and pseudomonas. Even the dipsticks for these children did not show traces of white blood cells.
So what does this mean? Should every child we get a urine on be started on antibiotics empirically for a urinalysis or dipstick that has no evidence of pyuria or a positive leukocyte esterase marker? Pediatric nephrologist Aaron Friedman (peds.2016-1247) takes a peek at this question in an accompanying commentary which puts the results in context—and context is certainly important here since the children who did have UTIs in this study also had symptoms and other signs that indicated there was a problem even if the white cell indicators were absent. Go with the flow of information in this study and commentary and at least keep your diagnostic radar for suspecting a UTI high if your patient is symptomatic even if the urinalysis doesn’t show the white cells you might normally be expecting.
How often have you diagnosed a UTI that is culture confirmed in the absence of pyuria? Share your experience with us by responding to this blog, posting a comment on our website, or providing a thought via our Facebook or Twitter sites.