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Special Issue "Antimicrobial Resistance in Environmental Waters"

A special issue of Water (ISSN 2073-4441). This special issue belongs to the section "Water Quality and Ecosystems".

Deadline for manuscript submissions: closed (31 August 2018).

Printed Edition Available!
A printed edition of this Special Issue is available here.

Special Issue Editors

Guest Editor
Prof. Dr. Karina Yew-Hoong Gin

Department of Civil and Environmental Engineering, National University of Singapore, 1 Engineering Drive 2, E1A 07-03, Singapore 117576, Singapore
Website | E-Mail
Interests: water quality; pathogens; harmful algal blooms; cyanotoxins and off-flavors; antimicrobial resistance; emerging organic contaminants; environmental modelling; fate and transport processes
Guest Editor
Dr. Charmaine Ng

Department of Civil and Environmental Engineering, National University of Singapore, 5A Engineering Drive 1, #08-03, T-Lab building, Singapore 117576, Singapore
Website | E-Mail
Interests: antimicrobial resistance; microbial water quality analysis; marine microbial ecology; pathogens; metagenomics

Special Issue Information

Dear Colleagues,

In recent years, the emergence of antimicrobial resistance has drawn heightened global concern because of the severe ramifications on the treatment of microbial infections. In particular, the issue of antibiotic resistance arises due to the overuse and misuse of antibiotics in both developed and developing countries. Bacteria develop antibiotic resistance in the presence of residual levels of antibiotics and these antibiotic resistant bacteria in turn, are able to spread their resistance to other bacteria through mechanisms such as horizontal gene transfer, mediated by mobile genetic elements (e.g. plasmids, integrons) or co-selecting agents such as biocides and toxic metals. There is a worrying trend that pathogens are developing antibiotic resistance to a degree where last resort antibiotics are no longer effective. This, in turn, has severe implications on public health and healthcare costs.

In an effort to better understand the rising levels of antimicrobial resistance, surveillance studies have been undertaken across countries in a common effort to explore the occurrence of antimicrobial resistance in both clinical and natural environments. Implementating such initiatives through assessing the types of antibiotics used, antibiotic resistant bacteria (ARB) present and associated antibiotic resistant genes (ARG) in microbiomes enables better understanding of the impact of antibiotics in the medical, agriculture and aquaculture industries. Aquatic environments harbor diverse freshwater bacterial communities which may be subjected to anthropogenic pressures, while domestic wastewaters receive direct loads of antibiotics and pathogenic bacteria from human excretion. The nature of these environments allows them to function as hotspots for resistance through the selection of ARB and circulation of ARG through stimulation of horizontal gene transfer between members of the microbiome.

The aims of this Special Issue are to present current trends in antimicrobial/antibiotic resistance in diverse environmental waters, ranging from the detection and occurrence of antimicrobial factors (e.g. antimicrobials, antibiotics, ARB, ARG) to their fate and transformations in different environments such as surface waters, groundwaters, biofilms and water and wastewater treatment processes. Such knowledge would be needed to assist in the management and control of antimicrobial/antibiotic resistance and ultimately, the protection of public health.

Prof. Dr. Karina Yew-Hoong Gin
Guest Editor

Manuscript Submission Information

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Keywords

  • Antimicrobial resistance

  • Antibiotic resistance

  • Antibiotics

  • Antimicrobials

  • Antibiotic resistant bacteria

  • Antibiotic resistant genes

  • Resistome

Published Papers (12 papers)

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Editorial

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Open AccessEditorial
Monitoring Antimicrobial Resistance Dissemination in Aquatic Systems
Water 2019, 11(1), 71; https://doi.org/10.3390/w11010071
Received: 13 December 2018 / Revised: 28 December 2018 / Accepted: 28 December 2018 / Published: 3 January 2019
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Abstract
This special issue on Antimicrobial Resistance in Environmental Waters features 11 articles on monitoring and surveillance of antimicrobial resistance (AMR) in natural aquatic systems (reservoirs, rivers), and effluent discharge from water treatment plants to assess the effectiveness of AMR removal and resulting loads [...] Read more.
This special issue on Antimicrobial Resistance in Environmental Waters features 11 articles on monitoring and surveillance of antimicrobial resistance (AMR) in natural aquatic systems (reservoirs, rivers), and effluent discharge from water treatment plants to assess the effectiveness of AMR removal and resulting loads in treated waters. The occurrence and distribution of antimicrobials, antibiotic resistant bacteria (ARB), antibiotic resistance genes (ARGs) and mobile genetic elements (MGEs) was determined by utilizing a variety of techniques including liquid chromatography—mass spectrometry in tandem (LC-MS/MS), traditional culturing, antibiotic susceptibility testing (AST), molecular and OMIC approaches. Some of the key elements of AMR studies presented in this special issue highlight the underlying drivers of AMR contamination in the environment and evaluation of the hazard imposed on aquatic organisms in receiving environments through ecological risk assessments. As described in this issue, screening antimicrobial peptide (AMP) libraries for biofilm disruption and antimicrobial candidates are promising avenues for the development of new treatment options to eradicate resistance. This editorial puts into perspective the current AMR problem in the environment and potential new methods which could be applied to surveillance and monitoring efforts. Full article

Research

Jump to: Editorial

Open AccessArticle
Microbial Community Composition and Antibiotic Resistance Genes within a North Carolina Urban Water System
Water 2018, 10(11), 1539; https://doi.org/10.3390/w10111539
Received: 13 September 2018 / Revised: 7 October 2018 / Accepted: 24 October 2018 / Published: 29 October 2018
Cited by 1 | PDF Full-text (17434 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Wastewater treatment plants (WWTPs) are thought to be potential incubators of antibiotic resistance. Persistence of commonly used antibiotics in wastewater may increase the potential for selection of resistance genes transferred between bacterial populations, some of which might pose a threat to human health. [...] Read more.
Wastewater treatment plants (WWTPs) are thought to be potential incubators of antibiotic resistance. Persistence of commonly used antibiotics in wastewater may increase the potential for selection of resistance genes transferred between bacterial populations, some of which might pose a threat to human health. In this study, we measured the concentrations of ten antibiotics in wastewater plant influents and effluents, and in surface waters up- and downstream from two Charlotte area treatment facilities. We performed Illumina shotgun sequencing to assay the microbial community and resistome compositions at each site across four time points from late winter to mid-summer of 2016. Antibiotics are present throughout wastewater treatment, and elevated concentrations of multiple antibiotics are maintained in moving stream water downstream of effluent release. While some human gut and activated sludge associated taxa are detectable downstream, these seem to attenuate with distance while the core microbial community of the stream remains fairly consistent. We observe the slight suppression of functional pathways in the downstream microbial communities, including amino acid, carbohydrate, and nucleic acid metabolism, as well as nucleotide and amino acid scavenging. Nearly all antibiotic resistance genes (ARGs) and potentially pathogenic taxa are removed in the treatment process, though a few ARG markers are elevated downstream of effluent release. Taken together, these results represent baseline measurements that future studies can utilize to help to determine which factors control the movement of antibiotics and resistance genes through aquatic urban ecosystems before, during, and after wastewater treatment. Full article
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Open AccessArticle
Distribution and Genotyping of Aquatic Acinetobacter baumannii Strains Isolated from the Puzi River and Its Tributaries Near Areas of Livestock Farming
Water 2018, 10(10), 1374; https://doi.org/10.3390/w10101374
Received: 1 July 2018 / Revised: 10 August 2018 / Accepted: 28 September 2018 / Published: 1 October 2018
Cited by 1 | PDF Full-text (1938 KB) | HTML Full-text | XML Full-text
Abstract
Acinetobacter baumannii is an important health care-associated bacterium and a common multidrug-resistant pathogen. The use of antibiotics in the husbandry industry has raised concerns about drug-resistant A. baumannii strains, which may affect humans. This study aimed to investigate the seasonal distribution of A. [...] Read more.
Acinetobacter baumannii is an important health care-associated bacterium and a common multidrug-resistant pathogen. The use of antibiotics in the husbandry industry has raised concerns about drug-resistant A. baumannii strains, which may affect humans. This study aimed to investigate the seasonal distribution of A. baumannii in aquatic environments near areas of livestock farming. The geographic distribution, antibiotic resistance characteristic, and DNA fingerprinting genotype of A. baumannii were also studied. The results showed that environmental A. baumannii was prevalent during the summer and autumn. The hotspots for A. baumannii were found at the sampling sites of livestock wastewater channels (21.4%; 3/14) and the tributaries adjacent to livestock farms (15.4%; 2/13). The prevalence of A. baumannii at these locations was significantly higher than those adjacent to the Puzi River. Multidrug-resistant strain of A. baumannii was not found in this study, with only one strain (5%; 1/20) being resistant to tetracycline. Of the isolates that were obtained, 10% (2/20) and 20% (4/20) were found to be intermediately resistant to tetracycline and sulphamethoxazole/trimethoprim, respectively. The genotyping patterns and clustering analysis indicated that enterobacterial repetitive intergenic consensus sequence polymerase chain reaction (ERIC-PCR) differentiated A. baumannii strains effectively. There were two major clusters that could then be subtyped into 20 A. baumannii strains with 15 profiles. The A. baumannii strains that were isolated from upstream of the Puzi River and livestock wastewater channels were composed of Cluster I. Cluster II only contained isolates from downstream of the Puzi River area. Furthermore, isolates from adjacent sites were shown to have identical profiles (100%). These results suggest that A. baumannii may have spread through free-flowing water in this study. Therefore, we propose that livestock wastewater is one of the sources that contribute to A. baumannii pollution in water bodies. In summary, continuous monitoring of antibiotic pollution in livestock wastewater is required. Full article
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Open AccessArticle
Presence of Antibiotic-Resistant Escherichia coli in Wastewater Treatment Plant Effluents Utilized as Water Reuse for Irrigation
Water 2018, 10(6), 805; https://doi.org/10.3390/w10060805
Received: 20 May 2018 / Revised: 8 June 2018 / Accepted: 15 June 2018 / Published: 18 June 2018
Cited by 4 | PDF Full-text (1162 KB) | HTML Full-text | XML Full-text
Abstract
Providing safe water through water reuse is becoming a global necessity. One concern with water reuse is the introduction of unregulated contaminants to the environment that cannot be easily removed by conventional wastewater treatment plants (WWTP). The occurrence of ampicillin, sulfamethoxazole, ciprofloxacin, and [...] Read more.
Providing safe water through water reuse is becoming a global necessity. One concern with water reuse is the introduction of unregulated contaminants to the environment that cannot be easily removed by conventional wastewater treatment plants (WWTP). The occurrence of ampicillin, sulfamethoxazole, ciprofloxacin, and tetracycline-resistant Escherichia coli through the treatment stages of a WWTP (raw sewage, post-secondary, post-UV and post-chlorination) was investigated from January to May 2016. The highest concentrations of antibiotic resistant E. coli in the effluent were detected in April after rainfall. Ampicillin-resistant E. coli was the most common at the post UV and chlorination stages comprising 63% of the total E. coli population. The minimum inhibitory concentration (MIC) analysis showed that one in five isolates was resistant to three or more antibiotics, and the majority of these E. coli were resistant to ampicillin, followed by sulfamethoxazole and ciprofloxacin. The highest MIC was detected at the finished water after application of multiple disinfection methods. Tetracycline resistance was the least observed among others, indicating that certain drug families may respond to wastewater treatment differently. Currently, there are no policies to enforce the monitoring of antibiotic-resistant pathogen removal in WWTP. Better guidelines are needed to better regulate reuse water and prevent health risk upon exposure to antibiotic-resistant bacteria. Full article
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Open AccessArticle
Antibiotic Resistance and Extended-Spectrum Beta-Lactamase Production of Escherichia coli Isolated from Irrigation Waters in Selected Urban Farms in Metro Manila, Philippines
Water 2018, 10(5), 548; https://doi.org/10.3390/w10050548
Received: 31 January 2018 / Revised: 19 April 2018 / Accepted: 20 April 2018 / Published: 25 April 2018
Cited by 4 | PDF Full-text (5680 KB) | HTML Full-text | XML Full-text
Abstract
Highly-polluted surface waters are increasingly used for irrigation in different agricultural settings because they have high nutrient content and are readily available. However, studies showed that they are reservoirs for the emergence and dissemination of antibiotic-resistant bacteria in the environment. In this study, [...] Read more.
Highly-polluted surface waters are increasingly used for irrigation in different agricultural settings because they have high nutrient content and are readily available. However, studies showed that they are reservoirs for the emergence and dissemination of antibiotic-resistant bacteria in the environment. In this study, the resistance of 212 Escherichia coli isolates from irrigation water, soil, and vegetables in selected urban farms in Metro Manila, Philippines was evaluated. Results showed that antibiotic resistance was more prevalent in water (67.3%) compared to soil (56.4%) and vegetable (61.5%) isolates. Resistance to tetracycline was the highest among water (45.6%) and vegetable (42.3%) isolates while ampicillin resistance was the highest among soil isolates (33.3%). Multidrug-resistant (MDR) isolates were also observed and they were more prevalent in water (25.3%) compared to soil (2.8%) and vegetable (8.4%) isolates. Interestingly, there are patterns of antibiotic resistance that were common to isolates from different samples. Extended-spectrum beta-lactamase production (ESBL) was also investigated and genes were observed to be present in 13 isolates. This provides circumstantial evidence that highly-polluted surface waters harbor antibiotic-resistant and MDR E. coli that may be potentially transferred to primary production environments during their application for irrigation purposes. Full article
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Open AccessArticle
An Increase of Abundance and Transcriptional Activity for Acinetobacter junii Post Wastewater Treatment
Water 2018, 10(4), 436; https://doi.org/10.3390/w10040436
Received: 29 January 2018 / Revised: 23 March 2018 / Accepted: 28 March 2018 / Published: 6 April 2018
Cited by 3 | PDF Full-text (27690 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
A membrane bioreactor (MBR)-based wastewater treatment plant (WWTP) in Saudi Arabia is assessed over a five-month period in 2015 and once in 2017 for bacterial diversity and transcriptional activity using metagenomics, metatranscriptomics and real time quantitative polymerase chain reaction (RT-qPCR). Acinetobacter spp. are [...] Read more.
A membrane bioreactor (MBR)-based wastewater treatment plant (WWTP) in Saudi Arabia is assessed over a five-month period in 2015 and once in 2017 for bacterial diversity and transcriptional activity using metagenomics, metatranscriptomics and real time quantitative polymerase chain reaction (RT-qPCR). Acinetobacter spp. are shown to be enriched in the chlorinated effluent. Members of the Acinetobacter genus are the most abundant in the effluent and chlorinated effluent. At the species level, Acinetobacter junii have higher relative abundances post MBR and chlorination. RNA-seq analysis show that, in A. junii, 288 genes and 378 genes are significantly upregulated in the effluent and chlorinated effluent, respectively, with 98 genes being upregulated in both. RT-qPCR of samples in 2015 and 2017 confirm the upregulation observed in RNA-seq. Analysis of the 98 genes show that majority of the upregulated genes are involved in cellular repair and metabolism followed by resistance, virulence, and signaling. Additionally, two different subpopulations of A. junii are observed in the effluent and chlorinated effluent. The upregulation of cellular repair and metabolism genes, and the formation of different subpopulations of A. junii in both effluents provide insights into the mechanisms employed by A. junii to persist in the conditions of a WWTP. Full article
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Open AccessArticle
Distribution and Abundance of Antibiotic Resistance Genes in Sand Settling Reservoirs and Drinking Water Treatment Plants across the Yellow River, China
Water 2018, 10(3), 246; https://doi.org/10.3390/w10030246
Received: 17 January 2018 / Revised: 22 February 2018 / Accepted: 23 February 2018 / Published: 28 February 2018
Cited by 5 | PDF Full-text (2645 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Understanding how antibiotic resistance genes (ARGs) are distributed in drinking water treatment processes is important due to their potential public health risk. Little is known about the occurrence and distribution of ARGs in typical drinking water treatment processes, such as sand settling reservoirs [...] Read more.
Understanding how antibiotic resistance genes (ARGs) are distributed in drinking water treatment processes is important due to their potential public health risk. Little is known about the occurrence and distribution of ARGs in typical drinking water treatment processes, such as sand settling reservoirs (SSRs) and drinking water treatment plants (DWTPs), in the Yellow River, especially at the catchment scale. In this study, ARG profiling was investigated from water samples of influent (river water) and effluent (source water) of SSRs and finished water of DWTPs in six cities along the Yellow River catchment using real-time quantitative polymerase chain reaction (qPCR) and 16S rRNA gene sequencing. Seventeen ARGs and two mobile genetic elements (MGEs) were detected, among which aadE, strA, strB, tetA, sulII, intl1, and Tn916 had high detection rates (over 80%). The absolute abundances (gene copies/mL of water) of ARGs were reduced by the SSRs and DWTPs generally, but no reductions were observed for the relative abundances (gene copies/16S rRNA gene) of ARGs. Spatial distributions of ARGs and bacteria were not observed. The distribution of bacterial genera was clustered into four dominant patterns in different water type samples. The bacterial genera Pseudomonas, Massilia, Acinetobacter, Sphingomonas, Methylobacterium, and Brevundimonas dominated the finished water, with Brevundimonas and Methylobacterium being speculated to be potential hosts for two ARGs (strA and strB) through network analysis. The enrichment of these two genera, likely caused by selection of disinfection process, may contribute to the higher relative abundance of ARGs in finished water. This study provides insight and effective assessment of the potential risk of ARGs in drinking water treatment processes at the catchment scale. Full article
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Open AccessArticle
The Effects of Antibiotics on Microbial Community Composition in an Estuary Reservoir during Spring and Summer Seasons
Water 2018, 10(2), 154; https://doi.org/10.3390/w10020154
Received: 23 November 2017 / Revised: 24 December 2017 / Accepted: 17 January 2018 / Published: 6 February 2018
Cited by 2 | PDF Full-text (4085 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
The increased antibiotic pollutants in aquatic environments pose severe threats on microbial ecology due to their extensive distribution and antibacterial properties. A total of 16 antibiotics including fluoroquinolones (FQs) (ofloxacin (OFX), ciprofloxacin (CFX), norfloxacin (NFX)), Sulfonamides (SAs) (sulfamonomethoxine (SMM), sulfadiazine (SDZ), sulfaquinoxaline (SQX)), [...] Read more.
The increased antibiotic pollutants in aquatic environments pose severe threats on microbial ecology due to their extensive distribution and antibacterial properties. A total of 16 antibiotics including fluoroquinolones (FQs) (ofloxacin (OFX), ciprofloxacin (CFX), norfloxacin (NFX)), Sulfonamides (SAs) (sulfamonomethoxine (SMM), sulfadiazine (SDZ), sulfaquinoxaline (SQX)), Tetracyclines (TCs) (tetracycline (TC), doxycycline (DC)), β-lactams (penicillin G (PEN G), penicillin V (PEN V), cefalexin (LEX)), Macrolides (MLs) (erythromycin-H2O (ETM), tylosin (TYL)) and other antibiotics (Polymix-B (POL), Vancomycin (VAN), Lincomycin (LIN)) were detected in the surface water of the Qingcaosha Reservoir. Multivariate statistical analysis indicated that both water quality and physicochemical indexes have less contributions on variations of these antibiotics, suggesting the concentrations of antibiotics inside the reservoir are mainly affected by upstream runoff and anthropic activity along the river. Antibiotics including TYL, PEN G and ETM showed significant correlations with variations of bacterial community composition, and closely connected with various gram-negative bacteria in co-occurrence/exclusion patterns of the network, suggesting these bacterial taxa play important roles in the course of migration and transformation of related antibiotics. In conclusion, further research is required to evaluate the potential risk of genetic transfer of resistance to related bacteria induced by long-term exposure to low levels of antibiotics in the environment. Full article
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Open AccessArticle
Occurrence, Seasonal Variation and Risk Assessment of Antibiotics in Qingcaosha Reservoir
Water 2018, 10(2), 115; https://doi.org/10.3390/w10020115
Received: 28 November 2017 / Revised: 6 January 2018 / Accepted: 19 January 2018 / Published: 29 January 2018
Cited by 4 | PDF Full-text (17676 KB) | HTML Full-text | XML Full-text
Abstract
Qingcaosha Reservoir is an important drinking water source in Shanghai. The occurrence of five groups of antibiotics was investigated in the surface water of this reservoir over a one-year period. Seventeen antibiotics were selected in this study based on their significant usage in [...] Read more.
Qingcaosha Reservoir is an important drinking water source in Shanghai. The occurrence of five groups of antibiotics was investigated in the surface water of this reservoir over a one-year period. Seventeen antibiotics were selected in this study based on their significant usage in China. Of these antibiotics, 16 were detected, while oxytetracycline was not detected in any sampling site. The detected frequency of tylosin was only 47.92% while the other 15 antibiotics were above 81.25%. The dominant antibiotic was different in four seasons: norfloxacin was dominant in spring, and penicillinV was dominant in summer, autumn and winter, with medium concentrations of 124.10 ng/L, 89.91 ng/L, 180.28 ng/L, and 216.43 ng/L, respectively. The concentrations and detection frequencies of antibiotics were notably higher in winter than in other seasons, demonstrating that low temperature and low flow may result in the persistence of antibiotics in the aquatic environment. Risk assessment suggested that norfloxacin, ciprofloxacin, penicillinV, and doxycycline in the surface water presented high ecological risks. Full article
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Open AccessArticle
Occurrence, Distribution, and Risk Assessment of Antibiotics in a Subtropical River-Reservoir System
Water 2018, 10(2), 104; https://doi.org/10.3390/w10020104
Received: 25 November 2017 / Revised: 9 January 2018 / Accepted: 23 January 2018 / Published: 26 January 2018
Cited by 5 | PDF Full-text (2277 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Antibiotic pollutions in the aquatic environment have attracted widespread attention due to their ubiquitous distribution and antibacterial properties. The occurrence, distribution, and ecological risk assessment of 17 common antibiotics in this study were preformed in a vital drinking water source represented as a [...] Read more.
Antibiotic pollutions in the aquatic environment have attracted widespread attention due to their ubiquitous distribution and antibacterial properties. The occurrence, distribution, and ecological risk assessment of 17 common antibiotics in this study were preformed in a vital drinking water source represented as a river-reservoir system in South China. In general, 15 antibiotics were detected at least once in the watershed, with the total concentrations of antibiotics in the water samples ranging from 193.6 to 863.3 ng/L and 115.1 to 278.2 μg/kg in the sediment samples. For the water samples, higher rain runoff may contribute to the levels of total concentration in the river system, while perennial anthropic activity associated with the usage pattern of antibiotics may be an important factor determining similar sources and release mechanisms of antibiotics in the riparian environment. Meanwhile, the reservoir system could act as a stable reactor to influence the level and composition of antibiotics exported from the river system. For the sediment samples, hydrological factor in the reservoir may influence the antibiotic distributions along with seasonal variation. Ecological risk assessment revealed that tetracycline and ciprofloxacin could pose high risks in the aquatic environment. Taken together, further investigations should be performed to elaborate the environmental behaviors of antibiotics in the river-reservoir system, especially in drinking water sources. Full article
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Open AccessArticle
The Effect of Primary, Secondary, and Tertiary Wastewater Treatment Processes on Antibiotic Resistance Gene (ARG) Concentrations in Solid and Dissolved Wastewater Fractions
Water 2018, 10(1), 37; https://doi.org/10.3390/w10010037
Received: 20 November 2017 / Revised: 20 December 2017 / Accepted: 27 December 2017 / Published: 4 January 2018
Cited by 10 | PDF Full-text (704 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Wastewater treatment plants (WWTPs) have been identified as potential sources of antibiotic resistance genes (ARGs) but the effects of tertiary wastewater treatment processes on ARGs have not been well characterized. Therefore, the objective of this study was to determine the fate of ARGs [...] Read more.
Wastewater treatment plants (WWTPs) have been identified as potential sources of antibiotic resistance genes (ARGs) but the effects of tertiary wastewater treatment processes on ARGs have not been well characterized. Therefore, the objective of this study was to determine the fate of ARGs throughout a tertiary-stage WWTP. Two ARGs, sul1 and bla, were quantified via quantitative polymerase chain reaction (qPCR) in solids and dissolved fractions of raw sewage, activated sludge, secondary effluent and tertiary effluent from a full-scale WWTP. Tertiary media filtration and chlorine disinfection were studied further with the use of a pilot-scale media filter. Results showed that both genes were reduced at each successive stage of treatment in the dissolved fraction. The solids-associated ARGs increased during activated sludge stage and were reduced in each subsequent stage. Overall reductions were approximately four log10 with the tertiary media filtration and disinfection providing the largest decrease. The majority of ARGs were solids-associated except for in the tertiary effluent. There was no evidence for positive selection of ARGs during treatment. The removal of ARGs by chlorine was improved by filtration compared to unfiltered, chlorinated secondary effluent. This study demonstrates that tertiary-stage WWTPs with disinfection can provide superior removal of ARGs compared to secondary treatment alone. Full article
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Open AccessArticle
Pseudomonas aeruginosa Psl Exopolysaccharide Interacts with the Antimicrobial Peptide LG21
Water 2017, 9(9), 681; https://doi.org/10.3390/w9090681
Received: 9 June 2017 / Revised: 30 August 2017 / Accepted: 4 September 2017 / Published: 16 September 2017
Cited by 1 | PDF Full-text (3849 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Biofilm formation by opportunistic pathogens serves as one of the major causes of chronic and persistent infections. Bacterial cells in the biofilms are embedded in their self-generated protective extracellular polymeric substances (EPS), which include exopolysaccharides, large adhesin proteins and extracellular DNA. In this [...] Read more.
Biofilm formation by opportunistic pathogens serves as one of the major causes of chronic and persistent infections. Bacterial cells in the biofilms are embedded in their self-generated protective extracellular polymeric substances (EPS), which include exopolysaccharides, large adhesin proteins and extracellular DNA. In this study, we identified an antimicrobial peptide (AMP) LG21 that is able to interact specifically with the Psl exopolysaccharide of Pseudomonas aeruginosa, thus it can be used as a diagnostic tool for P. aeruginosa biofilms. Molecular dynamics simulation analysis showed that residues numbered from 15 to 21 (WKRKRFG) in LG21 are involved in interacting with Psl. Our study indicates that host immune systems might detect and interact with microbial biofilms through AMPs. Engineering biofilm EPS-targeting AMPs might provide novel strategies for biofilm detection and treatment. Full article
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