title: Rapid count of microbial cells in dialysate.
abstract: An apparatus for the non-culture method (NCM) of microbial cell count was formerly developed and named a bioplorer. The bioplorer NCM is based on the double staining of cells with 4', 6-diamidino-2-phenylindole (DAPI) and propidium iodide (PI) and the automatic analysis of their fluorescent microscopic images. Viable cells can be stained with DAPI, while dead cells can be stained with DAPI and PI. In this study, the bioplorer NCM has been applied to the dialysate. The viable and dead cells in dialysate could be counted within 20 min. The detection limit expressed by log(10)[cells/100 mL] was 2.0. When cell-spiked dialysate samples containing prescribed number of Bacillus subtilis cells were assayed, the numbers of cells determined by the bioplorer NCM (N(VIA)(NCM)) and a conventional culture method (CM) on R2A medium (N(VIA)(R2A-CM)) were similar in the range of 2.6-4.6 within the 95% confidence interval (NCM-CM equivalent range). When test solutions sampled from a practical facility in a hospital were assayed, N(VIA)(NCM) was greater than, but comparable to, N(VIA)(R2A-CM). The endotoxin (ET) in the test samples were assayed as well using a test kit for limulus amoebocyte lysate assay. The results of microbial cells and ET concentration indicated that the dialysate supplying line was clean and well maintained. The bioplorer NCM can determine if the microbial contamination of dialysate supplying facilities is greater than 2.6 (398 cells/100 mL).
authors.affiliation: Biosensing Business Project, Matsushita Ecology Systems Co. Ltd., Kasugai, Aichi, Japan.
authors.forename: Tomonori
authors.initials: T
authors.lastname: Shimakita
authors.forename: Hidenori
authors.initials: H
authors.lastname: Yamamoto
authors.forename: Tomotaka
authors.initials: T
authors.lastname: Naramura
authors.forename: Akira
authors.initials: A
authors.lastname: Fujimori
authors.forename: Takao
authors.initials: T
authors.lastname: Ide
authors.forename: Yoshikazu
authors.initials: Y
authors.lastname: Tashiro
authors.forename: Mikako
authors.initials: M
authors.lastname: Saito
authors.forename: Hideaki
authors.initials: H
authors.lastname: Matsuoka
mesh_terms: D015169:Colony Count, Microbial; D004731:Endotoxins / Q000032:analysis; D004866:Equipment Contamination; D015312:Hemodialysis Solutions
chemical_list: D004731:Endotoxins; D015312:Hemodialysis Solutions