Correspondence

Does a Clean-Catch Urine Sample Reduce Bacterial Contamination?

N Engl J Med 1993; 328:289-290January 28, 1993

Article

To the Editor:

Standard practice for collecting a urine specimen from women for bacterial culture includes cleansing of the perineum and urethral meatus before collection. To determine whether such cleansing affects the rate of bacterial contamination of midstream urine specimens, we studied 105 asymptomatic health care workers (Table 1Table 1Comparison of Clean-Catch and Non-Clean-Catch Urine Samples According to Culture and Urinalysis.). We did not exclude women who were pregnant, were menstruating, or had a known history of urinary tract infection or anatomical abnormality.

Each woman collected two midstream urine samples during consecutive urinations. The first sample was not a clean-catch specimen, and the second was a clean-catch specimen. Both specimens were studied by urinalysis and bacterial culture with standard methods1,2 and definitions of a positive urine culture, contaminated urine culture, and contaminated urinalysis3.

One hundred women met the study criteria and successfully completed the study. Sixty-four of the 100 non-clean-catch urine cultures and 64 of the 100 clean-catch cultures were found to be contaminated. Seventy-two of the 200 cultures (36 percent) were found to be sterile. None of the urine cultures were positive. Comparison of the results in individual subjects identified 10 women whose cultures of non-clean-catch specimens were sterile but whose clean-catch cultures were contaminated. Ten others had contaminated cultures of the non-clean-catch specimens and sterile clean-catch cultures. Eighty subjects had similar culture results in both urine samples (i.e., both were either sterile or contaminated). On urinalysis, 11 specimens (5.5 percent) were thought to be contaminated, but none of the corresponding cultures were positive.

We have shown in earlier studies that perineal cleansing in young boys4 and girls5 does not decrease bacterial contamination of urine culture. In women, the midstream clean-catch technique remains standard practice for collecting a urine specimen for bacterial culture despite studies showing its lack of efficacy6-8. None of the 200 urine specimens in this study were culture-positive. There was no difference in the rate of bacterial contamination between the specimens obtained by the clean-catch method and those obtained by the non-clean-catch method. For the 11 contaminated specimens, none of the corresponding urine cultures were positive.

At our hospital, a clean-catch urine-collection kit costs $0.47, as compared with $0.21 for a sterile specimen cup. We use approximately 45,000 clean-catch kits per year.

Women can obtain a reliable midstream urine sample for culture without using clean-catch kits and perineal washing. This should facilitate collection and substantially reduce the cost of each culture.

Marketa Kyncl Leisure, M.D.
Sharon M. Dudley, M.T. (A.S.C.P.), M.T. (A.S.C.P.)
Leigh G. Donowitz, M.D.
University of Virginia Health Sciences Center, Charlottesville, VA 22908

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Citing Articles (6)

Citing Articles

1. 1

   David R. Lane, Sukhjit S. Takhar. (2011) Diagnosis and Management of Urinary Tract Infection and Pyelonephritis. Emergency Medicine Clinics of North America 29:3, 539-552
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2. 2

   Fabio Manoni, Alberta Caleffi, Gianluca Gessoni, Maria Grazia Alessio, Giuseppe Lippi, Sara Valverde, Cosimo Ottomano, Maria Grazia Silvestri, Piero Cappelletti, Mauro Ercolin, Michele Schinella, Graziella Saccani. (2011) L’esame delle urine chimico morfologico e colturale: proposta di linee guida per una procedura standardizzata della fase preanalitica. La Rivista Italiana della Medicina di Laboratorio - Italian Journal of Laboratory Medicine 7:1, 25-35
   CrossRef

3. 3

   Hayriye Ünlü, Yeşim Çetinkaya Şardan, Saadet Ülker. (2007) Comparison of Sampling Methods for Urine Cultures. Journal of Nursing Scholarship 39:4, 325-329
   CrossRef

4. 4

   José Juan Hernández-Burruezo, Mohamed Omar Mohamed-Balghata, Luis Aliaga Martínez. (2007) Infecciones del aparato urinario. Medicina Clínica 129:18, 707-715
   CrossRef

5. 5

   Michael L. Wilson, Loretta Gaido. (2004) Laboratory Diagnosis of Urinary Tract Infections in Adult Patients. Clinical Infectious Diseases 38:8, 1150-1158
   CrossRef

6. 6

   Dana Prandoni, Mary Helen Boone, Elaine Larson, Cheryl G. Blane, Helen Fitzpatrick. (1996) Assessment of urine collection technique for microbial culture. American Journal of Infection Control 24:3, 219-221
   CrossRef