Can urine dipstick testing for urinary tract infection at point of care reduce laboratory workload?

AIM: The University Hospitals of Leicester NHS Trust microbiology laboratory receives 150 000 urine samples each year, approximately 80% of which prove to be culture negative. The aim of this study was to reduce the proportion of culture negative urines arriving in the laboratory, by producing local evidence based guidelines for the use of urine dipstick testing at point of care within the trust's three acute hospitals. METHODS: One thousand and seventy six unborated urine samples were dipstick tested at the point of care using an automatic strip reader. Quantitative results for the four infection associated markers-leucocyte esterase, nitrite, blood, and protein-were compared with the results of conventional laboratory microscopy and culture. RESULTS: The performance of different marker combinations was calculated against the routine laboratory methods. One hundred and seventy five (16.3%) samples were negative for all four markers. Of these dipstick negative samples, only three (1.7% of all true positives) were positive by culture. The absence of all four infection associated markers was found to have a greater than 98% negative predictive value and a sensitivity and specificity of 98.3% and 19.2%, respectively. CONCLUSIONS: A urinary dipstick testing algorithm for infection associated markers was derived for use in hospital patients to screen out negative urines. Two years after distributing the algorithm and promoting access to reagent strips and strip readers, a reduction in the urine workload has been seen against an otherwise increasing laboratory specimen load.

Near patient testing for Helicobacter pylori: a detailed evaluation of the Cortecs Helisal Rapid Blood test.

OBJECTIVE: To evaluate the Cortecs Helisal Rapid Blood test for accuracy overall and in specific subgroups by age and ethnic origin. Additionally, to assess readability of results, including inter-observer error, with consideration also given to usability and acceptability. DESIGN: A prospective evaluation using four reference tests. SETTING: A hospital endoscopy unit. METHODS: Two hundred patients attending for endoscopy were recruited for H. pylori testing with the Helisal test, plus antral biopsies for CLO test, culture and histology and serology using a commercial enzyme-linked immunosorbent assay (ELISA). The Helisal test was carried out and results read strictly according to the manufacturer's instructions. Two or more reference tests positive were taken as a gold standard positive; all results negative as negative and any remaining cases were regarded as equivocal. Performance figures were calculated twice, treating patients with equivocal status as either positive or negative. Results were in most cases double-read, blinded, by two observers and readings subsequently compared. RESULTS: The test was considered convenient, easy to use and acceptable to symptomatic patients, but a notable proportion (10%) of results were very difficult to read. Sensitivity was acceptable (91-92% overall, 95% confidence interval (CI) 82-97%), but specificity was poor overall (56-62%, 95% CI 45-72%), and particularly in patients aged 45 years or over (44-51%) and those of South Asian origin (42-50%). CONCLUSION: The test could be appropriate for testing younger symptomatic patients. Its usefulness was, however, found to be limited by poor readability of some results and poor specificity. Reading of some results as equivocal would be appropriate.

Turbidimetric urine screening.

Several studies have shown that urine clarity can be used as an infection screening method. Previous publications have involved patients from specific clinics or of specific age groups, and turbidimetric assessment has often been subjective and unscientific in nature. In this study all specimen types and sources with the exception of catheterised samples were included. Turbidimetric readings were performed using a double-beam turbidimeter, followed by quantitative microscopy and culture. Clinical significance was assessed using a combination of culture results, microscopy and clinical details. Performance varied in relation to the chosen turbidity threshold level, but at a sensitivity of 94.1%, 55.7% of samples could be discarded as 'screen-negative'. The rapid nature of this screening method, combined with the ability subsequently to concentrate resources on the remaining 'screen-positive' samples, can result in an improved service at reduced cost.

Evaluation of Questor urine screening system for bacteriuria and pyuria.

AIMS: To evaluate the Questor automated bacteriuria and pyuria screening system; to compare its performance with that of a reference method; and to assess its usefulness in a routine clinical laboratory. METHODS: The Questor urine screening system was compared with a comprehensive regimen to detect urinary tract infection, using pour-plate viable counts to determine the numbers of bacteria present in urine samples, a wide range of other cultural methods, microscopic findings and clinical information. RESULTS: The optimal performance in detecting significant growths was a sensitivity of 93%, a specificity of 74%, a positive predictive value of 43% and a negative predictive value of 98%. The list price per test is 0.17 pounds and the capital cost of the system is 39,950 pounds. Questor can test 50 samples an hour and can be operated by one member of the laboratory staff, who is not required to make interpretative judgments--for example, a medical laboratory assistant. CONCLUSIONS: The sensitivity and specificity of the Questor was better than that obtained from other screening systems using the same protocol. The system was easy to use and is a useful addition to the methods available for screening for bacteriuria.