Microbial contamination during manufacture of dialysis equipment and appropriateness of clinical use after cleaning

Abstract

[Background] Microbial contamination of most of the dialysis monitoring devices newly installed in 2015-2016 was noted, and the same residual strain was isolated year after year even following clinical use that met the water quality standards for standard dialysate. There was also information that the cleaning and disinfection method was voluntarily changed at the time of manufacturing. [Purpose and Method] We evaluated the level of contamination at the time of installation (end of 2022) of 25 new devices when relocating to a new facility. The total number of bacteria before passing through the endotoxin (ET) retentive filter and ET activity were measured, and the bacteria were cultured for 10 days and identified by mass spectrometry. Devices with high levels of contamination were retested for clinical use 25 days after the initial cleaning and disinfection. [Results] Six units had a total bacterial count of 1,000 cells/mL or higher, and three units had ET of 50 mEU/mL or higher (high level of contamination). There were 7 genera and 14 species of bacteria, the α-β-proteobacterial network was 76%, and 25 days after initial cleaning and disinfection, even those showing high-level contamination were improved by 1 to 2 digits. [Conclusion] Although the level of contamination of the new dialysis equipment had improved in comparison with 2015-2016, it was still not sterile, and initial cleaning was considered important.