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[Diagnostic yield of various urine tests in urinary tract infections].
Rev Invest Clin. 1996 Mar-Apr; 48(2):117-23.RI

Abstract

OBJECTIVES

1. To determine the value of pyuria and bacteriuria by high-power field (hpf) in centrifuged urine and of tests with reactive strips for determining leukocyte estearase activity and nitrites in the diagnosis of urinary tract infection (UTI). 2. To establish the ideal cut-off point for these tests.

DESIGN

Comparative survey.

SETTING

Second level health care unit of the Instituto Mexicano del Seguro Social.

PATIENTS AND METHODS

A total of 105 patients were prospectively studied, with or without urinary symptoms, seen in the emergency ward.

MEASUREMENTS

A clinical history and physical exploration was done in each patient. A urine sample was used for microscopic analysis for determining leukocytes and bacteria using hpf microscopy; the urine leukocytes count was assayed as well as leukocyte estearase and nitrites using reactive strips. All samples were subjected to urine culture. Urine samples were obtained using a Nelaton probe in 65% of the patients and the rest using the midstream urination technique.

RESULTS

Forty patients (38%) were identified as UTI cases based on clinical and laboratory criteria (urine culture and leukocyte count). The best cut-off point for number of leukocytes was 8 per hpf and for bacteriuria it was 2+ per hpf and for leukocyte estearase it was 1+. The sensitivity, specificity and predictive values of the pyuria hpf, bacteriuria by hpf and leukocyte estearase by reactive strip were comparable. The nitrites had a lower sensitivity than the other tests (p < 0.05). The negative predictive value of the nitrites was less than the microscopic bacteriuria (74% vs 85%, p = 0.005). The combination of positive tests in leukocytes and bacteriuria increased the specificity and the positive predictive value (99% and 96% respectively) when compared to the individual tests.

CONCLUSIONS

The diagnostic performance of leukocyte estearase by reactive strips was similar to the microscopy of leukocytes and bacteria but the nitrite test had a lower performance. The combination of the leukocytes and bacteriuria measured by hpf appears to be very useful in the diagnosis of UTI.

Authors+Show Affiliations

Hospital General de Zona No. 1-A Los Venados, Instituto Mexicano del Seguro Social, México, D.F.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Clinical Trial
Comparative Study
English Abstract
Journal Article

Language

spa

PubMed ID

8815495

Citation

Leaños-Miranda, A, et al. "[Diagnostic Yield of Various Urine Tests in Urinary Tract Infections]." Revista De Investigacion Clinica; Organo Del Hospital De Enfermedades De La Nutricion, vol. 48, no. 2, 1996, pp. 117-23.
Leaños-Miranda A, Contreras-Hernández I, Camacho R, et al. [Diagnostic yield of various urine tests in urinary tract infections]. Rev Invest Clin. 1996;48(2):117-23.
Leaños-Miranda, A., Contreras-Hernández, I., Camacho, R., Villagómez-Salcedo, E., & Cervantes-Gorayeb, I. (1996). [Diagnostic yield of various urine tests in urinary tract infections]. Revista De Investigacion Clinica; Organo Del Hospital De Enfermedades De La Nutricion, 48(2), 117-23.
Leaños-Miranda A, et al. [Diagnostic Yield of Various Urine Tests in Urinary Tract Infections]. Rev Invest Clin. 1996 Mar-Apr;48(2):117-23. PubMed PMID: 8815495.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - [Diagnostic yield of various urine tests in urinary tract infections]. AU - Leaños-Miranda,A, AU - Contreras-Hernández,I, AU - Camacho,R, AU - Villagómez-Salcedo,E, AU - Cervantes-Gorayeb,I, PY - 1996/3/1/pubmed PY - 1996/3/1/medline PY - 1996/3/1/entrez SP - 117 EP - 23 JF - Revista de investigacion clinica; organo del Hospital de Enfermedades de la Nutricion JO - Rev Invest Clin VL - 48 IS - 2 N2 - OBJECTIVES: 1. To determine the value of pyuria and bacteriuria by high-power field (hpf) in centrifuged urine and of tests with reactive strips for determining leukocyte estearase activity and nitrites in the diagnosis of urinary tract infection (UTI). 2. To establish the ideal cut-off point for these tests. DESIGN: Comparative survey. SETTING: Second level health care unit of the Instituto Mexicano del Seguro Social. PATIENTS AND METHODS: A total of 105 patients were prospectively studied, with or without urinary symptoms, seen in the emergency ward. MEASUREMENTS: A clinical history and physical exploration was done in each patient. A urine sample was used for microscopic analysis for determining leukocytes and bacteria using hpf microscopy; the urine leukocytes count was assayed as well as leukocyte estearase and nitrites using reactive strips. All samples were subjected to urine culture. Urine samples were obtained using a Nelaton probe in 65% of the patients and the rest using the midstream urination technique. RESULTS: Forty patients (38%) were identified as UTI cases based on clinical and laboratory criteria (urine culture and leukocyte count). The best cut-off point for number of leukocytes was 8 per hpf and for bacteriuria it was 2+ per hpf and for leukocyte estearase it was 1+. The sensitivity, specificity and predictive values of the pyuria hpf, bacteriuria by hpf and leukocyte estearase by reactive strip were comparable. The nitrites had a lower sensitivity than the other tests (p < 0.05). The negative predictive value of the nitrites was less than the microscopic bacteriuria (74% vs 85%, p = 0.005). The combination of positive tests in leukocytes and bacteriuria increased the specificity and the positive predictive value (99% and 96% respectively) when compared to the individual tests. CONCLUSIONS: The diagnostic performance of leukocyte estearase by reactive strips was similar to the microscopy of leukocytes and bacteria but the nitrite test had a lower performance. The combination of the leukocytes and bacteriuria measured by hpf appears to be very useful in the diagnosis of UTI. SN - 0034-8376 UR - https://www.unboundmedicine.com/medline/citation/8815495/[Diagnostic_yield_of_various_urine_tests_in_urinary_tract_infections]_ DB - PRIME DP - Unbound Medicine ER -