Removal efficiency of antibiotic residues, antibiotic resistant bacteria, and genes across parallel secondary settling tank and membrane bioreactor treatment trains in a water reclamation plant.

Antimicrobial resistance is recognized as a potent threat to human health. Wastewater treatment facilities are viewed as hotspots for the spread of antimicrobial resistance. This study provides comprehensive data on the occurrences of 3 different antibiotic resistant opportunistic pathogens (with resistance to up to 5 antibiotics), 13 antibiotic resistant genes and intI1, and 22 different antimicrobial residues in a large water reclamation plant (176 million gallons per day) that runs a conventional Modified Ludzack-Ettinger (MLE) reactor followed by a secondary settling tank (SST) and membrane bioreactor (MBR) in parallel.

A new modelling framework for assessing the relative burden of antimicrobial resistance in aquatic environments.

The infections caused by antibiotic resistant bacteria (ARB) can lead to higher medical costs, prolonged hospital stays, and increased mortality compared to bacteria that are susceptible to antibiotics. Challenges exist in quantifying the potential risk/burden associated with antimicrobial resistance (AMR) as there is a lack of dose-response models available for pathogens which are resistant to antibiotics, in addition to the fact that very little is known regarding the health risks posed by antibiotic resistant genes (ARG). In this paper, we proposed a new modelling framework to evaluate the relative burden of AMR in natural aquatic environments.

[Antibiotics Induce Horizontal Gene Transfer of Resistance at Sublethal Concentrations].

In order to explore the conjugation of genes encoding extended-spectrum -lactamase (ESBL), ESBL-expressing and strains isolated from the wastewater of major hospitals in Singapore were used as donors. gfp-tagged SCC1 strains resistant to chloramphenicol (CHL) were chosen as recipients. Using response surface analysis, we detected and analyzed the induction of conjugal transfer under single-exposure and co-exposure of tetracycline (TC), sulfamethoxazole (SMZ), and ceftazidime (CAZ) at sublethal concentrations.

Draft Genome Sequences of a Ceftazidime-Resistant Acinetobacter baumannii Donor and a Conjugal Escherichia coli Recipient with Acquired Resistance.

A ceftazidime-resistant strain was isolated from hospital wastewater and used as the donor in a filter mating experiment with an strain as the recipient. Recipient, donor, and transconjugant were sequenced, and both donor and transconjugant were found to harbor highly similar plasmid sequences, suggesting that plasmid transfer had occurred.

Metagenomic and Resistome Analysis of a Full-Scale Municipal Wastewater Treatment Plant in Singapore Containing Membrane Bioreactors.

Reclaimed water provides a water supply alternative to address problems of scarcity in urbanized cities with high living densities and limited natural water resources. In this study, wastewater metagenomes from 6 stages of a wastewater treatment plant (WWTP) integrating conventional and membrane bioreactor (MBR) treatment were evaluated for diversity of antibiotic resistance genes (ARGs) and bacteria, and relative abundance of class 1 integron integrases (). ARGs confering resistance to 12 classes of antibiotics (ARG types) persisted through the treatment stages, which included genes that confer resistance to aminoglycoside '''″, beta-lactams [class A, class C, class D beta-lactamases ( )], chloramphenicol (acetyltransferase, exporters, ), fosmidomycin (), macrolide-lincosamide-streptogramin (), multidrug resistance (subunits of transporters), polymyxin (), quinolone (), rifamycin (), sulfonamide (), and tetracycline ().

Draft Genome Sequences of Four Multidrug-Resistant Pseudomonas aeruginosa Isolates from Hospital Wastewater in Singapore.

Four multidrug-resistant Pseudomonas aeruginosa isolates were cultured from intensive care unit wastewater. All isolates exhibited resistance to carbapenem and extended-spectrum beta-lactam antibiotics. Genome characterization revealed the presence of beta-lactamase resistance genes ( and ), and three out of the four isolates carried the gene encoding resistance against carbapenems.

Microbial water quality and the detection of multidrug resistant E. coli and antibiotic resistance genes in aquaculture sites of Singapore.

Poor microbial water quality jeopardizes the health and safety of food produced by aquaculture farms. Three fish farms and transect sites in Singapore were assessed for microbial water quality and antimicrobial resistance determinants. Of the 33 multidrug resistant E.

Occurrence and characteristics of extended-spectrum β-lactamase- and carbapenemase- producing bacteria from hospital effluents in Singapore.

One of the most important resistance mechanisms in Gram-negative bacteria today is the production of enzymes causing resistance to cephalosporin and carbapenem antibiotics. The spread of extended-spectrum β-lactamases (ESBL)- and carbapenemase- producing Gram-negative bacteria is an emerging global public health problem. The aim of the present study was to (i) assess the prevalence of carbapenem-resistant bacteria (CRB) and ESBL-producing strains in sewage effluents from two major hospitals in Singapore, (ii) characterize the isolated strains and (iii) identify some of the ESBL and carbapenemase genes responsible for the resistance.

Corrigendum: Characterization of Metagenomes in Urban Aquatic Compartments Reveals High Prevalence of Clinically Relevant Antibiotic Resistance Genes in Wastewaters.

[This corrects the article on p. 2200 in vol. 8, PMID: 29201017.

Characterization of Metagenomes in Urban Aquatic Compartments Reveals High Prevalence of Clinically Relevant Antibiotic Resistance Genes in Wastewaters.

The dissemination of antimicrobial resistance (AMR) is an escalating problem and a threat to public health. Comparative metagenomics was used to investigate the occurrence of antibiotic resistant genes (ARGs) in wastewater and urban surface water environments in Singapore. Hospital and municipal wastewater ( = 6) were found to have higher diversity and average abundance of ARGs (303 ARG subtypes, 197,816 x/Gb) compared to treated wastewater effluent ( = 2, 58 ARG subtypes, 2,692 x/Gb) and surface water ( = 5, 35 subtypes, 7,985 x/Gb).

Composition of bacterial and archaeal communities in freshwater sediments with different contamination levels (Lake Geneva, Switzerland).

The aim of this study was to compare the composition of bacterial and archaeal communities in contaminated sediments (Vidy Bay) with uncontaminated sediments (Ouchy area) of Lake Geneva using 16S rRNA clone libraries. Sediments of both sites were analysed for physicochemical characteristics including porewater composition, organic carbon, and heavy metals. Results show high concentrations of contaminants in sediments from Vidy.

Persistence and growth of faecal culturable bacterial indicators in water column and sediments of Vidy Bay, Lake Geneva, Switzerland.

The aims of this study was to investigate the persistence and the growth of culturable bacterial indicators (CBI) including total coliforms (TC) and faecal coliforms represented by Escherichia coli, enterococcus (ENT), and aerobic mesophilic bacteria (AMB) in the surface sediments and the water column of Vidy Bay (Lake Geneva, City of Lausanne, Switzerland). The study was carried out for 60 d using microcosms containing Sewage Treatment Plant (STP) effluent and nonsterile water without CBI, as well as contaminated and non-contaminated sediments. The effects of water temperature and of organic matter associated with sediments on the survival of CBI in the sediments and the water column were observed.

Origin and spatial-temporal distribution of faecal bacteria in a bay of Lake Geneva, Switzerland.

The origin and distribution of microbial contamination in Lake Geneva's most polluted bay were assessed using faecal indicator bacteria (FIB). The lake is used as drinking water, for recreation and fishing. During 1 year, water samples were taken at 23 points in the bay and three contamination sources: a wastewater treatment plant (WWTP), a river and a storm water outlet.

Effects of a sewage treatment plant outlet pipe extension on the distribution of contaminants in the sediments of the Bay of Vidy, Lake Geneva, Switzerland.

In 2001, the municipality of Lausanne extended the outlet pipe of the sewage treatment plant into the Bay of Vidy (Lake Geneva, Switzerland) as a measure to reduce bacterial water pollution and sediment contamination close to the lake beaches. The aim of the present study was to assess the impact of this measure. Lake bottom sediments were collected and analyzed for grain size, organic matter, organic carbon, nitrogen, phosphorus, heavy metals and hydrophobic organic compounds to evaluate their concentration and spatial distribution.

Cost-effectiveness of water quality interventions for preventing diarrhoeal disease in developing countries.

Using effectiveness data from a recent systematic review and cost data from programme implementers and World Health Organization (WHO) databases, we conducted a cost-effectiveness analysis to compare non-piped in source- (dug well, borehole and communal stand post) and four types of household- (chlorination, filtration, solar disinfection, flocculation/disinfection) based interventions to improve the microbial quality of water for preventing diarrhoeal disease. Results are reported for two WHO epidemiological sub-regions, Afr-E (sub-Saharan African countries with very high adult and child mortality) and Sear-D (South East Asian countries with high adult and child mortality) at 50% intervention coverage. Measured against international benchmarks, source- and household-based interventions were generally cost effective or highly cost effective even before the estimated saving in health costs that would offset the cost of implementation.

Global cost-benefit analysis of water supply and sanitation interventions.

The aim of this study was to estimate the economic benefits and costs of a range of interventions to improve access to water supply and sanitation facilities in the developing world. Results are presented for eleven developing country WHO sub-regions as well as at the global level, in United States Dollars (US$) for the year 2000. Five different types of water supply and sanitation improvement were modelled: achieving the water millennium development goal of reducing by half in 2015 those without improved water supply in the year 1990; achieving the combined water supply and sanitation MDG; universal basic access to water supply and sanitation; universal basic access plus water purification at the point-of-use; and regulated piped water supply and sewer connection.

Estimating the costs and health benefits of water and sanitation improvements at global level.

The aim of this study was to estimate the costs and the health benefits of the following interventions: increasing access to improved water supply and sanitation facilities, increasing access to in house piped water and sewerage connection, and providing household water treatment, in ten WHO sub-regions. The cost-effectiveness of each intervention was assessed in terms of US dollars per disability adjusted life year (DALY) averted. This analysis found that almost all interventions were cost-effective, especially in developing countries with high mortality rates.

Characterizing water circulation and contaminant transport in Lake Geneva using bacteriophage tracer experiments and limnological methods.

Multi-tracer tests with three types of marine bacteriophages (H4/4, H6/1, and H40/1), together with various limnological methods, including physicochemical depth profiling, surface drifters, deep current measurements, and fecal indicator bacteria analyses, have been applied to characterize water circulation and pathogen transport in the Bay of Vidy (Lake Geneva, Switzerland). The experimental program was carried out twice, first in November 2005, when the lake was stratified, and a second time during holomixis in February 2006. The bacteriophages were injected at three points at different depths, where contaminated waters enter the lake, including the outlet pipe of a wastewater treatment plant, a river, and a stormwater outlet.

Water, sanitation, and hygiene interventions to reduce diarrhoea in less developed countries: a systematic review and meta-analysis.

Many studies have reported the results of interventions to reduce illness through improvements in drinking water, sanitation facilities, and hygiene practices in less developed countries. There has, however, been no formal systematic review and meta-analysis comparing the evidence of the relative effectiveness of these interventions. We developed a comprehensive search strategy designed to identify all peer-reviewed articles, in any language, that presented water, sanitation, or hygiene interventions.