Alternative hemodialysis ultrafilter for sampling microbes in water

Authors: FIRNSTAHL, AARON - Us Geological Survey (USGS); DOUGHAN, GABI - Iowa State University; Opelt, Sarah; Cook, Rachel; Heffron, Joseph; Borchardt, Mark; KARRIKER, LOCKE - Iowa State University; STOKDYK, JOEL - Us Geological Survey (USGS); Burch, Tucker

Submitted to: American Society for Microbiology Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 2/28/2024
Publication Date: 6/14/2024
Citation: Firnstahl, A.D., Doughan, G., Opelt, S.A., Cook, R.M., Heffron, J.A., Borchardt, M.A., Karriker, L.A., Stokdyk, J.P., Burch, T.R. 2024. Alternative hemodialysis ultrafilter for sampling microbes in water. American Society for Microbiology Annual Meeting. June 13-17, 2024.

Interpretive Summary:

Technical Abstract: Enteric pathogens can be found in groundwater used for drinking water. Pathogen concentrations in groundwater are often low and require concentrating large sample volumes for reliable detection. Dead-end ultrafiltration is a standard method for capturing a wide variety of viruses, bacteria, and protozoa from water. The Asahi Kasei Rexeed™ hemodialyzer is the most widely used ultrafilter for dead-end ultrafiltration pathogen sampling and is cited in standard methods of the Environmental Protection Agency, Centers for Disease Control and Prevention, and Food and Drug Administration. However, Asahi Kasei operations have concluded in the United States, so a suitable replacement hemodialyzer is needed. Our objective was to evaluate the recovery of another commercially available hemodialyzer (Nipro Elisio™) and compare it to the Asahi Kasei Rexeed™ hemodialyzer. Recovery was evaluated for 7 microbes (2 bacteria, 3 viruses, and 1 protozoan): Campylobacter jejuni, Salmonella enterica, adenovirus 41, vaccine-derived poliovirus Sabin 3, modified live porcine reproductive and respiratory syndrome virus, and Cryptosporidium parvum. Microbes were added to 10L of dechlorinated tap water and concentrated using both hemodialyzers (n=6). Following elution and secondary concentration by polyethylene glycol precipitation, sample replicates were analyzed by qPCR. To calculate recovery, microbes were added to 500 mL of the experimental matrix (n=6) and were processed and analyzed like the experimental replicates; resulting concentrations were used as the denominator for determining efficiency of the ultrafiltration step. Average recovery efficiencies for bacteria ranged from 33% to 76% (Rexeed™) and 39% to 84% (Elisio™). Average recovery efficiencies for viruses ranged from 17% to 64% (Rexeed™) and 10% to 78% (Elisio™). Average recovery efficiencies for Cryptosporidium parvum were 98% (Rexeed™) and 100% (Elisio™). Recoveries for each microbe were comparable for the two filter types, and both had better recovery for protozoa than bacteria and viruses. Results demonstrate the Nipro Elisio™ hemodialyzer is a viable alternative to the Asahi Kasei Rexeed™ hemodialyzer for large volume dead-end ultrafiltration.