Enumeration and characterization of antimicrobial-resistant Escherichia coli bacteria in effluent from municipal, hospital, and secondary treatment facility sources

Impact of effluent parameters and vancomycin concentration on vancomycin resistant Escherichia coli and its host specific bacteriophage lytic activity in hospital effluent

Vancomycin resistance in bacteria has been classified under high priority category by World Health Organization (WHO) and its presence in hospital effluent is reported to be increasing owing to excess antibiotics use. Among various strategies, bacteriophage has been recently considered as a promising biological agent for combating such antimicrobial resistant bacteria (ARB). However, the influence of effluent's properties on phage-ARB interaction in actual hospital effluent is not completely understood. The present works intends to study this influence of hospital effluent and its parameters on the interaction between vancomycin resistant E. coli (VRE) and its host specific bacteriophage. The isolated VRE was identified by 16S rRNA sequencing, matrix-assisted laser desorption/ionization-time of flight (MALDI - TOF) and whole genome sequencing. The infectivity of phage onto host bacteria was investigated using electron microscopic techniques, dynamic light scattering (DLS), spectrofluorophotometer and confirmed using double agar overlay method. The monovalency and polyvalency of isolated phage against various bacterial species were determined. The phage morphology was identical to T7 phage belonging to Podoviridae. The phage lysis was maximum at pH 7 (90.2%), 37 °C (91.6%) and vancomycin concentration of 50 μg/mL in both synthetic media (89.13%) and effluent (100%). At a maximum vancomycin concentration of 100 μg/mL, decrease in Ca, K, Mg and P (up to 19.70, 14.18, 28, and 15.82% respectively) concentration in effluent was observed due to phage infectivity when compared to control. The whole genome sequencing was performed and the bioinformatics analysis presented the role of mdfA gene encoding the efflux pump in causing vancomycin resistance in E. coli. It also depicted the presence of multiple genes responsible for mercury, cobalt, zinc and cadmium resistance in VRE. These results clearly indicate that bacteriophage mediated combating of VRE is possible in actual hospital effluent and can be used as one of the treatment methods.

Simultaneous stream assessment of antibiotics, bacteria, antibiotic resistant bacteria, and antibiotic resistance genes in an agricultural region of the United States

Antimicrobial resistance (AMR) is now recognized as a leading global threat to human health. Nevertheless, there currently is a limited understanding of the environment's role in the spread of AMR and antibiotic resistance genes (ARGs). In 2019, the U.S. Geological Survey conducted the first statewide assessment of antibiotic resistant bacteria (ARB) and ARGs in surface water and bed sediment collected from 34 stream locations across Iowa. Environmental samples were analyzed for a suite of 29 antibiotics and plated on selective media for 15 types of bacteria growth; DNA was extracted from culture growth and used in downstream polymerase chain reaction (PCR) assays for the detection of 24 ARGs. ARGs encoding resistance to antibiotics of clinical importance to human health and disease prevention were prioritized as their presence in stream systems has the potential for environmental significance. Total coliforms, Escherichia coli (E. coli), and staphylococci were nearly ubiquitous in both stream water and stream bed sediment samples, with enterococci present in 97 % of water samples, and Salmonella spp. growth present in 94 % and 67 % of water and bed sediment samples. Bacteria enumerations indicate that high bacteria loads are common in Iowa's streams, with 23 (68 %) streams exceeding state guidelines for primary contact for E. coli in recreational waters and 6 (18 %) streams exceeding the secondary contact advisory level. Although antibiotic-resistant E. coli growth was detected from 40 % of water samples, vancomycin-resistant enterococci (VRE) and penicillinase-resistant Staphylococcus aureus (MRSA) colony growth was detected from nearly all water samples. A total of 14 different ARGs were detected from viable bacteria cells from 30 Iowa streams (88 %, n = 34). Study results provide the first baseline understanding of the prevalence of ARB and ARGs throughout Iowa's waterways and health risk potential for humans, wildlife, and livestock using these waterways for drinking, irrigating, or recreating.

Wastewater from healthcare centers in Burkina Faso is a source of ESBL, AmpC-β-lactamase and carbapenemase-producing Escherichia coli and Klebsiella pneumoniae

BACKGROUND

Extended-spectrum β-lactamase (ESBL), plasmid-mediated AmpC-β-lactamase and carbapenemase-producing Escherichia coli and Klebsiella pneumoniae have spread into the environment worldwide posing a potential public health threat. However, the prevalence data for low- and middle-income countries are still scarce. The aim of this study was to evaluate the presence of ESBL, AmpC-β-lactamase and carbapenemase-producing and multidrug-resistant E. coli and K. pneumoniae in wastewaters from healthcare centers in Burkina Faso.

RESULTS

Eighty-four (84) wastewater samples were collected from five healthcare centers and plated on selective ESBL ChromAgar. E. coli and Klebsiella pneumoniae isolates were identified using API20E. ESBL-producing bacteria were detected in 97.6% of the samples and their average concentration per hospital ranged from 1.10 × 105 to 5.23 × 106 CFU/mL. Out of 170 putative ESBL-producing isolates (64% of them were E. coli) and 51 putative AmpC-β-lactamase-producing isolates, 95% and 45% were confirmed, respectively. Carbapenemase production was detected in 10 isolates, of which 6 were NDM producers, 3 were OXA-48 producers and 1 was NDM and OXA-48 producer. All isolates were multidrug resistant and, moreover, all of them were resistant to all tested β-lactams. Resistance to ESBL inhibitors was also common, up to 66% in E. coli and 62% in K. pneumoniae. Amikacin, fosfomycin and nitrofurantoin were the antibiotics to which the least resistance was detected.

CONCLUSIONS

This study showed that wastewater from healthcare centers constitutes a reservoir of multidrug-resistant bacteria in Burkina Faso, including carbapenemase producers. Untreated healthcare wastewater entering the environment exposes people and animals to infections caused by these multi-resistant bacteria, which are difficult to treat, especially in the resource-poor settings.

Evaluation of a Tetracycline-Resistant E. coli Enumeration Method for Correctly Classifying E. coli in Environmental Waters in Kentucky, USA

The global concern over antimicrobial resistance (AMR) and its impact on human health is evident, with approximately 4.95 million annual deaths attributed to antibiotic resistance. Regions with inadequate water, sanitation, and hygiene face challenges in responding to AMR threats. Enteric bacteria, particularly E. coli, are common agents linked to AMR-related deaths (23% of cases). Culture-based methods for detecting tetracycline-resistant E. coli may be of practical value for AMR monitoring in limited resource environments. This study evaluated the ColiGlow™ method with tetracycline for classifying tetracycline-resistant E. coli. A total of 61 surface water samples from Kentucky, USA (2020-2022), provided 61 presumed E. coli isolates, of which 28 isolates were obtained from tetracycline-treated media. Species identification and tetracycline resistance evaluation were performed. It was found that 82% of isolates were E. coli, and 18% were other species; 97% were identified as E. coli when using the API20E identification system. The MicroScan system yielded Enterobacter cloacae false positives in 20% of isolates. Adding tetracycline to ColiGlow increased the odds of isolating tetracycline-resistant E. coli 18-fold. Tetracycline-treated samples yielded 100% tetracycline-resistant E. coli when the total E. coli densities were within the enumeration range of the method. ColiGlow with tetracycline shows promise for monitoring tetracycline-resistant E. coli in natural waters and potentially aiding AMR surveillance in resource-limited settings among other environments.

An overview on the prevalence and potential impact of antimicrobials and antimicrobial resistance in the aquatic environment of India

India at present is one of the leading countries in antimicrobial drug production and use, leading to increasing antimicrobial resistance (AMR) and public health problems. Attention has mainly been focused on the human and food animals' contribution to AMR neglecting the potential contribution of the perceptibly degraded aquatic environment in India. The paper reviews the available published literature in India on the prevalence of antimicrobial residues and their dissemination pathways in wastewater of pharmaceutical industries, sewage treatment plants, hospitals, riverine, community pond water, and groundwater. The prevalence of antimicrobial residue concentration, pathogenic and non-pathogenic bacteria antimicrobial resistant bacteria (ARB), their drug resistance levels, and their specific antimicrobial resistant genes (ARGs) occurring in various water matrices of India have been comprehensively depicted from existing literature. The concentration of some widely used antimicrobials recorded from the sewage treatment plants and hospital wastewater and rivers in India has been compared with other countries. The ecotoxicological risk posed by these antimicrobials in the various water matrices in India indicated high hazard quotient (HQ) values for pharmaceutical effluents, hospital effluents, and river water. The degraded aquatic environment exhibited the selection of a wide array of co-existent resistant genes for antibiotics and metals. The review revealed improper use of antibiotics and inadequate wastewater treatment as major drivers of AMR contaminating water bodies in India and suggestion for containing the challenges posed by AMR in India has been proposed.

Microbiome and Resistome Profiles along a Sewage-Effluent-Reservoir Trajectory Underline the Role of Natural Attenuation in Wastewater Stabilization Reservoirs

Antibiotic-resistant bacteria and antibiotic resistance gene (ARGs) loads dissipate through sewage treatment plants to receiving aquatic environments, but the mechanisms that mitigate the spread of these ARGs are not well understood due to the complexity of full-scale systems and the difficulty of source tracking in downstream environments. To overcome this problem, we targeted a controlled experimental system comprising a semicommercial membrane-aerated bioreactor (MABR), whose effluents fed a 4,500-L polypropylene basin that mimicked effluent stabilization reservoirs and receiving aquatic ecosystems. We analyzed a large set of physicochemical measurements, concomitant with the cultivation of total and cefotaxime-resistant Escherichia coli, microbial community analyses, and quantitative PCR (qPCR)/digital droplet PCR (ddPCR) quantification of selected ARGs and mobile genetic elements (MGEs). The MABR removed most of the sewage-derived organic carbon and nitrogen, and simultaneously, E. coli, ARG, and MGE levels dropped by approximately 1.5- and 1.0-log unit mL-1, respectively. Similar levels of E. coli, ARGs, and MGEs were removed in the reservoir, but interestingly, unlike in the MABR, the relative abundance (normalized to 16S rRNA gene-inferred total bacterial abundance) of these genes also decreased. Microbial community analyses revealed the substantial shifts in bacterial and eukaryotic community composition in the reservoir relative to the MABR. Collectively, our observations lead us to conclude that the removal of ARGs in the MABR is mainly a consequence of treatment-facilitated biomass removal, whereas in the stabilization reservoir, mitigation is linked to natural attenuation associated with ecosystem functioning, which includes abiotic parameters, and the development of native microbiomes that prevent the establishment of wastewater-derived bacteria and associated ARGs. IMPORTANCE Wastewater treatment plants are sources of antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs), which can contaminate receiving aquatic environments and contribute to antibiotic resistance. We focused on a controlled experimental system comprising a semicommercial membrane-aerated bioreactor (MABR) that treated raw sewage, whose effluents fed a 4,500-L polypropylene basin that mimicked effluent stabilization reservoirs. We evaluated ARB and ARG dynamics across the raw-sewage-MABR-effluent trajectory, concomitant with evaluation of microbial community composition and physicochemical parameters, in an attempt to identify mechanisms associated with ARB and ARG dissipation. We found that removal of ARB and ARGs in the MABR was primarily associated with bacterial death or sludge removal, whereas in the reservoir it was attributed to the inability of ARBs and associated ARGs to colonize the reservoir due to a dynamic and persistent microbial community. The study demonstrates the importance of ecosystem functioning in removing microbial contaminants from wastewater.

Microplastics and Antibiotic Resistance: The Magnitude of the Problem and the Emerging Role of Hospital Wastewater

The role of microplastics (MPs) in the spread of antibiotic resistance genes (ARGs) is increasingly attracting global research attention due to their unique ecological and environmental effects. The ubiquitous use of plastics and their release into the environment by anthropic/industrial activities are the main sources for MP contamination, especially of water bodies. Because of their physical and chemical characteristics, MPs represent an ideal substrate for microbial colonization and formation of biofilm, where horizontal gene transfer is facilitated. In addition, the widespread and often injudicious use of antibiotics in various human activities leads to their release into the environment, mainly through wastewater. For these reasons, wastewater treatment plants, in particular hospital plants, are considered hotspots for the selection of ARGs and their diffusion in the environment. As a result, the interaction of MPs with drug-resistant bacteria and ARGs make them vectors for the transport and spread of ARGs and harmful microorganisms. Microplastic-associated antimicrobial resistance is an emerging threat to the environment and consequently for human health. More studies are required to better understand the interaction of these pollutants with the environment as well as to identify effective management systems to reduce the related risk.

Spatiotemporal dissemination of ESBL-producing Enterobacterales in municipal sewer systems: a prospective, longitudinal study in the city of Basel, Switzerland

Background

The contribution of community and hospital sources to the transmission of extended-spectrum β-lactamase producing Enterobacterales (ESBL-PE) remains elusive.

Aim

To investigate the extent of community dissemination and the contribution of hospitals to the spread of ESBL-PE by exploring their spatiotemporal distribution in municipal wastewater of the central European city of Basel.

Methods

Wastewater samples were collected monthly for two consecutive years throughout Basel, Switzerland, including 21 sites across 10 postcode areas of the city collecting either community wastewater (urban sites, n = 17) or community and hospital wastewater (mixed sites, n = 4). Presumptive ESBL-PE were recovered by selective culture methods. Standard methodologies were applied for species identification, ESBL-confirmation, and quantification.

Results

Ninety-five percent (477/504) of samples were positive for ESBL-PE. Among these isolates, Escherichia coli (85%, 1,140/1,334) and Klebsiella pneumoniae (11%, 153/1,334) were most common. They were recovered throughout the sampling period from all postcodes, with E. coli consistently predominating. The proportion of K. pneumoniae isolates was higher in wastewater samples from mixed sites as compared to samples from urban sites, while the proportion of E. coli was higher in samples from urban sites (p = 0.003). Higher numbers of colony forming units (CFUs) were recovered from mixed as compared to urban sites (median 3.2 × 10² vs. 1.6 × 10² CFU/mL). E. coli-counts showed moderate correlation with population size (rho = 0.44), while this correlation was weak for other ESBL-PE (rho = 0.21).

Conclusion

ESBL-PE are widely spread in municipal wastewater supporting that community sources are important reservoirs entertaining the spread of ESBL-PE. Hospital-influenced abundance of ESBL-PE appears to be species dependent.

Occurrence and Treatment of Antibiotic-Resistant Bacteria Present in Surface Water

According to the World Health Organization, antibiotic resistance is one of the main threats to global health. The excessive use of several antibiotics has led to the widespread distribution of antibiotic-resistant bacteria and antibiotic resistance genes in various environment matrices, including surface water. In this study, total coliforms, Escherichia coli and enterococci, as well as total coliforms and Escherichia coli resistant to ciprofloxacin, levofloxacin, ampicillin, streptomycin, and imipenem, were monitored in several surface water sampling events. A hybrid reactor was used to test the efficiency of membrane filtration, direct photolysis (using UV-C light emitting diodes that emit light at 265 nm and UV-C low pressure mercury lamps that emit light at 254 nm), and the combination of both processes to ensure the retention and inactivation of total coliforms and Escherichia coli as well as antibiotic-resistant bacteria (total coliforms and Escherichia coli) present in river water at occurrence levels. The membranes used (unmodified silicon carbide membranes and the same membrane modified with a photocatalytic layer) effectively retained the target bacteria. Direct photolysis using low-pressure mercury lamps and light-emitting diode panels (emitting at 265 nm) achieved extremely high levels of inactivation of the target bacteria. The combined treatment (unmodified and modified photocatalytic surfaces in combination with UV-C and UV-A light sources) successfully retained the bacteria and treated the feed after 1 h of treatment. The hybrid treatment proposed is a promising approach to use as point-of-use treatment by isolated populations or when conventional systems and electricity fail due to natural disasters or war. Furthermore, the effective treatment obtained when the combined system was used with UV-A light sources indicates that the process may be a promising approach to guarantee water disinfection using natural sunlight.

Correlations among Antibiotic Resistance Genes, Mobile Genetic Elements and Microbial Communities in Municipal Sewage Treatment Plants Revealed by High-Throughput Sequencing

Municipal sewage treatment plants (MSTPs) are environmental pools for antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs), which is cause for growing environmental-health concerns. In this study, the effects of different wastewater treatment processes on microbial antibiotic resistance in four MSTPs were investigated. PCR, q-PCR, and molecular cloning integrally indicated that the tetracycline resistance (tet) genes significantly reduced after activated-sludge treatment. Illumina high-throughput sequencing revealed that the broad-spectrum profile of ARGs and mobile element genes (MGEs) were also greatly decreased by one order of magnitude via activated sludge treatment and were closely associated with each other. Correlations between ARGs and bacterial communities showed that potential ARB, such as Acinetobacter, Bacteroides, and Cloaibacterium, were removed by the activated-sludge process. Sedimentation processes cannot significantly affect the bacterial structure, resulting in the relative abundance of ARGs, MGEs, and ARB in second-clarifier effluent water being similar to activated sludge. A comprehensive study of ARGs associated with MGEs and bacterial structure might be technologically guided for activated sludge design and operation in the MSTPs, to purposefully control ARGs carried by pathogenic hosts and mobility.

Validation of a modified IDEXX defined-substrate assay for detection of antimicrobial resistant E. coli in environmental reservoirs

The emergence of antimicrobial resistant (AMR) bacteria has been identified as one of the principal public health threats of the 21st century. The World Health Organization (WHO) has long recognized the threat of AMR bacteria and highlights environmental surveillance as a key step in understanding and combating the global rise of antimicrobial resistance. Here, we modified and validated an IDEXX defined-substrate assay commonly used for recreational water quality monitoring of E. coli to enumerate cefotaxime resistant E. coli in environmental reservoirs. We then applied this method to understand AMR trends in multiple environmental matrices over time. This modified IDEXX assay performed highly similarly to two widely accepted plating methods (TBX and MacConkey agar) for enumerating AMR bacteria in pure culture samples and environmental matrices, indicating it is a valid method for enumerating AMR E. coli in the environment. We detected AMR E. coli in urban surface water (63%, 15/24 samples), surface soil (35%, 8/23), and waterfowl feces (43%, 3/7). Sampling around a heavy rain event also revealed that concentrations of AMR E. coli and total E. coli co-vary over time in both surface water and surface soil. This novel method can reliably be performed outside of a laboratory setting and has very low equipment requirements, meaning it has tremendous potential to bolster global monitoring efforts, particularly in resource-restricted and highly rural settings.

Genetic diversity and prevalence of extended-spectrum beta-lactamase-producing Escherichia coli and Klebsiella pneumoniae in aquatic environments receiving untreated hospital effluents

The spread of extended-spectrum beta-lactamase (ESBL)-producing bacteria in the environment has been recognized as a challenge to public health. The aim of the present study was to assess the occurrence of ESBL-producing Escherichia coli and Klebsiella pneumoniae from selected water bodies receiving hospital effluents in Kerala, India. Nearly 69.8% of Enterobacteriaceae isolates were multi-drug resistant by the Kirby-Bauer disc diffusion method. The double disc synergy test was used to detect the ESBL production and the genes responsible for imparting resistance were detected by PCR. Conjugation experiments confirmed the mechanism of plasmid-mediated transfer of resistance. The prevalence of ESBL production in E. coli and K. pneumoniae was 49.2 and 46.8%, respectively. Among the ESBL-encoding genes, bla_CTX-M was the most prevalent group followed by bla_TEM, bla_OXA, bla_CMY, and bla_SHV. The results suggest that healthcare settings are one of the key contributors to the spread of ESBL-producing bacteria, not only through cross-transmission and ingestion of antibiotics but also through the discharge of waste without a proper treatment, leading to harmful effects on the aquatic environment. The high prevalence of ESBL-producing Enterobacteriaceae with resistance genes in public water bodies even post-treatment poses a serious threat.

(Antibiotic-Resistant) E. coli in the Dutch-German Vecht Catchment─Monitoring and Modeling

Fecally contaminated waters can be a source for human infections. We investigated the occurrence of fecal indicator bacteria (E. coli) and antibiotic-resistant E. coli, namely, extended spectrum beta-lactamase (ESBL)-producing E. coli (ESBL-EC) and carbapenemase-producing E. coli (CP-EC) in the Dutch-German transboundary catchment of the Vecht River. Over the course of one year, bacterial concentrations were monitored in wastewater treatment plant (WWTP) influents and effluents and in surface waters with and without WWTP influence. Subsequently, the GREAT-ER model was adopted for the prediction of (antibiotic-resistant) E. coli concentrations. The model was parametrized and evaluated for two distinct scenarios (average flow scenario, dry summer scenario). Statistical analysis of WWTP monitoring data revealed a significantly higher (factor 2) proportion of ESBL-EC among E. coli in German compared to Dutch WWTPs. CP-EC were present in 43% of influent samples. The modeling approach yielded spatially accurate descriptions of microbial concentrations for the average flow scenario. Predicted E. coli concentrations exceed the threshold value of the Bathing Water Directive for a good bathing water quality at less than 10% of potential swimming sites in both scenarios. During a single swimming event up to 61 CFU of ESBL-EC and less than 1 CFU of CP-EC could be taken up by ingestion.

Dynamics of Genotypic and Phenotypic Antibiotic Resistance in a Conventional Wastewater Treatment Plant in 2 Years

Wastewater treatment plants (WWTPs) are considered a sink and a source of antibiotic resistance. In this study, we applied both culture-dependent and SmartChip-based culture-independent approaches for the investigation of antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARGs) at Jungnang (JN), located in the Han River, Seoul, South Korea, for 2 years, i.e., 2017 and 2018. The JN WWTP reduced the diversity and abundance of ARB and ARGs but was not sufficient for removing them all. Interestingly, through the treatment process in the JN WWTP, the composition of diverse multidrug-resistant (MDR) bacteria was concentrated mainly into some genera of the Gammaproteobacteria class (Citrobacter, Escherichia-Shigella, and Stenotrophomonas), which could be key carriages to spread ARGs into the environments. In addition, SmartChip analyses showed that the relative abundance and the number of ARGs were significantly decreased from the influents to the effluents in both 2017 and 2018. SmartChip analyses for 2 years also allowed to notify the core ARGs in the influents and the effluents with the presence of clinically relevant core ARGs, such as vanC, bla_OXA, and bla_NDM, which persisted in the treatment process. Considering diverse bacterial mechanisms for exchanging and transferring ARGs, the occurrence of MDR bacteria and core ARGs could be a source for the blooming of the antibiotic resistome in the WWTP and nearby environments.

Characterization of β-Lactamases and Multidrug Resistance Mechanisms in Enterobacterales from Hospital Effluents and Wastewater Treatment Plant

Antimicrobials in wastewater promote the emergence of antibiotic resistance, facilitated by selective pressure and transfer of resistant genes. Enteric bacteria belonging to Escherichia coli, Klebsiella pneumoniae, Klebsiella oxytoca, Enterobacter cloacae, and Citrobacter species (n = 126) from hospital effluents and proximate wastewater treatment plant were assayed for susceptibility to four antimicrobial classes. The β-lactamase encoding genes harbored in plasmids were genotyped and the plasmids were sequenced. A multidrug resistance phenotype was found in 72% (n = 58) of E. coli isolates, 70% (n = 43) of Klebsiella species isolates, and 40% (n = 25) of Enterobacter and Citrobacter species. Moreover, 86% (n = 50) of E. coli, 77% (n = 33) of Klebsiella species, and 25% (n = 4) of Citrobacter species isolates phenotypically expressed extended spectrum β-lactamase. Regarding ESBL genes, bla_CTX-M-27 and bla_TEM-1 were found in E. coli, while Klebsiella species harbored bla_CTX-M-15, bla_CTX-M-30, or bla_SHV-12. Genes coding for aminoglycoside modifying enzymes, adenylyltransferases (aadA1, aadA5), phosphotransferases (aph(6)-1d, aph(3″)-Ib), acetyltransferases (aac(3)-IIa), (aac(6)-Ib), sulfonamide/trimethoprim resistant dihydropteroate synthase (sul), dihydrofolate reductase (dfrA), and quinolone resistance protein (qnrB1) were also identified. Monitoring wastewater from human sources for acquired resistance in clinically important bacteria may provide a cheaper alternative in regions facing challenges that limit clinical surveillance.

A comprehensive review on current technologies for removal of endocrine disrupting chemicals from wastewaters

In the recent years, endocrine disrupting compounds (EDCs) has received increasing attention due to their significant toxic effects on human beings and wildlife by affecting their endocrine systems. As an important group of emerging pollutant, EDCs have been detected in various aquatic environments, including surface waters, groundwater, wastewater, runoff, and landfill leachates. Their removal from water resources has also been an emerging concern considering growing population as well as reducing access to fresh water resources. EDC removal from wastewaters is highly dependent on physicochemical properties of the given EDCs present in each wastewater types as well as various aquatic environments. Due to chemical, physical and physicochemical diversities in these parameters, variety of technologies consisting of physical, biological, electrochemical, and chemical processes have been developed for their removal. This review highlights that the effectiveness of EDC removal is highly dependent of selecting the appropriate technology; which decision is made upon a full wastewater chemical characterization. This review aims to provide a comprehensive perspective about all the current technologies used for EDCs removal from various aquatic matrices along with rising challenges such as the antimicrobial resistance gene transfer during EDC treatment.

Antimicrobial Resistance Patterns and Clonal Distribution of E. coli, Enterobacter spp. and Acinetobacter spp. Strains Isolated from Two Hospital Wastewater Plants

The objective of this study was to determine the presence and persistence of antimicrobial-resistant enterobacteria and their clonal distribution in hospital wastewater. A descriptive cross-sectional study was carried out in wastewater from two Mexico City tertiary level hospitals. In February and March of 2020, eight wastewater samples were collected and 26 isolates of enterobacteria were recovered, 19 (73.1%) isolates were identified as E. coli, 5 (19.2%) as Acinetobacter spp. and 2 (7.7%) as Enterobacter spp. Antimicrobial susceptibility profiles were performed using the VITEK 2^® automated system and bacterial identification was performed by the Matrix-Assisted Laser Desorption/Ionization-Time of Flight mass spectrometry (MALDI-TOF MS^®). ESBL genes were detected by polymerase chain reaction (PCR) and clonal distributions of isolates were determined by pulsed-field gel electrophoresis (PFGE). E. coli susceptibility to different classes of antimicrobials was analyzed and resistance was mainly detected as ESBLs and fluoroquinolones. One E. coli strain was resistant to doripenem, ertapenem, imipenem and meropenem. The analysis by PCR showed the presence of specific β-lactamases resistance genes (bla_KPC, bla_CTX-M). The PFGE separated the E. coli isolates into 19 different patterns (A–R). PFGE results of Acinetobacter spp. showed the presence of a majority clone A. Surveillance of antimicrobial resistance through hospital wastewater is an important tool for early detection of clonal clusters of clinically important bacteria with potential for dissemination.

Environmental contamination in a high-income country (France) by antibiotics, antibiotic-resistant bacteria, and antibiotic resistance genes: Status and possible causes

Antimicrobial resistance (AMR) is a major global public health concern, shared by a large number of human and animal health actors. Within the framework of a One Health approach, actions should be implemented in the environmental realm, as well as the human and animal realms. The Government of France commissioned a report to provide policy and decision makers with an evidential basis for recommending or taking future actions to mitigate AMR in the environment. We first examined the mechanisms that underlie the emergence and persistence of antimicrobial resistance in the environment. This report drew up an inventory of the contamination of aquatic and terrestrial environments by AMR and antibiotics, anticipating that the findings will be representative of some other high-income countries. Effluents of wastewater treatment plants were identified as the major source of contamination on French territory, with spreading of organic waste products as a more diffuse and incidental contamination of aquatic environments. A limitation of this review is the heterogeneity of available data in space and time, as well as the lack of data for certain sources. Comparing the French Measured Environmental Concentrations (MECs) with predicted no effect concentrations (PNECs), fluoroquinolones and trimethoprim were identified as representing high and medium risk of favoring the selection of resistant bacteria in treated wastewater and in the most contaminated rivers. All other antibiotic molecules analyzed (erythromycin, clarithromycin, azithromycin, tetracycline) were at low risk of resistance selection in those environments. However, the heterogeneity of the data available impairs their full exploitation. Consequently, we listed indicators to survey AMR and antibiotics in the environment and recommended the harmonization of sampling strategies and endpoints for analyses. Finally, the objectives and methods used for the present work could comprise a useful example for how national authorities of countries sharing common socio-geographic characteristics with France could seek to better understand and define the environmental dimension of AMR in their particular settings.

Microbiome and antibiotic resistance profiling in submarine effluent-receiving coastal waters in Croatia

Wastewater treatment plant (WWTP) effluents are pointed as hotspots for the introduction of both commensal and pathogenic bacteria as well as their antibiotic resistance genes (ARGs) in receiving water bodies. For the first time, the effect of partially treated submarine effluents was explored at the bottom and surface of the water column to provide a comprehensive overview of the structure of the microbiome and associated AR, and to assess environmental factors leading to their alteration. Seawater samples were collected over a 5-month period from submarine outfalls in central Adriatic Sea, Croatia. 16S rRNA amplicon sequencing was used to establish taxonomic and resistome profiles of the bacterial communities. The community differences observed between the two discharge areas, especially in the abundance of Proteobacteria and Firmicutes, could be due to the origin of wastewaters treated in WWTPs and the limiting environmental conditions such as temperature and nutrients. PICRUSt2 analysis inferred the total content of ARGs in the studied microbiomes and showed the highest abundance of resistance genes encoding multidrug efflux pumps, such as MexAB-OprM, AcrEF-TolC and MdtEF-TolC, followed by the modified peptidoglycan precursors, transporter genes encoding tetracycline, macrolide and phenicol resistance, and the bla operon conferring β-lactam resistance. A number of pathogenic genera introduced by effluents, including Acinetobacter, Arcobacter, Bacteroides, Escherichia-Shigella, Klebsiella, Pseudomonas, and Salmonella, were predicted to account for the majority of efflux pump-driven multidrug resistance, while Acinetobacter, Salmonella, Bacteroides and Pseudomonas were also shown to be the predominant carriers of non-efflux ARGs conferring resistance to most of nine antibiotic classes. Taken together, we evidenced the negative impact of submarine discharges of treated effluents via alteration of physico-chemical characteristics of the water column and enrichment of bacterial community with nonindigenous taxa carrying an arsenal of ARGs, which could contribute to the further propagation of the AR in the natural environment.

A 'time bomb' in the human intestine-the multiple emergence and spread of antibiotic-resistant bacteria

Antibiotics have a strong killing effect on bacteria and are the first choice for the prevention and treatment of bacterial infectious diseases. Therefore, they have been widely used in the medical field, animal husbandry and planting industry. However, with the massive use of antibiotics, more and more antibiotic-resistant bacteria (ARB) have emerged. Because human intestines are rich in nutrients, have suitable temperature, and are high in bacterial abundance, they can easily become a hotbed for the spread of ARB and antibiotic-resistant genes (ARGs). When opportunistic pathogenic bacteria in the intestine acquire ARGs, the infectious diseases caused by such opportunistic pathogens will become more difficult to treat, or even impossible to cure. Therefore, ARB in the human intestine are like a 'time bomb'. In this review, we discuss the sources of intestinal ARB and the transmission routes of ARGs in the human intestine from the perspective of One Health. Further, we describe various methods to prevent the emergence of ARB and inhibit the spread of ARGs in the human intestine. Finally, we may be able to overcome ARB in the human intestine using an interdisciplinary 'One Health' approach.

Differences in chlorine and peracetic acid disinfection kinetics of Enterococcus faecalis and Escherichia fergusonii and their susceptible strains based on gene expressions and genomics

This study was conducted to investigate mechanisms of cross-resistance to chlorine and peracetic acid (PAA) disinfectants by antibiotic-resistant bacteria. Our study evaluated chlorine and PAA based disinfection kinetics of erythromycin-resistant Enterococcus faecalis, meropenem-resistant Escherichia fergusonii, and susceptible strains of these species. Using the integrated second-order disinfectant decay model and first-order Chick-Watson's Law, it was found that the meropenem-resistant Escherichia fergusonii strain showed significantly less log inactivation compared to the susceptible E. fergusonii strain in response to both chlorine and PAA disinfection (p-value = 0.059, 3.5 × 10^-6). On the other hand, the susceptible Enterococcus faecalis strain showed similar log inactivation compared to the erythromycin-resistant strain in response to either treatment (p-value = 0.075, 0.28). Meropenem-resistant E. fergusonii showed an increase in gene expression of New Delhi metallo-β-lactamase (bla_NDM-1) gene to chlorine, but there was no increase in expression to PAA. Whole genome sequencing (WGS) was then conducted to elucidate the differences in genes among both resistant and susceptible table E. fergusonii strains. The average nucleotide identity (ANI) analysis of the draft genomes (>97% similarity) suggests that meropenem-resistant E. fergusonii (S1) and meropenem-susceptible E. fergusonii (S2) are the same species but different strains. Both strains have the same genes for oxidative stress pathways, oxidative scavenger genes, and nearly 40 different antibiotic efflux pump genes. The chromosomal and plasmid draft genomes of meropenem-resistant and susceptible E. fergusonii strains each have 65 and 52 antibiotic resistance genes, respectively. Of these, the resistant E. fergusonii strain harbored the extended-spectrum beta-lactamases bla_CTX-M-15 and bla_TEM-1 genes located on the chromosome, and a bla_TEM-1 gene on the plasmid. The overall findings of this study are significant, as they reveal that antibiotic-resistant and susceptible strains of E. fergusonii exhibit different responses towards chlorine and PAA disinfection.

The association between antimicrobials and the antimicrobial-resistant phenotypes and resistance genes of Escherichia coli isolated from hospital wastewaters and adjacent surface waters in Sri Lanka

The presence of antimicrobials, antimicrobial-resistant bacteria (ARB), and the associated antimicrobial resistance genes (ARGs) in the environment is a global health concern. In this study, the concentrations of 25 antimicrobials, the resistance of Escherichia coli (E. coli) strains in response to the selection pressure imposed by 15 antimicrobials, and enrichment of 20 ARGs in E. coli isolated from hospital wastewaters and surface waters were investigated from 2016 to 2018. In hospital wastewaters, clarithromycin was detected at the highest concentration followed by sulfamethoxazole and sulfapyridine. Approximately 80% of the E. coli isolates were resistant, while 14% of the isolates exhibited intermediate resistance against the tested antimicrobial agents. Approximately 61% of the examined isolates were categorized as multidrug-resistant bacteria. The overall abundance of phenotypes that were resistant toward drugs was in the following order: β-lactams, tetracycline, quinolones, sulfamethoxazole/trimethoprim, aminoglycosides, and chloramphenicol. The data showed that the E. coli isolates frequently harbored bla_TEM, bla_CTX-M, tetA, qnrS, and sul2. These results indicated that personal care products were significantly associated with the presence of several resistant phenotypes and resistance genes, implying their role in co-association with multidrug resistance. Statistical analysis also indicated a disparity specific to the site, treatment, and year in the data describing the prevalence of ARB and ARGs and their release into downstream waters. This study provides novel insights into the abundance of antimicrobial, ARB and ARGs in Sri Lanka, and could further offer invaluable information that can be integrated into global antimicrobial resistance databases.

Prevalence of multidrug-resistant and extended-spectrum beta-lactamase-producing Escherichia coli in urban community wastewater

Antibiotic resistance (ABR) and the spread of multidrug-resistant and extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli via wastewater to environmental compartments are of rapidly growing global health concern. Health care facilities, industries and slaughterhouses discharge high loads of ABR bacteria with their wastewater. However, the general community is often the biggest indirect discharger. Yet, research focusing explicitly on this important diffuse source is rather scarce raising questions about variations in the occurrence of ESBL-producing E. coli in wastewater from different communities and over time. Between April 2019 and March 2020, wastewater from three socio-spatially different districts in the Ruhr Metropolis, Germany, and the receiving wastewater treatment plant was sampled monthly and analysed for the occurrence of ESBL-producing E. coli via culture-based methods. Isolates were validated with matrix assisted laser desorption ionization time of flight mass spectrometry and antibiotic resistance profiles were analysed via microdilution. Results were interpreted using the European Committee on Antimicrobial Susceptibility Testing criteria. The German Commission for Hospital Hygiene and Infection Prevention criteria were used for multidrug-resistance categorization. Phenotypic ESBL-producing E. coli could be isolated from every wastewater sample demonstrating that the general community is an important indirect discharger. The socio-spatially disadvantaged area displayed higher absolute loads of ESBL-producing E. coli compared to the other two areas, as well as higher adjusted loads for domestic discharge and inhabitants, particularly during winter, indicating a higher ABR burden. Thirty-two isolates (28.6%) were characterized as multidrug-resistant Gram-negative bacteria (3MRGN). Resistance profiles varied only for those antibiotics, which can be administered in outpatient care. Resistance levels tended to be around 10% lower in the socio-spatially advantaged area. This study shows that spatial and seasonal influences regarding the occurrence of ESBL-producing E. coli in wastewater from socio-spatially different communities are identifiable.

Local characteristics associated with higher prevalence of ESBL-producing Escherichia coli in community-acquired urinary tract infections: an observational, cross-sectional study

OBJECTIVES

The prevalence of ESBL-producing Escherichia coli (ESBL-E. coli) in community-acquired urinary tract infections (UTI) has been increasing worldwide since 2000, but with large geographical variations. The aim of this study was to determine whether the ESBL-E. coli rate in urine samples from individuals with community-acquired UTI was associated with the local socio-economic, environmental, agricultural and healthcare characteristics.

METHODS

This was a cross-sectional study in western France using data on antibiotic susceptibility of E. coli isolated from urine samples of individuals with community-acquired UTI analysed in non-hospital laboratories from 2015 to 2017. The ESBL-E. coli rate was calculated for each laboratory. Data on socio-economic characteristics, human antibiotic consumption, hospital bed density, animal farming density and percentage of agricultural land and surface water were retrieved at the municipality level and aggregated by study area. Their association with ESBL-E. coli prevalence was quantified using multivariate linear regression models with a backward selection.

RESULTS

From 358 291 E. coli isolates from urine samples tested in 92 laboratories, the mean ESBL-E. coli prevalence for the study period was 3.30%. In an adjusted model, the ESBL-E. coli rate was significantly (P < 0.05) and positively associated with the local percentage of people >65 years old, third-generation cephalosporin use (DDD/1000 inhabitants), number of hospital beds/km2, poultry density, pig density and percentage of agricultural land. Lower deprivation was associated with a higher ESBL-E. coli rate.

CONCLUSIONS

Several anthropogenic factors (primary care, hospitals and animal farming) are associated with the local ESBL-E. coli rate in community-acquired UTI. These results could contribute to improve risk management, including identification of at-risk patient groups.

A Point Prevalence Survey of Antibiotic Resistance in the Irish Environment, 2018-2019

Water bodies worldwide have proven to be vast reservoirs of clinically significant antibiotic resistant organisms. Contamination of waters by anthropogenic discharges is a significant contributor to the widespread dissemination of antibiotic resistance. The aim of this research was to investigate multiple different anthropogenic sources on a national scale for the role they play in the environmental propagation of antibiotic resistance. A total of 39 water and 25 sewage samples were collected across four local authority areas in the West, East and South of Ireland. In total, 211 Enterobacterales were isolated (139 water, 72 sewage) and characterised. A subset of isolates (n=60) were chosen for whole genome sequencing. Direct comparisons of the water versus sewage isolate collections revealed a higher percentage of sewage isolates displayed resistance to cefoxitin (46%) and ertapenem (32%), while a higher percentage of water isolates displayed resistance to tetracycline (55%) and ciprofloxacin (71%). Half of all isolates displayed extended spectrum beta-lactamase (ESBL) production phenotypically (n = 105/211; 50%), with bla_CTX-M detected in 99/105 isolates by PCR. Carbapenemase genes were identified in 11 isolates (6 sewage, 5 water). The most common variant was bla_OXA-48 (n=6), followed by bla_NDM-5 (n=2) and bla_KPC-2 (n=2). Whole genome sequencing analysis revealed numerous different sequence types in circulation in both waters and sewage including E. coli ST131 (n=15), ST38 (n=8), ST10 (n=4) along with Klebsiella ST405 (n=3) and ST11 (n=2). Core genome MLST (cgMLST) comparisons uncovered three highly similar Klebsiella isolates originating from hospital sewage and two nearby waters. The Klebsiella isolates from an estuary and seawater displayed 99.1% and 98.8% cgMLST identity to the hospital sewage isolate respectively. In addition, three pairs of E. coli isolates from different waters also revealed cgMLST similarities, indicating widespread dissemination and persistence of certain strains in the aquatic environment. These findings highlight the need for routine monitoring of water bodies used for recreational and drinking purposes for the presence of multi-drug resistant organisms.

Antibiotic residues in the aquatic environment - current perspective and risk considerations

Antimicrobial resistance is a major concern for human and animal health, projected to deteriorate with time and given current trends of antimicrobial usage. Antimicrobial use, particularly in healthcare and agriculture, can result in the release of antimicrobials into surface waters, promoting the development of antibiotic resistance in the environment, and potentially leading to human health risks. This study reviews relevant literature, and investigates current European and Irish antimicrobial usage trends in humans and animals, as well as potential pathways that antibiotics can take into surface waters following use. Reported levels in the aquatic environment are summarized, with particular focus on Ireland. There are relatively few studies examining Irish water bodies or sewage effluent for antibiotic residues, however, five antibiotics, namely azithromycin, ciprofloxacin, clarithromycin, metronidazole, and trimethoprim, have been measured in Irish waters, in concentrations predicted to select for resistance. Numerous isolates of multi-drug resistant bacteria have also been found in water bodies throughout Ireland and Europe. The value of risk assessment methodologies in understanding risks posed by antibiotic residues is reviewed including the advantages and disadvantages of specific approaches. Hazard quotient and bespoke Monte Carlo approaches are predominant risk assessment tools used to examine antimicrobial release and their complex pathways. This study highlights the need for monitoring of antimicrobial releases and the potential for resistance development, persistence and transmission while highlighting the role of risk assessment methodologies in assessing potential human and environmental health impacts.

A review on hospital wastewater treatment: A special emphasis on occurrence and removal of pharmaceutically active compounds, resistant microorganisms, and SARS-CoV-2

The hospital wastewater imposes a potent threat to the security of human health concerning its high vulnerability towards the outbreak of several diseases. Furthermore, the outbreak of COVID-19 pandemic demanded a global attention towards monitoring viruses and other infectious pathogens in hospital wastewater and their removal. Apart from that, the presence of various recalcitrant organics, pharmaceutically active compounds (PhACs), etc. imparts a complex pollution load to water resources and ecosystem. In this review, an insight into the occurrence, persistence and removal of drug-resistant microorganisms and infectious viruses as well as other micro-pollutants have been documented. The performance of various pilot/full-scale studies have been evaluated in terms of removal of biochemical oxygen demand (BOD), chemical oxygen demand (COD), total suspended solids (TSS), PhACs, pathogens, etc. It was found that many biological processes, such as membrane bioreactor, activated sludge process, constructed wetlands, etc. provided more than 80% removal of BOD, COD, TSS, etc. However, the removal of several recalcitrant organic pollutants are less responsive to those processes and demands the application of tertiary treatments, such as adsorption, ozone treatment, UV treatment, etc. Antibiotic-resistant microorganisms, viruses were found to be persistent even after the treatment of hospital wastewater, and high dose of chlorination or UV treatment was required to inactivate them. This article circumscribes the various emerging technologies, which have been used to treat PhACs and pathogens. The present review also emphasized the global concern of the presence of SARS-CoV-2 RNA in hospital wastewater and its removal by the existing treatment facilities.

Detection of bla OXA-1, bla TEM-1, and Virulence Factors in E. coli Isolated From Seals

Marine mammals are frequently considered good sentinels for human, animal and environmental health due to their long lifespan, coastal habitat, and characteristics as top chain predators. Using a One Health approach, marine mammals can provide information that helps to enhance the understanding of the health of the marine and coastal environment. Antimicrobial resistance (AMR) is the quintessential One Health problem that poses a well-recognised threat to human, animal, and ecosystem health worldwide. Treated and untreated sewage, hospital waste and agricultural run-off are often responsible for the spread of AMR in marine and freshwater ecosystems. Rescued seals (n = 25) were used as sentinels to investigate the levels of AMR in the Irish coastal ecosystem. Faecal swabs were collected from these animals and bacterial isolates (E. coli and cefotaxime-resistant non-E. coli) from each swab were selected for further investigation. E. coli isolates were characterised in terms of phylogenetic group typing, AMR, and virulence factors. All E. coli isolates investigated in this study (n = 39) were ampicillin resistant while 26 (66.6%) were multi-drug resistant (MDR). Resistance genes bla _OXA-1 and bla _TEM-1 were detected in 16/39 and 6/39 isolates, respectively. Additionally, virulence factors associated with adhesion (sfa, papA, and papC) and siderophores (fyuA and iutA) were identified. An additional 19 faecal cefotaxime-resistant non-E. coli isolates were investigated for the presence of β-lactamase encoding genes. These isolates were identified as presumptive Leclercia, Pantoea and Enterobacter, however, none were positive for the presence of the genes investigated. To the authors knowledge this is the first study reporting the detection of bla _OXA-1 and bla _TEM-1 in phocid faecal E. coli in Europe. These results highlight the importance of marine mammals as sentinels for the presence and spread of AMR in the marine and coastal environment.

Antimicrobial sensitivity profiling of bacterial communities recovered from effluents of municipal solid waste dumping site

The diversity of antibiotic-resistance bacteria (ARB) from the effluents of Aizawl city municipal waste dumping site was studied using a culture-dependent method. The present study molecularly identified 73 isolates that were differentiated into three phyla (Proteobacteria, Actinobacteria, and Firmicutes) belonging to 17 family and 22 genera. Bacillus constitutes the most dominant genus comprising 16% of the total isolates. The topology of the phylogenetic tree differentiates them into five major clades. Corynebacterium and Rhodococcus which are morphologically alike were clustered together and the Gram-positive bacteria such as Staphylococcus, Bacillus, and Lysinibacillus formed a separate cluster. Antibiotic resistance of the identified bacterial isolates was performed using 19 different antibiotics. Among the isolates, 70 of them found resistant to polymixin B and nalidixic acid and 10 isolates exhibited resistance to 15 tested antibiotics. The present study revealed that bacteria with antibiotic resistance are extensively distributed in the effluents of the dumping site and may serve as a significant reservoir for the spreading of antibiotic resistance to opportunistic pathogens.

Investigating the impact of hospital antibiotic usage on aquatic environment and aquaculture systems: A molecular study of quinolone resistance in Escherichia coli

Quinolones are one of the most important classes of antibacterials available for the treatment of infectious diseases in humans. However, there is a growing concern about bacterial resistance to antimicrobials including quinolones. The spread of antibiotic-resistant bacteria in the aquatic environment has been recognized as a growing threat to public health and hospitals appear to be a major contributor to this. The objective of this study was to investigate the prevalence of quinolone resistance in Escherichia coli from selected water bodies receiving direct hospital effluents in Kerala, India. Standard disc diffusion and E-test were used for antibiotic susceptibility testing. As antibiotic resistance can develop in bacterial isolates by different means, EtBr Agar Cartwheel method was used to detect the efflux pump activity and presence of resistant genes was detected by PCR. The mechanism of transfer of plasmid mediated resistance was confirmed by conjugation experiments. A total of 209 multidrug-resistant Escherichia coli were isolated from different hospital effluent discharge sites and aquaculture farms located in their vicinity. Among them, qnrB was found to be most prevalent followed by qnrS, OqxAB, qnrA and aac (6')-Ib-cr. The results suggested that the antibiotics present at sub-inhibitory concentrations in direct hospital effluents increases the selection pressure impacting the cell function of even normal microorganisms in the aquatic environment to change the genetic expression of virulence factors or acquire resistance genes by different transfer mechanisms, posing a serious threat to public health.

Bacteria isolated from hospital, municipal and slaughterhouse wastewaters show characteristic, different resistance profiles

Multidrug-resistant bacteria cause difficult-to-treat infections and pose a risk for modern medicine. Sources of multidrug-resistant bacteria include hospital, municipal and slaughterhouse wastewaters. In this study, bacteria with resistance to 3rd generation cephalosporins were isolated from all three wastewater biotopes, including a maximum care hospital, municipal wastewaters collected separately from a city and small rural towns and the wastewaters of two pig and two poultry slaughterhouses. The resistance profiles of all isolates against clinically relevant antibiotics (including β-lactams like carbapenems, the quinolone ciprofloxacin, colistin, and trimethoprim/sulfamethoxazole) were determined at the same laboratory. The bacteria were classified according to their risk to human health using clinical criteria, with an emphasis on producers of carbapenemases, since carbapenems are prescribed for hospitalized patients with infections with multi-drug resistant bacteria. The results showed that bacteria that pose the highest risk, i. e., bacteria resistant to all β-lactams including carbapenems and ciprofloxacin, were mainly disseminated by hospitals and were present only in low amounts in municipal wastewater. The isolates from hospital wastewater also showed the highest rates of resistance against antibiotics used for treatment of carbapenemase producers and some isolates were susceptible to only one antibiotic substance. In accordance with these results, qPCR of resistance genes showed that 90% of the daily load of carbapenemase genes entering the municipal wastewater treatment plant was supplied by the clinically influenced wastewater, which constituted approximately 6% of the wastewater at this sampling point. Likewise, the signature of the clinical wastewater was still visible in the resistance profiles of the bacteria isolated at the entry into the wastewater treatment plant. Carbapenemase producers were not detected in slaughterhouse wastewater, but strains harboring the colistin resistance gene mcr-1 could be isolated. Resistances against orally available antibiotics like ciprofloxacin and trimethoprim/sulfamethoxazole were widespread in strains from all three wastewaters.

The dissemination of antibiotic resistance in various environmental objects (Russia)

Environmental objects (surface and groundwater, soil, bottom sediments, wastewater) are reservoirs in which large-scale multidirectional exchange of determinants of antibiotic resistance between clinical strains and natural bacteria takes place. The review discusses the results of studies on antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARG) isolated from environmental objects (water, soil, sewage, permafrost) of the Russian Federation. Despite the relevance of the topic, the number of available publications examining the resistomes of Russian water bodies and soils is small. The most studied environmental objects are surface waters (rivers, lakes), permafrost deposits. Soil resistomes are less studied. Data on ARG and ARB in wastewater are the least covered in publications. In most of the studies, antibiotic resistance of isolated pure bacterial cultures was determined phenotypically. A significant number of publications are devoted to the resistance of natural isolates of Vibrio cholerae, since the lower reaches of the Volga and Don rivers are endemic to cholera. Molecular genetic methods were used in a small number of studies. Geographically, the south of the European part of Russia is the most studied. There are also publications on the distribution of ARG in water bodies of Siberia and the Russian Far East. There are practically no publications on such developed regions of Russia as the center and northwest of the European part of Russia. The territory of the country is very large, anthropogenic and natural factors in its various regions vary significantly; therefore, it seems interesting to combine all available data in one work.

Comparison of antibiotic-resistant bacteria and antibiotic resistance genes abundance in hospital and community wastewater: A systematic review

Antibiotic-resistant bacteria (ARB) and antibiotic-resistance genes (ARGs) are constantly shed into the aquatic environment, with hospital wastewater potentially acting as an important source for resistance spread into the environment. A systematic review was conducted aiming to investigate the role of hospital wastewater on dissemination of antimicrobial resistance in the aquatic environment. Studies included in the review compared the prevalence of ARB and/or ARGs in hospital versus community wastewater. Data were extracted on ARB and/or ARG prevalence. Data on sampling techniques, microbiological methodology and risk of bias of included studies were recorded. Thirty-seven studies were included. Higher frequencies of antibiotic resistance determinants were found in hospital wastewater compared to community sources in 30/37 (81%) of included studies. However, trends for specific multi-drug-resistant bacteria differed. Antibiotic-resistant Gram-negative were more prevalent in hospital compared to community wastewaters, with higher concentrations of extended-spectrum-beta-lactamase-producing pathogens and carbapenemase-producing Enterobacteriaceae in hospital sources in 9/9 studies and 6/7 studies, respectively. Hospitals did not contribute consistently to the abundance of vancomycin-resistant Enterococci (VRE); 5/10 studies found higher abundance of VRE in hospital compared to community wastewaters. Reporting on sampling methods, wastewater treatment processes and statistical analysis were at high risk of bias. Extreme heterogeneity in study methods and outcome reporting precluded meta-analysis. Current evidence concurs that hospital wastewater is an important source for antibiotic resistance in aquatic environments, mainly multidrug-resistant Gram-negative bacteria. Future research is needed to assess the effect of wastewater treatment processes on overall antibiotic resistance in the aquatic environment.

Antibiotic Resistance in Recreational Waters: State of the Science

Ambient recreational waters can act as both recipients and natural reservoirs for antimicrobial resistant (AMR) bacteria and antimicrobial resistant genes (ARGs), where they may persist and replicate. Contact with AMR bacteria and ARGs potentially puts recreators at risk, which can thus decrease their ability to fight infections. A variety of point and nonpoint sources, including contaminated wastewater effluents, runoff from animal feeding operations, and sewer overflow events, can contribute to environmental loading of AMR bacteria and ARGs. The overall goal of this article is to provide the state of the science related to recreational exposure and AMR, which has been an area of increasing interest. Specific objectives of the review include (1) a description of potential sources of antibiotics, AMR bacteria, and ARGs in recreational waters, as documented in the available literature; (2) a discussion of what is known about human recreational exposures to AMR bacteria and ARGs, using findings from health studies and exposure assessments; and (3) identification of knowledge gaps and future research needs. To better understand the dynamics related to AMR and associated recreational water risks, future research should focus on source contribution, fate and transport-across treatment and in the environment; human health risk assessment; and standardized methods.

High frequency of gram-negative bacilli harboring blaKPC-2 in the different stages of wastewater treatment plant: A successful mechanism of resistance to carbapenems outside the hospital settings

Wastewater treatment plants (WWTPs) are considered to be a reservoir and a source of bacterial resistance. Worryingly, the presence of carbapenem-resistant Gram-negative bacilli (CRGNB) in WWTPs has recently been reported, but there are still many research gaps regarding its emergence and impact. The distribution of CRGNB in the different stages of a WWTP in Colombia and the relationship between the physicochemical factors involved with their presence are described in this paper. Additionally, given the impact on public health, the CRGNB detected were compared with isolates previously found in hospital patients. Residual water samples were taken from five different stages of a WWTP between January and July 2017. A total of 390 GNB were isolated, and a significant frequency of CRGNB harboring bla_KPC-2 (38.2%, n = 149/390) was detected, of which 57% were Enterobacteriaceae, 41.6% Aeromonadaceae, and 1.3% Pseudomonadaceae. The Enterobacteriaceae were more frequent in the raw effluent compared to the Aeromonadaceae, which in turn were more prevalent in the recycled activated sludge and final effluent. Environmental variables such as pH, oxygen, chemical oxygen demand, and temperature were significantly correlated with the quantification of carbapenem-resistant Enterobacteriaceae (CRE) at specific points in the WWTP. Interestingly, isolated K. pneumoniae harboring bla_KPC-2 from the WWTPs were diverse and did not relate genetically to the hospital strains with which they were compared. In conclusion, these results confirm the worrying scenario of the dissemination and persistence of emerging contaminants such as CRGNB harboring bla_KPC-2, and reinforce the need to establish strategies aimed at containing this problem using multifocal interventions.

Antibiotic resistance profile of Gram-negative bacteria isolated from Lafenwa abattoir effluent and its receiving water (Ogun River) in Abeokuta, Ogun state, Nigeria

Untreated abattoir effluent constitutes potential reservoir for transmission of pathogenic strains of multiple antibiotic-resistant bacteria by pollution of surface and ground water sources. This study was carried out to determine the antibiotic resistance and extended spectrum β-lactamase (ESBL) production profiles of Gram-negative bacteria isolated from effluent collected from Lafenwa municipal abattoir and its receiving surface water, Ogun River, in Abeokuta, Ogun state, Nigeria. Twelve effluent and 18 water samples were collected for this study. Total heterotrophic and coliform counts were estimated, bacterial identification was performed using standard culture-based procedures, whilst antibiotic resistance profiles of isolated bacteria against five antibiotics (ceftazidime, cefpodoxime, cefotaxime, ertapenem and amoxicillin-clavulanate) and detection of ESBLs were done using disk diffusion and double-disc synergy tests. A total of 54 Gram-negative bacteria were isolated, including Salmonella spp. (9), Escherichia coli (15), Klebsiella spp. (7), Shigella spp. (5), Pseudomonas spp. (12) and Enterobacter spp. (6). Both Enterobacteriaceae and Pseudomonas isolates (31% and 66.6%, respectively) were resistant to all selected antibiotics except ertapenem (98% susceptibility). Overall, 77% isolates had multiple antibiotic resistance index (MARI) values, but none of the antibiotic-resistant isolates showed evidence of ESBL production. The presence of multiple antibiotic-resistant isolates in the effluent and receiving water of Lafenwa abattoir suggests a major risk to public health and food safety. Current methods of waste disposal at the abattoir are unacceptable and greatly reduce the qualities of the processed meat and contaminate the environment. There is a need for improved abattoir waste management and water treatment strategies.

Antibiotic-contaminated wastewater irrigated vegetables pose resistance selection risks to the gut microbiome

Wastewater reuse in food crop irrigation has led to agroecosystem pollution concerns and human health risks. However, there is limited attention on the relationship of sub-lethal antibiotic levels in vegetables and resistance selection. Most risk assessment studies show non-significant toxicity, but overlook the link between antibiotics in crops and propagation of gut microbiome resistance selection. The review highlights the risk of antibiotics in treated water used for irrigation, uptake, and accumulation in edible vegetable parts. Moreover, it elucidates the risks to the adaptive resistance selection of the gut microbiome from sub-lethal antibiotic levels, as a result of dietary contaminated vegetables. Experiments have reported that bacterial resistance selection is possible at concentrations that are several hundred-folds lower than lethal effect levels on susceptible cells. Consequently, mutants selected at low antibiotic levels, such as those from vegetables, are fitter and more resistant compared to those selected at high concentrations. Necessary standardization, such as the development of minimum acceptable antibiotic limits allowable in food crop irrigation water, with a focus on minimum selection concentration, and not only toxicity, has been proposed. Wastewater irrigation offers environmental benefits and can contribute to food security, but it has non-addressed risks. Research gaps, future perspectives, and frameworks of mitigating the potential risks are discussed.

Population-level surveillance of antibiotic resistance in Escherichia coli through sewage analysis

IntroductionThe occurrence of antibiotic resistance in faecal bacteria in sewage is likely to reflect the current local clinical resistance situation.AimThis observational study investigated the relationship between Escherichia coli resistance rates in sewage and clinical samples representing the same human populations.MethodsE. coli were isolated from eight hospital (n = 721 isolates) and six municipal (n = 531 isolates) sewage samples, over 1 year in Gothenburg, Sweden. An inexpensive broth screening method was validated against disk diffusion and applied to determine resistance against 11 antibiotics in sewage isolates. Resistance data on E. coli isolated from clinical samples from corresponding local hospital and primary care patients were collected during the same year and compared with those of the sewage isolates by linear regression.ResultsE. coli resistance rates derived from hospital sewage and hospital patients strongly correlated (r2 = 0.95 for urine and 0.89 for blood samples), as did resistance rates in E. coli from municipal sewage and primary care urine samples (r2 = 0.82). Resistance rates in hospital sewage isolates were close to those in hospital clinical isolates while resistance rates in municipal sewage isolates were about half of those measured in primary care isolates. Resistance rates in municipal sewage isolates were more stable between sampling occasions than those from hospital sewage.ConclusionOur findings provide support for development of a low-cost, sewage-based surveillance system for antibiotic resistance in E. coli, which could complement current monitoring systems and provide clinically relevant antibiotic resistance data for countries and regions where surveillance is lacking.

Adsorption Behavior of Polyelectrolyte onto Alumina and Application in Ciprofloxacin Removal

This study aims to investigate the adsorption behavior of a strong polyelectrolyte poly(styrenesulfonate) (PSS) onto alumina particles. Adsorption of PSS onto positively charged alumina surface increased with increasing ionic strength, indicating that non-electrostatic and electrostatic interaction controlled the adsorption. The removal of an emerging antibiotic ciprofloxacin (CFX) from water environment using PSS-modified alumina (PMA) was also studied. The removal of CFX using PMA was much higher than that using alumina particles without PSS modification in all pH ranges of 2–11. The removal of CFX reached 98% under the optimum conditions of pH 6, contact time of 120 min, adsorbent dosage of five milligrams per milliliter and ionic strength 10⁴-M NaCl. The adsorption isotherms of CFX at different salt concentrations fit well with a two-step adsorption model, while the adsorption kinetic fit well with a pseudo-second-order model with a good correlation coefficient (R² > 0.9969). The CFX-removal from a hospital wastewater using PMA was more than 75%. Our study demonstrates that adsorption of PSS onto alumina to modify the particle surface is important to form a novel adsorbent PMA for CFX-removal from water environments.

Antibiotic resistant and extended-spectrum β-lactamase producing faecal coliforms in wastewater treatment plant effluent

Wastewater treatment plants (WWTPs) provide optimal conditions for the maintenance and spread of antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs). In this work we describe the occurrence of antibiotic resistant faecal coliforms and their mechanisms of antibiotic resistance in the effluent of two urban WWTPs in Ireland. This information is critical to identifying the role of WWTPs in the dissemination of ARB and ARGs into the environment. Effluent samples were collected from two WWTPs in Spring and Autumn of 2015 and 2016. The bacterial susceptibility patterns to 13 antibiotics were determined. The phenotypic tests were carried out to identify AmpC or extended-spectrum β-lactamase (ESBL) producers. The presence of ESBL genes were detected by PCR. Plasmids carrying ESBL genes were transformed into Escherichia coli DH5α recipient and underwent plasmid replicon typing to identify incompatibility groups. More than 90% of isolated faecal coliforms were resistant to amoxicillin and ampicillin, followed by tetracycline (up to 39.82%), ciprofloxacin (up to 31.42%) and trimethoprim (up to 37.61%). Faecal coliforms resistant to colistin (up to 31.62%) and imipenem (up to 15.93%) were detected in all effluent samples. Up to 53.98% of isolated faecal coliforms expressed a multi-drug resistance (MRD) phenotype. AmpC production was confirmed in 5.22% of isolates. The ESBL genes were confirmed for 11.84% of isolates (9.2% of isolates carried bla_TEM, 1.4% bla_SHV-12, 0.2% bla_CTX-M-1 and 1% bla_CTX-M-15). Plasmids extracted from 52 ESBL isolates were successfully transformed into recipient E. coli. The detected plasmid incompatibility groups included the IncF group, IncI1, IncHI1/2 and IncA/C. These results provide evidence that treated wastewater is polluted with ARB and MDR faecal coliforms and are sources of ESBL-producing, carbapenem and colistin resistant Enterobacteriaceae.

Pulsed electric field application reduces carbapenem- and colistin-resistant microbiota and blaKPC spread in urban wastewater

Wastewater flows from metropolitan areas, especially those with healthcare inputs, can serve as transport reservoirs for the dissemination of clinically-relevant antimicrobial resistant bacteria (ARB) such as carbapenem- (CR) and colistin-resistant (CoR) strains. Pulsed electric field (PEF) is an emerging wastewater management tool for reducing bacterial loads without generating environmentally harmful byproducts, but it's ability to reduce ARB and their genetic determinants is not well reported. We collected 86, 10-L raw wastewater influent samples from a large metropolitan wastewater treatment plant in Columbus, Ohio and subjected them to low (34 kV cm^-1 for 67 μsec) and high (36 kV cm^-1 for 89 μsec) PEF treatment. We quantified the PEF effectiveness by measuring concentrations of total coliform bacteria, CR and CoR bacteria, and the epidemic carbapenemase gene, bla_KPC, before and after PEF treatment. Utilizing marginal linear regression models with generalized estimating equations, we observed that low and high PEF treatment resulted in a 1.94 (95% CI 2.06-1.81; P < 0.001) and 2.32 (95% CI 2.46-2.18; P < 0.001) log reduction of total coliform bacteria concentrations, respectively. Low and high PEF treatment produced similar log reductions between CR E. coli (2.01 (95% CI 2.15-1.86; P < 0.001); 2.14 (95% CI: 5.30-4.61; P < 0.001)) and CR Enterobacteriaceae concentrations (1.55 (95% CI 1.70-1.41; P < 0.001); 1.86 (95% CI 2.05-1.68; P < 0.001)), and resulted in a 1.15 log (95% CI 1.38-0.93, P < 0.001) and 1.28 log (95% CI 1.54-1.03, P < 0.001) reduction of absolute bla_KPC concentrations. Log CoR E. coli concentrations were reduced by 2.47 (95% CI 2.78-2.15; P < 0.001) and 2.52 (95% CI 2.91-2.15; P < 0.001) and CoR Enterobacteriaceae by 2.24 (95% CI 2.52-1.95; P < 0.001) and 2.50 (95% CI 2.89-2.11; P < 0.001) following low and high PEF application. PEF can be applied for wastewater management as an independent treatment method, particularly at critical control points, such as an on-site management of wastewater from hospitals or other healthcare facilities, or in series with other conventional methods to reduce total bacterial loads and concentrations of clinically-relevant ARB.

Winter is coming - Impact of temperature on the variation of beta-lactamase and mcr genes in a wastewater treatment plant

Wastewater treatment plants (WWTP) play a key role in the dissemination of antibiotic resistance and analyzing the abundance of antibiotic resistance genes (ARGs) and resistant bacteria is necessary to evaluate the risk of proliferation caused by WWTPs. Since few studies investigated the seasonal variation of antibiotic resistance, this study aimed to determine the abundance of beta-lactamase and mcr genes and to characterize phenotypic resistant strains in a WWTP in Germany over the seasons. Wastewater, sewage sludge and effluent samples were collected over a one year period and analyzed using quantitative real-time PCR. Resistant strains were isolated, followed by identification and antibiotic susceptibility testing using VITEK 2. The results show a significantly higher occurrence of nearly all investigated ARGs in the wastewater compared to sewage sludge and effluent. ARG abundance and temperature showed a negative correlation in wastewater and significant differences between ARG abundance during warmer and colder seasons were determined, indicating a seasonal effect. Co-occurrence of mcr-1 and carbapenemase genes in a multi-drug resistant Enterobacter cloacae and Escherichia coli producing extended-spectrum beta-lactamase (ESBL) was determined. To the best of our knowledge, this is the first detection of mcr-1, bla_VIM and bla_OXA-48 in an ESBL-producing E. coli. Although wastewater treatment reduced the abundance of ARGs and resistant strains, a dissemination into the river might be possible because carbapenemase-, CTX-M- and mcr-1-gene harboring strains were still present in the effluent.

Treatment enhances the prevalence of antibiotic-resistant bacteria and antibiotic resistance genes in the wastewater of Sri Lanka, and India

Wastewater treatment plants (WWTPs) are being debated for being the hot spots for the development of antibiotic resistance in pathogenic microbial communities. We observed the prevalence of antibiotic-resistant bacteria (ARB), antibiotic resistance genes (ARG), and multidrug resistance (MDR) in two municipal WWTPs and one hospital WWTP in Western and Southern Sri Lanka, and compared the results with particular reference to Indian and the World scenario to trace the imprints of treatment on ARB and ARG. Result suggests that although wastewater treatment resulted in higher than 1.06 log Escherichia coli (E. coli) reduction at all WWTPs, yet the percent of E. coli resistant to most of the antibiotics increased from influent to effluent. Higher prevalence of ARB, ARG, and MDR were noted in hospital WWTP owing to the higher antibiotic concentrations used and excreted by the patients. With reference to India, the WWTPs in Sri Lanka showed more ARB and a consistent increase in its percentages after the treatment but were less resistant to Fluoroquinolone (FQ). E. coli strains isolated from each location of both countries showed multidrug resistance, which has increased after the treatment and was strongly correlated with FQ in every WWTP. Resistant genes for Fluoroquinolone (FQ) (aac-(6')-1b-cr, qnrB, qnrS), β-lactams (ampC), and sulphonamides (sul1) were common in all the wastewaters except additional parC gene in the hospital effluent of Sri Lanka, implying much higher resistance for quinolones, especially for Ciprofloxacin. Multivariate statistical treatments suggest that effluent showed higher loadings and association for MDR/ARB, where pH change and more extensive interaction with metals during the treatment processes seem to have profound effects.

Principal component analysis exploring the association between antibiotic resistance and heavy metal tolerance of plasmid-bearing sewage wastewater bacteria of clinical relevance

This paper unravels the occurrence of plasmid-mediated antibiotic resistance in association with tolerance to heavy metals among clinically relevant bacteria isolated from sewage wastewater. The bacteria isolated were identified following conventional phenotypic and/or molecular methods, and were subjected to multiple-antibiotic resistance (MAR) profiling. The isolates were tested against the heavy metals Hg²⁺, Cd²⁺, Cr²⁺ and Cu²⁺. SDS-PAGE and agarose gel electrophoretic analyses were performed, respectively, for the characterization of heavy metal stress protein and R-plasmid among the isolated bacteria. Principal component analysis was applied in determining bacterial resistance to antibiotics and heavy metals. Both lactose-fermenting ( Escherichia coli ) and non-fermenting ( Acinetobacter baumannii and Pseudomonas putida ) Gram-negative bacterial strains were procured, and showed MAR phenotypes with respect to three or more antibiotics, along with resistance to the heavy metals Hg²⁺, Cd²⁺, Cr²⁺ and Cu²⁺. The Gram-positive bacteria, Enterococcus faecalis , isolated had 'ampicillin-kanamycin-nalidixic acid' resistance. The bacterial isolates had MAR indices of 0.3-0.9, indicating their ( E. faecalis , E. coli , A. baumannii and P. putida ) origin from niches with high antibiotic pollution and human faecal contamination. The Gram-negative bacteria isolated contained a single plasmid (≈54 kb) conferring multiple antibiotic resistance, which was linked to heavy metal tolerance; the SDS-PAGE analysis demonstrated the expression of heavy metal stress proteins (≈59 and ≈10 kDa) in wastewater bacteria with a Cd²⁺ stressor. The study results grant an insight into the co-occurrence of antibiotic resistance and heavy metal tolerance among clinically relevant bacteria in sewage wastewater, prompting an intense health impact over antibiotic usage.

Microbiology of hospital wastewater

The study of hospital wastewater (HWW) microbiology is important to understand the pollution load, growth of particular pathogenic microbes, shift and drift in microbial community, development and spread of antibiotic resistance in microbes, and subsequent change in treatment efficiencies. This chapter investigates the potential microbes such as bacteria, viruses, fungi, and parasites present in HWW along with the diseases associated and methods of treatment used. Due to the indiscriminate release of antibiotics from hospitals, HWW serves as a hotspot for emergence of antibiotic-resistance genes (ARGs) and antibiotic-resistance bacteria. This chapter discusses the ARGs occurrence in HWW, their prevalence in the environment, the molecular tools used for identification, and different mechanisms of horizontal gene transfer. Thus better understanding of the microbiology of HWW could further help in development of advanced treatment technologies for effective removal of microbes and their bioproducts (toxins and infectious nucleic acid) from HWW and contaminated water.

Antibiotic resistance genes identified in wastewater treatment plant systems - A review

The intensive use of antibiotics for human, veterinary and agricultural purposes, results in their continuous release into the environment. Together with antibiotics, antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARGs) are introduced into wastewater. Wastewater treatment plants (WWTPs) are believed to be probable hotspots for antibiotic resistance dissemination in the environment as they offer convenient conditions for ARB proliferation as well as for horizontal transfer of ARGs among different microorganisms. In fact, genes conferring resistance to all classes of antibiotics together with mobile genetic elements (MGEs) like plasmids, transposons, bacteriophages, integrons are detected in WWTPs in different countries. It seems that WWTPs with conventional treatment processes are capable of significant reduction of ARB but are not efficient in ARG removal. Implementation of advanced wastewater cleaning processes in addition to a conventional wastewater treatment is an important step to protect the aquatic environment. Growing interest in presence and fate of ARB and ARGs in WWTP systems resulted in the fact that knowledge in this area has increased staggeringly in the past few years. The main aim of the article is to collect and organize available data on ARGs, that are commonly detected in raw sewage, treated wastewater or activated sludge. Resistance to the antibiotics usually used in antibacterial therapy belonging to main classes like beta-lactams, macrolides, quinolones, sulfonamides, trimethoprim and tetracyclines was taken into account. The presence of multidrug efflux genes is also included in this paper. The occurrence of antibiotics may promote the selection of ARB and ARGs. As it is important to discuss the problem considering all aspects that influence it, the levels of antibiotics detected in influent and effluent of WWTPs were also presented.