Nitrite Dipstick Test Research Articles

Evaluation of Leukocyte esterase and Nitrite dipstick tests with routine urine microscopic analysis in detecting urinary tract infections

Evaluation of Leukocyte esterase and Nitrite dipstick tests with routine urine microscopic analysis in detecting urinary tract infections

Nitrite-negative results in urinary tract infection by Enterobacterales: does the nitrite dipstick test have low sensitivity?

Urinary tract infection (UTI) is one of the most common bacterial infections among humans. Urine culture is the gold standard diagnostic method for UTI; however, the dipstick test for nitrite is a widely used method signalling the presence of urinary nitrate-reducing bacteria. Unlike the gold standard, the dipstick test is easy to perform, while it is also less time-consuming and less expensive, and produces a result in a few minutes. This study investigates the sensitivity of the dipstick test for nitrite compared with the Griess test in urine samples from UTI caused by Enterobacterales species. We used the Griess test, which is the gold standard in nitrite measurement, to determine the sensitivity of the nitrite dipstick test. Semiquantitative urine culture was performed using standard procedures, and Enterobacterales identification was performed by manual conventional biochemical tests. In the first sample selection, 3 % (8/267) of urine samples suspected of UTI, analysed from March to April 2016, were nitrite-negative by dipstick test but positive for Enterobacterales in the urine culture. In the second sample selection, 5 % (2/44) of urine samples from October to December 2022 were also nitrite-negative but showed urine Enterobacterales isolation. All nitrite-negative dipstick results were consistent with the Griess test. Escherichia coli was the most prevalent bacterium, followed by Klebsiella pneumoniae, independent of sample selection. The dipstick test is a safe alternative for investigating nitrite in urine samples. We believe that the cause of nitrite-negative results is a lack of dietary nitrate, dilution of urine and exogenous interference (e.g. ascorbic acid). These findings support the idea that standard urine culture is necessary to rule out UTI.

Effect of asymptomatic bacteriuria on readmissions and rate of urosepsis after ureterorenoscopy for urolithiasis

Objective: This study aims to assess whether the rate of readmissions after ureterorenoscopy (URS) is dependent on results of urine microscopy, culture and sensitivity (MC&S) or nitrite dipstick test performed before the procedure. Patients and Methods: All patients attending for ureteroscopy for stone disease over 12 months were included and had urine dipstick performed immediately prior to the surgery with mid-stream urine (MSU) sample sent for culture. Asymptomatic bacteriuria (ABU) was not treated before ureteroscopy. All included patients received standard antibiotic prophylaxis. Readmissions within 30 days of the procedure were evaluated. Results: A total 120 ureteroscopies were included, of which 20% had ABU. Eight patients (6.67%) were readmitted due to all procedure-related complications; among them, five (4.17%) were readmitted with urinary tract infection (UTI). Readmission rates with UTIs were similar for patients with sterile urine and those who had untreated ABU. Of those patients who were readmitted with UTI, all had a negative nitrite result on preoperative urine dipstick specimens. Most patients (54.17%) who had ABU also had a negative urinary nitrite test. Conclusions: Screening and routine treatment of ABU before ureteroscopy for urolithiasis may be unnecessary provided patients have standard antibiotic prophylaxis. Moreover, urine nitrite testing before ureteroscopy may not be a useful screening test for ABU before ureteroscopy. Level of evidence: 2

Evaluation of rapid screening methods in the diagnosis of urinary tract infection

Introduction: Urinary Tract Infection (UTI) is one of the most common bacterial infection encountered in clinical practice. Even though urine culture is considered as the gold standard in detection of bacteriuria, many alternative screening methods like urine microscopy, chemical analysis using dipstick method and Gram’s staining have been evaluated which are more economical and rapid. Hence, this study was undertaken to evaluate various screening methods in the rapid diagnosis of Urinary Tract Infections. Objectives: To evaluate Gram staining of urine, leucocyte esterase and nitrite dipstick test methods in the rapid diagnosis of Urinary Tract Infections. Materials and Methods: All urine samples received at Microbiology laboratory, McGann hospital, attached to Shimoga Institute of Medical Sciences, during study period was subjected to Gram staining, leucocyte esterase and nitrite dip stick test along with culture. Results of these tests were compared to culture results. Sensitivity and specificity of the tests was determined taking culture as standard. Results: A total of 560 urine samples were processed. Culture showed significant bacteriuria in 210 cases. The sensitivity of urine microscopy was 70.9%, leucocyte esterase test was 98% and nitrite test was 74.8%. Whereas the specificity of urine microscopy was 70%, leucocyte esterase test was 79.1% and nitrite test was 98.8%. Similarly, the sensitivity of combined leucocyte esterase and nitrite tests was 90.9% and specifity was 97.4%. Sensitivity and specificity of all the three screening tests combined were 95.7% and 94.8% respectively. Conclusion: Screening tests such as, Urine microscopy by Gram’s staining, Leucocyte esterase and nitrite dipstick test in combination can be used routinely to exclude bacteriuria. Urine culture can be employed only in the screening tests positive cases and in symptomatic cases irrespective of test results, thereby making diagnosis of UTI cost effective and rapid. Keywords: Bact

A positive nitrite test was an independent risk factor for invasive bacterial infections in infants under 90days of age with fever without source.

This study analysed the association between a positive nitrite dipstick test and an invasive bacterial infection (IBI) in infants younger than 90days of age with fever without source (FWS). We performed a secondary analysis of data from a prospective multicentre study of infants up to 90days of age with FWS undergoing care in 19 paediatric EDs between October 2011 and September 2013. Invasive bacterial infection was defined as a positive blood or cerebrospinal fluid culture. The dipstick urinalysis was positive for nitrite or leucocyte esterase in 766 (22.5%) of the 3401 infants we studied, and 270 (35.2%) had a dipstick test that was just positive for nitrite. Overall, 107 were diagnosed with an IBI (3.1%). The IBI prevalence was 2.2% among patients with a normal urine dipstick, 4.4% if they had positive leucocyte esterase test results, 8.3% where the nitrite test was positive and 10.6% when both tests were positive. After multivariate analysis, a positive nitrite test remained an independent risk factor for IBI (odds ratio 2.7, 95% confidence interval 1.4-4.9). In infants under 90days of age with FWS, a positive nitrite urine dipstick test was an independent risk factor for IBI.

Incidence, risk factors and causative bacteria of urinary tract infections and their antimicrobial sensitivity patterns in toddlers and children: A report from two tertiary care hospitals.

Urinary tract infection (UTI) is one of the most common bacterial infections among children. It is noted that the risk of renal damage from UTI is the greatest in children younger than five years, thus early diagnosis and prompt treatment are important. The aim of this study was to assess the incidence of UTI in children attending pediatric outpatient clinics in Zagazig and Tanta University Hospitals as tertiary care hospitals. Furthermore, we attempted to determine related risk factors, isolate the organisms that cause UTI in children, and study their antibiotic susceptibility patterns. This cross-sectional descriptive study was conducted on 1200 toddlers and children, (754 boys and 446 girls) aged between 30 months and seven years attending the pediatric outpatient clinics of Zagazig and Tanta University Hospitals. All patient groups were subjected to full medical history, physical examination, dipstick analysis by using both nitrite and leukocyte esterase (LE) detectors, microscopic examinations, and urine culture for cases with the positive LE, positive nitrite dipstick test for urine or positive for both LE and nitrite. The incidence of UTI among children included in the current study was 7%. Positive LE was seen in 112 (9.3%), nitrite positivity was seen in 94 (7.8%), and both LE and nitrite positivity in 34 (2.8%). Escherichia coli was the most common organism. Cefotaxime and amikacin were the most common sensitive antibiotics to the isolates.

Urinary ATP and visualization of intracellular bacteria: a superior diagnostic marker for recurrent UTI in renal transplant recipients?

Renal transplant recipients (RTR) are highly susceptible to urinary tract infections (UTIs) with over 50% of patients having at least one UTI within the first year. Yet it is generally acknowledged that there is considerable insensitivity and inaccuracy in routine urinalysis when screening for UTIs. Thus a large number of transplant patients with genuine urine infections may go undiagnosed and develop chronic recalcitrant infections, which can be associated with graft loss and morbidity. Given a recent study demonstrating ATP is released by urothelial cells in response to bacteria exposure, possibly acting at metabotropic P2Y receptors mediating a proinflammatory response, we have investigated alternative, and possibly more appropriate, urinalysis techniques in a cohort of RTRs.Mid-stream urine (MSU) samples were collected from 53 outpatient RTRs. Conventional leukocyte esterase and nitrite dipstick tests, and microscopic pyuria counts (in 1 μl), ATP concentration measurements, and identification of intracellular bacteria in shed urothelial cells, were performed on fresh unspun samples and compared to ‘gold-standard’ bacterial culture results.Of the 53 RTRs, 22% were deemed to have a UTI by ‘gold-standard’ conventional bacteria culture, whereas 87%, 8% and 4% showed evidence of UTIs according to leukocyte esterase dipstick, nitrite dipstick, and a combination of both dipsticks, respectively. Intracellular bacteria were visualized in shed urothelial cells of 44% of RTRs, however only 1 of the 23 RTRs (44%) was deemed to have a UTI by conventional bacteria culture. A significant association of the ‘gold-standard’ test with urinary ATP concentration combined with visualization of intracellular bacteria in shed urothelial cells was determined using the Fisher’s exact test.It is apparent that standard bedside tests for UTIs give variable results and that seemingly quiescent bacteria in urothelial cells are very common in RTRs and may represent a focus of subclinical infection. Furthermore, our results suggest urinary ATP concentration combined with detection of intracellular bacteria in shed urinary epithelial cells may be a sensitive means by which to detect ‘occult’ infection in RTRs.

Asymptomatic bacteriuria in women attending an antenatal clinic at a tertiary care centre

Objective . To compare the diagnostic performance of urine microscopy, leucocyte esterase and nitrite dipstick tests and various combinations of these as screening tests for asymptomatic bacteriuria in pregnancy. Methods . Pregnant women (N=800) attending an antenatal clinic were recruited at their first visit. Urine microscopy, culture and dipstick testing were performed on a random clean-catch midstream urine sample. A count of >105 colony-forming units of a single organism per millilitre of urine was taken as significant. Dipstick results were read as positive according to the manufacturer’s instructions. Results . A total of 800 eligible women were screened. The prevalence of asymptomatic bacteriuria as diagnosed by urine culture was 5.0% (n=40). Escherichia coli was the most prevalent uropathogen isolated by culture (60.0%). Neither urine microscopy nor the leucocyte test was found to be sufficiently sensitive to be used as a single screening test for asymptomatic bacteriuria in pregnant patients. The nitrite test alone had a sensitivity of 82.5% and a specificity of 99.9%. Combined dipstick testing had an improved sensitivity of 87.3% and a specificity of 96.2%. Addition of urine microscopy to combined dipstick testing increased the sensitivity to 95.0%, and the specificity became 92.4%. Conclusion . Combined dipstick testing is a useful screening test for asymptomatic bacteriuria in pregnancy. Addition of urine microscopy to combined dipstick testing further improves its diagnostic performance.

Irrigation of Continent Catheterizable Ileal Pouches: Tap Water Can Replace Sterile Solutions Because It Is Safe, Easy, and Economical

BackgroundContinent catheterizable ileal pouches require regular irrigations to reduce the risk of bacteriuria and urinary tract infections (UTIs). ObjectiveOur aim was to compare the UTI rate, patient friendliness, and costs of standard sterile irrigation versus irrigation with tap water. Design, setting, and participantsTwenty-three patients participated in a prospective randomized two-arm crossover single-center trial. Aseptic intermittent self-catheterization (ISC) combined with sterile sodium chloride (NaCl) 0.9% irrigation was compared with clean ISC and irrigation with tap water (H2O) during two study periods of 90 d each. InterventionPatients underwent daily pouch irrigations with NaCl 0.9% solution or tap water. MeasurementsUrine nitrite dipstick tests were evaluated daily; urine culture (UC) and patient friendliness were evaluated monthly. Costs were documented. Results and limitationsA total of 3916 study days with nitrite testing and irrigation were analyzed, 1876 (48%) in the NaCl arm and 2040 (52%) in the H2O arm. In the NaCl arm, 418 study days (22%) with nitrite-positive dipsticks were recorded, 219 d (11%) in the H2O arm, significantly fewer (p=0.01). Of the 149 UCs, 96 (64%) were positive, 48 in each arm, revealing a total of 16 different germs. All patients preferred the H2O method. Monthly costs were up to 20 times lower in the H2O arm. ConclusionsPouch irrigation with sterile NaCl 0.9% solution and tap water had comparable rates of positive UC. Irrigation with tap water significantly lowered the incidence of nitrite-positive study days and was substantially less costly and more patient friendly than NaCl irrigation. We therefore recommend the use of tap water (or bottled water) instead of sterile NaCl 0.9% solution for daily irrigation of continent catheterizable ileal pouches. Trial registrationAustralian New Zealand Clinical Trials Registry, ACTRN12610000618055, http://www.ANZCTR.org.au/ACTRN12610000618055.aspx.

Dipstick Urinalysis as a Screening Tool in the Diagnosis of Urinary Tract Infection in Children.

Urinary tract infection (UTI), a significant but preventable cause of morbidity in children, is an important risk factor for development of renal insufficiency. Having simple and reliable means of screening children facilitate its prompt treatment.To evaluate the use of dipstick test for leukocyte esterase (LE) and nitrite as screening tool in the diagnosis of UTI in children.This cross-sectional study was done in the department of Paediatrics, University of Port Harcourt Teaching Hospital (UPTH) from February to October 2005. Children 2 to 15 years with symptoms suggestive of UTI were studied. Midstream urine specimen was collected from each patient forLEtest, nitrite test and culture.Out of 139 children, 72(51.8 percent) males and 67(48.2 percent) females studied, 33(23.7 percent) had positive urine culture. The prevalence of UTI was significantly higher in females than in males (p=0.001). The LE dipstick test correctly identified 17 of the 33 patients with culture proven UTI, with 51.5 percent sensitivity and 79.2 percent specificity. The nitrite dipstick test showed 42.4 percent sensitivity and 93.3 percent specificity. The combination ofLEand nitrite correctly identified 24, giving 73 percent sensitivity and 75.5 percent specificity. The LE seemed to have a higher sensitivity as a screening tool in the diagnosis of UTI than nitrite, but the difference was not statistically significant (p=0.46). However, the combination of LE and nitrite provided a higher sensitivity than either of them with a statistically significant difference (p=0.04).Key words: Dipstick urinalysis, Screening tool

Premarital screening for sickle cell haemoglobin: awareness and acceptability among some categories of Health Professionals and Medical Students at the Lagos University Teaching Hospital.

Urinary tract infection (UTI), a significant but preventable cause of morbidity in children, is an important risk factor for development of renal insufficiency. Having simple and reliable means of screening children facilitate its prompt treatment.To evaluate the use of dipstick test for leukocyte esterase (LE) and nitrite as screening tool in the diagnosis of UTI in children.This cross-sectional study was done in the department of Paediatrics, University of Port Harcourt Teaching Hospital (UPTH) from February to October 2005. Children 2 to 15 years with symptoms suggestive of UTI were studied. Midstream urine specimen was collected from each patient forLEtest, nitrite test and culture.Out of 139 children, 72(51.8 percent) males and 67(48.2 percent) females studied, 33(23.7 percent) had positive urine culture. The prevalence of UTI was significantly higher in females than in males (p=0.001). The LE dipstick test correctly identified 17 of the 33 patients with culture proven UTI, with 51.5 percent sensitivity and 79.2 percent specificity. The nitrite dipstick test showed 42.4 percent sensitivity and 93.3 percent specificity. The combination ofLEand nitrite correctly identified 24, giving 73 percent sensitivity and 75.5 percent specificity. The LE seemed to have a higher sensitivity as a screening tool in the diagnosis of UTI than nitrite, but the difference was not statistically significant (p=0.46). However, the combination of LE and nitrite provided a higher sensitivity than either of them with a statistically significant difference (p=0.04). Keywords: Sickle cell anaemia, premarital screening, Haemoglobin genotype.

Performance of the Urine Leukocyte Esterase and Nitrite Dipstick Test for the Diagnosis of Acute Prostatitis

Performance of the Urine Leukocyte Esterase and Nitrite Dipstick Test for the Diagnosis of Acute Prostatitis

Nitrite and Leukocyte Dipstick Testing For Urinary Tract Infection in Individuals With Spinal Cord Injury

Objective: Todetermine sensitivity, specificity, and positive and negative predictive values of nitrite (NIT) and leukocyte esterase (LE) testing in relation to Iabaratory evidence of significant bacteriuria and urinary tract infection (UTI) in persons with spinal cord injury (SCI).Design: Monthly urine cultures were compared with results of dipstick testing. Setting: Community based.Methods: Fifty-six people with SCI were evaluated on a monthly basis with dipstick testing for NIT and LE as weil as urine cultures. Participants reported whether they believed that they had a UTI and, if so, whether they were treated for the UTI and what symptoms they had experienced.Results: The sensitivity rate for the most comprehensive criteria-defined as positive NIT test, a positive LE positive, or both a positive NIT test and positive LE test-was 0.64 and the specificity rate was only 0.52. No singletype ofbacteria was found to occur in more than 3 0% of the urine samples.Conclusion: Reliance on dipstick testing for NIT and LEin individuals with SCI can Iead to high rates of overtreatment for UTI, given the fact that regular catheterization is associated with significant bacteriuria. lndividuals with SCI should be evaluated with urine culture to ensure proper treatment.

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 offirst morning urines (n = 420) of hospital inpatients. Results—The sensitivity, specificity, and negative predictive value of the leucocyte esterase test for the cutoV of > 10 WBC/µl were 57%, 94%, and 68%, respectively. For > 5 WBC per high powerfield (HPF) these variables were 84%, 90%, and 93%. For >1 0 5 colony counts/ml, the sensitivity of the nitrite test was 27%, specificity 94%, and negative predictive value 87%. When either leucocyte esterase or nitrite positivity was accepted as a marker of urinary tract infection, the sensitivity was 78%, specificity 75%, and negative predictive value 94%, and there were 22% false negative results. Semiquantitative microscopic estimation of bacteria per HPF yielded 40% false positives. Conclusions—Leucocyte esterase and nitrite dipstick tests are not suitable for screening for urinary tract infections. (J Clin Pathol 1998;51:471‐472)

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,...

Spectrum bias in the evaluation of diagnostic tests: lessons from the rapid dipstick test for urinary tract infection.

To determine if the leukocyte esterase and bacterial nitrite rapid dipstick test for urinary tract infection (UTI) is susceptible to spectrum bias (when a diagnostic test has different sensitivities or specificities in patients with different clinical manifestations of the disease for which the test is intended). Cross-sectional study. A total of 366 consecutive adult patients in whom clinicians performed urinalysis to diagnose or exclude UTI. An urban emergency department and walk-in clinic. After the patient encounter, but before dipstick test or culture was done, clinicians recorded the signs and symptoms that were the basis for suspecting UTI and for performing a urinalysis and an estimate of the probability of UTI based on the clinical evaluation. For all patients who received urinalysis, dipstick tests and culture were done in the clinical microbiology laboratory by medical technologists blinded to clinical evaluation. Sensitivity for the dipstick was calculated using a positive result in either leukocyte esterase or bacterial nitrite, or both, as the criterion for a positive dipstick, and greater than 10(5) CFU/mL for a positive culture. In the 107 patients with a high (greater than 50%) prior probability of UTI, who had many characteristic UTI symptoms, the sensitivity of the test was excellent (0.92; 95% CI, 0.82 to 0.98). In the 259 patients with a low (less than or equal to 50%) prior probability of UTI, the sensitivity of the test was poor (0.56; CI, 0.03 to 0.79). The leukocyte esterase and bacterial nitrite dipstick test for UTI is susceptible to spectrum bias, which may be responsible for differences in the test's sensitivity reported in previous studies. As a more general principle, diagnostic tests may have different sensitivities or specificities in different parts of the clinical spectrum of the disease they purport to identify or exclude, but studies evaluating such tests rarely report sensitivity and specificity in subgroups defined by clinical symptoms. When diagnostic tests are evaluated, information about symptoms in the patients recruited for study should be included, and analyses should be done within appropriate clinical subgroups so that clinicians may decide if reported sensitivities and specificities are applicable to their patients.

Dipstick urinalysis screening of asymptomatic adults for urinary tract disorders. II. Bacteriuria

Using criteria adopted by the US Preventive Services Task Force, we evaluated use of the dipstick urinalysis to screen for bacteriuria. When the leukocyte esterase and nitrite dipstick tests are combined, the positive predictive value for detecting bacteriuria exceeded 12% in groups with a 5% or higher prevalence of bacteriuria: women who are pregnant, diabetic, or over 60 years of age and all institutionalized elderly. Conventional antimicrobial regimens for asymptomatic bacteriuria have proved efficacious only for pregnant women. We conclude that pregnant women should be screened for bacteriuria, but with the more sensitive urine culture, because treatment prevents serious fetal and maternal sequelae. Dipstick screening may be justified in women who are over 60 years of age or diabetic. The prevalence of bacteriuria in other groups is too low to justify screening. (JAMA. 1989;262:1220-1224)

EVALUATION OF FOUR SCREENING TESTS FOR BACTERIURIA IN ELDERLY PEOPLE

Four screening tests for bacteriuria were assessed at ward level in 418 elderly subjects and were compared with standard methods of bacterial culture. The tests were visual appearance; microscopy; dipstick for nitrite, leucocyte esterase, protein, and blood; and dipstick for nitrite and organisms. The sensitivity of the tests varied from 85·6% to 98·3%, and the specificity from 18·4% to 82·9%. A combination of visual appearance and dipstick testing for nitrite and leucocyte esterase gave a sensitivity of 96·1% with a specificity of 50·6%, and could have reduced by almost one-third the number of urine samples submitted to the laboratory for processing.