Performance assessment of urine flow cytometry (UFC) to screen urines to reflex to culture in immunocompetent and immunosuppressed hosts
| Autor: | Karen Ng, Charlene Porter, Romali Ranasinghe, Titus Wong, Elizabeth Bryce, Morris Pudek, Jennifer Grant, Diane Roscoe, Aleksandra Stefanovic, Adelina Lim |
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| Rok vydání: | 2017 |
| Předmět: |
Male
0301 basic medicine Microbiology (medical) medicine.medical_specialty Bacteriuria Urinalysis Urinary system 030106 microbiology Urine Microbiology Gastroenterology Leukocyte Count 03 medical and health sciences 0302 clinical medicine Internal medicine White blood cell medicine Humans Mass Screening 030212 general & internal medicine Pyuria Receiver operating characteristic medicine.diagnostic_test business.industry General Medicine Middle Aged Immunosuppressed Hosts Flow Cytometry medicine.anatomical_structure ROC Curve Urinary Tract Infections Immunology Reflex Female business Cytometry |
| Zdroj: | Journal of Medical Microbiology. 66:1308-1315 |
| ISSN: | 1473-5644 0022-2615 |
| Popis: | Purpose. Urine flow cytometry (UFC) is an automated method to quantify bacterial and white blood cell (WBC) counts. We aimed to determine whether a threshold for these parameters can be set to use UFC as a sensitive screen to predict which urine samples will subsequently grow in culture. Methodology. Urines submitted to our microbiology laboratory at a tertiary care centre from 22 July 2015–17 February 2016 underwent UFC (Sysmex UF-1000i) analysis, regular urinalysis and urine culture. Positive urine cultures were defined as growth ≥104 c.f.u. ml−1 of organisms associated with urinary tract infections. The correlation of UFC bacterial and WBC counts with urine culture was assessed using receiver operating characteristics curves. The sensitivity (SN), specificity (SP), negative predictive values (NPVs), positive predictive values (PPVs) and false negative rate (FNR) were calculated at various thresholds in immunocompetent and immunosuppressed patients. Results. A total of 15 046 urine specimens were submitted, of which 14 908 were analysable in the study. The average time to UFC result from receipt in the laboratory was 0.76 h (+/−1.04). The test performance at a set threshold of UFC bacteria ≥20 or WBC >5 was: SN=96.0 %, SP=39.2 %, PPV=47.0 %, NPV=94.5 % and FNR=4.0 %. This threshold eliminates 26 % of urine cultures. Immunosuppressed hosts had a lower sensitivity of 90.6 % and a higher FNR of 9.4 %. Conclusions. UFC is a rapid and sensitive method to screen out urine samples that will subsequently be negative and to reflex urines to culture that will subsequently grow. UFC results are available within 1 h from receipt and enable the elimination of culture when the set threshold is not met. |
| Databáze: | OpenAIRE |
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