Urological Research

, Volume 33, Issue 3, pp 220–222

Diagnostic value and cost utility analysis for urine Gram stain and urine microscopic examination as screening tests for urinary tract infection

  • Viroj Wiwanitkit
  • Nibhond Udomsantisuk
  • Chaiyaporn Boonchalermvichian
Original Paper

Abstract

The aim of this study was to evaluate the diagnostic properties of urine Gram stain and urine microscopic examination for screening for urinary tract infection (UTI), and to perform an additional cost utility analysis. This descriptive study was performed on 95 urine samples sent for urine culture to the Department of Microbiology, Faculty of Medicine, Chulalongkorn University. The first part of the study was to determine the diagnostic properties of two screening tests (urine Gram stain and urine microscopic examination). Urine culture was set as the gold standard and the results from both methods were compared to this. The second part of this study was to perform a cost utility analysis. The sensitivity of urine Gram stain was 96.2%, the specificity 93.0%, the positive predictive value 94.3% and the negative predictive value 95.2%. False positives occurred with a frequency of 7.0% and false negatives 3.8%. For the microscopic examination, the sensitivity was 65.4%, specificity 74.4%, positive predictive value 75.6% and negative predictive value 64.0%. False positives occurred with a frequency of 25.6% and false negatives 34.6%. Combining urine Gram stain and urine microscopic examination, the sensitivity was 98.1%, specificity 74.4%, positive predictive value 82.3% and negative predictive value 97.0%. False positives occurred with a frequency of 25.6% and false negatives 1.9%. However, the cost per utility of the combined method was higher than either urine microscopic examination or urine Gram stain alone. Urine Gram stain provided the lowest cost per utility. Economically, urine Gram stain is the proper screening tool for presumptive diagnosis of UTI.

Keywords

Urinary tract infection Gram stain Microscopic examination 

References

  1. 1.
    Blumberg EA, Abrutyn E (1997) Methods for the reduction of urinary tract infection. Curr Opin Urol 7: 47Google Scholar
  2. 2.
    Gillenwater JA (1996) Adult and pediatric urology, 3rd edn. Mosby-Year Book, St. LouisGoogle Scholar
  3. 3.
    Kunin CM (1997) Urinary tract infections: detection, prevention, and management, 5th edn. Williams & Wilkins, BaltimoreGoogle Scholar
  4. 4.
    Washington JA, Henry JB (1984) Medical microbiology. In: Henry JB (ed) Clinical diagnosis and management, 17th edn. Saunders, PhiladelphiaGoogle Scholar
  5. 5.
    Paritpokee N (2001) Urine sediment. In: Charuruks N, Sutheesophon K, Boonchalermvichian C (eds) Clinical pathology. Chulalongkorn University Press, Bangkok, p 361Google Scholar
  6. 6.
    Krieger JN (2002) Urinary tract infections: what’s new? J Urol 168: 2351Google Scholar
  7. 7.
    Hooton TM (2000) Pathogenesis of urinary tract infections: an update. J Antimicrob Chemother 46 [Suppl 1]: 1Google Scholar
  8. 8.
    Hummers-Pradier E, Kochen MM (2002) Urinary tract infections in adult general practice patients. Br J Gen Pract 52: 752Google Scholar
  9. 9.
    Crout FV, Tilton RC (1984) Rapid screening of urine for significant bacteriuria by Gram stain, acridine orange stain, and the Autobac MTS system. Diagn Microbiol Infect Dis 2: 179Google Scholar
  10. 10.
    Olson ML, Shanholtzer CJ, Willard KE, Peterson LR (1991) The slide centrifuge Gram stain as a urine screening method. Am J Clin Pathol 96: 454Google Scholar
  11. 11.
    Goldsmith BM, Campos JM (1990) Comparison of urine dipstick, microscopy, and culture for the detection of bacteriuria in children. Clin Pediatr (Philadelphia) 29: 214Google Scholar
  12. 12.
    Carroll KC, Hale DC, Von Boerum DH, Reich GC, Hamilton LT, Matsen JM (1994) Laboratory evaluation of urinary tract infections in an ambulatory clinic. Am J Clin Pathol 101: 100Google Scholar
  13. 13.
    Hussain R, Chaudhry NA, Anwar MS, Khan SA, Munir M, Tayyab M (1996) Evaluation of dipstrips, direct gram stain and pyuria as screening tests for the detection of bacteriuria. J Pakistan Med Assoc 46: 38Google Scholar

Copyright information

© Springer-Verlag 2005

Authors and Affiliations

  • Viroj Wiwanitkit
    • 1
  • Nibhond Udomsantisuk
    • 2
  • Chaiyaporn Boonchalermvichian
    • 1
  1. 1.Department of Laboratory MedicineFaculty of Medicine
  2. 2.Department of MicrobiologyFaculty of Medicine

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