Bioplorer® enables rapid quantification of microbial contamination of dialysate
Original article
Shimakita T et al. (2007) Rapid count of microbial cells in dialysate. Ther Apher Dial 11: 363–369 PubMed
The ability to directly detect microbial cells is vital for ensuring that dialysate is uncontaminated. Conventional approaches to microbial cell detection involve counting colonies after culture on agar. Such culture methods only detect viable cells and take a relatively long time to produce a result. A Japanese group has recently reported a non-culture method of quantifying microbial cells that detects dead as well as viable cells and returns results within as little as 20 min.
The investigators had previously developed 'Bioplorer®' (Matsushita Electric Industrial Co., Osaka-fu, Japan), and tested it with filterable foodstuffs. Bioplorer® automatically analyzes fluorescent microscopic images of cells double-stained with propidium iodide, which labels dead cells, and 4',6-diamidino-2-phenylindole (DAPI), which labels both viable and dead cells. Analysis of freshly prepared dialysate determined the detection limit of Bioplorer® to be 106 cells/100 ml (2.0 log10[cells/100 ml]) at a sample volume of 100 ml. No colonies were detected when the same sample was cultured on agar medium. This detection limit is sufficiently below the recommended lower limit for standard dialysate (4.0 log10[cells/100 ml]), but would not be suitable for the preparation of ultrapure dialysate. A range of freshly prepared dialysate samples spiked with known quantities of Bacillus subtilis were analyzed with both the Bioplorer® method and a culture method, and the results did not differ significantly between the two methods over the range 2.6–4.6 log10[cells/100 ml].
The authors conclude that the Bioplorer® apparatus can be used to rapidly detect microbial contamination of dialysate.
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Subject areas under which this article appears: Dialysis (hemodialysis, peritoneal dialysis, continuous renal replacement)
