Sysmex Journal International

2014Vol.24 No.1


Effect of the centrifugal force for preparing urinary sediment in the patients with urinary tract infection on the number of leucocytes and bacteria


Bunsei ONO

Kyurin Corporation


The urinary sediment microscopy are performed to predict various renal and urological diseases by observing erythrocytes, leucocytes, epithelium cells, casts, bacteria, fungi, protozoa, crystals. In accordance with "urinary sediment examination procedure 2000" edited by the Japanese clinical laboratory standard meeting, it is provided that urinary sediment microscopy have performed using sediment of 10 mL urine after centrifuging of 500 × g × 5 min. This centrifugal force is not enough for the bacterial collection.

There is no defined method to prepare urinary sediment when we perform gram-stain microscopy to detect bacteria, fungi, and leucocytes. When we perform gram-stain microscopic test, we examined the suitable centrifugal force at the time of the preparation of the urinary sediments to detect 103 cfu/mL which was the number of the meaningful bacteria of the uncomplicated urinary tract infection.

Because it is necessary to observe bacteria, fungi and leucocytes in the examination of urinary tract infection, centrifugal force in the urinary sediment preparation is able to set higher speed and longer time than the normal urinary sediment preparation. We evaluated suitable centrifugal force by counting bacteria in the supernatant after centrifuging at various centrifugal forces. The bacterial counting were performed with culture method and UF-1000i  ( Sysmex Corporation ) that is flow cytometer.

It has been shown in this study that the centrifugal force of 500 × g × 5 min was insufficient to collect bacteria, and the centrifugal force of 1,400 × g × 10 min was at least necessary.


Urinary Sediment, Gram-stain, Centrifugal Force, Urinary Tract Infection, Bacteriological Examination


This article is translated and republished from the Sysmex Journal Vol. 34 Suppl. 1, 2011. (Japanese)