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Reagent strip screening for sediment abnormalities identified by automated microscopy in urine from patients suspected to have urinary tract disease.

We assessed the ability of reagent strip screening to predict the finding of blood cells and bacteria using an automated urinalysis workstation (The Yellow IRIS, International Remote Imaging Systems, Chatsworth, Calif) in 427 specimens submitted for urine culture. The sensitivities of leukocyte esterase, hemoglobin, and nitrite detection on reagent strips were 71.9%, 70.8%, and 56.7%, respectively, at 5 or more white blood cells per high-power field, at 3 or more red blood cells per high-power field and bacteria observed using the IRIS. Screening results for leukocyte esterase associated with negative results using the IRIS for white blood cells represented mostly false-positive screening test results based on chart review. Positive screening test results for hemoglobin associated with negative results obtained with the IRIS for red blood cells consisted of equal numbers of false-positive screening test results and IRIS test results based on chart review. A common screening algorithm using a combination of these three reagent strip variables exhibited a false-negative rate of 30.1%: review of medical records found clinical evidence of urinary tract infection in 14 patients and genitourinary or renal disease or hypertension in another 13 patients. Adding more variables to the algorithm increases the sensitivity and decreases the specificity. Both microscopic examination and reagent strip testing of urine are necessary for the detection of abnormalities associated with disease.

Algorithms↗

[Evaluation of a method for determining the specific gravity of urine with a reagent strip].

The performance of a new reagent strip method for determining the urine specific gravity was evaluated. 342 clinical specimens were assayed in duplicate by the new method and by the "falling drop" technique. The reproducibility (two lots of strips, four operators) was very good (96.2 per cent agreement between replicates within a range of 0,0100 specific gravity units). The correlation with the comparative method was satisfactory [81,2 per cent concordance within a range of 0,0100 specific gravity units]. No interference was found from ketones, blood or urobilinogen. The influence of proteins and glucose is discussed. The practical advantages of the new method are described.

Acute Kidney Injury↗

Urine reagent strips for diagnosis of schistosomiasis haematobium in women of fertile age.

Hematuria, proteinuria and leukocyturia were semiquantitatively assessed by reagent strips in single morning urine of women of fertile age visiting the outpatient department of the Mangochi district hospital, Malawi. This was part of a diagnostic approach to female genital schistosomiasis (FGS). In 51 women ova of Schistosoma haematobium were detected in urine by a filtration technique. In 33 of these women ova were also present in genital tissue as demonstrated by microscopic examination of biopsies. In 209 women no ova were found in the single urine filtered. There were significantly higher scores for hematuria, proteinuria and leukocyturia as well as of the combined reagent strip index (RSI) in egg-excreting than in egg-negative women. The sensitivity of a single hematuria, proteinuria and leukocyturia reading was 98, 84 and 73%, respectively. However, the respective specificity was only 24, 22 and 23%. The best prediction of urinary schistosomiasis was achieved by a +2 score for hematuria, of which the sensitivity was 94% and the specificity was 61%. The high false-positive rates can probably be explained by contamination of urine by vaginal secretion. Moreover, cases of schistosomiasis have probably been overlooked because only a single morning urine sample was examined. The total absence of hematuria, proteinuria and leukocyturia, however, may be used to rule out heavy infections in community surveys. There was no difference in reagent strip scores between women with genital and urinary schistosomiasis as compared with those with urinary tract lesions alone. Thus urine analysis reagent strip readings do not help to discriminate between S. haematobium infected women with and without FGS.

Adolescent↗

[Evaluation of the reagent strip method to detect urinary tract infections. In hospital patients].

Asymptomatic urinary tract infections (UTI) are frequent in hospital patients. Two prospective studies were carried out to evaluate the reagent strip method used to detect these infections. The diagnosis of UTI rested on cytobacteriological examination of urine. Detection by reagent strip was performed either in the microbiology laboratory (study 1:976 samples) or at the patient's bedside and in the laboratory (Study 2:312 samples). The strips were examined visually and by an automated device. There was no significant difference between the results obtained with these two reading methods. Study 1 showed that the reagent strip is more useful to exclude the diagnosis of UTI by using the leucocyte zone alone or combined with the nitrite zone (negative predictive value 98 percent) than to assert this diagnosis. Study 2 showed that the nitrite zone was less sensitive when it was examined at the laboratory than at the patient's bedside. Analysis of discordances between reagent strip and cytobacteriology in the light of data supplied by the patient's medical records made it possible to improve the negative predictive value of the tests. (100 percent). Thus, 60 percent of cytobacteriological examinations might be avoided if this type of examination was performed only in urine with positive leucocyte or nitrite zones. This means a 15 percent saving in B-coded examinations performed in hospital microbiology laboratories.

Hospitals↗

Urine specific gravity measurement: reagent strip versus refractometer.

OBJECTIVE: To compare the results of urinalysis screenings for specific gravity (SG) using the reagent strip and the refractometer. SETTING: United Hospital, Grand Forks, North Dakota. PRACTICE DESCRIPTION: United Hospital is a 384-bed teaching hospital. PRODUCT COMPARISON: The Ames Multistix 10 SG reagent strip (Miles, Inc., Elkhart, IN 46515) was compared with the TS Meter (Leica, Inc., Deerfield, IL 60015). MAIN OUTCOME MEASUREMENT: The degree of correlation between the results produced by each method. RESULTS: The percentage of difference between the means of the direct strip readings and the refractometer readings was 9.68%. The percentage of difference between the means of the adjusted strip readings and the refractometer readings was 22.58%, which was significantly different. When the direct strip readings and the refractometer readings were plotted together on a graph, the points were widely scattered; this fact, and a correlation coefficient of 0.725, suggest that random error occurred in both methods. Analysis of the slope and intercept of the correlation indicated systematic error. CONCLUSION: The reagent strip method of measuring SG is accurate only in a narrow range of "average" values, and should not be used as the basis for medical diagnoses.

Humans↗

Rapid diagnosis of meningitis using reagent strips.

OBJECTIVES: Identification of causative agent with estimation of cerebrospinal fluid (CSF) glucose, protein, cells is necessary for accurate diagnosis of meningitis. Unfortunately, even these facilities are not available in many areas. Reagent strips that measure glucose and protein in blood and urine can serve this task but have been used with varying results in the past. This study was carried out to evaluate the utility and efficacy of Combur 10 strips in the diagnosis of meningitis. DESIGN, SETTINGS AND METHODS: A prospective clinical single blinded study of 63 children suspected to have meningitis undergoing CSF analysis. Each CSF sample was divided in to two and was utilised for reagent strip analysis in addition to standard laboratory evaluation and a correlation analysis were made. STATISTICAL METHOD USED: Results were analysed using standard statistical tests. Accuracy of the reagent strips as a screening tool was established using Godyn's test. RESULTS: The sensitivity, specificity of the reagent strips for the diagnosis of meningitis was 97.14%, 96.42%. The sensitivity, specificity for tuberculous meningitis and bacterial meningitis were 100%, and 96.55%. That for the aseptic meningitis was 70% and 96.55%. Accuracy for the diagnosis of meningitis as a whole, bacterial meningitis, tuberculous meningitis, and aseptic meningitis were 96.78%, 98.2%, 98.27% and 83.0% respectively. CONCLUSION: Combur10 strips thus can be used for the rapid CSF analysis and screening with good accuracy. In situations where facilities of routine laboratory testing are not available this can be of an immense help.

Child, Preschool↗

[Usefulness of reagent strips for the diagnosis of spontaneous bacterial peritonitis].

BACKGROUND/AIMS: Spontaneous bacterial peritonitis (SBP) is one of the potentially life-threatening complications for patients with liver cirrhosis, and it has a mortality rate of over 20%. Early diagnosis of SBP and immediate use of an adequate antibiotic therapy are very important for achieving a better prognosis. The aim of our study was to assess the usefulness of reagent strips for making the rapid diagnosis of SBP. METHODS: A diagnostic paracentesis procedure was performed upon hospital admission in 257 cirrhotic patients (187 males, 70 females; mean age: 54 years) with ascites. Each fresh sample of ascitic fluid was tested using a reagent strip, and the result was scored as 0, 1+, 2+ or 3+. The leukocyte count, polymorphonuclear cell count, blood bottle culture, and chemistry of ascites were also done. RESULTS: We diagnosed 79 cases of SBP and 2 cases of secondary bacterial peritonitis by means of the polymorphonuclear cell count and the classical criteria. When a reagent strip result of 3+ was considered positive, the test's sensitivity was 86% (70 of 81), the specificity was 100% (176 of 176), and the positive predictive value was 94%. Furthermore, when a reagent strip result of 2+ or more was considered positive, the test sensitivity was 100% (81 of 81), the specificity was 99% (174 of 176), and negative predictive value was 99%. CONCLUSIONS: The use of reagent strips is a very sensitive and specific tool for the rapid diagnosis of SBP in cirrhotic patients. A positive result should be an indication for empirical antibiotic therapy, and a negative result may be useful as a screening test to exclude SBP.

Aged↗

The usefulness of urinalysis reagent strips in selecting Schistosoma haematobium egg positives before and after treatment with praziquantel.

The effectiveness of urinalysis reagent strips for haematuria and proteinuria in selecting Schistosoma haematobium egg-positive persons was studied on 426 subjects of all ages in a Kenyan community before and 3 months after treatment with praziquantel. Before and after treatment, the degree of urinary blood or protein and prevalence of egg positives were closely associated. Haematuria and proteinuria were positively correlated with urinary egg counts. For selecting egg-positive persons with reagent strips, a combined criterion 'haematuria trace up or proteinuria 1 + up' was considered the best in this area. With this criterion, sensitivity and specificity before treatment were 69.6 and 84.4 respectively. These values remained at the same level (70.7 and 81.2%) even after treatment with praziquantel reduced prevalence from 59.4 to 13.6% (77% reduction) and intensity of infection from 57.2 to 11.3 eggs 10 ml-1 of urine (80% reduction). Although the sensitivity was not very high, heavy infections were not missed. If all those selected with reagent strips were treated and cured, a 98% reduction in total egg excretion by the community would be expected in both our first and second urine examinations.

Adolescent↗

Rapid diagnosis of spontaneous bacterial peritonitis with leukocyte esterase reagent strips in a European and in an American center.

BACKGROUND: Timely diagnosis and treatment of spontaneous bacterial peritonitis (SBP) are essential to survival. The purpose of the present paper was to evaluate leukocyte esterase reagent strips (Nephur-Test and MultistixSG10) in the bedside diagnosis of SBP. METHODS: Patients with cirrhotic ascites were prospectively included in France (center 1) and in the USA (center 2). Paracenteses were performed on admission and repeated as indicated. Bedside reagent strip testing was performed on the ascitic fluid and compared to manual cell count with differential and ascitic fluid culture. In center 1, the Nephur-Test was tested in all cases, with dual testing with MultistixSG10 in a subgroup. In center 2, all cases had dual testing. Spontaneous bacterial peritonitis was defined as a polymorphonuclear ascites count > or =250/microL. RESULTS: A total of 184 samples was obtained in 76 patients. Center 1 included 151 samples from 53 patients. Seven samples had SBP, obtained in six patients. Center 2 included 33 samples from 23 patients. Six samples had SBP, obtained in five patients. The sensitivity, specificity, positive and negative predictive value of the reagent strips were as follows. Center 1/Nephur-Test: 86%, 100%, 100%, 99%; center 1/MultistixSG10: 100%, 100%, 100%, 100%; center 2/Nephur-Test: 100%, 92.5%, 75%, 100%; center 2/MultistixSG10: 83%, 96%, 83%, 96%. CONCLUSION: Leukocyte esterase reagent strips may provide a rapid bedside diagnosis of SBP.

Ascites↗

Screening for bacteriuria in urological patients using reagent strips.

A rapid and accurate ward-based method of diagnosing urinary infection would be of value in determining the prescription of antibiotics in pre-operative urological patients. This study describes the sensitivity and specificity of a screening technique based on commercially available reagent strips in the diagnosis of urinary infection. A total of 222 pre-operative samples and 83 post-operative samples was studied to compare the results of formal urine culture and reagent strips. Using a definition of a positive nitrite or a positive leucocyte esterase on the reagent strips as being suggestive of infection, it was found that the strips had a sensitivity of 91% and a specificity of 85% compared with formal culture in pre-operative samples. The results from post-operative samples were less satisfactory, the strips having a sensitivity of only 71% and specificity of 55%. The strips were insensitive but specific in the identification of pyuria in pre-operative specimens. These results suggest that reagent strips can be used as a ward-based method to identify men at risk of infection before urological procedures, and may allow selectivity in the use of peri-operative antibiotics.

Adolescent↗

Comparison of reagent strip (dipstick) and microscopic haematuria in urological out-patients.

Dipstick (reagent strip) and microscopic urine analysis for haematuria was performed prospectively on 1000 consecutive urine samples taken from urological out-patients. Haematuria was present in 185 samples (18.5%) and absent in 687 (68.7%) using both tests; 98 samples (9.8%) had dipstick haematuria that was not confirmed by microscopy and 30 samples (3%) had microscopic haematuria that was missed on dipstick urine analysis. Dipstick urine analysis had a sensitivity of 86.1% and a specificity of 85%. This study confirms that reagent strip testing for haematuria has both false positive and false negative results and indicates that cytoscopy should be considered in all patients with suspected haematuria.

Adolescent↗

Reagent strip glucose monitoring methods in chronic hemodialysis.

Reagent strip blood glucose testing methods have not been extensively validated in dialysis patients, a serious omission as thousands of diabetic patients are now entering dialysis. Severe anemia and uremia are potentially confounding variables that might impair those testing methods. Various methods were tested pre- and postdialysis, and compared with standard laboratory results. In general, strip methods (SM) underestimated laboratory results by approximately 15%. Extremes of blood urea nitrogen, hematocrit, or blood glucose levels did not affect this reliability. Such methods appear to be suitable for use in chronic hemodialysis patients.

Blood Glucose↗

The effect of haematocrit on reagent strip tests for glucose.

Four blood glucose reagent strips (BM-Test 1-44, Glucostix, Hypoguard GA, and Exactech), used in conjunction with measuring devices produced by the same manufacturer, were investigated with respect to the influence of haematocrit. The erythrocytes and plasma of fresh blood samples were separated, then remixed in different proportions to achieve a range of haematocrit values and the resulting specimens subjected to glucose assay. All the strip tests showed some influence of haematocrit, low haematocrits producing higher glucose results and vice versa, but some were much more affected than others. The Hypoguard GA was most affected and the BM-Test 1-44 least. In the worst case, glucose results differed by 49% from one end of the normal adult haematocrit range to the other.

Adult↗

Inadequate hemolysis of erythrocytes on reagent strips at low pH causes false-negative readings.

Patients' urines gave an unexpectedly high percentage of false-negative results for erythrocytes on a reagent strip, even when the test field for ascorbic acid indicated that none of this substance was present to inhibit the test reaction. By adding known amounts of erythrocytes to normal urines, we found that this phenomenon was time-dependent and occurred with three different brands of reagent strips in urines having a pH below 6.0. Hemolysis of erythrocytes was totally inhibited below pH 5.1 after 4 h of incubation with 50 X 10(6) erythrocytes per liter. The inhibition is apparently caused by shrinkage of the erythrocytes, rending them insensitive to the hemolytic agents in the different reagent strips tested.

Detergents↗

Instant diagnosis of spontaneous bacterial peritonitis using leukocyte esterase reagent strips: Nephur-Test vs. MultistixSG.

BACKGROUND/AIM: Spontaneous bacterial peritonitis (SBP), defined by an ascites neutrophil count >250/mul, is a severe complication of cirrhosis and demands prompt diagnosis. Leukocyte esterase reagent strips can rapidly detect leukocytes in physiological fluids. We compared the performance of two leukocyte esterase reagent strips in the diagnosis of SBP. METHODS: Non-selected patients with cirrhosis and ascites were prospectively included in a Community Hospital. Manual ascites cytology, culture and BIOCHEMISTRY were compared with the Nephur-Test (read at 60 s: negative + 1 to + 3) and MultistixSG (read at 120 s: negative, trace, +1 to +3). Multiple investigators performed the tests with repeat readings by one nurse. RESULTS: Two hundred and forty five ascites fluid samples were obtained in 51 patients: 44% in conditions of SBP antibiotic prophylaxis, 64% in an ambulatory setting. Seventeen samples had an ascites polymorphonuclear count of > or =250/microl, associated with a positive ascites culture in seven, obtained in 12 patients (24%), 53% in an ambulatory setting. Sensitivity, specificity, and positive and negative predictive values were: Nephur-Test (88.2%, 99.6%, 93.8%, 99.1%); MultistixSG (64.7%, 99.6%, 91.7%, 97.4%). There was excellent agreement between the investigators and the nurse. CONCLUSIONS: Leukocyte esterase reagent strips may provide a rapid bedside diagnosis of SBP and thereby shorten time to appropriate management. The Nephur-Test appeared to out-perform MultistixSG. These tests might be particularly useful in ambulatory settings or whenever ascites fluid analysis is not rapidly available.

Adult↗

Evaluation of a new reagent strip rapid urease test for detection of Helicobacter pylori infection.

BACKGROUND: Rapid urease tests are commonly used as a convenient method to detect Helicobacter pylori infection. Our previous experiments demonstrated enhanced efficacy of agar gel rapid urease test compared with reagent strip rapid urease tests. We evaluated the efficacy of PyloriTek, a new reagent strip rapid test for detecting H. pylori infection. METHODS: Gastric antral mucosal biopsy specimens were obtained for comparison between agar gel rapid urease tests and PyloriTek (200 specimens). The rapid urease test to be used first was selected randomly. H. pylori status was determined using the Genta stain. Culture was performed to confirm H. pylori status when false rapid urease tests were suspected. RESULTS: One hundred patients were studied; 68 had H. pylori infection. There were two false-negative and one false-positive PyloriTek when scored at 1 hour, compared with only one false-positive and no false-negative tests at 2 hours. With the agar gel rapid urease tests, there were no false-positive tests and 5 false-negative tests when scored at 1 hour, 2 false-negative tests at 12 hours and 1 at 24 hours; there were no false-positive tests. At 1 hour, 3% (95% CI = 1% to 9%) of PyloriTek tests had an erroneous categorization of H. pylori status compared with 5% for the agar gel rapid urease tests (95% CI = 1.6% to 11%) (p > 0.7). CONCLUSION: The new reagent strip rapid urease test, PyloriTek, is rapid and comparable in accuracy to agar gel rapid urease tests for detecting H. pylori Infection.

Adult↗

Diagnostic and cost comparisons of a questionnaire against a chemical reagent strip test in identifying high risk communities for Schistosoma haematobium infection in northern Zambia.

A comparative study was conducted in northern Zambia in order to compare both the economical and diagnostic performance of a questionnaire with that of the chemical reagent strip test in diagnosing urinary schistosomiasis with a view to replacing the more economically expensive reagent strip test with the questionnaire in the identification of high risk communities. A total of 57 schools participated in the study and each school was considered as a community. Among the symptoms and conditions of blood in urine, pain when passing urine and bilharzia for urinary schistosomiasis, blood in the urine was the best predictor for urinary schistosomiasis with 73.9 pc (95 pc CI 56.0 to 91.9 pc) sensitivity, 82.4 pc (95 pc CI 69.5 to 95.2 pc) specificity and 78.9 pc (95 pc CI 68.4 to 89.5 pc) diagnostic efficiency in the identification of schools with high levels of infection. A diagnostic questionnaire for urinary schistosomiasis was two times cheaper than the reagent strip test in economical terms. The questionnaire approach in identifying high risk communities for urinary schistosomiasis is promising and should be tried in other endemic areas.

Adolescent↗

Rapid diagnosis of bacterial meningitis with reagent strips.

Laboratory examination of cerebrospinal fluid (CSF) is not available in many parts of the world, and without knowledge of CSF glucose, protein, and cells, a diagnosis of meningitis may be missed. Testing CSF with urine reagent strips that measure glucose and protein has given variable results. We tested CSF samples from 234 children with suspected meningitis for glucose, protein, and leucocytes with Combur9 reagent strips. The results were compared with those obtained from the laboratory and also interpreted as indicating bacterial or viral meningitis. There was good agreement between the strip and laboratory method of estimating CSF glucose, protein, and leucocytes. All but 4 of the cases of meningitis were correctly identified by the strip method (sensitivity 97%). 2 (2.9%) of 69 cases of bacterial meningitis were judged by an independent observer to be viral, and 2 (3.3%) of 60 cases of viral meningitis as normal. No normal CSF was diagnosed as meningitis (specificity 100%). The results indicate that Combur9 reagent strips can distinguish normal from infected CSF and are of value in the diagnosis of meningitis.

Cerebrospinal Fluid↗