The diagnosis of UTI: liquid gold and the problem of gold standards.

Abstract

Why is urine yellow? Because it is liquid gold! Pediatric nephrologist William Primack* For >50 years, the gold standard for the diagnosis of urinary tract infections (UTIs) has been a positive culture result without regard for urinalysis findings. Both the definition of “positive” and the role of urinalysis stem from a publication in 1956.1 Edward Kass applied quantitative culture methods to urine specimens obtained from adults by catheterization to determine a dividing line between contamination and infection. The urine of most, but not all, patients with symptoms of acute pyelonephritis (chills, fever, flank pain, and dysuria) contained >100 000 CFU/mL. Urine specimens from some asymptomatic women also had such high colony counts but most were much lower. Kass concluded: “For survey purposes, a count of 105 bacteria or more per mL of urine has been designated arbitrarily as the dividing line between true bacilluria and contamination.” He acknowledged that for “individual clinical purposes,” lower colony counts needed to be considered and noted that pyuria did not reliably accompany bacteriuria in the asymptomatic women. During the subsequent decade, screening programs were widely conducted, applying ≥10 … Address correspondence to Kenneth B. Roberts, MD, 3005 Bramblewood Dr, Mebane, NC 27302. E-mail: kenrobertsmd{at}gmail.com