The influence of urbanization and water reclamation plants on fecal indicator bacteria and antibiotic resistance in the Los Angeles River watershed: A case study with complementary monitoring methods.

Urban land use and water reclamation plants (WRPs) can impact fecal indicator bacteria (FIB) and antimicrobial resistance (AMR) in coastal watersheds. However, there is a lack of studies exploring these effects on the US West Coast. Additionally, there is limited research using a complementary approach across culture-, qPCR-, and metagenomics-based techniques for characterizing environmental AMR.

Stormwater biofilter response to high nitrogen loading under transient flow conditions: Ammonium and nitrate fates, and nitrous oxide emissions.

Nitrogen (N) in urban runoff is often treated with green infrastructure including biofilters. However, N fates across biofilters are insufficiently understood because prior studies emphasize low N loading under laboratory conditions, or use "steady-state" flow regimes over short time scales. Here, we tested field scale biofilter N fates during simulated storms delivering realistic transient flows with high N loading.

Incorporating field-based research into remote learning: An assessment of soil lead pollution in different land-use types in Los Angeles.

A research-based course was developed to investigate the legacy of soil lead (Pb) pollution in Los Angeles, California. During the course, undergraduate and graduate students collected a total of 270 soil samples for analyses of metal (loid) concentrations in different land-use types (residential, park, and school). Residential soils had significantly higher Pb concentrations than other land uses (p < 0.

Turbidity and fecal indicator bacteria in recreational marine waters increase following the 2018 Woolsey Fire.

Wildfires increase runoff and sediment yields that impact downstream ecosystems. While the effects of wildfire on stream water quality are well documented, oceanic responses to wildfire remain poorly understood. Therefore, this study investigated oceanic responses to the 2018 Woolsey Fire using satellite remote sensing and in situ data analyses.

Influence of soil characteristics and metal(loid)s on antibiotic resistance genes in green stormwater infrastructure in Southern California.

The synergetic effects of metal(loid)s and soil characteristics on bacterial antibiotic resistance genes (ARGs) in green stormwater infrastructure (GSI) has been relatively understudied. Surface soil samples from six GSIs in Southern California over three time periods were assessed for selected ARGs, class 1 integron-integrase genes (intI1), 16S rRNA genes, and bioavailable and total concentrations of nine metal(loid)s, to investigate the relationships among ARGs, soil characteristics, and co-occurring metal(loid)s. Significant correlations existed among relative gene abundances (sul1, sul2, tetW, and intI1), total metal(loid)s (arsenic, copper, lead, vanadium, and zinc), and bioavailable metal(loid) (arsenic) (r = 0.

Commercially available garden products as important sources of antibiotic resistance genes-a survey.

The dissemination of antibiotic resistance genes (ARGs) in the environment contributes to the global rise in antibiotic resistant infections. Therefore, it is of importance to further research the exposure pathways of these emerging contaminants to humans. This study explores commercially available garden products containing animal manure as a source of ARGs in a survey of 34 garden products, 3 recently landscaped soils, and 5 native soils.

Antibiotic Resistance of Isolated from , , and Retail Broiler Chicken Meat.

The use of antibiotics for therapeutic and especially non-therapeutic purposes in livestock farms promotes the development of antibiotic resistance in previously susceptible bacteria through selective pressure. In this work, we examined isolates using the standard Kirby-Bauer disk diffusion susceptibility protocol and the CLSI standards. Companies selling retail chicken products in Los Angeles, California were grouped into three production groupings-, , and .

Impact of a Scalable, Multi-Campus "Foodprint" Seminar on College Students' Dietary Intake and Dietary Carbon Footprint.

Background: Dietary patterns affect both human health and environmental sustainability. Prior research found a ten-unit course on food systems and environmental sustainability shifted dietary intake and reduced dietary carbon footprint among college students. This research evaluated the impact of a similar, more scalable one-unit taught at multiple universities.

Fate of antibiotic resistance genes and antibiotic-resistant bacteria in water resource recovery facilities.

Many important diseases are showing resistance to commonly used antibiotics, and the resistance is potentially caused by widespread use of antibiotics for maintaining human health and improving food production. Antibiotic resistance genes (ARGs) and antibiotic-resistant bacteria (ARB) are associated with this increase, and their fate in water resource recovery facilities is an important, emerging area of research. This literature review summarizes current findings of worldwide research on the fate of ARB and ARGs in various types of treatment plants.

Multi-tiered approach utilizing microbial source tracking and human associated-IMS/ATP for surveillance of human fecal contamination in Baja California, Mexico.

As both the need for reuse of reclaimed wastewater and the burden placed on existing wastewater treatment plants increase, so does the need for methods that can reliably, rapidly and economically identify human-associated contamination. A survey of surface water quality was conducted in Baja California, Mexico where inadequate infrastructure or its inefficient operation leads to poor water quality. The HF183 and Bacteroides thetaiotaomicron (B.

Remediation of groundwater contaminated with arsenic through enhanced natural attenuation: Batch and column studies.

Batch and column laboratory experiments were conducted on natural sediment and groundwater samples from a contaminated site in Maine, USA with the aim of lowering the dissolved arsenate [As(V)] concentrations through chemical enhancement of natural attenuation capacity. In batch factorial experiments, two levels of treatment for three parameters (pH, Ca, and Fe) were studied at different levels of phosphate to evaluate their impact on As(V) solubility. Results illustrated that lowering pH, adding Ca, and adding Fe significantly increased the sorption capacity of sediments.

Disparate Antibiotic Resistance Gene Quantities Revealed across 4 Major Cities in California: A Survey in Drinking Water, Air, and Soil at 24 Public Parks.

Widespread prevalence of multidrug and pandrug-resistant bacteria has prompted substantial concern over the global dissemination of antibiotic resistance genes (ARGs). Environmental compartments can behave as genetic reservoirs and hotspots, wherein resistance genes can accumulate and be laterally transferred to clinically relevant pathogens. In this work, we explore the ARG copy quantities in three environmental media distributed across four cities in California and demonstrate that there exist city-to-city disparities in soil and drinking water ARGs.

Effect of freshwater sediment characteristics on the persistence of fecal indicator bacteria and genetic markers within a Southern California watershed.

In this study, the aging of culturable FIB and DNA representing genetic markers for Enterococcus spp. (ENT1A), general Bacteroides (GB3), and human-associated Bacteroides (HF183) in freshwater sediments was evaluated. Freshwater sediment was collected from four different sites within the upper and lower reach of the Topanga Creek Watershed and two additional comparator sites within the Santa Monica Bay, for a total of six sites.

Sources and persistence of fecal indicator bacteria and in sand as measured by culture-based and culture-independent methods: A case study at Santa Monica Pier, California.

This study investigated causes of persistent fecal indicator bacteria (FIB) in beach sand under the pier in Santa Monica, CA. FIB levels were up to 1,000 times higher in sand underneath the pier than that collected from adjacent to the pier, with the highest concentrations under the pier in spring and fall. (EC) and enterococci (ENT) under the pier were significantly positively correlated with moisture (ρ = 0.

Adsorption and desorption of arsenate on sandy sediments from contaminated and uncontaminated saturated zones: Kinetic and equilibrium modeling.

Application of empirical models to adsorption of contaminants on natural heterogeneous sorbents is often challenging due to the uncertainty associated with fitting experimental data and determining adjustable parameters. Sediment samples from contaminated and uncontaminated portions of a study site in Maine, USA were collected and investigated for adsorption of arsenate [As(V)]. Two kinetic models were used to describe the results of single solute batch adsorption experiments.

Virulence Genes among Enterococcus faecalis and Enterococcus faecium Isolated from Coastal Beaches and Human and Nonhuman Sources in Southern California and Puerto Rico.

Most Enterococcus faecalis and E. faecium are harmless to humans; however, strains harboring virulence genes, including esp, gelE, cylA, asa1, and hyl, have been associated with human infections. E.

Enterococcus growth on eelgrass (Zostera marina); implications for water quality.

Enterococci are fecal indicator bacteria used to monitor fecal pollution of recreational waters. When enterococci levels exceed health standards, fecal pollution is assumed as the cause. Enterococci growing on plants limit their usefulness as fecal indicator bacteria.

Sources of Mercury Exposure to Children in Low- and Middle-Income Countries.

Background: Many children in low- and middle-income countries face enhanced risks of exposure to contaminants via the environment, parental occupation, and other routes. While mercury (Hg) is a global pollutant whose transport properties allow it to have an impact even in pristine areas, the presence of significant Hg sources in the developing world can cause localized effects that are more severe than those observed in other areas.

Objectives: This paper provides a narrative review of sources of Hg exposure to people in the developing world with a particular focus on children, and presents an overview of key aspects to this important issue.

Long-term monitoring of molecular markers can distinguish different seasonal patterns of fecal indicating bacteria sources.

Elevated levels of fecal indicator bacteria (FIB) have been observed at Topanga Beach, CA, USA. To identify the FIB sources, a microbial source tracking study using a dog-, a gull- and two human-associated molecular markers was conducted at 10 sites over 21 months. Historical data suggest that episodic discharge from the lagoon at the mouth of Topanga Creek is the main source of bacteria to the beach.

Detection limits and cost comparisons of human- and gull-associated conventional and quantitative PCR assays in artificial and environmental waters.

Some molecular methods for tracking fecal pollution in environmental waters have both PCR and quantitative PCR (qPCR) assays available for use. To assist managers in deciding whether to implement newer qPCR techniques in routine monitoring programs, we compared detection limits (LODs) and costs of PCR and qPCR assays with identical targets that are relevant to beach water quality assessment. For human-associated assays targeting Bacteroidales HF183 genetic marker, qPCR LODs were 70 times lower and there was no effect of target matrix (artificial freshwater, environmental creek water, and environmental marine water) on PCR or qPCR LODs.

Performance and specificity of the covalently linked immunomagnetic separation-ATP method for rapid detection and enumeration of enterococci in coastal environments.

The performance and specificity of the covalently linked immunomagnetic separation-ATP (Cov-IMS/ATP) method for the detection and enumeration of enterococci was evaluated in recreational waters. Cov-IMS/ATP performance was compared with standard methods: defined substrate technology (Enterolert; IDEXX Laboratories), membrane filtration (EPA Method 1600), and an Enterococcus-specific quantitative PCR (qPCR) assay (EPA Method A). We extend previous studies by (i) analyzing the stability of the relationship between the Cov-IMS/ATP method and culture-based methods at different field sites, (ii) evaluating specificity of the assay for seven ATCC Enterococcus species, (iii) identifying cross-reacting organisms binding the antibody-bead complexes with 16S rRNA gene sequencing and evaluating specificity of the assay to five nonenterococcus species, and (iv) conducting preliminary tests of preabsorption as a means of improving the assay.

Performance evaluation of canine-associated Bacteroidales assays in a multi-laboratory comparison study.

The contribution of fecal pollution from dogs in urbanized areas can be significant and is an often underestimated problem. Microbial source tracking methods (MST) utilizing quantitative PCR of dog-associated gene sequences encoding 16S rRNA of Bacteroidales are a useful tool to estimate these contributions. However, data about the performance of available assays are scarce.

Evaluation of the repeatability and reproducibility of a suite of qPCR-based microbial source tracking methods.

Many PCR-based methods for microbial source tracking (MST) have been developed and validated within individual research laboratories. Inter-laboratory validation of these methods, however, has been minimal, and the effects of protocol standardization regimes have not been thoroughly evaluated. Knowledge of factors influencing PCR in different laboratories is vital to future technology transfer for use of MST methods as a tool for water quality management.