Pathogens In Surface Waters Research Articles

A one health approach for monitoring antimicrobial resistance: developing a national freshwater pilot effort.

Antimicrobial resistance (AMR) is a world-wide public health threat that is projected to lead to 10 million annual deaths globally by 2050. The AMR public health issue has led to the development of action plans to combat AMR, including improved antimicrobial stewardship, development of new antimicrobials, and advanced monitoring. The National Antimicrobial Resistance Monitoring System (NARMS) led by the United States (U.S) Food and Drug Administration along with the U.S. Centers for Disease Control and U.S. Department of Agriculture has monitored antimicrobial resistant bacteria in retail meats, humans, and food animals since the mid 1990's. NARMS is currently exploring an integrated One Health monitoring model recognizing that human, animal, plant, and environmental systems are linked to public health. Since 2020, the U.S. Environmental Protection Agency has led an interagency NARMS environmental working group (EWG) to implement a surface water AMR monitoring program (SWAM) at watershed and national scales. The NARMS EWG divided the development of the environmental monitoring effort into five areas: (i) defining objectives and questions, (ii) designing study/sampling design, (iii) selecting AMR indicators, (iv) establishing analytical methods, and (v) developing data management/analytics/metadata plans. For each of these areas, the consensus among the scientific community and literature was reviewed and carefully considered prior to the development of this environmental monitoring program. The data produced from the SWAM effort will help develop robust surface water monitoring programs with the goal of assessing public health risks associated with AMR pathogens in surface water (e.g., recreational water exposures), provide a comprehensive picture of how resistant strains are related spatially and temporally within a watershed, and help assess how anthropogenic drivers and intervention strategies impact the transmission of AMR within human, animal, and environmental systems.

Rapid detection method of bacterial pathogens in surface waters and a new risk indicator for water pathogenic pollution

In this study, a accurate, rapid quantitative PCR method for the simultaneous detection of 4 kinds of pathogenic bacteria in water was established, and the distribution of pathogenic bacteria in surface waters with different levels of pollution (Yulin region, China) was detected. The results showed that the detection accuracy was 94%; the detection limit was 2.7 in bacterial cells. Salmonella enterica subsp. enterica serovar typhimurium and Salmonella dysenteria were always present in water when the universal primer for pathogenic bacteria abundance detection was greater than 104 copies 100 mL−1. When the detection value is lower than 104 copy 100 mL−1, the bacteria in the water are rarely pathogenic bacteria, so the detection value of 104 copy 100 mL−1 can be used as a new indicator of waterborne pathogen pollution.

Sunlight-mediated CaO2 inactivation of pathogen indicator organisms in surface water system: Roles of reactive species, characterization of pathogen inactivation

In the era of the current epidemic, it is urgent to control pathogens in sewage, eliminate the source of infection, and optimize the technology for killing pathogens. Combining calcium peroxide (CaO2) with sunlight is considered a potentially efficient, economical, and eco-friendly method for pathogen-contaminated water remediation. This paper evaluated the solar activating properties of CaO2 for inactivating pathogenic indicators and explored the roles of reactive species contributing to pathogen inactivation. Moreover, these reactive species’ average steady-state concentrations and second-order reaction rate were tentatively explored, and mechanistic model for photoinactivation were establishment. Pathogen's inactivation was mainly attributed to direct photoinactivation (13∼50%) and exogenous indirect mechanisms with corresponding contributions of reactive species, i.e., OH− (14∼23%), 1O2 (12∼28%), •OH (20∼32%), O2•– (12∼16%), and H2O2 (6∼11%). Furthermore, cell membrane rupture and DNA damage were observed by transmission electron microscopy (TEM) and agarose gel electrophoresis (AGE) experiments. Among experiments on common aqueous constituents influencing photoinactivation, copper and iron ions were found to promote a pathogen-inactivating ability of the system, while fulvic acids (FA) and humic acid (HA) had the opposite effect. This study revealed the potential of CaO2/sunlight to inactivate pathogens and laid a foundation for its application in inactivating pathogens in surface water.

<i>Escherichia coli</i> concentration, multiscale monitoring over the decade 2011–2021 in the Mekong River basin, Lao PDR

Abstract. Bacterial pathogens in surface waters may threaten human health, especially in developing countries, where untreated surface water is often used for domestic needs. The objective of the long-term multiscale monitoring of Escherichia coli ([E. coli]) concentration in stream water, and that of associated variables (temperature (T), electrical conductance (EC), dissolved oxygen concentration ([DO]) and saturation (DO%), pH (pH), oxidation-reduction potential (ORP), turbidity (Turb), and total suspended sediment concentration ([TSS])), was to identify the drivers of bacterial dissemination across tropical catchments. This data description paper presents three datasets (see “Data availability” section) collected at 31 sampling stations located within the Mekong River and its tributaries in Lao PDR (0.6–25 946 km2) from 2011 to 2021. The 1602 records have been used to describe the hydrological processes driving in-stream E. coli concentration during flood events, to understand the land-use impact on bacterial dissemination on small and large catchment scales, to relate stream water quality and diarrhea outbreaks, and to build numerical models. The database may be further used, e.g., to interpret new variables measured in the monitored catchments, or to map the health risk posed by fecal pathogens.

Bacterial Indicators of Contamination in Highly Impacted Segment of Tropical Lagoon, Southwest Nigeria

Increasing deterioration of coastal waters is a major public health concern in many regions of the developing world. This study investigates the impact of water quality on the proliferation of bacterial pathogens in surface water, sediment and tissues of fish, Sarotherodon melanotheron from the Makoko axis of Lagos Lagoon. Analysis of physicochemical characteristics and microbial quality of samples followed standard methods and procedures. Measured water quality parameters (water temperature, turbidity, pH, salinity and dissolved oxygen) which showed no significant variation (p>0.05) across study stations were within the Nigerian Federal Environmental Protection Agency set limit The highest total bacterial count (TBC) (214.09±43.95 x 105 CFU g-1), total coliform counts (TCC) (91.15±15.05 ×104 CFU g-1) and total faecal coliform (TFC) (36.22±12.98×10³ CFU g-1) were recorded in fish muscle tissue while the lowest TBC (52.39±39.72 x 105 CFU ml-1), TCC (33.45±33.94 ×104 CFU ml-1) and TFC (0.19±0.18×10³ CFU ml-1) were recorded in water sample. The bacterial species with the highest percentages of occurrence in water, sediment, fish gill and fish muscle tissue were Klebsiella pneumoniae (22.11 %), Enterobacter aerogenes (32.37 %), Escherichia coli (32.97 %) and E. coli (29.00 %) respectively. A very strong positive correlation (r = 1.00) was obtained between TBC in water and salinity as well as with dissolved oxygen levels. Likewise, the TBCs in fish parts (muscle tissue and gill) were positively correlated with the water temperature and turbidity. On the other hand, a negative correlation was obtained between pH and TBC in fish muscle tissue (r = -0.81) as well as with fish gut (r = -0.77). The relatively high counts of pathogenic bacteria species recorded during the study have serious public health implications.

Factors Associated With E. coli Levels in and Salmonella Contamination of Agricultural Water Differed Between North and South Florida Waterways

The microbial quality of agricultural water is often assessed using fecal indicator bacteria (FIB) and physicochemical parameters. The presence, direction, and strength of associations between microbial and physicochemical parameters, and the presence of human pathogens in surface water vary across space (e.g., region) and time. This study was undertaken to understand these associations in two produce-growing regions in Florida, USA, and to examine the pathogen ecology in waterways used for produce production. The relationship between Salmonella presence, and microbial and physicochemical water quality; as well as weather and land use factors were evaluated. Water samples were collected from six sites in North Florida (N = 72 samples) and eight sites in South Florida (N = 96 samples) over 12 sampling months. Land use around each sampling site was characterized, and weather and water quality data were collected at each sampling. Salmonella, generic Escherichia coli, total coliform, and aerobic plate count bacteria populations were enumerated in each sample. Univariable and multivariable regression models were then developed to characterize associations between microbial water quality (i.e., E. coli levels and Salmonella presence), and water quality, weather, and land use factors separately for North and South Florida. The E. coli and total coliforms mean concentrations (log10 MPN/100 mL) were 1.8 ± 0.6 and >3.0 ± 0.4 in North and 1.3 ± 0.6 and >3.3 ± 0.2 in South Florida waterways, respectively. While Salmonella was detected in 23.6% (17/72) of North Florida and 28.1% (27/96) of South Florida samples, the concentration ranged between <0.48 and 1.4 log10 MPN/100 mL in North Florida, and <0.48 and 3.0 log10 MPN/100 mL in South Florida. Regression analyses showed no evidence of a correlation between either log10 total coliforms or E. coli levels, and if a sample was Salmonella-positive. The factors associated with Salmonella presence and log10E. coli levels in North Florida differed from those in South Florida; no factors retrained in multivariable regression models were the same for the North and South Florida models. The differences in associations between regions highlight the complexity of understanding pathogen ecology in freshwater environments and suggest substantial differences between intra-state regions in risk factors for Salmonella contamination of agricultural water.

The Persistence of Bacterial Pathogens in Surface Water and Its Impact on Global Food Safety.

Water is vital to agriculture. It is essential that the water used for the production of fresh produce commodities be safe. Microbial pathogens are able to survive for extended periods of time in water. It is critical to understand their biology and ecology in this ecosystem in order to develop better mitigation strategies for farmers who grow these food crops. In this review the prevalence, persistence and ecology of four major foodborne pathogens, Shiga toxin-producing Escherichia coli (STEC), Salmonella, Campylobacter and closely related Arcobacter, and Listeria monocytogenes, in water are discussed. These pathogens have been linked to fresh produce outbreaks, some with devastating consequences, where, in a few cases, the contamination event has been traced to water used for crop production or post-harvest activities. In addition, antimicrobial resistance, methods improvements, including the role of genomics in aiding in the understanding of these pathogens, are discussed. Finally, global initiatives to improve our knowledge base of these pathogens around the world are touched upon.

Quantifying the effect of overland flow on Escherichia coli pulses during floods: Use of a tracer-based approach in an erosion-prone tropical catchment

Bacterial pathogens in surface waters threaten human health. The health risk is especially high in developing countries where sanitation systems are often lacking or deficient. Considering twelve flash-flood events sampled from 2011 to 2015 at the outlet of a 60-ha tropical montane headwater catchment in Northern Lao PDR, and using Escherichia coli as a fecal indicator bacteria, our objective was to quantify the contributions of both surface runoff and sub-surface flow to the in-stream concentration of E. coli during flood events, by (1) investigating E. coli dynamics during flood events and among flood events and (2) designing and comparing simple statistical and mixing models to predict E. coli concentration in stream flow during flood events. We found that in-stream E. coli concentration is high regardless of the contributions of both surface runoff and sub-surface flow to the flood event. However, we measured the highest concentration of E. coli during the flood events that are predominantly driven by surface runoff. This indicates that surface runoff, and causatively soil surface erosion, are the primary drivers of in-stream E. coli contamination. This was further confirmed by the step-wise regression applied to instantaneous E. coli concentration measured in individual water samples collected during the flood events, and by the three models applied to each flood event (linear model, partial least square model, and mixing model). The three models showed that the percentage of surface runoff in stream flow was the best predictor of the flood event mean E. coli concentration. The mixing model yielded a Nash-Sutcliffe efficiency of 0.65 and showed that on average, 89% of the in-stream concentration of E. coli resulted from surface runoff, while the overall contribution of surface runoff to the stream flow was 41%. We also showed that stream flow turbidity and E. coli concentration were positively correlated, but that turbidity was not a strong predictor of E. coli concentration during flood events. These findings will help building adequate catchment-scale models to predict E. coli fate and transport, and mapping the related risk of fecal contamination in a global changing context.

Solar UV radiation modulates animal health and pathogen prevalence in coastal habitats—knowledge gaps and implications for bivalve aquaculture

Ultraviolet radiation (UVR) is an important environmental factor that can have an impact directly, or indirectly, on the health of organisms. UVR also has the potential to inactivate pathogens in surface waters. As a result, UVR can alter host-pathogen relationships. Bivalve species are threatened by various pathogens. Here, we assessed the impacts of UVR on (i) bivalves, (ii) bivalve pathogens and (iii) the bivalve host-pathogen relationship. UVR consistently impedes pathogens. However, the effect of UVR on marine animals is variable, with both positive and negative impacts. The limited available data allude to the potential to exploit natural UVR for disease management in aquaculture, but also highlight a striking knowledge gap and uncertainty relating to climate change.

Adaptation of Human Enterovirus to Warm Environments Leads to Resistance against Chlorine Disinfection.

Sunlight, temperature, and microbial grazing are among the environmental factors promoting the inactivation of viral pathogens in surface waters. Globally, these factors vary across time and space. The persistence of viral pathogens, and ultimately their ecology and dispersion, hinges on their ability to withstand the environmental conditions encountered. To understand how virus populations evolve under changing environmental conditions, we experimentally adapted echovirus 11 (E11) to four climate regimes. Specifically, we incubated E11 in lake water at 10 and 30 °C and in the presence and absence of sunlight. Temperature was the main driver of adaptation, resulting in an increased thermotolerance of the 30 °C adapted populations, whereas the 10 °C adapted strains were rapidly inactivated at higher temperatures. This finding is consistent with a source-sink model in which strains emerging in warm climates can persist in temperate regions, but not vice versa. A microbial risk assessment revealed that the enhanced thermotolerance increases the length of time in which there is an elevated probability of illness associated with swimming in contaminated water. Notably, 30 °C-adapted viruses also exhibited an increased tolerance toward disinfection by free chlorine. Viruses adapting to warm environments may thus become harder to eliminate by common disinfection strategies.

Zero-Valent Iron-Sand Filtration Reduces Escherichia coli in Surface Water and Leafy Green Growing Environments

Surface water is used for irrigation by farmers. However, surface waters may be a source of bacterial foodborne pathogens which contaminate fresh produce intended for human consumption. Proposed but not finalized standards for microbial quality of irrigation water through the Produce Safety Rule (PSR) of the Food Safety Modernization Act (FSMA) in the US emphasize the need for effective reduction of levels of pathogens in surface water intended to be used on fruit and vegetable crops. This study evaluated a zero-valent iron (ZVI)-sand filtration system to reduce E. coli populations in pond water and those transferred to growing spinach plants in a field trial. Six filtration events were conducted with the same ZVI-sand or sand (S) laboratory filtration systems. Filtration systems were constructed by connecting 4 PVC pipes (1.25 L) together. ZVI-sand filters contained 50% ZVI/ 50% sand (0.43-0.60 mm particle size), while sand filters contained 100% sand (0.45-55 mm particle size). In each event, autoclaved pond water (PW) inoculated with E. coli (ca. 4 log CFU/ml) – 8 L - was pumped (1 L/min) through each filter followed by uninoculated autoclaved PW (15 L) with samples taken throughout the filtering process for enumeration of E. coli. Data were fit to a linear model to determine reductions of E. coli levels. ZVI-sand filtration removed significantly (p < 0.05) more E. coli (1.1 log CFU) compared to sand filtration. For ZVI-sand-filtered water, there was a statistically significant (p < 0.05) difference of E. coli removal from early trials (trials 1-3, average removal 96%) than in later trials (trial 4-6, average removal 44%), suggesting that age of the ZVI-sand filters influences E. coli inactivation. Overall, ZVI-sand and sand filtration reduced E. coli populations by 70% and -10%, respectively, indicating that ZVI filtration lowered or inactivated E. coli populations while sand filters accumulated E. coli. Field trials showed that soil and spinach plant samples irrigated with ZVI-sand-filtered water had significantly lower E. coli levels than soils irrigated with sand-filtered water or unfiltered control water. Overall, ZVI-sand filtration significantly reduced E. coli populations in water compared to sand filtration.

Antimicrobial resistance of Salmonella and generic Escherichia coli isolated from surface water samples used for recreation and a source of drinking water in southwestern Ontario, Canada.

Antimicrobial resistance (AMR) in the aquatic environment represents an important means of introduction and dissemination of resistance genes, and presence of resistant pathogens in surface waters may pose a public health concern to recreational and drinking water users. The purpose of this study was to explore antimicrobial resistance patterns in water samples collected from the Grand River watershed (southwestern Ontario, Canada) to describe the composition, trends and potential risks of AMR in the aquatic environment. As part of FoodNet Canada and the Canadian Integrated Program for Antimicrobial Resistance Surveillance (CIPARS), stream water samples were collected bi-weekly from sampling sites within the Grand River watershed in the Waterloo, Ontario sentinel site and tested for the presence and antimicrobial susceptibility of Salmonella spp. (2005-2013) and generic Escherichia coli (2012-2013). Of all samples tested, 16% of Salmonella and 22% of E.coli isolates were resistant to at least one antimicrobial, including three Salmonella isolates and two E.coli isolates that were resistant to Category I antimicrobials, which are classified as very high importance for the treatment of serious bacterial infections in humans. The greatest proportion of resistant E.coli isolates were observed from the river site upstream of the drinking water intake, while the greatest proportion of resistant Salmonella isolates were from sites upstream in the watershed, and at one recreational water site. Salmonella resistance trends remained fairly stable between 2007 and 2013, with the exception of streptomycin and tetracycline which increased in 2010 and 2013. Continued surveillance of antimicrobial resistance patterns and exploration of risk factor data will allow for a better understanding of resistance transmission in the aquatic environment.

Urbanization Impacts the Physicochemical Characteristics and Abundance of Fecal Markers and Bacterial Pathogens in Surface Water.

Urbanization is increasing worldwide and is happening at a rapid rate in China in line with economic development. Urbanization can lead to major changes in freshwater environments through multiple chemical and microbial contaminants. We assessed the impact of urbanization on physicochemical characteristics and microbial loading in canals in Suzhou, a city that has experienced rapid urbanization in recent decades. Nine sampling locations covering three urban intensity classes (high, medium and low) in Suzhou were selected for field studies and three locations in Huangshan (natural reserve) were included as pristine control locations. Water samples were collected for physicochemical, microbiological and molecular analyses. Compared to medium and low urbanization sites, there were statistically significant higher levels of nutrients and total and thermotolerant coliforms (or fecal coliforms) in highly urbanized locations. The effect of urbanization was also apparent in the abundances of human-associated fecal markers and bacterial pathogens in water samples from highly urbanized locations. These results correlated well with land use types and anthropogenic activities at the sampling sites. The overall results indicate that urbanization negatively impacts water quality, providing high levels of nutrients and a microbial load that includes fecal markers and pathogens.

Role of Wall Shear Stress in Cryptosporidium parvum Oocyst Attachment to Environmental Biofilms.

This study investigated Cryptosporidium parvum oocyst deposition onto biofilms as a function of shear stress under laminar or turbulent flow. Annular rotating bioreactors were used to grow stabilized stream biofilms at shear stresses ranging from 0.038 to 0.46 Pa. These steady-state biofilms were then used to assess the impact of hydrodynamic conditions on C. parvum oocyst attachment. C. parvum deposition onto biofilms followed a pseudo-second-order model under both laminar (after a lag phase) and turbulent flows. The total number of oocysts attached to the biofilm at steady state decreased as the hydrodynamic wall shear stress increased. The oocyst deposition rate constant increased with shear stress but decreased at high shear, suggesting that increasing wall shear stress results in faster attachment of Cryptosporidium due to higher mass transport until the shear forces exceed a critical limit that prevents oocyst attachment. These data show that oocyst attachment in the short and long term are impacted differently by shear: higher shear (to a certain limit) may be associated with faster initial oocyst attachment, but lower shear is associated with greater numbers of oocysts attached at equilibrium.IMPORTANCE This research provides experimental evidence to demonstrate that shear stress plays a critical role in protozoan-pathogen transport and deposition in environmental waters. The data presented in this work expand scientific understanding of Cryptosporidium attachment and fate, which will further influence the development of timely and accurate sampling strategies, as well as advanced water treatment technologies, to target protozoan pathogens in surface waters that serve as municipal drinking water sources.

Climate change-induced increases in precipitation are reducing the potential for solar ultraviolet radiation to inactivate pathogens in surface waters

Climate change is accelerating the release of dissolved organic matter (DOM) to inland and coastal waters through increases in precipitation, thawing of permafrost, and changes in vegetation. Our modeling approach suggests that the selective absorption of ultraviolet radiation (UV) by DOM decreases the valuable ecosystem service wherein sunlight inactivates waterborne pathogens. Here we highlight the sensitivity of waterborne pathogens of humans and wildlife to solar UV, and use the DNA action spectrum to model how differences in water transparency and incident sunlight alter the ability of UV to inactivate waterborne pathogens. A case study demonstrates how heavy precipitation events can reduce the solar inactivation potential in Lake Michigan, which provides drinking water to over 10 million people. These data suggest that widespread increases in DOM and consequent browning of surface waters reduce the potential for solar UV inactivation of pathogens, and increase exposure to infectious diseases in humans and wildlife.

Environmental Transport of Emerging Human-Pathogenic Cryptosporidium Species and Subtypes through Combined Sewer Overflow and Wastewater

The environmental transport of Cryptosporidium spp. through combined sewer overflow (CSO) and the occurrence of several emerging human-pathogenic Cryptosporidium species in developing countries remain unclear. In this study, we collected 40 CSO samples and 40 raw wastewater samples from Shanghai, China, and examined them by PCR and DNA sequencing for Cryptosporidium species (targeting the small subunit rRNA gene) and Giardia duodenalis (targeting the triosephosphate isomerase, β-giardin, and glutamate dehydrogenase genes) and Enterocytozoon bieneusi (targeting the ribosomal internal transcribed spacer) genotypes. Human-pathogenic Cryptosporidium species were further subtyped by sequence analysis of the 60-kDa glycoprotein gene, with additional multilocus sequence typing on the emerging zoonotic pathogen Cryptosporidium ubiquitum. Cryptosporidium spp., G. duodenalis, and E. bieneusi were detected in 12 and 15, 33 and 32, and 37 and 40 CSO and wastewater samples, respectively, including 10 Cryptosporidium species, 3 G. duodenalis assemblages, and 8 E. bieneusi genotypes. In addition to Cryptosporidium hominis and Cryptosporidium parvum, two new pathogens identified in industrialized nations, C. ubiquitum and Cryptosporidium viatorum, were frequently detected. The two novel C. ubiquitum subtype families identified appeared to be genetic recombinants of known subtype families. Similarly, the dominant group 1 E. bieneusi genotypes and G. duodenalis subassemblage AII are known human pathogens. The similar distribution of human-pathogenic Cryptosporidium species and E. bieneusi and G. duodenalis genotypes between wastewater and CSO samples reaffirms that storm overflow is potentially a significant contamination source of pathogens in surface water. The frequent identification of C. ubiquitum and C. viatorum in urban wastewater suggests that these newly identified human pathogens may be endemic in China.IMPORTANCECryptosporidium spp., Giardia duodenalis, and Enterocytozoon bieneusi are major waterborne pathogens. Their transport into surface water through combined sewer overflow, which remains largely untreated in developing countries, has not been examined. In addition, the identification of these pathogens to genotypes and subtypes in urban storm overflow and wastewater is necessary for rapid and accurate assessment of pathogen transmission in humans and transport in the environment. Data from this study suggest that, like untreated urban wastewater, combined sewer overflow is commonly contaminated with human-pathogenic Cryptosporidium, G. duodenalis, and E. bieneusi genotypes and subtypes, and urban storm overflow potentially plays a significant role in the contamination of drinking source water and recreational water with human pathogens. They also indicate that Cryptosporidium ubiquitum and Cryptosporidium viatorum, two newly identified human pathogens, may be common in China, and genetic recombination can lead to the emergence of novel C. ubiquitum subtype families.

A quantitative microbial risk assessment model for total coliforms and E. coli in surface runoff following application of biosolids to grassland

In Ireland, the land application of biosolids is the preferred option of disposing of municipal sewage waste. Biosolids provide nutrients in the form of nitrogen, phosphorus, potassium and increases organic matter. It is also an economic way for a country to dispose of its municipal waste. However, biosolids may potentially contain a wide range of pathogens, and following rainfall events, may be transported in surface runoff and pose a potential risk to human health. Thus, a quantitative risk assessment model was developed to estimate potential pathogens in surface water and the environmental fate of the pathogens following dilution, residence time in a stream, die-off rate, drinking water treatment and human exposure. Surface runoff water quality data was provided by project partners. Three types of biosolids, anaerobically digested (AD), lime stabilised (LS), and thermally dried (TD)) were applied on micro plots. Rainfall was simulated at three time intervals (24, 48 and 360 h) following land application. It was assumed that this water entered a nearby stream and was directly abstracted for drinking water. Consumption data for drinking water and body weight was obtained from an Irish study and assigned distributions. Two dose response models for probability of illness were considered for total and faecal coliform exposure incorporating two different exposure scenarios (healthy populations and immuno-compromised populations). The simulated annual risk of illness for healthy populations was below the US EPA and World Health Organisation tolerable level of risk (10−4 and 10−6, respectively). However, immuno-compromised populations may still be at risk as levels were greater than the tolerable level of risk for that subpopulation. The sensitivity analysis highlighted the importance of residence time in a stream on the bacterial die-off rate.

Variability of Intra-event Statistics for Multiple Fecal Indicator Bacteria in Urban Stormwater

Pathogens in surface waters continue to be a worldwide concern. The potential presence of pathogens is often identified through the use of fecal indicator bacteria such as fecal coliform, E. coli, and enterococci, each of which are still utilized worldwide depending on local regulations. Urban stormwater runoff has been shown to convey fecal indicator bacteria to surface waters; however, the fate and transport dynamics of these microbes in urban stormwater are not well established. This is particularly the case for intra-event (within event) processes. The intra-event characteristics of total suspended solids and three types of fecal indicator bacteria (FIB), fecal coliform, E. coli, and enterococci, were analysed for a watershed in Raleigh, NC, USA. FIB showed higher variability than TSS among intra-event characteristics such as normalized peak concentration, rate of change, and normalized concentration in the first 3 mm of rainfall (C3mm), but similar variability in concentrations throughout each storm. FIB intra-event statistics appear to be influenced by climate variables whereas total suspended sediments statistics are most influenced by hydrologic variables. Changes in intra-event total suspended concentrations were consistently well described by rainfall intensity, while FIB correlations with rainfall intensity were weaker and inconsistent between events. This study showed similar patterns of variability among the intra-event FIB statistics and comparable correlations to climatic and hydrologic variables between fecal coliform, E. coli, and enterococci. Thus, similar processes appear to influence the variability of all three indicator bacteria, suggesting that microbial models may be adaptable amongst various types of FIB.

Detection of viable bacterial pathogens in a drinking water source using propidium monoazide-quantitative PCR

Research Article| September 10 2014 Detection of viable bacterial pathogens in a drinking water source using propidium monoazide-quantitative PCR Avid Banihashemi; Avid Banihashemi 1NSERC Chair in Water Treatment, Department of Civil and Environmental Engineering, University of Waterloo, 200 University Avenue West, Waterloo, Ontario, Canada N2L 3G1 E-mail: a2baniha@uwaterloo.ca Search for other works by this author on: This Site PubMed Google Scholar Michele I. Van Dyke; Michele I. Van Dyke 1NSERC Chair in Water Treatment, Department of Civil and Environmental Engineering, University of Waterloo, 200 University Avenue West, Waterloo, Ontario, Canada N2L 3G1 Search for other works by this author on: This Site PubMed Google Scholar Peter M. Huck Peter M. Huck 1NSERC Chair in Water Treatment, Department of Civil and Environmental Engineering, University of Waterloo, 200 University Avenue West, Waterloo, Ontario, Canada N2L 3G1 Search for other works by this author on: This Site PubMed Google Scholar Journal of Water Supply: Research and Technology-Aqua (2015) 64 (2): 139–148. https://doi.org/10.2166/aqua.2014.063 Article history Received: May 16 2014 Accepted: August 09 2014 Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Cite Icon Cite Permissions Search Site Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAll JournalsThis Journal Search Advanced Search Citation Avid Banihashemi, Michele I. Van Dyke, Peter M. Huck; Detection of viable bacterial pathogens in a drinking water source using propidium monoazide-quantitative PCR. Journal of Water Supply: Research and Technology-Aqua 1 March 2015; 64 (2): 139–148. doi: https://doi.org/10.2166/aqua.2014.063 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex A cell viability assay was applied to measure bacterial enteric pathogens in a river in southern Ontario, Canada that is used as a source of drinking water. Pathogen concentrations were measured using both propidium monoazide (PMA)-quantitative polymerase chain reaction (PCR) and quantitative PCR (qPCR) without PMA pretreatment to compare viable and total (live and dead) cells. The pathogens evaluated were Salmonella enterica, thermophilic Campylobacter, and Escherichia coli O157:H7, and the suspected enteric pathogen Arcobacter butzleri was also investigated. Results showed that for all strains dead cells were detected in few river water samples, and the difference between total and viable cell concentrations for each pathogen group was always less than 0.5 log. A. butzleri was detected at concentrations 2–3 log higher than the other pathogens. S. enterica, Campylobacter, and E. coli O157:H7 were detected at low concentrations at one sample location and at higher concentrations at a second sampling location. Results from this study show qPCR with PMA pretreatment can provide reliable enumeration of viable pathogens in surface water, and that dead cells were rarely present in water used as a source for drinking water treatment. Arcobacter butzleri, PCR, propidium monoazide, river water, viability, waterborne pathogen © IWA Publishing 2015 You do not currently have access to this content.

Receiver-operating characteristics analysis: a new approach to predicting the presence of pathogens in surface waters.

Fecal indicator microbes are used to monitor the public health risks of recreating in surface waters. However, the importance of indicator tests as predictors of waterborne pathogens has been unclear. Numerous studies have also shown that the survival and growth of indicator organisms may depend on location-specific factors that cannot be broadly generalized. We used receiver-operating characteristic (ROC) methods to determine whether fecal indicator species are capable of predicting the presence of Giardia and Cryptosporidium in fresh surface waters in the Chicago area. We also derived recreational water quality criteria specific to our location with respect to this end point. We considered five fecal indicators: enterococci measured by culture and quantitative polymerase chain reaction (qPCR), Escherichia coli measured by culture, somatic coliphage, and F+ coliphage. All fecal indicators were found to predict the presence and absence of protozoan pathogens. The test for enterococci measured by culture was the poorest predictor of the presence of pathogens. The test for enterococci measured by qPCR was the best predictor of the presence of Giardia, but not an important predictor of the presence of Cryptosporidium. The test for somatic coliphage was a relatively strong predictor of the presence of both pathogens. This analysis supports the use of qPCR-based assays over culture-based assays for predicting the presence of Giardia in fresh surface water. Our criteria were optimized for the prediction of the presence of Giardia and Cryptosporidium in our location and were closely aligned with criteria of the U.S. Environmental Protection Agency derived from epidemiological risk assessment. The ROC approach is flexible and can inform location-specific interpretation of water quality monitoring data and decision making.