Detection of opportunistic premise plumbing pathogens using qPCR to assess the efficacy of water treatment methods in a model home
Citation:
McNeely, M., L. Boczek, V. Gomez-Alvarez, M. Tang, M. Urbanic, C. Muhlen, D. Williams, D. Lytle, AND H. Ryu. Detection of opportunistic premise plumbing pathogens using qPCR to assess the efficacy of water treatment methods in a model home. WQTC 2023, Dallas, TX, November 05 - 09, 2023.
Impact/Purpose:
Outbreaks and infections with opportunistic premise plumbing pathogens such as Legionella spp., Pseudomonas aeruginosa, and non-tuberculosis mycobacteria (NTM) have been increasing dramatically in the last 15 years. These organisms have been known to form complex biofilms and are often difficult to treat once they colonize a premise plumbing system. Moreover, they are often associated with amoeba, which can offer protection from typical water treatment. This project was aimed at characterizing the microbial water quality using molecular techniques and determining treatment efficacy of these organisms by studying their occurrence in a simulated home plumbing system. The results suggest that more than one type of treatment may be needed to achieve the highest level of water quality.
Description:
The plumbing systems of buildings are often found to contain opportunistic premise plumbing pathogens (OPPPs) such as Legionella, nontuberculous mycobacteria (NTM), and Pseudomonas with the potential to cause waterborne diseases. The objective of this study is to characterize microbial water quality using molecular technology and its applicability for assessing treatment performance against these OPPPs along with phagocytic amoeba in a simulated home plumbing system (HPS). Water samples were initially collected from the HPS at eight locations weekly for four months. A point of entry (POE) carbon filtration system was installed onto the HPS, and then samples were collected from the same locations with two additional locations added: pre and post POE. Samples were analyzed for three major OPPPs along with amoebae using eight qPCR assays. In addition, next-generation sequencing technologies (NGS) and genomic analysis were used to reconstruct environmental bacterial genomes. Overall, while the POE device appears to effectively reduce the occurrence of Legionella, Mycobacterium and V. vermiformis in the HPS, it may also have the potential to increase the occurrence of Pseudomonas spp. NGS makes the reconstruction of environmental bacterial genomes possible and opens new perspectives in microbial ecology studies. Genomic analysis reveals that the HPS has been colonized by a single strain of L. pneumophila belonging to serogroup1, representing one sequence type (ST), and confirmed the presence of the lpneAB genes encoding a macrolide efflux pump, which confers a reduced sensitivity to azithromycin.