Diagnosis of Urinary Tract Infections - Essay Example

Although microscopic urine sediment analysis is generally regarded as the gold standard for urinalysis, its flaws are also acknowledged. Besides the problem with interobserver variability and imprecision, this method is also labor-intensive and very time-consuming.

While the culture method is the preferred method of detecting and quantifying bacteria in urine, non-culture tests include Gram staining of uncentrifuged urine specimens, Gram staining of centrifuged specimens, or direct observation of bacteria in urine specimens, Nitrite test, leukocyte esterase tests, etc. Suprapubic aspiration is generally considered the best method to avoid contamination of specimens, however, this method is rarely used because it is invasive and thus uncomfortable and dangerous.

Semi-automatic equipment like the Yellow IRIS, followed by the UA-1000 and UA-2000 (Sysmex Corporation, Kobe, Japan) were early attempts at the automation of urine analysis. With the Yellow IRIS, precision and sensitivity are reported to be considerably better as compared to visual microscopy, especially at the lower concentration range. The Yellow IRIS device after removing mucus strands from native urine, adds a dye, and the stained urine is passed through an optical pathway. A strobe lamp interrupts the motion of the fluid and the particles in it are captured on a color video camera. The resulting images of the particles are differentiated concerning their lengthwise dimensions and then presented for validation by a trained analyst. UA-1000 and UA-2000 follow the same principle, but provide better image resolution compared with the Yellow IRIS because the particles are captured by a color CCD camera.

Sysmex UF-100, an argon flow cytometer, designed to completely automate the recognition and counting of particles and cells in urine is quite effective, accurate, and precise.

Several studies evaluating and/or validating these automated urine examination methods have been carried out and published. From its findings, a few authors concluded that though the UF-100 might not be seen as a substitute for the conventional microscopic sediment analysis, it can, especially when combined with the results of the automated dipstick reader, improve the productivity of urinalysis and greatly reduce the number of specimens that are finally submitted for microscopy. By combining a test strip analyzer and UF-100, they also came to the same conclusion that this approach to urinalysis will greatly reduce urine microscopy analysis, thus completely automating the urine analysis process, and reducing turnaround times and manual labor. Critically evaluating these studies show that most of them support the precision, accuracy, and reliability of automated urinalysis. Even in an isolated case where the reliability of automated urinalysis was questioned, the study showed that there were only 1.6% false negative results, which in any way, could be considered negligible, because automated process saves time, reduce labor, and cost.