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Detection of Significant Bacteriuria by Automated Urinalysis Using Flow Cytometry

Detection of Significant Bacteriuria by Automated Urinalysis Using Flow Cytometry,HIROSHI OKADA,YUTAKA SAKAI,SHIGENORI MIYAZAKI,SOICHI ARAKAWA,YUKIO H

Detection of Significant Bacteriuria by Automated Urinalysis Using Flow Cytometry   (Citations: 9)
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A new flow cytometry-based automated urine analyzer, the UF-50, was evaluated for its ability to screen urine samples for significant bacteriuria. One hundred eighty-six urine specimens from patients attending an outpatient clinic of a university-based hospital were examined. The results obtained with the UF-50 were compared with those obtained by conventional quantitative urine culture. The UF-50 detected significant bacteriuria with a sensitivity of 83.1%, a specificity of 76.4%, a positive predictive value of 62.0%, a negative predictive value of 90.7%, and an accuracy of 78.5%. These results are comparable to those obtained by previously reported screening procedures. Besides detecting significant bacteriuria, the UF-50 can also per- form routine urinalysis, including measurement of concentrations of red blood cells, white blood cells, epi- thelial cells, and casts, within 70 s. This capability renders this new flow cytometry-based urine analyzer superior to previously reported rapid screening methods. Urinary tract infection is diagnosed on the basis of symp- toms, signs, and urinalysis. For a final diagnosis, quantitative measurement of bacterial concentrations in the urine is man- datory. However, quantitative bacterial culture is very time- consuming and expensive. Therefore, clinicians have sought a reliable screening method for differentiation of urine samples which contain significant numbers of bacteria from those which do not. Approximately 80% of urine cultures are negative (5). If positivity of urine cultures can be predicted before urine culture is performed, the time and cost expended on examina- tion of negative cultures can be avoided. We have been working with an industrial company to create a new device that can perform urinalysis automatically. Ad- vancements in computer technology make it possible to use flow cytometric techniques to perform automated urinalyses. A new automatic urine analyzer, the UF-50 (Sysmex Corpora- tion, Kobe, Japan), is the first compact machine that quanti- tatively measures the concentrations of red blood cells (RBCs), white blood cells (WBCs), epithelial cells (ECs), casts, and bacteria in urine samples with high reproducibility (H. Okada, Y. Nakano, Y. Sakai, S. Miyazaki, M. Fujisawa, S. Arakawa, Y. Hamaguchi, and S. Kamidono, submitted for publication). In the present study, we investigated the feasibility of using the UF-50 to predict the outcome of quantitative urine cultures. MATERIALS AND METHODS Urine specimens. Urine specimens were collected from patients who attended the outpatient clinic of Kobe University Hospital. Patients with urinary diver- sions or those with orthotopic neobladder with bowel segments were excluded, and all patients had normal urinary tract anatomies. A sterile container with a wide opening was used to collect midstream urine. Female patients were asked to wipe their external genitalia with a wet tissue before urinating. Ten milliliters of each specimen was used for routine urinalysis including qualitative measurement of protein and sugar and microscopic exam- ination of centrifuged urinary sediments. The rest of the specimen was processed for automated urinalysis with the UF-50 and by urine culture immediately fol- lowing collection. Semiquantitative urine culture. Semiquantitative urine cultures were per- formed by procedures based on the recommendation of Cintron (4) with cystine- lactose-electrolyte-deficient (CLED) agar (Nissui Pharmaceutical Co. Ltd., To- kyo, Japan). Most urinary pathogens can grow on CLED agar, and it can inhibit the swarming of Proteus species. A 0.001-ml loop was used for inoculation of urine samples. Bacterial concentrations were determined by a single technician and were expressed as the numbers of CFU per milliliter.
Published in 2000.
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    • ...Studies using automated microscopy performed in adult patients demonstrated superiority to both urine microscopy and dipstick methods in the diagnosis of UTI....

    Andy Lunnet al. Automated microscopy, dipsticks and the diagnosis of urinary tract inf...

    • ...The aim of this study was to evaluate the Sysmex UF-100 flow cytometer (Sysmex Corporation, Kobe, Japan)...

    R Evanset al. Testing by Sysmex UF100 flow cytometer and with bacterial culture in a...

    • ...We have reported that the flow cytometrybased automatic urinalysis device UF-50 can detect significant bacteriuria with a false-negative rate (FN) of 5.4% (7)...
    • ...(7), coagulase-negative Staphylococcus (5), Staphylococcus aureus (4), Klebsiella pneumoniae (3), Candida albicans (3), Citrobacter freundii (3), Stenotrophomonas maltophilia (2), Morganella morganii (2), Serratia marcescens (2), Proteus vulgaris (1), and Corynebacterium spp...
    • ...The UF-50 was reported to detect significant bacteriuria with a sensitivity of 83.1%, a specificity of 76.4%, a PPV of 62.0%, an NPV of 90.7%, a falsepositive rate of 16.1%, and a false-negative rate of 5.4% (7)...

    Hiroshi Okadaet al. Enumeration of Bacterial Cell Numbers and Detection of Significant Bac...

    • ...In the Clinical Microbiology Service of the Columbia University Medical Center, 70% to 80% of urine cultures yield either no growth or clinically insignificant commensal organisms, which is consistent with the findings published in the literature (4, 8). Semiquantitative plate culture is the accepted standard for the laboratory diagnosis of urinary tract infections (UTIs) but does not provide same-day results...

    Preeti Pancholiet al. Rapid Screening of Urine Specimens for Bacteriuria by the Cellenium Sy...

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