When faced with the diagnostic evaluation of the young, febrile infant fewer than three months of age, the definitive tool for sepsis from urinary tract infection has traditionally been urine culture. This stems from uncertainty over the adequacy of urinalysis sensitivity for serious bacterial infection, i.e., those truly bacteremic from a urinary source.
This is an analysis of a multicenter database of infants with bacteremia and urinary tract infection, as measured by isolation of the same pathologic organism from both blood and urine. The key numbers:
- Trace or greater leukocyte esterase: 97.6% (94.5-99.2) sensitive and 93.9% (87.9-97.5) specific.
- Pyuria, >3 WBC/HPF: 96% (92.5-98.1) sensitive and 91.3% (84.6-95.6) specific.
- Pyuria or any LE: 99.5% (98.5-100) sensitive and 87.8% (80.4-93.2) specific.
These are pretty impressive statistics, and differ significantly from the prior supposed sensitivity of the UA in young infants. These authors postulate the problem with prior study has been its over-reliance on urine culture, and the resulting false positives. If this seems a reasonable interpretation of the evidence, it has substantial ramifications for the diagnostic evaluation of young infants. Importantly, it has the potential for obviating invasive procedures and unnecessary over-treatment.
I would like to see independent confirmation of these authors’ findings, but, considering this study required 15 years to produce the 276 patients analyzed in this paper, this may be the best evidence we see for awhile.
“Diagnostic Accuracy of the Urinalysis for Urinary Tract Infection in Infants, 3 Months of Age”
http://www.ncbi.nlm.nih.gov/pubmed/26009628