The relationship between pyuria and infection in patients with indwelling urinary catheters: a prospective study of 761 patients

Arch Intern Med. 2000 Mar 13;160(5):673-7. doi: 10.1001/archinte.160.5.673.


Background: Pyuria is universally considered as essential for identifying urinary tract infections in noncatheterized patients. The utility of pyuria in the catheterized patient, to identify catheter-associated urinary tract infection (CAUTI), has not been adequately defined.

Methods: We prospectively studied 761 newly catheterized patients in a university hospital; 82 (10.8%) developed nosocomial CAUTI (> 10(3) colony-forming units per milliliter). While catheterized, each patient was seen daily, a quantitative urine culture was obtained, and the urine white blood cell concentration was measured quantitatively using a hemocytometer.

Results: The mean urine leukocyte count in patients with CAUTI was significantly higher than in patients without infections (71 vs 4 per microliter; P= .006). Pyuria was most strongly associated with CAUTI caused by gram-negative bacilli (white blood cell count, 121 vs 4 per microliter; P = .03); infection with coagulase-negative staphylococci and enterococci (white blood cell count, 39 vs 4 per microliter; P = .25) or yeasts (white blood cell count, 25 vs 4 per microliter; P = .15) produced much less pyuria. Pyuria with a white blood cell count greater than 10 per microliter (>5 per high-power field in a conventional urinalysis) had a specificity of 90% for predicting CAUTI with greater than 10(5) colony-forming units per milliliter but a sensitivity of only 37%.

Conclusions: In patients with short-term indwelling urinary catheters, pyuria is less strongly correlated with CAUTI than in noncatheterized patients with urinary tract infection. The strongest association is with CAUTI caused by gram-negative bacilli; the association is far weaker for infections caused by gram-positive cocci or yeasts. Most patients with CAUTI are asymptomatic and do not have associated fever. Pyuria should not be used as the sole criterion to obtain a urine culture in a patient with a catheter.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Bacteriuria / complications*
  • Bacteriuria / diagnosis
  • Bacteriuria / etiology*
  • Bacteriuria / microbiology
  • Catheters, Indwelling / adverse effects
  • Catheters, Indwelling / microbiology
  • Cross Infection / diagnosis
  • Cross Infection / etiology*
  • Cross Infection / microbiology
  • Diagnosis, Differential
  • Female
  • Humans
  • Leukocyte Count
  • Male
  • Middle Aged
  • Prospective Studies
  • Pyuria / diagnosis
  • Pyuria / etiology*
  • Pyuria / microbiology
  • Sensitivity and Specificity
  • Urinalysis
  • Urinary Catheterization / adverse effects*