Harnessing Microbial Ecology for the Inhibition of Opportunistic Pathogens in Premise Plumbing

Virginia Polytechnic Institute And State University, Blacksburg VA

Investigators

Abstract

PI: Amy Pruden Proposal Number: CBET-1033498 Institution: Virginia Tech Title: Harnessing Microbial Ecology for the Inhibition of Opportunistic Pathogens in Premise Plumbing Opportunistic pathogens residing in premise (i.e., building) plumbing; such as Legionella pneumophila, Mycobacterium avium, Acanthamoeba polyphaga, and Pseudomonas aeruginosa, are now the leading cause of waterborne disease in developed countries. Because these pathogens multiply within premise plumbing systems, rather than emanate from treatment plants, a paradigm shift is required to mitigate this threat. Specifically, the PIs maintain that microbes are unavoidable in premise plumbing systems and their activity can be beneficial. A transformative research approach will investigate the feasibility of harnessing microbial ecology to inhibit pathogen proliferation. The overarching hypothesis is that inoculation of beneficial microbes into premise plumbing systems can serve to inhibit the ability of opportunistic pathogens to establish and grow. Moreover, water treatments and distribution system materials naturally generate the inoculum that is continually introduced into premise plumbing systems, and a fundamental understanding of how these factors can ?select? for beneficial organisms could be exploited by water utilities and regulators to prevent waterborne disease. The specific objectives of this research are to: 1) Characterize the interplay between water treatment, water main pipe material, and water distribution system operation in selecting microbial communities with potential to inhibit growth of opportunistic pathogens in premise plumbing systems; 2) Quantify the extent to which these selectors can mitigate pathogen growth under extremes of regrowth potential that may be encountered in premise plumbing systems through development and application of a pathogen regrowth potential assay; and 3) Conduct a field survey linking microbial ecology at the point of entry of buildings to nutrient levels, prior water treatments and distribution system materials, and verify relationships between microbial ecology and pathogen regrowth potential. It is expected that various pipe materials, assimilable organic carbon concentrations, disinfectant residuals, and water ages will select for distinct microbes that vary in their inherent capabilities to inhibit or amplify opportunistic pathogens within premise plumbing systems. Furthermore, unifying factors that select for beneficial inocula during water treatment and distribution will be identified and related to actual incidence of disease in the field. The PIs believe that the probiotic concept proposed has never been applied to control of pathogens in plumbing systems, though it has been demonstrated in medical and corrosion studies. Furthermore, viewing water treatment plants and distribution systems as selectors of microbial ecology with desirable traits builds on the success of similar approaches in the wastewater treatment realm, while also being practically implementable. The experimental design provides a holistic understanding of chemical and microbiological factors driving the proliferation of opportunistic pathogens in premise plumbing, which is vital for rational development of future mitigation strategies. Other disciplines are anticipated to be impacted, biofilm and pathogen ecology, in particular. This study will benefit society by addressing the leading source of waterborne disease in developed countries and by helping to clarify the relative roles/responsibilities of utilities versus individuals in managing pathogen growth. The proposed opportunistic pathogen regrowth potential assay represents a practical outcome with applications beyond the scope of the proposed work, as it can be applied to compare the pathogen ?regrowth potential? of various waters. The results are also expected to explain how the likelihood of waterborne disease from premise plumbing pathogens varies from neighborhood to neighborhood even in the same city, as a function of water age, chloramines residual and microbial ecologies associated with different pipe materials. Two graduate research assistants will be supported by the project and supplemental funds will be sought for REUs. Additionally, hands-on activities will be developed and delivered to high school summer camps (e.g., CTech2 and NASA INSPIRE), with a particular focus on recruiting of women into STEM fields. The PIs will also engage in outreach to communities and individuals who have been directly impacted by opportunistic pathogens through NTMir, Inc., collaborate with scientists at the U.S. Environmental Protection Agency, and support evaluations of pathogen regrowth potential in real distribution systems in partnership with Blacksburg and Pinellas Country.