Poster Presentation Australian Society for Microbiology Annual Scientific Meeting 2024

Passive sampling for wastewater-based epidemiology of pathogens (#98)

Andreana G Shakallis 1 , Kirstin E Ross 1 , Howard Fallowfield 1 2 , Harriet Whiley 1 2
  1. Flinders University, Bedford Park, SA, Australia
  2. ARC Training Centre for Biofilm Research and Innovation, Bedford Park, SA, Australia

Wastewater-based epidemiology (WBE) played a crucial role in monitoring the spread of COVID-19 worldwide. The accuracy and sensitivity of WBE depends largely on the sampling technique employed, with passive sampling emerging as a promising method due to its ease, feasibility and expected greater spatial coverage. This is a diffusion-based sampling technique that involves deploying a sampling medium in an aqueous matrix for extended periods of time. Due to the urgency of implementing monitoring programs during the pandemic, passive samplers were deployed in wastewater systems without extensive laboratory analysis. As such, there are limited studies investigating viral adsorption and recovery from passive samplers. To address this gap in knowledge, our research aimed to explore the deployment and variability of passive samplers used for biological targets through laboratory-based studies. Employing Escherichia coli bacteriophage MS2 as a surrogate organism, this study investigated the impact of various environmental factors on viral adsorption characteristics. These environmental factors included aqueous matrix, virus concentration, pH, and deployment time. Findings revealed that the efficacy of viral recovery was dependent on concentration, with higher concentrations yielding an increase in viral recovery. Furthermore, adsorption was lowest in alkaline matrices, with improved viral recovery observed as the acidity of the matrix increased. Surprisingly, time appeared to have no statistically significant effect on viral adsorption. Despite passive sampling offering advantages in continuous data collection and alignments with clinical sampling, passive sampling is susceptible to temporal fluctuations that may affect accuracy. Additional experiments were conducted to explore how concentration fluctuations in aqueous matrices impact sampling and whether viral recovery is accumulative on the passive sampler (continuous sampling) or an average of total viral exposure. Results showed that the passive samplers were not able to adequately retain the virus under fluctuating concentrations, specifically when the viral concentration in the aqueous matrix decreased or reached nil. While this research enhances our understanding of the complexities of passive sampling in WBE, further studies on viral adsorption kinetics are needed to inform public health surveillance and policy development.

  1. Shakallis, A. G., Fallowfield, H., Ross, K. E., & Whiley, H. (2022). The Application of Passive Sampling Devices in Wastewater Surveillance. Water, 14(21), 3478. Retrieved from https://www.mdpi.com/2073-4441/14/21/3478