Antimicrobial resistance
(AMR) is a grand societal challenge with
important dimensions in the water environment that contribute to its
evolution and spread. Environmental monitoring could provide vital
information for mitigating the spread of AMR; this includes assessing
antibiotic resistance genes (ARGs) circulating among human populations,
identifying key hotspots for evolution and dissemination of resistance,
informing epidemiological and human health risk assessment models,
and quantifying removal efficiencies by domestic wastewater infrastructure.
However, standardized methods for monitoring AMR in the water environment
will be vital to producing the comparable data sets needed to address
such questions. Here we sought to establish scientific consensus on
a framework for such standardization, evaluating the state of the
science and practice of AMR monitoring of wastewater, recycled water,
and surface water, through a literature review, survey, and workshop
leveraging the expertise of academic, governmental, consulting, and
water utility professionals.
Maria made a landfall in Puerto Rico
on September 20, 2017 as a
category 4 hurricane, causing severe flooding, widespread electricity
outages, damage to infrastructure, and interruptions in water and
wastewater treatment. Small rural community water systems face unique
challenges in providing drinking water, which intensify after natural
disasters. The purpose of this study was to evaluate the functionality
of six very small rural public water systems and one large regulated
system in Puerto Rico six months after Maria and survey a broad sweep
of fecal, zoonotic, and opportunistic pathogens from the source to
tap. Samples were collected from surface and groundwater sources,
after water treatment and after distribution to households. Genes
indicative of pathogenic Leptospira spp. were detected by polymerase chain reaction (PCR) in all systems
reliant on surface water sources. Salmonella spp. was detected in surface and groundwater sources and some distribution
system water both by culture and PCR. Legionella spp. and Mycobacteria spp. gene numbers
measured by quantitative PCR were similar to nonoutbreak conditions
in the continental U.S. Amplicon sequencing provided a nontarget screen
for other potential pathogens of concern. This study aids in improving
future preparedness, assessment, and recovery operations for small
rural water systems after natural disasters.
Diverse
pathogens can potentially persist and proliferate in reclaimed
water distribution systems (RWDSs). The goal of this study was to
evaluate interactive effects of reclaimed water treatments and water
age on persistence and proliferation of multiple fecal (e.g., Klebsiella, Enterobacter) and non-fecal (e.g., Legionella,
mycobacteria) gene markers in RWDSs. Six laboratory-scale RWDSs were
operated in parallel receiving the influent with or without biologically
active carbon (BAC) filtration + chlorination, chloramination, or
no disinfectant residual. After 3 years of operation, the RWDSs were
subject to sacrificial sampling and shotgun metagenomic sequencing.
We developed an in-house metagenome-derived pathogen quantification
pipeline, validated by quantitative polymerase chain reaction and
mock community analysis, to estimate changes in abundance of ∼30
genera containing waterborne pathogens. Microbial community composition
in the RWDS bulk water, biofilm, and sediments was clearly shaped
by BAC filtration, disinfectant conditions, and water age. Key commonalities
were noted in the ecological niches occupied by fecal pathogen markers
in the RWDSs, while non-fecal pathogen markers were more varied in
their distribution. BAC-filtration + chlorine was found to most effectively
control the widest range of target genera. However, filtration alone
or chlorine secondary disinfection alone resulted in proliferation
of some of these genera containing waterborne pathogens.
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