Laboratory evaluation of urinary tract infections in an ambulatory clinic

K. C. Carroll, D. C. Hale, D. H. Von Boerum, G. C. Reich, L. T. Hamilton, J. M. Matsen

Research output: Contribution to journalArticlepeer-review

29 Scopus citations


A 4-month evaluation of ambulatory patients with a suspicion of a urinary tract infection was performed. Specific objectives included assessment of five urinary screening methods, reevaluation of the necessity of the phenylethyl alcohol plate (PEA), and cost-effectiveness of screening for low colony count bacteriuria. Urine samples were collected as midstream, clean- caught specimens. A total of 142 samples, 87 from 79 symptomatic patients and 55 negative controls, were evaluated. All urine specimens were cultured using a 0.01 mL loop and a 0.001 mL loop onto Columbia sheep blood agar, MacConkey agar, and PEA agar. Twenty-four specimens (17%) were sterile, 64 (45%) were contaminated, and 54 (38%) were infected. Five urine screening methods were performed. These tests and their associated sensitivity and specificity are as follows. The Chemstrip 9 (Behring, Inc., Somerville, NJ) for leukocyte esterase and nitrate, 67%, 98%; microscopic analysis on spun urine, 79%, 93%; methylene blue stain for pyuria, 60%, 99%; Gram stain for pyuria, 45%, 93%; Gram stain for bacteriuria, 65%, 75%; and the URISCREEN (Analytab Products, Plainview, NY), 92%, 89%. Inclusion of a PEA plate for isolation of gram- positive organisms provided no additional information. Routine culture of urine samples at 10-2 mL increased the contamination rate by 19%.

Original languageEnglish (US)
Pages (from-to)100-103
Number of pages4
JournalAmerican journal of clinical pathology
Issue number1
StatePublished - Jan 1 1994
Externally publishedYes


  • Urinary tract infections
  • Urine screening tests

ASJC Scopus subject areas

  • Pathology and Forensic Medicine


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