Leukocyte Esterase Test Research Articles

Disappointing dipstick screening for urinary tract infection in hospital inpatients.

AIM: To compare the performance of leucocyte esterase and nitrite dipstick tests with microscopic examination and culture of first morning urines (n = 420) of hospital inpatients. RESULTS: The sensitivity,...

Noninvasive screening for genital chlamydial infections in asymptomatic men: Strategies and costs using a urine PCR assay.

To evaluate cost saving strategies to screen for genital chlamydial infection in men using polymerase chain reaction (PCR) technology. Men with no urethral symptoms presenting to a sexually transmitted disease (STD) clinic were recruited. Study participants underwent a questionnaire interview. Urethral swabs were taken to perform a smear for polymorphonuclear leucocytes (PMN) and for the detection of Chlamydia trachomatis by culture and PCR. First-catch urine was collected for a leukocyte esterase test (LET) and PCR. C trachomatis infection was detected in 36 of 463 (7.8%) men. LET and PMN were positive in 10 (28%) and 12 (33%) infected men, respectively. Risk factors for chlamydial infection were younger than age 25 years, LET-positive, PMN-positive and STD contact (P<0.001). The direct cost of genital chlamydial infection in men in Canada has been previously estimated at $381/case. Based on a sensitivity of 90% for urine PCR, the estimated direct cost of testing all participants to detect 32 cases was $453/case. Using risk factors recommended in the Canadian STD Guidelines (age younger than 25 years, new partner, STD contact or unprotected sex), the same number of cases would have been detected by testing only 384 men at $376/case. Using age younger than 25 years or STD contact as the screening criterion, 78% of those infected would have been detected at $259/case, and no new cases would have been detected by adding LET-positive or PMN-positive as risk factors. Targeted screening for chlamydial infection using urine PCR assay and risk factors recommended in the Canadian guidelines could substantially reduce the cost of screening at a STD clinic setting. LET and PMN smear did not appear to be useful indicators of chlamydial infection in this population.

Diagnostic microbiologique des infections urinaires chez l'enfant. Intérêt des tests rapides

Urine collection study is one of the most common means of bacteriological diagnosis in the laboratory. However, numerous interpretation problems exist. The aim of this paper is to specify these problems and to indicate the place of rapid tests in the screening for urinary tract infection. Direct examination must be performed on rapidly collected and transported urine. In such conditions, absence or presence of both leukocytes or germs presents a good negative or positive predictive value. However, false positive leukocyturia is frequent. False positive bacteriuria is mostly due to bad collection or transport. In some cases the threshold of bacteriuria > or = 10(5) cfu/mL can be reduced. Rapid tests include leukocyte esterase and nitrite tests. In our study, recording 289 tests, we observed negative and positive predictive values of respectively, 92% and 100% when the two tests were used together. Dipsticks can be used to exclude a urinary tract infection when clinical symptoms are absent, but only if they are used correctly. When both tests are positive, a urinary tract infection is likely. Study on urine collection is difficult in children. Collaboration between clinician and bacteriologist is essential.

Community-based urine screening for Chlamydia trachomatis with a ligase chain reaction assay.

Urine tests for Chlamydia trachomatis permit expansion of screening beyond traditional clinic environments. Prevention of infection in teenagers is a high priority. To define the prevalence of C. trachomatis among teenagers by using the ligase chain reaction assay on urine specimens and to evaluate leukocyte esterase testing of urine specimens as an indicator of infection. Cross-sectional study. An adolescent clinic, a juvenile detention facility, seven school-based clinics, and three community-based youth organizations in Seattle, Washington. 10,118 sexually active teenagers and young adults. Chlamydia trachomatis infection detected in urine specimens by ligase chain reaction assay and leukocyturia detected by leukocyte esterase testing. The prevalence of chlamydial infection among female participants was 8.6% and declined with increasing age; among male participants, it was 5.4% and increased with increasing age. In female participants, independent predictors of infection were being 17 years of age or younger (odds ratio [OR], 1.49), having had two or more sex partners in the previous 2 months (OR, 1.61), and having genitourinary symptoms (OR, 1.46). In male participants, independent predictors were being of nonwhite race or ethnicity (OR, 2.00 to 3.08), having had two or more sex partners in the previous 2 months (OR, 1.57), and having used a condom during the most recent sexual encounter (OR, 0.67). For identifying infection in male participants, the sensitivity of leukocyte esterase testing was 58.9%, the specificity was 94.9%, the positive predictive value was 38.4%, and the negative predictive value was 97.7%. Chlamydial infection is common in teenagers and young adults in community settings. The urine ligase chain reaction assay will permit widespread screening for C. trachomatis, but leukocyte esterase testing had low sensitivity for selecting persons for screening with this assay. Indicators of chlamydial infection differed substantially in male and female participants.

Rapid screening and treatment for sexually transmitted diseases in arrestees: a feasible control measure.

The purpose of this study was to determine the feasibility and usefulness of rapid screening and immediate presumptive treatment for sexually transmitted diseases among arrestees at a county jail. The rapid plasma reagin test (for syphilis) and the urine leukocyte esterase test (for urethritis) were used in establishing routine screening and presumptive treatment for sexually transmitted diseases among arrestees. Of 4757 arrestees screened, 82 (1.7%) had untreated syphilis, and, of 4174 male arrestees screened, 541 (13%) had a positive leukocyte esterase test. The syphilis prevalence rate was higher among women than among men (3.1% vs 1.5%), and the rate was higher among Blacks than among Whites (2.3% vs 0.7%). Although leukocyte esterase test positivity was higher among persons reporting a urethral discharge (57% vs 12%), 88% of persons with a positive test result did not report such symptoms. The program described here has reached persons with sexually transmitted diseases who are unlikely to use traditional health care services and thus are likely to remain untreated. Rapid screening and treatment for sexually transmitted diseases among arrestees is feasible and should be considered in areas with high sexually transmitted disease rates.

Clinical evaluation of a leukocyte esterase test-strip for detection of feline pyuria.

Commercial macroscopic test-strips (dipsticks) that indirectly detect urine leukocytes by quantifying leukocyte esterase (LE) activity have been advocated as a simple, rapid, and inexpensive alternative to microscopic examination for detection of significant pyuria in urine specimens. The purpose of this study was to evaluate the diagnostic performance of a commercial LE test-strip for detection of feline pyuria. Two hundred and thirteen consecutive urine specimens were collected from 188 different feline patients and analyzed for LE activity with a LE test-strip (Multistix 2 Reagent Strips:Ames Division, Bayer Corp., Elkhart, IN). Results of the LE test-strip were compared with those of standard urine biochemical and microscopic sediment evaluations. Compared with urine sediment leukocyte counts, the LE test-strip had a sensitivity of 77%, a specificity of 34%, positive and negative predictive values of 14 and 91 % respectively, and an overall test efficiency of 39%. Multivariable logistic regression analysis did not reveal significant associations between pyuria (>5 WBC/hpf) and a positive LE test- strip reaction; however, hematuria, lipiduria, increasing age, and decreasing urine specific gravity were associated with a significantly increased risk for positive LE test-strip reactions. We conclude that the LE test-strip evaluated in this study is highly nonspecific for detection of significant pyuria in feline urine specimens and should not replace routine microscopic urine sediment examination in this species.

Pattern of sexually transmitted diseases among pregnant women in Burkina Faso, west Africa: potential for a clinical management based on simple approaches.

OBJECTIVES: (1) To determine the prevalence of sexually transmitted diseases (STDs) in pregnant women in Burkina Faso. (2) To evaluate the potential of clinical management of STDs based on screening...

Utilization of leukocyte esterase test (LET) in screening adolescent males in preparticipation sports physicals for sexually transmitted infections (STI's) and bacturia: Margaret J. Blythe, M.D., Dennis Fortenberry, M.D., Don Orr, M.D., Robert Jones, M.D., PhD. Departments of Pediatrics and Medicine, Indiana University Medical Center, Indianapolis, Indiana

Utilization of leukocyte esterase test (LET) in screening adolescent males in preparticipation sports physicals for sexually transmitted infections (STI's) and bacturia: Margaret J. Blythe, M.D., Dennis Fortenberry, M.D., Don Orr, M.D., Robert Jones, M.D., PhD. Departments of Pediatrics and Medicine, Indiana University Medical Center, Indianapolis, Indiana

STD rapid assessment in Rwandan refugee camps in Tanzania.

OBJECTIVE: To obtain baseline information on sexually transmitted diseases (STDs) in the Rwandan refugees camps in Tanzania, prior to establishment of STD services. SETTING: The largest camps of Rwandan refugees...

Pyuria Among Chronically Incontinent but Otherwise Asymptomatic Nursing Home Residents

To determine the prevalence of pyuria and its relationship to bacteriuria in a representative sample of chronically incontinent nursing home residents. Prospective, descriptive case series. Six nursing homes. Two hundred fourteen chronically incontinent, but otherwise asymptomatic, nursing home residents who were enrolled in a clinical intervention trial for urinary incontinence. Two hundred fourteen urine specimens were collected by a validated clean catch technique. Each specimen underwent dipstick testing for leukocyte esterase, microscopic urinalysis to determine the number of white blood cells per high power field of centrifuged urine, and quantitative urine culture using standard laboratory techniques. The overall prevalence of pyuria was 45%, as defined by > 10 white blood cells per high field of spun urine, and the overall prevalence of bacteriuria was 43%, as defined by the growth of > 100,000 colony forming units of a urinary pathogen. Fifty-nine percent of the specimens with bacteriuria and 34% of the specimens without bacteriuria had pyuria. Of specimens with pyuria, 56% had bacteriuria, and of specimens without pyuria, 31% had bacteriuria. When any colon change on the leukocyte esterase pad was considered positive, this finding had a sensitivity of 83% and a specificity of 52% for pyuria on microscopic urinalysis. Pyuria is common among chronically incontinent nursing home residents, both in the presence and absence of bacteriuria. Clinicians must therefore be cautious in interpreting the presence of pyuria to indicate symptomatic infection in this population. Using pyuria to determine the need for antimicrobial treatment could result in unnecessary expense and morbidity as well as contribute to the development of resistant organisms in nursing homes. Research is needed to define pyuria better, to determine its prevalence and relationship to bacteriuria among nursing home residents with symptoms of acute urinary tract infection, and to elucidate the etiology and significance of sterile pyuria in this population.

Is urine leukocyte esterase test a useful screening method to predict Chlamydia trachomatis infection in women?

We evaluated the use of the leukocyte esterase test (LET) on first-catch urine specimens from women as a screening test to predict infection with Chlamydia trachomatis. For diagnosis, we used Abbott's ligase chain reaction (LCR) on urine specimens and isolation by tissue culture (TC) on cervical brushes. Of 4,053 women attending sexually transmitted disease and family planning clinics, 4.3% (n = 174) were positive by TC and 5.9% (n = 239) were positive by LCR. When LET was compared to TC, the sensitivity, specificity, positive predictive value, and negative predictive value were 54.0, 67.0, 6.8, and 97.0%, respectively. The corresponding performance of LET versus LCR was 53.1, 67.3, 10.1, and 95.8%. Almost half of the laboratory-confirmed chlamydial infections were negative by LET. The low specificity probably reflects multiple causes of pyuria in women and results in a low positive predictive value. LET is neither sensitive nor specific as a predictor of chlamydial infection and cannot be recommended for use as a screening test for C. trachomatis with first-catch urine samples from females from low- or moderate-prevalence populations.

Uriscreen, a rapid enzymatic urine screening test: useful predictor of significant bacteriuria in pregnancy

To establish the reliability of a new rapid enzymatic screening test, the Uriscreen, in the detection of significant bacteriuria in pregnancy. During a 6-month period, from July 1 to December 30, 1993, 313 consecutive pregnant patients were evaluated. Randomly voided, midstream, clean-catch urine specimens were used. Each sample was tested by routine laboratory culture and four rapid screening tests: the nitrite and leukocyte esterase dipstick, microscopic examination for pyuria, and the Uriscreen test. Results of the four rapid tests were compared with those of the urine culture. Twenty-four women (7.6%) had urine culture results indicating significant bacteriuria. The sensitivity of the nitrite test, the leukocyte esterase test, and a microscopic examination for pyuria was low (37, 52, and 56%, respectively). The Uriscreen test showed very high sensitivity (100%), lower specificity (81%), a high predictive value of negative results (100%), and a low positive predictive value (30%). The Uriscreen test is a reliable alternative to culture screening of all pregnant patients. A policy of performing a urine culture during pregnancy only on patients with a positive Uriscreen test will save as much as 80% of unnecessary cultures.

Screening urine samples by leukocyte esterase test and ligase chain reaction for chlamydial infections among asymptomatic men.

Urine samples from 358 asymptomatic males were screened for urethral inflammation by the leukocyte esterase (LE) test and for Chlamydia trachomatis by the ligase chain reaction (LCR). LE and LCR positivity rates were 7.5% (27 of 358 samples) and 2.8% (10 of 358 samples), respectively. Eight of the 10 LCR-positive samples were detected by the LE screening test. The urine LE prescreening test in combination with the LCR assay may be a reasonable approach for genitourinary chlamydial disease control.

Accuracy of Rapid Urine Screening Tests Among Incontinent Nursing Home Residents with Asymptomatic Bacteriuria

To determine the accuracy of rapid urine screening tests in detecting bacteriuria among incontinent nursing home residents. Six nursing homes. 214 chronically incontinent, but otherwise asymptomatic, nursing home residents who were enrolled in a clinical intervention trial for urinary incontinence. 684 urine specimens were collected, the majority (76%) by a clean catch technique and the remainder by in-and-out catheterization. Each specimen underwent dipstick testing for nitrite and leukocyte esterase, a rapid, enzyme-based screening test for bacteriuria, and a quantitative urine culture using standard laboratory techniques. No one screening test or combination of tests had adequate sensitivity and specificity for clinical purposes. However, using all three tests, the sensitivity increases to 97% in females and 92% in males when any one of the tests is positive, and the specificity increases to 95% in females and 97% in males when all three tests are negative. Among nursing home residents suspected of having a symptomatic urinary tract infection, the prevalence of bacteriuria is probably higher than in our study population (e.g., 60-70%, compared with 32%). At these prevalence rates, the positive predictive value of any of the three tests being positive is 93% and higher, and the negative predictive value of all three tests being negative is 80 to 90%. Our data must be interpreted cautiously because of the specimen collection methods, the definitions we used, and the fact that we studied a population who did not have symptoms of an acute urinary tract infection. In addition, we did not examine the absolute accuracy of the screening tests, but their accuracy as a clinician might use them in a nursing home. Despite these caveats, our data suggest that a combination of these screening tests could be useful in the initial assessment of nursing home residents for bacteriuria, and result in considerable cost savings. Studies are needed to replicate our findings among nursing home residents with symptomatic urinary tract infections.

Neutrophil enzymes in urine for the detection of urethral infection in men.

To determine if assaying the neutrophil enzymes, neutrophil elastase (NE) and myeloperoxidase (MPO) in the urine of men attending a genitourinary medicine clinic could identify those with Neisseria gonorrhoeae or Chlamydia trachomatis infections, and those with urethritis (with or without an identified infection with either organism), and to compare the new assays with the performance of the leucocyte esterase test (LET). 100 men had urethral specimens taken for Gram-stained urethral smear, culture for N gonorrhoeae, and for C trachomatis testing by enzyme immunoassay. First-voided urines were tested for leucocyte esterase by commercial dipstick (positives were defined as greater than "trace") and then frozen at -20 degrees C prior to being assayed for NE and MPO. Five patients had gonorrhoea, six had chlamydia and none had both. Evidence of urethritis (> 5 polymorphonuclear leucocytes in four x 1000 fields) was found in 29 men. The results of the urine assays showed MPO levels to be non-discriminatory; however NE levels were significantly elevated in patients with proven infection or urethritis or both. Using NE values from men with no infection or urethritis an upper limit for normal was defined. Utilising this, the sensitivity of the elastase assay was calculated and found to be superior to the sensitivity of LET for detecting proven infection (64% vs 36%) and urethritis (52% vs 31%). Further studies of neutrophil elastase in the pathogenesis, diagnosis and treatment of urethritis are indicated.

Urine Specimen Collection from Incontinent Female Nursing Home Residents

To determine if a clean catch technique can accurately diagnose bacteriuria among incontinent female nursing home residents. Cultures and dipstick screening test results from paired urine specimens, one collected by a clean catch technique and the other collected by sterile in-and-out catheterization, were compared. A total of 101 incontinent female nursing home residents who were being assessed for participation in a larger clinical intervention trial for incontinence. Each urine was tested by a dipstick method for leukocyte esterase and nitrite and sent to a bioclinical laboratory for quantitative culture. Positive and negative culture results matched in 92 of the 101 paired specimens. Using the catheter specimen as a gold standard, the clean catch had a sensitivity of 90%, specificity of 92%, positive predictive value of 81%, and a negative predictive value of 95%. In a population with symptoms suggestive of infection, among whom the prevalence of bacteriuria would likely be higher than in the asymptomatic residents we studied (e.g., 60% vs 30%), the positive predictive value would increase to 95%, but the negative predictive value would decrease to 86%. The concordance of the results of the urine screening tests was not as good, except for the detection of a positive leukocyte esterase test and a negative nitrite test. Incontinent female nursing home residents do not necessarily have to be catheterized in order to obtain an accurate quantitative urine culture. Our results using a careful clean catch technique are comparable to those previously reported using urine obtained from a urine-soiled diaper as well as those using a condom catheter technique in men.

Detecting Sexually Transmitted Disease.

In brief During a routine preparticipation exam, a 17-year-old asymptomatic boy had a 1+ leukocyte esterase reaction on urinalysis. A subsequent urethral smear was positive for Chlamydia trachomatis, a pathogen that can cause urethritis or epididymitis in men and cervicitis and infertility in women. Most authorities do not consider a screening urinalysis a necessary part of the preparticipation exam because the yield of significant renal or metabolic disease is low. However, the newer dipstick strips that incorporate the leukocyte esterase test may prompt a reassessment.

Rapid dipstick test for diagnosis of urinary tract infection

The rapid dipstick test of urine leukocyte esterase (LE) activity and nitrite has not been studied fully in pediatric clinical situations. We investigated the usefulness of the dipstick LE and nitrite test in the screening of urinary tract infection (UTI) in pediatric patients. Ninety-two fresh urine samples were obtained from children suspected of having UTI. Leukocyte esterase activity and nitrite were measured in the urine specimens read by a photometer. Leukocytes were also counted on a disposable slide. Urine samples were examined for bacteriuria by the standard culture method. The results of the urine dipstick test of LE showed a close relationship with leukocyte counts on a counting chamber. Leukocyte esterase (-) indicated leukocyte counts of less than 10/uL with a probability of 97% (58/60). Of the 22 urine samples with significant bacteriuria diagnosed by standard urine culture, the nitrite test did not detect bacteriuria in 10. While the sensitivities of the dipstick tests of nitrite (+) and LE +/- or more for the diagnosis of significant bacteriuria were 55% (12/22) and 86% (19/22), respectively, the sensitivity and negative predictive value of the combined test were 100%. These results suggest that use of the dipstick test of LE and nitrite can avoid a large part of the cost incurred by urine culture and is useful for screening UTI in children.

Screening for Chlamydia trachomatis: a case for empirical treatment

To the Editor. —The article by Dr Shafer and colleagues 1 regarding urine-based screening strategies to detect Chlamydia trachomatis infection among sexually active asymptomatic young men provided valuable information. As part of a Chlamydia Prevention Initiative in San Diego County, California, we advocate that sexually active asymptomatic adolescent males be screened during routine preventive health care visits, such as during sports physicals. We recommend first-void urine leukocyte esterase (LE) testing because it can be done in the physician's office at negligible cost (approximately 30 cents). For adolescents with a positive LE, especially those engaging in high-risk sexual behavior, we recommend strong consideration of empirical treatment, and for others, further evaluation and confirmatory testing. Confirmatory testing may not be available in certain settings, mainly because of cost concerns, and even when it can be done, some adolescents may not return to obtain results or treatment. Therefore, there is a need for a

The Investigation of Relation Between Pyuria and Bacteriuria in Symptomatic and Asymptomatic Urinary Tract Infections of Women

Greatly questionable, clacification of the diagnosis with the results of commonly used laboratory tests has great importance. in this study, relation between pyuria and bacteriuria was investigated. Pyuria was evaluated by white cell count and leukocyte esterase test in urine sedimen (Multistik 10 SG). Bacteriuria was detected in 153(51.94 %) of 298 urine specimens. In urine sediment of culture-positive specimens, pyuria was detected by white cell count in 33.3 % of these and by leukocyte esterase test in 34.6 % of these, the percentages were 22. 7 % and 12.4 % for culture--negative specimens, respectively. The correlation between bacteriuria and pyuria, especially for the specimens of symptomatic patients, was found to be high. Because of we couldn't find any statistical significance between white celi count and leucocyte esterase test, we think that both of the test can be used to determine the pyuria. However, for the diagnosis of urinary tract infection, it would be a proper management culturing the specimen, while evaluating the urine for pyuria.