Assessing Passive Sampling for the Monitoring of <i>E. coli</i> and <i>Cryptosporidium</i> spp. in Environmental Waters

Passive sampling has shown promise as an alternative approach for monitoring of pathogens in aquatic matrices. We conducted two controlled experiments to compare the efficacy of membrane passive sampling to composite sampling in both wastewater and surface water for the detection of <i>Escherichia coli</i> and <i>Cryptosporidium</i>. We also investigated the relative uptake of <i>E. coli</i> and <i>Cryptosporidium</i> onto membrane passive samplers over time. Both sampling methods returned positive detections of <i>E. coli</i> at all deployment times (4, 8, 24, 48, 72, and 96 h) in both water matrices. Passive sampling for <i>Cryptosporidium</i> showed similar detection rates as composite samples in surface water (31% passive; 41% composite) and wastewater (76% passive; 86% composite). We found significant linear uptake of <i>E. coli</i> onto passive samplers up to 96 h in surface water (<i>R</i> ² = 0.932; <i>p</i> = 0.002). In wastewater, maximum passive sampler uptake of <i>E. coli</i> was reached after 24 h. For <i>Cryptosporidium</i>, linear uptake was observed up to 96 h for both surface water (<i>R</i> ² = 0.805; <i>p</i> = 0.015) and wastewater (<i>R</i> ² = 0.877; <i>p</i> = 0.006). Our results support that membrane passive samplers may be used for the detection of <i>Cryptosporidium</i> and <i>E. coli</i> in surface waters for up to 96 h.