Novel Strategies for the Detection of Pathogens in Drinking Water

Abstract

To protect public health, detection methods have been developed to monitor drinking water for pathogens. The goal of this dissertation is to evaluate and utilize novel methods that enhances detection and further reduces the risk of waterborne pathogens. The study in Appendix A developed a method to monitor the microbial quality of treated drinking water at the tap utilizing point-of-use (POU) filter. Tap water supplies were monitored in vending machines throughout Southern Arizona using solid block carbon (SBC) filters as a monitoring tool. Out of 48 SBC filters 54.2% were positive for at least one organism. The number of filters positive for total coliforms, E. coli, Enterococci, and enterovirus was 13, 5, 19, and 3, respectively, corresponding to 27.1%, 10.4%, 39.6%, and 6.3% of the total filters. These results suggest that the SBC filter can be used to monitor large volumes of treated drinking water and detect the incidence of indicators and pathogens. The study in Appendix B evaluated the fate of infectious prions in multiple water sources quantitatively utilizing a method that only detects infectious prions. A reduction of PrPˢᶜ was observed at 25°C and 37°C ranging between 0.41-log₁₀ and 1.4-log₁₀ after 1 week. After 8 weeks at 25°C and 37°C, inactivation ranged between 1.65-log₁₀ and 2.15-log₁₀. A maximum rate of inactivation in water occurred at 50°C, ranging from 2.0-log₁₀ and 2.51-log₁₀ after one week. The results from all types of water suggest that dissolved organic matter and temperature influence PrPˢᶜ infectivity. The study in Appendix C evaluated real-time sensors for monitoring microbial contaminants. Most sensor parameters evaluated exhibited an increase in sensor response to an increase in E. coli concentrations. Responses to E. coli concentrations at or below 10³ cfu/mL were very low due to near background levels, and responses to concentrations above 10⁶ cfu/mL exceeded threshold levels for sensors that use light scattering methods due to saturation in the flow cell. The data produced effectively shows that the sensors evaluated could be used to monitor microbial intrusion events in water distribution systems.