title: Distribution System Water Quality Affects Responses of Opportunistic Pathogen Gene Markers in Household Water Heaters.
abstract: Illustrative distribution system operation and management practices shaped the occurrence and persistence of Legionella spp., nontuberculous mycobacteria (NTM), Pseudomonas aeruginosa, and two amoebae host (Acanthamoeba spp., Vermamoeba vermiformis) gene markers in the effluent of standardized simulated household water heaters (SWHs). The interplay between disinfectant type (chlorine or chloramine), water age (2.3-5.7 days) and materials (polyvinyl chloride (PVC), cement or iron) in upstream simulated distribution systems (SDSs) profoundly influenced levels of pathogen gene markers in corresponding SWH bulk waters. For example, Legionella spp. were 3-4 log higher in SWHs receiving water from chloraminated vs chlorinated SDSs, because of disinfectant decay from nitrification. By contrast, SWHs fed with chlorinated PVC SDS water not only harbored the lowest levels of all pathogen markers, but effluent from the chlorinated SWHs were even lower than influent levels in several instances (e.g., 2 log less Legionella spp. and NTM for PVC and 3-5 log less P. aeruginosa for cement). However, pathogen gene marker influent levels correlated positively to effluent levels in the SWHs (P < 0.05). Likewise, microbial community structures were similar between SWHs and the corresponding SDS feed waters. This study highlights the importance and challenges of distribution system management/operation to help control opportunistic pathogens.
authors.affiliation: †State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China.
authors.forename: Hong
authors.initials: H
authors.lastname: Wang
authors.affiliation: ‡Department of Civil and Environmental Engineering, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, United States.
authors.forename: Sheldon
authors.initials: S
authors.lastname: Masters
authors.affiliation: §Department of Biological Sciences, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, United States.
authors.forename: Joseph O
authors.initials: JO
authors.lastname: Falkinham
authors.affiliation: ‡Department of Civil and Environmental Engineering, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, United States.
authors.forename: Marc A
authors.initials: MA
authors.lastname: Edwards
authors.affiliation: ‡Department of Civil and Environmental Engineering, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, United States.
authors.forename: Amy
authors.initials: A
authors.lastname: Pruden
mesh_terms: D000656:Amoeba / Q000235:genetics / Q000302:isolation & purification / Q000472:pathogenicity; D002700:Chloramines / Q000737:chemistry; D002713:Chlorine / Q000737:chemistry; D004202:Disinfectants / Q000737:chemistry; D005819:Genetic Markers; D006794:Household Articles; D007875:Legionella / Q000235:genetics / Q000302:isolation & purification; D059013:Microbial Consortia / Q000235:genetics*; D009161:Mycobacterium / Q000235:genetics / Q000302:isolation & purification / Q000472:pathogenicity; D011143:Polyvinyl Chloride; D011550:Pseudomonas aeruginosa / Q000235:genetics / Q000302:isolation & purification / Q000472:pathogenicity; D014871:Water Microbiology; D060753:Water Quality; D014881:Water Supply
chemical_list: D002700:Chloramines; D004202:Disinfectants; D005819:Genetic Markers; D002713:Chlorine; D011143:Polyvinyl Chloride; C030816:chloramine