Automated flow cytometry analysis of peritoneal dialysis fluid

Background. Recently, the Sysmex UF-100 flow cytometer has been developed to automate urinalysis. We have evaluated this instrument to explore the possibilities of flow cytometry in the analysis of peritoneal dialysis fluid (PD) and have compared the obtained data with those of counting chamber techniques, biochemical analysis and bacterial culture. Methods. UF-100 data were correlated with microscopy and biochemical data in 135 PD samples. Microbiological analysis was performed in 63 suspected cases of peritonitis. Results. Good agreement (P < 0.001) was obtained between UF-100 and microscopy data for leukocytes (r = 0.825). UF-100 bacterial count correlated (P < 0.001) with UF-100 leukocyte count (r=0.549). UF-100 bacterial counts were unreliable in samples where interference by blood platelets was observed Another major problem was the UF-100 'bacterial' background signal in sterile PD samples. Yeast cells were detected by the flow cytometer in spiked samples. Conclusions. Flow cytometry of PD with the UF-100 offers a rapid and reliable leukocyte count. Sensitivity of the 'bacterial' channel count in predicting positive culture exceeds the sensitivity of conventional Gram stain. Furthermore, additional semi-quantitative information is provided regarding the presence of yeasts.