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

Metagenomic insights into plasmid-mediated antimicrobial resistance in poultry slaughterhouse wastewater: antibiotics occurrence and genetic markers

Slaughterhouse wastewater represents important convergence and concentration points for antimicrobial residues, bacteria, and antibiotic resistance genes (ARG), which can promote antimicrobial resistance propagation in different environmental compartments. This study reports the assessment of the metaplasmidome-associated resistome in poultry slaughterhouse wastewater treated by biological processes, employing metagenomic sequencing. Antimicrobial residues from a wastewater treatment plant (WWTP) that treats poultry slaughterhouse influents and effluents were investigated through high-performance liquid chromatography coupled to tandem mass spectrometry (HPLC-MS/MS). Residues from the macrolide, sulfonamide, and fluoroquinolone classes were detected, the latter two persisting after the wastewater treatment. The genetic markers 16S rRNA rrs (bacterial community) and uidA (Escherichia coli) were investigated by RT-qPCR and the sul1 and int1 genes by qPCR. After treatment, the 16S rRNA rrs, uidA, sul1, and int1 markers exhibited reductions of 0.67, 1.07, 1.28, and 0.79 genes copies, respectively, with no statistical significance (p > 0.05). The plasmidome-focused metagenomics sequences (MiSeq platform (Illumina®)) revealed more than 100 ARG in the WWTP influent, which can potentially confer resistance to 14 pharmacological classes relevant in the human and veterinary clinical contexts, in which the qnr gene (resistance to fluoroquinolones) was the most prevalent. Only 7.8% of ARG were reduced after wastewater treatment, and the remaining 92.2% were associated with an increase in the prevalence of ARG linked to multidrug efflux pumps, substrate-specific for certain classes of antibiotics, or broad resistance to multiple medications. These data demonstrate that wastewater from poultry slaughterhouses plays a crucial role as an ARG reservoir and in the spread of AMR into the environment.

A Surveillance Study of Culturable and Antimicrobial-Resistant Bacteria in Two Urban WWTPs in Northern Spain

BACKGROUND/OBJECTIVES

Wastewater treatment plants (WWTPs) are hotspots for the spread of antimicrobial resistance into the environment. This study aimed to estimate the proportion of clinically relevant antimicrobial-resistant bacteria in two Spanish urban WWTPs, located in the region of La Rioja (Spain); Methods: Ninety-four samples (48 water/46 sludge) were collected and streaked on ten different selective media, in order to recover the culturable bacterial diversity with relevant resistance phenotypes: Extended-Spectrum β-Lactamase-producing Escherichia coli/Klebsiella pneumoniae (ESBL-Ec/Kp), Carbapenem-resistant Enterobacteriaceae (CR-E), Methicillin-resistant Staphylococcus aureus (MRSA), and Vancomycin-resistant Enterococcus faecium/faecalis (VR-E. faecium/faecalis). Isolates were identified by MALDI-TOF and were tested for antimicrobial susceptibility using the disk diffusion method. The confirmation of ESBL production was performed by the double-disk test; Results: A total of 914 isolates were recovered (31 genera and 90 species). Isolates with clinically relevant resistance phenotypes such as ESBL-Ec/Kp and CR-E were recovered in the effluent (0.4 × 100-4.8 × 101 CFU/mL) and organic amendment samples (1.0-101-6.0 × 102 CFU/mL), which are discharged to surface waters/agricultural fields. We reported the presence of VR-E. faecium in non-treated sludge and in the digested sludge samples (1.3 × 101-1 × 103 CFU/mL). MRSA was also recovered, but only in low abundance in the effluent (0.2 × 101 CFU/mL); Conclusions: This study highlights the need for improved wastewater technologies and stricter regulations on the use of amendment sludge in agriculture. In addition, regular monitoring and surveillance of WWTPs are critical for early detection and the mitigation of risks associated with the spread of antimicrobial resistance.

Characterization of bacterial resistance in treated hospital wastewater

This article seeks to characterize the bacterial profile of pediatric hospital wastewater samples collected at the outlet of a wastewater treatment plant, and to estimate their relative susceptibility to antimicrobial agents. A total of 64 strains were isolated in the wastewater samples, of which 49 were identified as belonging to different families: Enterobacteriaceae (e.g. Escherichia coli, Klebsiella sp., Citrobacter sp.) comprised 57.2% of the identified bacteria, non-Enterobacteriaceae (e.g. Aeromonas sp., Pseudomonas sp.) comprised 30.6%, and Streptococcaceae (e.g. Enterococcus sp.) comprised 12.2%. The tests of the susceptibility of the bacteria to the antimicrobial agents used in the hospital showed that 100% of the bacterial species found discharged in the hospital wastewater treatment system were resistant to one or more of the antimicrobial agents according to the criteria of the U.S. Clinical Laboratory Standards Institute/National Committee for Clinical Laboratory Standards. The antimicrobial agent tests showed that meropenem, norfloxacin, ciprofloxacin, levofloxacin, and cefepime were the most effective antimicrobials against bacteria of the Enterobacteriaceae family. For bacteria of the non-Enterobacteriaceae family, norfloxacin, ciprofloxacin, levofloxacin, and cefepime presented the most effective antimicrobial action, whereas for bacteria of the Streptococcaceae family, ampicillin, vancomycin, and gentamicin were the most effective antimicrobials. Hospital wastewater treatment plants could be considered as places of selection pressure for bacterial resistance because of the presence of antibiotic-resistant bacteria coming from sewers or created at the treatment plant.

[Health risks from crop irrigation with treated wastewater containing antibiotic residues, resistance genes, and resistant microorganisms]

This review describes the effects and potential health risks of resistant microorganisms, resistance genes, and residues of drugs and biocides that occur when re-using wastewater for crop irrigation. It focusses on specific aspects of these contaminants and their interactions, but does not provide a general risk assessment of the microbial load when using reclaimed water.Antimicrobial residues, antimicrobial resistant microorganisms, and resistance genes are frequently detected in treated wastewater. They have effects on the soil and plant-associated microbiota (total associated microorganisms) and can be taken up by plants. An interaction of residues with microorganisms is mainly expected before using the water for irrigation. However, it may also occur as a combined effect on the plant microbiome and all the abundant resistance genes (resistome). Special concerns are raised as plants are frequently consumed raw, that is, without processing that might reduce the bacterial load. Washing fruits and vegetables only has minor effects on the plant microbiome. On the other hand, cutting and other processes may support growth of microorganisms. Therefore, after such process steps, cooling of the foods is required.Further progress has to be made in the treatment of wastewater that will be used for crop irrigation with respect to removing micropollutants and microorganisms to minimize the risk of an increased exposure of consumers to transferable resistance genes and resistant bacteria.

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.

Hospital sanitary facilities on wards with high antibiotic exposure play an important role in maintaining a reservoir of resistant pathogens, even over many years

BACKGROUND

Hospitals with their high antimicrobial selection pressure represent the presumably most important reservoir of multidrug-resistant human pathogens. Antibiotics administered in the course of treatment are excreted and discharged into the wastewater system. Not only in patients, but also in the sewers, antimicrobial substances exert selection pressure on existing bacteria and promote the emergence and dissemination of multidrug-resistant clones. In previous studies, two main clusters were identified in all sections of the hospital wastewater network that was investigated, one K. pneumoniae ST147 cluster encoding NDM- and OXA-48 carbapenemases and one VIM-encoding P. aeruginosa ST823 cluster. In the current study, we investigated if NDM- and OXA-48-encoding K. pneumoniae and VIM-encoding P. aeruginosa isolates recovered between 2014 and 2021 from oncological patients belonged to those same clusters.

METHODS

The 32 isolates were re-cultured, whole-genome sequenced, phenotypically tested for their antimicrobial susceptibility, and analyzed for clonality and resistance genes in silico.

RESULTS

Among these strains, 25 belonged to the two clusters that had been predominant in the wastewater, while two others belonged to a sequence-type less prominently detected in the drains of the patient rooms.

CONCLUSION

Patients constantly exposed to antibiotics can, in interaction with their persistently antibiotic-exposed sanitary facilities, form a niche that might be supportive for the emergence, the development, the dissemination, and the maintenance of certain nosocomial pathogen populations in the hospital, due to antibiotic-induced selection pressure. Technical and infection control solutions might help preventing transmission of microorganisms from the wastewater system to the patient and vice versa, particularly concerning the shower and toilet drainage. However, a major driving force might also be antibiotic induced selection pressure and parallel antimicrobial stewardship efforts could be essential.

Prevalence and distribution of antimicrobial resistance in effluent wastewater from animal slaughter facilities: A systematic review

The extensive use of antibiotics in food animal production and disposal of untreated wastewater from food animal slaughter facilities may create a shift in microbiomes of different ecosystems by generating reservoirs of antimicrobial resistance along the human-animal-environmental interface. This epidemiological problem has been studied, but its magnitude and impact on a global scale is poorly characterised. A systematic review was done to determine global prevalence and distribution patterns of antimicrobial resistance in effluent wastewater from animal slaughter facilities. Extracted data were stratified into rational groups for secondary analyses and presented as percentages. Culture and sensitivity testing was the predominant method; Escherichia spp., Enterococcus spp., and Staphylococcus aureus were the most targeted isolates. Variable incidences of resistance were detected against all major antimicrobial classes including reserved drugs such as ceftazidime, piperacillin, gentamicin, ciprofloxacin, and chloramphenicol; the median frequency and range in resistant Gram-negative isolates were: 11 (0-100), 62 (0-100), 8 (0-100), 14 (0-93) and 12 (0-62) respectively. Ciprofloxacin was the most tested drug with the highest incidences of resistance in livestock slaughterhouses in Iran (93%), Nigeria (50%) and China (20%), and poultry slaughterhouses in Germany (21-81%) and Spain (56%). Spatial global distribution patterns for antimicrobial resistance were associated with previously reported magnitude of antibiotic use in livestock or poultry farming and, the implicit existence of jurisdictional policies to regulate antibiotic use. These data indicate that anthropogenic activities in farming systems are a major contributor to the cause and dissemination of antimicrobial resistance into the environment via slaughterhouse effluents.

PVDF/PLA electrospun fiber membrane impregnated with metal nanoparticles for emulsion separation, surface antimicrobial, and antifouling activities

Although many superwetting materials have been designed for the treatment of oil-containing wastewater, separation strategies for oil-in-water systems containing bacteria have rarely been reported. Herein, poly(vinylidene difluoride)- and poly(lactic acid)-blended fibrous membranes loaded with silver and copper oxide nanoparticles were successfully prepared by a two-step method of electrostatic spinning and liquid-phase synthesis. The product membrane showed excellent super-oleophilic properties in air and hydrophobicity under oil. It could separate water-in-oil emulsion systems containing surfactants with an efficiency above 90%. More importantly, the nanoparticle-loaded fibers were characterized by material degradability and slowly released ions. The fibers exhibited excellent antibacterial activities against both gram-positive and -negative bacteria. This work provides a feasible strategy for water-in-oil emulsion separation and bacterial treatment of wastewater.

Antibiotic concentrations in raw hospital wastewater surpass minimal selective and minimum inhibitory concentrations of resistant Acinetobacter baylyi strains

Antibiotics are essential for modern medicine, they are employed frequently in hospitals and, therefore, present in hospital wastewater. Even in concentrations, that are lower than the minimum inhibitory concentrations (MICs) of susceptible bacteria, antibiotics may exert an influence and select resistant bacteria, if they exceed the MSCs (minimal selective concentrations) of resistant strains. Here, we compare the MSCs of fluorescently labelled Acinetobacter baylyi strains harboring spontaneous resistance mutations or a resistance plasmid with antibiotic concentrations determined in hospital wastewater. Low MSCs in the μg/L range were measured for the quinolone ciprofloxacin (17 μg/L) and for the carbapenem meropenem (30 μg/L). A 24 h continuous analysis of hospital wastewater showed daily fluctuations of the concentrations of these antibiotics with distinctive peaks at 7-8 p.m. and 5-6 a.m. The meropenem concentrations were always above the MSC and MIC values of A. baylyi. In addition, the ciprofloxacin concentrations were in the range of the lowest MSC for about half the time. These results explain the abundance of strains with meropenem and ciprofloxacin resistance in hospital wastewater and drains.

Facultative pathogenic bacteria and antibiotic resistance genes in swine livestock manure and clinical wastewater: A molecular biology comparison

Manure contains vast amounts of biological contaminants of veterinary origin. Only few studies analyse clinically critical resistance genes against reserve antibiotics in manure. In general, resistances against these high priority antibiotics involve a high potential health risk. Therefore, their spread in the soil as well as the aquatic environment has to be prevented. Manures of 29 different swine livestock were analysed. Abundances of facultative pathogenic bacteria including representatives of the clinically critical ESKAPE-pathogens (P. aeruginosa, K. pneumoniae, A. baumannii, E. faecium) and E. coli were investigated via qPCR. Antibiotic resistance genes against commonly used veterinary antibiotics (ermB, tetM, sul1) as well as various resistance genes against important (mecA, vanA) and reserve antibiotics (bla_NDM, bla_KPC3, mcr-1), which are identified by the WHO, were also obtained by qPCR analysis. The manures of all swine livestock contained facultative pathogenic bacteria and commonly known resistance genes against antibiotics used in veterinary therapies, but more important also a significant amount of clinically critical resistance genes against reserve antibiotics for human medicine. To illustrate the impact the occurrence of these clinically critical resistance genes, comparative measurements were taken of the total wastewater of a large tertiary care hospital (n = 8). Both manure as well as raw hospital wastewaters were contaminated with significant abundances of gene markers for facultative pathogens and with critical resistance genes of reserve antibiotics associated with genetic mobile elements for horizontal gene transfer. Hence, both compartments bear an exceptional potential risk for the dissemination of facultative pathogens and critical antibiotic resistance genes.

Hospital wastewater treatment and the role of membrane filtration - removal of micropollutants and pathogens: A review

Dissemination of multiresistant bacteria and high concentrations of micropollutants by hospitals and other medical facilities can be significantly reduced by a wide variety of on-site treatment approaches. Membrane filtration technologies, ranging from microfiltration to reverse osmosis, have been adapted in many studies and offer multiple purposes in advanced wastewater treatment configurations. While the direct rejection of pharmaceutical compounds and pathogens can only be achieved with nanofiltration and reverse osmosis processes, porous membranes are known for their pathogen removal capabilities and can be used in combination with other advanced treatment approaches, such as oxidation and adsorption processes. This review was conducted to systematically assess studies with membrane filtration technologies that are used as either stand-alone or hybrid systems for the treatment of hospital wastewater. In this review, four different databases were screened with a pre-set of search strings to thoroughly investigate the application of membrane filtration technology in hospital wastewater treatment. Hybrid systems that combine multiple treatment technologies seem to be the most promising way of consistently removing micropollutants and pathogens from hospital wastewater, but additional economic assessments are needed for an extensive evaluation.

Identification of critical control points for antibiotic resistance discharge in sewers

Disrupting the spread of clinically relevant antibiotic resistance genes (ARGs) is one of the key components for the success of the One Health strategy. While waste water treatment plants (WWTPs) represent a final control point for daily discharges of antibiotic resistance genes (ARGs) to the aquatic environment, a decentralized upstream monitoring of wastewater feeds of selected urban drainage areas for bla_CTX-M32, bla_CTX-M15, bla_OXA48, bla_CMY-2, mecA, bla_NDM-1, bla_KPC3, vanA, and mcr-1 representing clinically relevant ARGs has been performed. Besides hospitals, also retirement homes were found to be responsible for high levels of ARG discharges compared to housing area sewer systems. The monitoring combines qPCR-based quantifications, flow volume-based analyses, and multiple antibiotic resistance analyses of isolates. As result of the study, local actions at identified critical control points could help to prevent contaminations of larger volumes of wastewaters. This strategy will support a more cost-effective treatment compared to central actions at WWTPs, only. A polluter-pays principle should be applied by this monitoring strategy.

An assessment of hospital wastewater and biomedical waste generation, existing legislations, risk assessment, treatment processes, and scenario during COVID-19

Hospitals release significant quantities of wastewater (HWW) and biomedical waste (BMW), which hosts a wide range of contaminants that can adversely affect the environment if left untreated. The COVID-19 outbreak has further increased hospital waste generation over the past two years. In this context, a thorough literature study was carried out to reveal the negative implications of untreated hospital waste and delineate the proper ways to handle them. Conventional treatment methods can remove only 50%-70% of the emerging contaminants (ECs) present in the HWW. Still, many countries have not implemented suitable treatment methods to treat the HWW in-situ. This review presents an overview of worldwide HWW generation, regulations, and guidelines on HWW management and highlights the various treatment techniques for efficiently removing ECs from HWW. When combined with advanced oxidation processes, biological or physical treatment processes could remove around 90% of ECs. Analgesics were found to be more easily removed than antibiotics, β-blockers, and X-ray contrast media. The different environmental implications of BMW have also been highlighted. Mishandling of BMW can spread infections, deadly diseases, and hazardous waste into the environment. Hence, the different steps associated with collection to final disposal of BMW have been delineated to minimize the associated health risks. The paper circumscribes the multiple aspects of efficient hospital waste management and may be instrumental during the COVID-19 pandemic when the waste generation from all hospitals worldwide has increased significantly.

Exploring kinetics, removal mechanism and possible transformation products of tigecycline by Chlorella pyrenoidosa

The accumulation of antibiotics in wastewater leads to broad antibiotic resistance, threating human health. Microalgae have been receiving attention due to their ability to remove antibiotics from wastewater. Tigecycline (TGC) is a broad-spectrum glycylcycline antibiotic. It has not been investigated for removal by microalgae. The removal kinetics of TGC by Chlorella pyrenoidosa were evaluated under different initial dry cell densities, TGC concentrations, temperatures and light intensity conditions. Approximately 90% of TGC could be removed when the TGC concentration was 10 mg∙L^-1 and the initial dry cell density was more than 0.2 g∙L^-1. A low value of TGC per g dry cell weight ratio led to a high removal efficiency of TGC. The initial dry cell density of microalgae was also critical for the removal of TGC. A high initial dry cell density is better than a low initial dry cell density to remove TGC when the ratio of the TGC concentration to dry cell weight are the same at the beginning of the cultivation. The removal mechanisms were investigated. Photolysis was a slow process that did not lead to removal at the beginning. Adsorption, hydrolysis, photolysis and biodegradation by microalgae were the main contributors to the removal of TGC. TGC was easily hydrolyzed under high -temperature conditions. Three transformation products of TGC by microalgae were identified. The stability of TGC was evaluated in water and salt solutions of citric acid, K₂HPO₄·3H₂O and ferric ammonium citrate. TGC was stable in ultrapure water and citric acid solution. TGC was hydrolyzed in K₂HPO₄·3H₂O and ferric ammonium citrate solutions.

High burden and diversity of carbapenemase-producing Enterobacterales observed in wastewater of a tertiary care hospital in Germany

Hospitals are one of the main reservoirs of multi-resistant Enterobacterales (MRE). As MRE are resistant to the most frequently used antibiotics, therapy for patients with MRE infections is challenging. It has been previously described that MRE from hospital wastewater can pass into municipal wastewater and even surface water. In this study, we investigated the diversity and epidemiology of MRE in the wastewater of a large tertiary care hospital. Wastewater samples were collected for a four-day period and tested for the presence of Enterobacterales resistant to 3rd gen. cephalosporins. Representative isolates were further characterized by whole genome sequencing. In 120 β-glucuronidase-producing isolates, 68 Escherichia coli and, interestingly, also 52 Citrobacter freundii were identified. In 120 β-glucosidase-producing isolates 45 Serratia marcescens, 34 Klebsiella oxytoca, 32 Enterobacter cloacae and 9 Klebsiella pneumoniae were observed. For all species various MLST sequence types and different clusters of resistance genes were determined, showing a great diversity within the different Enterobacterales, further corroborated by clonal analysis performed by cgMLST. The most prominent clone was wastewater associated E. coli ST635, which accounted for 47.1% of all E. coli isolates. Interestingly, 45.6% of E. coli, 88.5% of C. freundii, 95.6% of S. marcescens, 91.2% of K. oxytoca, 96.9% of E. cloacae and 88.9% of K. pneumoniae isolates carried a carbapenemase gene, indicating a high burden with carbapenemase-producing Enterobacterales. Comparison with clinical isolates from the same hospital displayed few clonal matches. One wastewater isolate of K. pneumoniae was identified to be closely related compared to a clone that had been introduced into the hospital during an outbreak four years earlier. One E. coli isolate was identified as identical to an isolate from a patient, with inpatient stay during the sampling period. The data obtained in this study highlight the problem of antibiotic resistance of Enterobacterales in hospital wastewater. In particular, the clustered occurrence of carbapenemase genes is of great concern and underscores the problem of increasingly scarce antibiotic options against these bacteria.

Landscape of genes in hospital wastewater breaking through the defense line of last-resort antibiotics

Hospital wastewater contains abundant antibiotics, antibiotic resistance genes (ARGs), and pathogens. Last-resort antibiotic resistance genes (LARGs) include the New Delhi metallo-β-lactamase gene blaNDM, mobile colistin resistance gene mcr and tigecycline resistance gene tet(X) which confers resistance to carbapenems, colistin and tigecycline. The presence and significance of LARGs in hospital wastewater treatment systems (HWTS) have not yet been systematically explored. Here, LARG variants were shown to be prevalent both influents and effluents of HWTS. A total of 989 Enterobacteriaceae isolates that confer resistance to last-resort antibiotics were collected from effluents and multiple genetic contexts of LARGs were analyzed. LARGs-carrying plasmids were confirmed to show high multidrug phenotypes and transferability. We also discovered the co-occurrence of plasmids harboring blaNDM-1 and mcr-1 in single Escherichia coli, as well as E. coli HM016 containing two unique mcr-1-carrying plasmids. This result might accelerate co-dissemination of LARGs under environmental selection pressure. Different core genetic arrangements in these strains suggest several evolutionary pathways in HWTS. The resistance functions of LARGs were confirmed in vitro and in vivo by mass spectrometry. This study provides novel insights into the diversity, genetic context and function of critical ARGs in HWTS. The results raise the concern that LARGs may further spread into the environment, thus, more stringent discharge standards and regulations for hospital wastewater are urgently needed.

Dissemination of carbapenem resistant bacteria from hospital wastewater into the environment

Infections with antibiotic resistant pathogens threaten lives and cause substantial costs. For effective interventions, knowledge of the transmission paths of resistant bacteria to humans is essential. In this study, carbapenem resistant bacteria were isolated from the wastewater of a maximum care hospital during a period of two years, starting in the patient rooms and following the sewer system to the effluent of the wastewater treatment plant (WWTP). The bacteria belonged to six different species and 44 different sequence types (STs). The most frequent STs, ST147 K. pneumoniae (bla_NDM/bla_OXA-48) and ST235 P. aeruginosa (bla_VIM) strains, were present at nearly all sampling sites from the hospital to the WWTP effluent. After core genome multi-locus sequence typing (cgMLST), all ST147 K. pneumoniae strains presented a single epidemiological cluster. In contrast, ST235 P. aeruginosa formed five cgMLST clusters and the largest cluster contained the strain from the WWTP effluent, indicating without doubt, a direct dissemination of both high-risk clones into the environment. Thus, there are - at least two - possible transmission pathways to humans, (i) within the hospital by contact with the drains of the sanitary installations and (ii) by recreational or irrigation use of surface waters that have received WWTP effluent. In conclusion, remediation measures must be installed at both ends of the wastewater system, targeting the drains of the hospital as well as at the effluent of the WWTP.

Updates on the global dissemination of colistin-resistant Escherichia coli: An emerging threat to public health

Colistin drug resistance is an emerging public health threat worldwide. The adaptability, existence and spread of colistin drug resistance in multiple reservoirs and ecological environmental settings is significantly increasing the rate of occurrence of multidrug resistant (MDR) bacteria such as Escherichia coli (E. coli). Here, we summarized the reports regarding molecular and biological characterization of mobile colistin resistance gene (mcr)-positive E. coli (MCRPEC), originating from diverse reservoirs, including but not limited to humans, environment, waste water treatment plants, wild, pets, and food producing animals. The MCRPEC revealed the abundance of clinically important resistance genes, which are responsible for MDR profile. A number of plasmid replicon types such as IncI2, IncX4, IncP, IncX, and IncFII with a predominance of IncI2 were facilitating the spread of colistin resistance. This study concludes the distribution of multiple sequence types of E. coli carrying mcr gene variants, which are possible threat to "One Health" perspective. In addition, we have briefly explained the newly known mechanisms of colistin resistance i.e. plasmid-encoded resistance determinant as well as presented the chromosomally-encoded resistance mechanisms. The transposition of ISApl1 into the chromosome and existence of intact Tn6330 are important for transmission and stability for mcr gene. Further, genetic environment of co-localized mcr gene with carbapenem-resistance or extended-spectrum β-lactamases genes has also been elaborated, which is limiting human beings to choose last resort antibiotics. Finally, environmental health and safety control measures along with spread mechanisms of mcr genes are discussed to avoid further propagation and environmental hazards of colistin resistance.

A review on non-thermal plasma treatment of water contaminated with antibiotics

Large amounts of antibiotics are produced and consumed worldwide, while wastewater treatment is still rather inefficient, leading to considerable water contamination. Concentrations of antibiotics in the environment are often sufficiently high to exert a selective pressure on bacteria of clinical importance that increases the prevalence of resistance. Since the drastic reduction in the use of antibiotics is not envisaged, efforts to reduce their input into the environment by improving treatment of contaminated wastewater is essential to limit uncontrollable spread of antibiotic resistance. This paper reviews recent progress on the use of non-thermal plasma for the degradation of antibiotics in water. The target compounds removal, the energy efficiency and the mineralization are analyzed as a function of discharge configuration and the most important experimental parameters. Various ways to improve the plasma process efficiency are addressed. Based on the identified reaction intermediates, degradation pathways are proposed for various classes of antibiotics and the degradation mechanisms of these chemicals under plasma conditions are discussed.

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.

Silver, copper and copper oxide nanoparticles in the fight against human viruses: progress and perspectives

The rapid development of nanomedicine has created a high demand for silver, copper and copper oxide nanoparticles. Due to their high reactivity and potent antimicrobial activity, silver and copper-based nanomaterials have been playing an important role in the search for new alternatives for the treatment of several issues of concern, such as pathologies caused by bacteria and viruses. Viral diseases are a significant and constant threat to public health. The most recent example is the pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). In this context, the object of the present review is to highlight recent progress in the biomedical uses of these metal nanoparticles for the treatment and prevention of human viral infections. We discuss the antiviral activity of AgNPs and Cu-based NPs, including their actions against SARS-CoV-2. We also discuss the toxicity, biodistribution and excretion of AgNPs and CuNPs, along with their uses in medical devices or on inert surfaces to avoid viral dissemination by fomites. The challenges and limitations of the biomedical use of these nanoparticles are presented.

Clinically relevant antibiotic-resistant bacteria in aquatic environments - An optimized culture-based approach

The emergence of antibiotic-resistant clinically relevant facultative pathogenic bacteria in the environment has become one of the most important global health challenges. Antibiotic-resistant bacteria (ARB) have been found in surface waters and wastewater treatment plants. Drinking water guidelines and the EU bathing water directive 2006/7/EC include the surveillance of defined microbiological parameters on species level, while the monitoring of ARB is missing in all existing guidelines. However, standardized methods for the detection of ARB exist for clinical investigations of human materials only. They are based on cultivation on selective agar plates. These methods cannot be used directly for environmental samples, because of the high amount and diversity of bacterial background flora which interferes with the detection of human-relevant ARB. The aim of this study was to introduce a proposal for future normative standard operation procedures, with international relevance, for the culture-based detection of clinically-relevant antibiotic resistant bacteria in aquatic environmental samples like wastewater and surface water: gram-negative bacteria resistant against 3rd generation cephalosporins (ESBL) and against carbapenems (CARBA), gram-positive vancomycin-resistant enterococci (VRE) and methicillin-resistant Staphylococcus aureus (MRSA). The final adaptation of standardized cultivation methods included increasing the standard incubation temperature from 36 °C to 42 °C, which effectively inhibits the environmental background flora on agar plates while the desired target species survive. This enables the detection of target species in suitable sample volumes. Putative target colonies which belong to the remaining background flora had to be excluded by morphological and physiological differentiation. Therefore, a time and cost optimized testing scheme with good performance was developed, which allows an effective exclusion of non-target isolates in samples. Depending on the target species and sample type, sensitivity of up to 100% is achieved, and specificity ranges from 91.1% to 99.7%, while the positive predictive value, negative predicted value and accuracy rate are always >90%.