Research

Jump to: Review

201 KiB

Open AccessCommunication

Antibiotic-Resistant Enteric Bacteria in Environmental Waters

by Lisa M. Casanova and Mark D. Sobsey

Water 2016, 8(12), 561; https://doi.org/10.3390/w8120561 - 30 Nov 2016

Cited by 16 | Viewed by 5578

Sources of antibiotic resistant organisms, including concentrated animal feeding operations (CAFOs), may lead to environmental surface and groundwater contamination with resistant enteric bacteria of public health concern. The objective of this research is to determine whether Salmonella, Escherichia coli, Yersinia enterocolitica [...] Read more.

Sources of antibiotic resistant organisms, including concentrated animal feeding operations (CAFOs), may lead to environmental surface and groundwater contamination with resistant enteric bacteria of public health concern. The objective of this research is to determine whether Salmonella, Escherichia coli, Yersinia enterocolitica, and enterococci resistant to clinically relevant antibiotics are present in surface and groundwater sources in two eastern North Carolina counties, Craven and Wayne. 100 surface and groundwater sites were sampled for Salmonella, E. coli, and enterococci, and the bacteria isolated from these samples were tested for susceptibility to clinically relevant antibiotics. Salmonella were detected at low levels in some surface but not groundwater. E. coli were in surface waters but not ground in both counties. Enterococci were present in surface water and a small number of groundwater sites. Yersinia was not found. Bacterial densities were similar in both counties. For Salmonella in surface water, the most frequent type of resistance was to sulfamethoxazole. There was no ciprofloxacin resistance. There were a few surface water E. coli isolates resistant to chloramphenicol, gentamicin, and ampicillin. Enterococci in surface water had very low levels of resistance to vancomycin, chloramphenicol, ampicillin, and streptomycin. E. coli and enterococci are present more frequently and at higher levels in surface water than Salmonella, but groundwater contamination with any of these organisms was rare, and low levels of resistance can be found sporadically. Resistant bacteria are relatively uncommon in these eastern N.C. surface and groundwaters, but they could pose a risk of human exposure via ingestion or primary contact recreation. Full article

(This article belongs to the Special Issue Pathogens in Water)

1458 KiB

Open AccessArticle

Near Real-Time Flow Cytometry Monitoring of Bacterial and Viral Removal Efficiencies during Water Reclamation Processes

by Xiao Huang, Zheng Zhao, Dana Hernandez and Sunny C. Jiang

Water 2016, 8(10), 464; https://doi.org/10.3390/w8100464 - 18 Oct 2016

Cited by 20 | Viewed by 8050

Abstract

Wastewater reuse has become an important part of the urban water supply portfolio in water stressed regions. Effective wastewater treatment processes are critical to protect public health during water reuse practices. However, the microbial removal efficiencies in wastewater reclamation plants are not routinely [...] Read more.

Wastewater reuse has become an important part of the urban water supply portfolio in water stressed regions. Effective wastewater treatment processes are critical to protect public health during water reuse practices. However, the microbial removal efficiencies in wastewater reclamation plants are not routinely monitored due to the lack of a simple quantification method. This study applied a near real-time flow cytometry (FCM) technique to quantify the removal of total bacteria and viruses at three wastewater reclamation plants in Southern California. The results showed that the activated sludge process removed 1–2 log₁₀ of bacteria but was not efficient at removing viruses. The membrane bioreactor process was capable of removing both bacteria and viruses with high efficiency. At the plant using chloramines as the main disinfectant, even though culturable total coliform bacteria were effectively reduced to the level meeting the California Title 22 Water Recycling Criteria (7-day median of 2.2 most probable number (MPN)/100 mL, and no more than one sample exceeds 23 MPN/100 mL), the disinfected final effluent still contained greater than 10⁶ bacterial and 10⁸ viral particles per mL in. In contrast, more than 4 log₁₀ removal of both bacteria and viruses were observed at the plant using free chlorine as the main disinfectant. The results indicate that additional microbial indicators are needed and suggest the potential use of FCM as a rapid monitoring tool for evaluation of microbial removal. Full article

(This article belongs to the Special Issue Pathogens in Water)

► Show Figures

Figure 1

2473 KiB

Open AccessArticle

Submerged Pond Sand Filter—A Novel Approach to Rural Water Supply

by Mia Øhlenschlæger, Sarah C.B. Christensen, Henrik Bregnhøj and Hans-Jørgen Albrechtsen

Water 2016, 8(6), 250; https://doi.org/10.3390/w8060250 - 13 Jun 2016

Cited by 9 | Viewed by 8357

Abstract

This study describes the new design and function of a modified version of a traditional slow sand filter. The Submerged Pond Sand Filter is built inside a pond and has a vertical as well as a horizontal flow of water through a sloped [...] Read more.

This study describes the new design and function of a modified version of a traditional slow sand filter. The Submerged Pond Sand Filter is built inside a pond and has a vertical as well as a horizontal flow of water through a sloped filter opening. The filter provides treated drinking water to a rural Indian village. The filter has functioned with minimal maintenance for five years without being subject to the typical scraping off and changing of sand as needed in traditional slow sand filters every few months. This five-year study showed bacterial removal efficiency of 97% on average with a level of faecal coliforms of 2 ± 2 colony forming units (CFU)/100 mL measured in the treated water. Turbidity was visibly removed during treatment. When water was retrieved from the filter through a manual pump for long consistent time intervals (60 min), faecal coliform counts increased from four to 10 CFU/100 mL on average compared to shorter pumping intervals (5 min). Though the treated water did not comply with the World Health Organization standards of 0 CFU/100 mL, the filter significantly improved water quality and provided one of the best sources of drinkable water in a water-depleted area, where only surface water was available. Furthermore, it is a sustainable treatment method due to low maintenance requirements. Full article

(This article belongs to the Special Issue Pathogens in Water)

► Show Figures

Graphical abstract

225 KiB

Open AccessArticle

Inter-Laboratory Evaluation and Successful Implementation of MS2 Coliphage as a Surrogate to Establish Proficiency Using a BSL-3 Procedure

by Latisha Mapp, Yildiz Chambers, Prisca Takundwa, Vincent R. Hill, Chandra Schneeberger, Jackie Knee, Malik Raynor, Patricia Klonicki, Kenneth Miller, Misty Pope and Nina Hwang

Water 2016, 8(6), 248; https://doi.org/10.3390/w8060248 - 10 Jun 2016

Cited by 2 | Viewed by 4858

Abstract

The U.S. Environmental Protection Agency’s (EPA) Water Laboratory Alliance relies on the Centers for Disease Control and Prevention’s ultrafiltration-based Water Processing Procedure (WPP) for concentration of biosafety level 3 (BSL-3) agents from 10 L to 100 L of drinking water. The WPP requires [...] Read more.

The U.S. Environmental Protection Agency’s (EPA) Water Laboratory Alliance relies on the Centers for Disease Control and Prevention’s ultrafiltration-based Water Processing Procedure (WPP) for concentration of biosafety level 3 (BSL-3) agents from 10 L to 100 L of drinking water. The WPP requires comprehensive training and practice to maintain proficiency, resulting in a critical need for quality control (QC) criteria. The aim of this study was to develop criteria using male-specific (MS2) coliphage (BSL-2 agent) to minimize safety hazards associated with BSL-3 agents and to use the criteria to evaluate analytical proficiency during a demonstration exercise. EPA Method 1602 with EasyPhage was used during the study to develop QC criteria for 100-mL, and 40–100 L samples. The demonstration exercise indicated that the MS2 criteria would allow laboratories to demonstrate proficiency using the WPP with 40–100 L samples. In addition, the QC criteria developed for 100-mL samples has broad applicability at laboratories that are using MS2 for other types of analyses, such as assessment of water treatment devices. The development of MS2 QC criteria allows laboratories to develop and confirm ongoing proficiency using the WPP. Full article

(This article belongs to the Special Issue Pathogens in Water)

1200 KiB

Open AccessArticle

Monitoring of β-d-Galactosidase Activity as a Surrogate Parameter for Rapid Detection of Sewage Contamination in Urban Recreational Water

by Ingun Tryland, Henrik Braathen, Aina C. Wennberg, Fasil Eregno and Anna-Lena Beschorner

Water 2016, 8(2), 65; https://doi.org/10.3390/w8020065 - 18 Feb 2016

Cited by 7 | Viewed by 6103

Abstract

Simple, automated methods are required for rapid detection of wastewater contamination in urban recreational water. The activity of the enzyme β-d-galactosidase (GAL) can rapidly (<2 h) be measured by field instruments, or a fully automated instrument, and was evaluated as a [...] Read more.

Simple, automated methods are required for rapid detection of wastewater contamination in urban recreational water. The activity of the enzyme β-d-galactosidase (GAL) can rapidly (<2 h) be measured by field instruments, or a fully automated instrument, and was evaluated as a potential surrogate parameter for estimating the level of fecal contamination in urban waters. The GAL-activity in rivers, affected by combined sewer overflows, increased significantly during heavy rainfall, and the increase in GAL-activity correlated well with the increase in fecal indicator bacteria. The GAL activity in human feces (n = 14) was high (mean activity 7 × 10⁷ ppb MU/hour) and stable (1 LOG₁₀ variation), while the numbers of Escherichia coli and intestinal enterococci varied by >5 LOG₁₀. Furthermore, the GAL-activity per gram feces from birds, sheep and cattle was 2–3 LOG₁₀ lower than the activity from human feces, indicating that high GAL-activity in water may reflect human fecal pollution more than the total fecal pollution. The rapid method can only be used to quantify high levels of human fecal pollution, corresponding to about 0.1 mg human feces/liter (or 10³ E. coli/100 mL), since below this limit GAL-activity from non-fecal environmental sources may interfere. Full article

(This article belongs to the Special Issue Pathogens in Water)

► Show Figures

Figure 1

Review

Jump to: Research

2931 KiB

Open AccessReview

Indicator and Pathogen Removal by Low Impact Development Best Management Practices

by Jian Peng, Yiping Cao, Megan A. Rippy, A. R. M. Nabiul Afrooz and Stanley B. Grant

Water 2016, 8(12), 600; https://doi.org/10.3390/w8120600 - 16 Dec 2016

Cited by 37 | Viewed by 9588

Abstract

Microbial contamination in urban stormwater is one of the most widespread and challenging water quality issues in developed countries. Low impact development (LID) best management practices (BMPs) restore pre-urban hydrology by treating and/or harvesting urban runoff and stormwater, and can be designed to [...] Read more.

Microbial contamination in urban stormwater is one of the most widespread and challenging water quality issues in developed countries. Low impact development (LID) best management practices (BMPs) restore pre-urban hydrology by treating and/or harvesting urban runoff and stormwater, and can be designed to remove many contaminants including pathogens. One particular type of LID BMP, stormwater biofilters (i.e., vegetated media filters, also known as bioinfiltration, bioretention, or rain gardens), is becoming increasingly popular in urban environments due to its multiple co-benefits (e.g., improved hydrology, water quality, local climate and aesthetics). However, increased understanding of the factors influencing microbial removal in biofilters is needed to effectively design and implement biofilters for microbial water quality improvement. This paper aims to provide a holistic view of microbial removal in biofilter systems, and reviews the effects of various design choices such as filter media, vegetation, infauna, submerged zones, and hydraulic retention time on microbial removal. Limitations in current knowledge and recommendations for future research are also discussed. Full article

(This article belongs to the Special Issue Pathogens in Water)

► Show Figures

Figure 1

1365 KiB

Open AccessReview

Current Status of Marker Genes of Bacteroides and Related Taxa for Identifying Sewage Pollution in Environmental Waters

by Warish Ahmed, Bridie Hughes and Valerie J. Harwood

Water 2016, 8(6), 231; https://doi.org/10.3390/w8060231 - 31 May 2016

Cited by 107 | Viewed by 12362

Abstract

Microbial source tracking (MST) endeavors to determine sources of fecal pollution in environmental waters by capitalizing on the association of certain microorganisms with the gastrointestinal tract and feces of specific animal groups. Several decades of research have shown that bacteria belonging to the [...] Read more.

Microbial source tracking (MST) endeavors to determine sources of fecal pollution in environmental waters by capitalizing on the association of certain microorganisms with the gastrointestinal tract and feces of specific animal groups. Several decades of research have shown that bacteria belonging to the gut-associated order Bacteroidales, and particularly the genus Bacteroides, tend to co-evolve with the host, and are, therefore, particularly suitable candidates for MST applications. This review summarizes the current research on MST methods that employ genes belonging to Bacteroidales/Bacteroides as tracers or “markers” of sewage pollution, including known advantages and deficiencies of the many polymerase chain reaction (PCR)-based methods that have been published since 2000. Host specificity is a paramount criterion for confidence that detection of a marker is a true indicator of the target host. Host sensitivity, or the prevalence of the marker in feces/waste from the target host, is necessary for confidence that absence of the marker is indicative of the absence of the pollution source. Each of these parameters can vary widely depending on the type of waste assessed and the geographic location. Differential decay characteristics of bacterial targets and their associated DNA contribute to challenges in interpreting MST results in the context of human health risks. The HF183 marker, derived from the 16S rRNA gene of Bacteroides dorei and closely related taxa, has been used for almost two decades in MST studies, and is well characterized regarding host sensitivity and specificity, and in prevalence and concentration in sewage in many countries. Other markers such as HumM2 and HumM3 show promise, but require further performance testing to demonstrate their widespread utility. An important limitation of the one-marker-one-assay approach commonly used for MST is that given the complexities of microbial persistence in environmental waters, and the methodological challenges of quantitative PCR (qPCR) in such samples, the absence of a given marker does not ensure the absence of fecal pollution in the source water. Approaches under development, such as microarray and community analysis, have the potential to improve MST practices, thereby increasing our ability to protect human and ecosystem health. Full article

(This article belongs to the Special Issue Pathogens in Water)

► Show Figures

Figure 1

1258 KiB

Open AccessReview

Coliphages as Model Organisms in the Characterization and Management of Water Resources

by Juan Jofre, Francisco Lucena, Anicet R. Blanch and Maite Muniesa

Water 2016, 8(5), 199; https://doi.org/10.3390/w8050199 - 12 May 2016

Cited by 86 | Viewed by 20789

Abstract

Two groups of bacteriophages that infect Escherichia coli, somatic and F-specific coliphages, have been used in academia as both fecal and viral indicators for many years. Regulatory authorities in different parts of the world are beginning to consider coliphages as indicators of [...] Read more.

Two groups of bacteriophages that infect Escherichia coli, somatic and F-specific coliphages, have been used in academia as both fecal and viral indicators for many years. Regulatory authorities in different parts of the world are beginning to consider coliphages as indicators of water quality in a range of settings. However, issues such as their potential replication in natural water environments, the cumbersome detection and enumeration methods, a lack of definition concerning which of the two groups should be included in future regulations, and the lack of a clear correlation between coliphages and human viruses and health risks in different water settings remain controversial. This review attempts to shed some light on these contentious issues. The conclusions are that: 1) supposing that they can replicate in some natural water settings, the contribution of coliphages replicated outside the gut will not affect the numbers contributed by fecal pollution and detected by strains recommended for standardized methods; 2) there are easy, fast, and cost-effective methods that can be used in routine laboratories after a little training; 3) perhaps the best option is to determine both groups in a single step; and 4) the low correlation of coliphages with human viruses and health risks is no worse than the correlation between different human viruses. Full article

(This article belongs to the Special Issue Pathogens in Water)

► Show Figures

Figure 1

Journal Menu

Journal Browser

Pathogens in Water

Share This Special Issue

Special Issue Editors

Special Issue Information

Keywords

Published Papers (8 papers)

Research

Review

Further Information

Guidelines

MDPI Initiatives

Follow MDPI