Automated screening systems offer the promise of a large throughput with minimal labor and a rapid turnaround time compared with conventional cultures. However, these advantages may be offset by a substantial cost for the instrumentation. Often these costs can be justified only in laboratories that receive many specimens.
Several automated or semiautomated urine screening systems that are either bacterial growth independent or dependent are commercially available. By examining images of uncentrifuged urine samples using a video camera, the IRIS 939 UDx system (International Remote Imaging Systems, Inc., Chatsworth, Calif) and the Sys-mex UF-100 (TOA Medical Electronics; Kobe, Japan) are able to recognize many cellular structures, including leukocytes and bacteria. A walk-away robotic instrument, CelIenium-lôOUS (Combact Diagnostic Systems Ltd., Hertzliya, Israel) has been introduced for urine screening using fluorescent probes to stain a monolayer of bacteria from urine on a membrane. Following staining the membrane is then examined at high magnification using computerized fluorescent microscopy imaging technology. Although the need to culture negative urine specimens is eliminated, only limited dinical performance data have been published. Finally, another semiautomated instrument, the Coral UII Screen system (Coral Biotechnology, San Diego, Calif) uses a somatic-cell release agent to first release and destroy the adenosine triphosphate (ATP) in somatic cells while bacterial AIT remains protected within the bacterial cell. Bacterial ATP is then liberated and detected by the instrument. Studies to date have demonstrated this instrument to have a sensitivity and specificity of 86% and 75.5%, respectively.3 Although a number of other automated urine screens are in various stages of development, to date these screens have not been widely accepted by clinical microbiology laboratories.1^20,21
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