Occurrence and diversity of antibiotic resistance in untreated hospital wastewater

Deciphering the profiles and hosts of antibiotic resistance genes and evaluating the risk assessment of general and non-general hospital wastewater by metagenomic sequencing

Hospital wastewater (HWW) is a substantial environmental reservoir of antibiotic resistance genes (ARGs) and poses risks to public health and aquatic ecosystems. However, research on the diversity, transmission mechanisms, pathogenic hosts, and risks of ARGs in different HWW types is limited. This study involved the collection of HWW samples from 15 hospitals in Hefei, China, which were subsequently categorized as general hospitals (GHs) and non-general hospitals (NGHs). A 280.28-Gbp sequencing dataset was generated using a metagenomic sequencing strategy and analyzed using metagenomic assembly and binning approaches to highlight these issues in GHs and NGHs. Results showed significant differences between GHs and NGHs in ARG distribution, microbial community composition, and hosts of ARGs. Potential pathogens such as Rhodocyclaceae bacterium ICHIAU1 and Acidovorax caeni were more abundant in GHs. Furthermore, plasmid-mediated ARGs (45.21%) were more prevalent than chromosome-mediated ARGs (25.74%) in HWW, with a significantly higher proportion of plasmid-mediated ARGs in GHs compared to NGHs. The co-occurrence of ARGs and mobile genetic elements was more frequent in GHs. Additionally, the antibiotic resistome risk index was higher in GHs (38.73 ± 12.84) than NGHs (22.53 ± 11.80), indicating a greater risk of ARG transmission in GHs. This pioneering study provides valuable insights into the transmission mechanisms and hosts of ARGs in hospital settings, emphasizing the increased risk of ARG transmission in GHs.

The effect of sample type and location on industrial workplace sink and hand dryer microbiomes

One major issue in tackling antimicrobial resistance (AMR) is the ability to effectively track resistance spread in environments where surveillance is limited. Such environments include those experiencing high volumes of hand washing and drying from multiple users. This study characterised the microbial populations and antimicrobial resistomes of two different sample types from a pharmaceutical industrial site as part of an AMR environmental surveillance programme. Paired samples were collected from hand dryers and adjacent sinks in distinct sampling locations: from toilets adjacent to 'wet' labs, and locations associated with 'dry' activities. Microbial populations in hand dryers were significantly different to those of sinks, whereas there was no significant difference based on sample location. The opposite effect was observed for resistomes, where profiles differed significantly based on sample location, but not sample type. When both sample type and location were considered together, differences in microbiomes were driven primarily by hand dryer profiles from different locations. Analysis of metagenomically-assembled genomes revealed the presence of many poorly characterised organisms, and suggested no specific families predominated in terms of ARG carriage. This study emphasises the impact of human activities in determining the resistome of commonly used appliances, and the need for continued AMR surveillance programmes.

Drug resistant Klebsiella pneumoniae from patients and hospital effluent: a correlation?

BACKGROUND

The application of wastewater-based epidemiology has gained traction as a cost effective tool in antimicrobial resistance (AMR) surveillance with studies showing a correlation between the presence of resistant bacteria from hospital sewage and patients. This study compared Klebsiella pneumoniae from patients and hospital effluent in terms of antibiotic resistance patterns, antibiotic resistance genes (ARGs), mobile genetic elements (MGEs) and phylogenomic relationships.

RESULTS

Pooled effluent samples were collected from the final effluent point of a regional hospital and K. pneumoniae isolates were identified on selective media. Clinical isolates were also collected from the same hospital. Antimicrobial susceptibility testing (AST) was performed using the VITEK® 2 system. DNA was extracted prior to whole genome sequencing (WGS). The resistome, mobilome, and phylogenetic lineages of sequenced isolates were assessed using bioinformatics analysis. A total of 10 randomly selected presumptive and 10 clinical K. pneumoniae constituted the sample and were subjected to AST. Total resistance was observed in the clinical samples to cefuroxime, cefotaxime, piperacillin/tazobactam, gentamicin, tobramycin and trimethoprim/sulfamethoxazole. The effluent isolates exhibited total susceptibility to most antibiotics but showed resistance to amoxicillin/clavulanic acid and piperacillin/tazobactam (100%), and tigecycline (10%). The effluent isolates did not exhibit a diverse resistome, while the clinical isolates harboured genes conferring resistance to aminoglycoside (aph(6)-Id, aph(3'')-Ib, aac(6')-Ib-cr, aadA16), ß-lactam (blaSVH group, blaOXA group, blaTEM group), and fluoroquinolone (oqxA, oqxB) antibiotics. Only class 1 integrons were identified. Phylogenetic analysis revealed that effluent isolates from this study were not closely related to the clinical isolates.

CONCLUSION

This study showed no correlation between the resistance profiles of the clinical and effluent isolates. The relationship between AMR in hospital effluent and clinical resistance may depend on the antimicrobial agents and bacterial species studied.

Degradation and Deactivation of Intracellular Bacterial Antibiotic Resistance Genes by Commonly Used Healthcare and Personal Care Disinfectants

This work investigated efficacies of commonly used healthcare and personal care disinfectants, including glutaraldehyde, chlorhexidine, ethanol, povidone-iodine, benzalkonium chloride, phenol, free chlorine, hydrogen peroxide (H2O2), and 254 nm UV light, in degrading (as measured by qPCR analyses of ∼1000 bp amplicon loss) and deactivating (as measured by transforming activity loss) bacterial antibiotic resistance genes (ARGs) during inactivation of antibiotic-resistant bacteria (ARB) on inanimate surfaces or in aqueous suspension. Intracellular ARGs (iARGs) blt, mecA, and ampC, within vegetative cells of Bacillus subtilis, Staphylococcus aureus, and Pseudomonas aeruginosa, respectively, were treated on PTFE and/or stainless-steel surfaces or in aqueous phosphate buffer (PB; H2O2 only), to simulate potential healthcare and personal care cleaning applications under representative disinfectant exposure conditions. No chemical disinfectant yielded more than limited (≤1.9log10) iARG degradation/deactivation under the conditions investigated, even when ARB cells were extensively inactivated (at levels from 3.1log10 to ≥6log10). In contrast, UV irradiation yielded up to ∼2.8-3.2log10 iARG degradation/deactivation at corresponding ARB inactivation levels up to ∼4log10 in the case of the blt gene within B. subtilis cells on PTFE surfaces, though levels of iARG degradation/deactivation and ARB inactivation were generally lower than expected based on prior aqueous-phase results, likely due to light-shielding effects at the typical ∼108-109 CFU/mL cell inoculum densities used for surface disinfection tests. During exposure to H2O2 in PB, iARG deactivation and ARB inactivation reached up to 1.7log10 and >3.5log10, respectively, while iARG degradation was minimal (≤0.2log10); this appears to be driven by DNA-strand fragmentation (as observed by pulsed-field gel electrophoresis analysis) likely resulting from reaction with endogenous HO• (or Fe(IV)) generated via intracellular iron-catalyzed H2O2 decomposition. While all investigated disinfectants were able to effectively inactivate ARB cells themselves, these results demonstrate that most are ineffective in simultaneously degrading and deactivating iARGs, highlighting the potential benefits of employing disinfectants such as 254 nm UV light, that selectively target bacterial DNA, to improve mitigation of antibiotic resistance dissemination.

Sludge water: a potential pathway for the spread of antibiotic resistance and pathogenic bacteria from hospitals to the environment

Hospitals play an important role in the spread of antibiotic resistance genes (ARGs) and antimicrobial resistance (AMR). The ARGs present in hospital wastewater tend to accumulate in activated sludge, with different ARGs exhibiting varying migration rates. As a result, sludge water produced during the activated sludge treatment process may be a significant source of ARGs entering the environment. Despite this, research into the behavior of ARGs during sludge concentration and dewatering remains limited. This study hypothesizes that ARGs might exhibit new behaviors in sludge water during sludge concentration. Using metagenomic analysis, we explored the distribution and migration risks of ARGs and human pathogenic bacteria (HPB) in sludge water, comparing them with those in hospital wastewater. The findings reveal a strong correlation between ARGs in sludge water and hospital wastewater, with subtypes such as arlR, efpA, and tetR showing higher abundance in sludge water. Although the horizontal gene transfer potential of ARGs is greater in hospital wastewater than in sludge water, the resistance mechanisms and migration pathways are similar even when their HPB host associations differ. ARGs in both environments are primarily transmitted through coexisting mobile genetic elements (MGEs). This suggests that sludge water serves as a critical route for the release of hospital-derived ARGs into the environment, posing potential threats to public health and ecological safety.

Dynamic interaction of antibiotic resistance between plant microbiome and organic fertilizers: sources, dissemination, and health risks

Antibiotic resistance is a global health problem driven by the irrational use of antibiotics in different areas (such as agriculture, animal farming, and human healthcare). Sub-lethal concentrations of antibiotic residues impose selective pressure on environmental, plant-associated, and human microbiome leading to the emergence of antibiotic-resistant bacteria (ARB). This review summarizes all sources of antibiotic resistance in agricultural soils (including manure, sewage sludge, wastewater, hospitals/pharmaceutical industry, and bioinoculants). The factors (such as the physicochemical properties of soil, root exudates, concentration of antibiotic exposure, and heavy metals) that facilitate the transmission of resistance in plant microbiomes are discussed. Potential solutions for effective measures and control of antibiotic resistance in the environment are also hypothesized. Manure exhibits the highest antibiotics load, followed by hospital and municipal WW. Chlortetracycline, tetracycline, and sulfadiazine have the highest concentrations in the manure. Antibiotic resistance from organic fertilizers is transmitted to the plant microbiome via horizontal gene transfer (HGT). Plant microbiomes serve as transmission routes of ARB and ARGS to humans. The ingestion of ARB leads to human health risks (such as ineffectiveness of medication, increased morbidity, and mortality).

Removal of antibiotics in constructed wetlands: a review and bibliometric analysis

This study offers a comprehensive systematic review on the removal of antibiotics in Constructed Wetlands (CWs), evaluating their efficacy as an alternative to conventional wastewater treatment methods. Data from 82 articles were analyzed, focusing on removal rates, antibiotic types, and system configurations, including scale, vegetation, sediment, flow, hydraulic retention time (HRT), and hydraulic loading rate (HLR). The findings indicate that full-scale CWs, particularly those utilizing vegetation like Cyperus alternifolius L. and materials such as shells, zeolites, medicinal stone, and ceramics, achieved removal rates exceeding 90% for various antibiotics. The study underscores the importance of optimizing both anaerobic and aerobic conditions to enhance removal efficiency, noting that aerobic environments promote oxidative processes effective for β-lactams, while anaerobic environments facilitate reduction processes beneficial for sulfonamides. Hybrid systems combining these zones demonstrated maximal removal efficiency. This review advances the understanding of antibiotic removal in CWs, presenting them as a viable, sustainable solution to mitigate environmental impacts, preserve water quality, and protect public health. Further research is recommended to explore the impact of root types and bed configurations on removal efficiency.

Is there a role for intestinal sporobiota in the antimicrobial resistance crisis?

Antimicrobial resistance (AMR) is a complex issue requiring specific, multi-sectoral measures to slow its spread. When people are exposed to antimicrobial agents, it can cause resistant bacteria to increase. This means that the use, misuse, and excessive use of antimicrobial agents exert selective pressure on bacteria, which can lead to the development of "silent" reservoirs of antimicrobial resistance genes. These genes can later be mobilized into pathogenic bacteria and contribute to the spread of AMR. Many socioeconomic and environmental factors influence the transmission and dissemination of resistance genes, such as the quality of healthcare systems, water sanitation, hygiene infrastructure, and pollution. The sporobiota is an essential part of the gut microbiota that plays a role in maintaining gut homeostasis. However, because spores are highly transmissible and can spread easily, they can be a vector for AMR. The sporobiota resistome, particularly the mobile resistome, is important for tracking, managing, and limiting the spread of antimicrobial resistance genes among pathogenic and commensal bacterial species.

Recent advances in nanocellulose-based adsorbent for sustainable removal of pharmaceutical contaminants from water bodies: A review

The long-term presence of pharmaceutical pollution in water bodies has raised public awareness. Nanocellulose is often used in adsorption to remove pollutants from wastewater since it is an abundant, green and sustainable material. This paper offers an extensive overview of the recent works reporting the potential of nanocellulose-based adsorbents to treat pharmaceutical wastewater. This study distinguishes itself by not only summarizing recent research findings but also critically integrating discussions on the improvements in nanocellulose production and sorts of alterations based on the type of pharmaceutical contaminants. Commonly, charged, or hydrophobic characteristics are introduced onto nanocellulose surfaces to accelerate and enhance the removal of pharmaceutical compounds. Although adsorbents based on nanocellulose have considerable potential, several significant challenges impede their practical application, particularly concerning cost and scalability. Large-scale synthesis of nanocellulose is technically challenging and expensive, which prevents its widespread use in wastewater treatment plants. Continued innovation in this area could lead to breakthroughs in the practical application of nanocellulose as a superior adsorbent. The prospects of utilization of nanocellulose are explained, providing a sustainable way to address the existing restriction and maximize the application of the modified nanocellulose in the field of pharmaceutical pollutants removal.

Integrative metagenomic dissection of last-resort antibiotic resistance genes and mobile genetic elements in hospital wastewaters

Hospital wastewater is a critical source of antimicrobial resistance (AMR), which facilitates the proliferation and spread of clinically significant antimicrobial resistance genes (ARGs) and pathogenic bacteria. This study utilized metagenomic approaches, including advanced binning techniques, such as MetaBAT2, MaxBin2, and CONCOCT, which offer significant improvements in accuracy and completeness over traditional binning methods. These methods were used to comprehensively assess the dynamics and composition of resistomes and mobilomes in untreated wastewater samples taken from two general hospitals and one cancer hospital. This study revealed a diverse bacterial landscape, largely consisting of Proteobacteria, Firmicutes, Bacteroidetes, and Actinobacteria, with notable variations in microbial composition among hospitals. Analysis of the top 15 genera showed unique microbial pattern distribution in each hospital: Aeromonas was predominant in 1stHWTS (49.39 %), Acidovorax in the CAHWTS at 16.85 %, and Escherichia and Bacteroides in the 2ndHWTS at 11.44 % and 11.33 %, respectively. A total of 114 pathogenic bacteria were identified, with drug-resistant Aeromonas caviae and Escherichia coli being the most prevalent. The study identified 34 types and 1660 subtypes of ARGs, including important last-resort antibiotic resistance genes (LARGs), such as blaNDM, mcr, and tet(X). Using metagenomic binning, this study uncovered distinct patterns of host-resistance associations, particularly with Proteobacteria and Firmicutes. Network analysis highlighted the complex interactions among ARGs, mobile genetic elements (MGEs), and bacterial species, all contributing to the dissemination of AMR. These findings emphasize the intricate nature of AMR in hospital wastewater and the influence of hospital-specific factors on microbial resistance patterns. This study provides support for implementing integrated management strategies, including robust surveillance, advanced wastewater treatment, and strict antibiotic stewardship, to control the dissemination of AMR. Understanding the interplay among bacterial communities, ARGs, and MGEs is important for developing effective public health measures against AMR.

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.

Comprehensive analysis of distribution characteristics and horizontal gene transfer elements of blaNDM-1-carrying bacteria

The worldwide dissemination of New Delhi metallo-β-lactamase-1 (NDM-1), which mediates resistance to almost all clinical β-lactam antibiotics, is a major public health problem. The global distribution, species, sources, and potential transfer risk of blaNDM-1-carrying bacteria are unclear. Results of a comprehensive analysis of literature in 2010-2022 showed that a total of 6002 blaNDM-1 carrying bacteria were widely distributed around 62 countries with a high trend in the coastal areas. Opportunistic pathogens or pathogens like Klebsiella sp., Escherichia sp., Acinetobacter sp. and Pseudomonas sp. were the four main species indicating the potential microbial risk. Source analysis showed that 86.45 % of target bacteria were isolated from the source of hospital (e.g., Hospital patients and wastewater) and little from surface water (5.07 %) and farms (3.98 %). A plasmid-encoded blaNDM-1Acinetobacter sp. with the resistance mechanisms of antibiotic efflux pump, antibiotic target change and antibiotic degradation was isolated from the wastewater of a typical tertiary hospital. Insertion sequences (IS3 and IS30) located in the adjacent 5 kbp of blaNDM-1-bleMBL gene cluster indicating the transposon-mediated horizontal gene transfer risk. These results showed that the worldwide spread of blaNDM-1-carrying bacteria and its potential horizontal gene transfer risk deserve good control.

Hospital wastewater treatment methods and its impact on human health and environments

The scientific development and economic advances have led to the identification of many pathogenic agents in hospital effluents. Hospital wastewaters are qualitatively similar to municipal wastewaters, with the difference that these wastewaters contain toxic and infectious substances and compounds that can be dangerous for the health of the environment, employees of these centers, and the entire community. Therefore, in the last few years, it has been emphasized that all hospitals and medical and health centers should have a treatment facility for their produced wastewater so that the health of the society and people is not threatened. An issue that is not paid attention to has become one of the environmental problems and concerns of the world today. The present study focused on the investigate hospital wastewater treatment methods and its impact on human health and the environment. In this narrative study, the first literature search was performed with four hundred and twenty-three articles were retrieved based on PubMed, Elsevier, Web of science, Spring, and Google Scholar databases. The results of this study showed that wastewater from hospitals and medical centers can play a significant impress in polluting soil and aquatic environments and spreading infectious diseases. According to the mentioned contents, collection and treatment of hospital wastewater is essential. In addition, if hospital wastewater enters the wastewater collection network without knowing its characteristics or with incomplete treatment and finally enters the municipal wastewater treatment plant. It causes many problems, including disturbing the balance of the biological system of the treatment plant. Purification and disposal of hospital wastewater is considered a vital action based on environmental standards. The results of this study also showed that the treatment methods of this type of hospital wastewater can play a significant role in reducing the spread of diseases caused by hospital wastewater treatment, including infectious diseases. The results of this study can be very useful for politicians, the managers of the Ministry of Energy and Health and the Environmental Organization in choosing the appropriate methods and process to reduce hospital wastewater and increase the efficiency of hospital wastewater treatment plants.

A review on hazards and treatment methods of released antibiotics in hospitals wastewater during the COVID-19 pandemic

Drugs and related goods are widely used in order to promote public health and the quality of life. One of the most serious environmental challenges affecting public health is the ongoing presence of antibiotics in the effluents generated by pharmaceutical industries and hospitals. Antibiotics cannot be entirely removed from wastewater using the traditional wastewater treatment methods. Unmetabolized antibiotics generated by humans can be found in urban and livestock effluent. The antibiotic present in effluent contributes to issues with resistance to antibiotics and the creation of superbugs. Over the recent 2 years, the coronavirus disease 2019 pandemic has substantially boosted hospital waste volume. In this situation, a detailed literature review was conducted to highlight the harmful effects of untreated hospital waste and outline the best approaches to manage it. Approximately 50 to 70% of the emerging contaminants prevalent in the hospital wastewater can be removed using traditional treatment strategies. This paper emphasizes the numerous treatment approaches for effectively eliminating emerging contaminants and antibiotics from hospital wastewater and provides an overview of global hospital wastewater legislation and guidelines on hospital wastewater administration. Around 90% of ECs might be eliminated by biological or physical treatment techniques when used in conjunction with modern oxidation techniques. According to this research, hybrid methods are the best approach for removing antibiotics and ECs from hospital wastewater. The document outlines the many features of effective hospital waste management and might be helpful during and after the coronavirus disease 2019 outbreak, when waste creation on all hospitals throughout the globe has considerably increased.

Extended-spectrum β-lactamase-producing bacteria and their resistance determinants in different wastewaters and rivers in Nepal

Wastewaters serve as significant reservoirs of antibiotic resistant bacteria. Despite the evidence of antimicrobial resistance in wastewaters and river water in Kathmandu, direct linkage between them is not discussed yet. This study investigated the prevalence of extended-spectrum β-lactamase (ESBL)-producing bacteria and associated resistance genes in wastewaters and river water. Out of 246 bacteria from wastewaters, 57.72% were ESBL producers and 77.64% of them were multidrug resistant (MDR). ESBL producing E. coli was dominant in municipal and hospital wastewaters (HWW) as well as in river water while K. pneumoniae was common in pharmaceutical wastewater. The blaSHV and blaTEM genes were prevalent and commonly co-occurred with aac(6')-Ib-cr in K. pneumoniae isolated pharmaceutical wastewater. blaCTX-M carrying E. coli from hospital co-harbored aac(6')-Ib-cr while that from municipal influent and river water co-harbored qnrS. Whole genome sequencing data revealed the presence of diverse ARGs in bacterial isolates against multiple antibiotics. In average, an E. coli and a K. pneumoniae isolate contained 55.75 ± 0.96 and 40.2 ± 5.36 ARGs, respectively. Multi-locus sequence typing showed the presence of globally high-risk clones with wider host range such as E. coli ST10, and K. pneumoniae ST15 and ST307 in HWW and river indicating frequent dissemination of antimicrobial resistance in wastewater of Kathmandu. Whole genome sequence data aligned with phenotypic antibiograms and resistance genes detected by PCR in selected isolates. The presence of significant plasmid replicons (IncF, IncY) and mobile genetic elements (IS903, IS26) indicate high frequency of spreading antibiotic resistance. These findings indicate burden and dissemination of antimicrobial resistance in the environment and highlight the need for effective strategies to mitigate the antibiotic resistance.

Unveiling the overlooked threat: antibiotic resistance in groundwater near an abandoned sulfuric acid plant in Xingyang, China

Groundwater near a sulfuric acid plant in Xingyang, Henan, China was sampled from seven distinct sites to explore the prevalence of antibiotic resistance genes (ARGs) and mobile genetic elements (MGEs). Results showed that genes aadA, blaCTX-M, tetA, qnrA, and sul1 were detected with 100% frequency followed by aac(6')-Ib (85.71%), ermB (85.71%), and tetX (71.42%). Most abundant ARGs were sul1 in LSA2 (1.15 × 1011 copies/mL), tetA in LSA6 (4.95 × 1010 copies/mL), aadA in LSA2 (4.56 × 109 copies/mL), blaCTX-M in LSA4 (1.19 × 109 copies/mL), and ermB in LSA5 (1.07 × 109 copies/mL). Moreover, in LSA2, intl1 as a marker of class 1 integron emerged as the most abundant gene as part of MGE (2.25 × 1011 copies/mL), trailed by ISCR1 (1.57 × 109 copies/mL). Environmental factors explained 81.34% of ARG variations, with a strong positive correlation between the intl2 and blaCTX-M genes, as well as the ISCR1 gene and qnrA, tetA, intl2, and blaCTX-M. Furthermore, the intI1 gene had a strong positive connection with the aadA, tetA, and sul1 genes. Moreover, the aac(6')-Ib gene was associated with As, Pb, Mg, Ca, and HCO3-. The intl2 gene was also shown to be strongly associated with Cd. Notably, network analysis highlighted blaCTX-M as the most frequently appearing gene across networks of at least five genera. Particularly, Lactobacillus, Plesiomonas, and Ligilactobacillus demonstrated correlations with aadA, qnrA, blaCTX-M, intI2, and ISCR1. Based on 16S rRNA sequencing, the dominant phyla were Proteobacteria, Firmicutes, Bacteroidota, Acidobacteriota, and Actinobacteriota, with dominant genera including Pseudomonas, Ligilactobacillus, Azoarcus, Vogesella, Streptococcus, Plesiomonas, and Ferritrophicum. These findings enhance our understanding of ARG distribution in groundwater, signaling substantial contamination by ARGs and potential risks to public health.

Occurrence and dissemination of antibiotics and antibiotic resistance in aquatic environment and its ecological implications: a review

The occurrence of antibiotics and antibiotic-resistant bacteria (ARBs), genes (ARGs), and mobile genetic elements (MGEs) in aquatic systems is growing global public health concern. These emerging micropollutants, stemming from improper wastewater treatment and disposal, highlight the complex and evolving nature of environmental pollution. Current literature reveals potential biases, such as a geographical focus on specific regions, leading to an insufficient understanding of the global distribution and dynamics of antibiotic resistance in aquatic systems. There is methodological inconsistency across studies, making it challenging to compare findings. Potential biases include sample collection inconsistencies, detection sensitivity variances, and data interpretation variability. Gaps in understanding include the need for comprehensive, standardized long-term monitoring programs, elucidating the environmental fate and transformation of antibiotics and resistance genes. This review summarizes current knowledge on the occurrence and dissemination of emerging micropollutants, their ecological impacts, and the global health implications of antimicrobial resistance. It highlights the need for interdisciplinary collaborations among researchers, policymakers, and stakeholders to address the challenges posed by antibiotic resistance in aquatic resistance in aquatic systems effectively. This review highlights widespread antibiotic and antibiotic resistance in aquatic environment, driven by human and agricultural activities. It underscores the ecological consequences, including disrupted microbial communities and altered ecosystem functions. The findings call for urgent measures to mitigate antibiotics pollution and manage antibiotic resistance spread in water bodies.

Dynamics of antimicrobial resistance and susceptibility profile in full-scale hospital wastewater treatment plants

Drug resistance has become a matter of great concern, with many bacteria now resist multiple antibiotics. This study depicts the occurrence of antibiotic-resistant bacteria (ARB) and resistance patterns in five full-scale hospital wastewater treatment plants (WWTPs). Samples of raw influent wastewater, as well as pre- and post-disinfected effluents, were monitored for targeted ARB and resistance genes in September 2022 and February 2023. Shifts in resistance profiles of Escherichia coli, Pseudomonas aeruginosa, and Acinetobacter baumannii antimicrobial-resistant indicators in the treated effluent compared to that in the raw wastewater were also worked out. Ceftazidime (6.78 × 105 CFU/mL) and cefotaxime (6.14 × 105 CFU/mL) resistant species showed the highest concentrations followed by ciprofloxacin (6.29 × 104 CFU/mL), and gentamicin (4.88 × 104 CFU/mL), in raw influent respectively. WWTP-D employing a combination of biological treatment and coagulation/clarification for wastewater decontamination showed promising results for reducing ARB emissions from wastewater. Relationships between treated effluent quality parameters and ARB loadings showed that high BOD5 and nitrate levels were possibly contributing to the persistence and/or selection of ARBs in WWTPs. Furthermore, antimicrobial susceptibility tests of targeted species revealed dynamic shifts in resistance profiles through treatment processes, highlighting the potential for ARB and ARGs in hospital wastewater to persist or amplify during treatment.

Removal of antibiotics, bacterial toxicity, and occurrence of antibiotic resistance genes in secondary hospital effluents treated with granular activated carbon and the impact of preceding chlorination

This comprehensive investigation highlighted the complex adsorption behaviors of antibiotics onto granular activated carbon (GAC), the effectiveness of this adsorption in reducing bacterial toxicity, and the reduction of antibiotic resistance genes (ARGs) and antibiotic resistant bacteria (ARB) in hospital wastewater (HWW) effluents. Six GACs were characterized for their physicochemical properties, and their ability to adsorb six antibiotics in the background matrix of actual HWW was evaluated. Coconut shell-derived GAC (Co-U), which had the highest hydrophobicity and lowest content of oxygen-containing acidic functional groups, demonstrated the highest adsorption capacities for the tested antibiotics. Bacterial toxicity tests revealed that GACs could eliminate the bacterial toxicity from antibiotic intermediates present in chlorinated HWW. By contrast, the bacterial toxicity could not be removed by GACs in non-chlorinated HWW due to the greater presence of intermediate components identified by LC-MS/MS. The intraparticle diffusion coefficient of antibiotics adsorbed onto Co-U could be calculated by adsorption kinetics derived from the linear driving force model and the homogenous intraparticle diffusion model associated with the linear adsorption isotherms (0-150 μg/L). Meropenem and sulfamethoxazole exhibited the highest adsorption capacities in a single-solute solution compared to penicillin G, ampicillin, cetazidime, and ciprofloxacin. However, the greater adsorption capacities of meropenem and sulfamethoxazole disappeared in mixed-solute solutions, indicating the lowest adsorption competition. GAC can eliminate most ARGs while also promoting the growth of some ARB. Chlorination (free chlorine residues at 0.5 mg Cl2/L) did not significantly affect the overall composition of ARGs and ARB in HWW. However, the accumulation of ARGs and ARB on GAC in fixed bed columns was lower in chlorinated HWW than in non-chlorinated HWW due to an increase in the adsorption of intermediates.

From disinfection to pathogenicity: Occurrence, resistome risks and assembly mechanism of biocide and metal resistance genes in hospital wastewaters

Hospital wastewaters (HWWs) represent critical reservoir for the accumulation and propagation of resistance genes. However, studies on biocide and metal resistance genes (BMRGs) and their associated resistome risks and driving mechanisms in HWWs are still in their infancy. Here, metagenomic assembly was firstly used to investigate host pathogenicity and transferability profiles of BMGRs in a typical HWWs system. As a result, genes conferring resistance to Ethidium Bromide, Benzylkonium Chloride, and Cetylpyridinium Chloride dominated biocide resistance genes (BRGs), whereas Cu resistance gene was the largest contributor of metal resistance genes (MRGs). Most BMRGs experienced significant reduction from anoxic-aerobic treatment to sedimentation stages but exhibited enrichment after chlorine disinfection. Network analysis indicated intense interactions between BMRGs and virulence factors (VFs). Polar_flagella, belonging to the adherence was identified to play important role in the network. Contig-based analysis further revealed noteworthy shifts in host associations along the treatment processes, with Pseudomonadota emerging as the primary carrier, hosting 91.1% and 85.3% of the BRGs and MRGs. A total of 199 opportunistic pathogens were identified to carry 285 BMRG subtypes, which mainly included Pseudomonas alcaligenes, Pseudomonas lundensis, and Escherichia coli. Notably, ruvB conferring resistance to Cr, Cetylpyridinium Chloride, and Dodine were characterized with the highest frequency carried by pathogens. Diverse co-occurrence patterns between BMRGs and mobile genetic elements (MGEs) were found from the raw influent to final effluent. Overall, 10.5% BRGs and 8.84% MRGs were mobile and among the 4 MGEs, transposase exhibited the greatest potential for the BMRGs dissemination. Furthermore, deterministic processes played a dominant role in bacterial communities and BMRGs assembly in HWWs. Bacterial communities contributed more than MGEs in shaping the resistome. Taken together, this work demonstrated widespread BMRGs pollution throughout the HWWs treatment system, emphasizing the potential for informing resistome risk and ecological mechanism in medical practice.

Ranking the risk of antibiotic resistance genes by metagenomic and multifactorial analysis in hospital wastewater systems

Antimicrobial resistance poses a serious threat to human health. Hospital wastewater system (HWS) is an important source of antibiotic resistance genes (ARGs). The risk of ARGs in HWS is still an under-researched area. In this study, we collected publicly metagenomic datasets of 71 hospital wastewater samples from 18 hospitals in 13 cities. A total of 9838 contigs were identified to carry 383 unique ARGs across all samples, of which 2946 contigs were plasmid-like sequences. Concurrently, the primary hosts of ARGs within HWS were found to be Escherichia coli and Klebsiella pneumoniae. To further evaluate the risk of each ARG subtype, we proposed a risk assessment framework based on the importance of corresponding antibiotics as defined by the WHO and three other indicators - ARG abundance (A), mobility (M), and host pathogenicity (P). Ninety ARGs were identified as R1 ARGs having high-risk scores, which meant having a high abundance, high mobility, and carried by pathogens in HWS. Furthermore, 25% to 49% of genomes from critically important pathogens accessed from NCBI carried R1 ARGs. A significantly higher number of R1 ARGs was carried by pathogens in the effluents of municipal wastewater treatment plants from NCBI, highlighting the role of R1 ARGS in accelerating health and environmental risks.

Oxygen mediated mobilization and co-occurrence of antibiotic resistance in lab-scale bioreactor using metagenomic binning

Sub-lethal levels of antibiotic stimulate bacteria to generate reactive oxygen species (ROS) that promotes emergence and spread of antibiotic resistance mediated by mobile genetic elements (MGEs). Nevertheless, the influence of dissolved oxygen (DO) levels on mobility of antibiotic resistance genes (ARGs) in response to ROS-induced stress remains elusive. Thus, the study employs metagenomic assembly and binning approaches to decipher mobility potential and co-occurrence frequency of ARGs and MGEs under hyperoxic (5.5-7 mgL- 1), normoxic (2.5-4 mgL- 1), and hypoxic (0.5-1 mgL- 1) conditions in lab-scale bioreactor for 6 months. Among 163 high-quality metagenome-assembled genomes (MAGs) recovered from 13 metagenomes, 42 MAGs harboured multiple ARGs and were assigned to priority pathogen group. Total ARG count increased by 4.3 and 2.5% in hyperoxic and normoxic, but decreased by 0.53% in hypoxic conditions after 150 days. On contrary, MGE count increased by 7.3-1.3% in all the DO levels, with only two ARGs showed positive correlation with MGEs in hypoxic compared to 20 ARGs under hyperoxic conditions. Opportunistic pathogens (Escherichia, Klebsiella, Clostridium, and Proteus) were detected as potential hosts of ARGs wherein co-localisation of critical ARG gene cassette (sul1, dfr1,adeF, and qacC) were identified in class 1 integron/Tn1 family transposons. Thus, enhanced co-occurrence frequency of ARGs with MGEs in pathogens suggested promotion of ARGs mobility under oxidative stress. The study offers valuable insights into ARG dissemination and hosts dynamics that is essential for controlling oxygen-related stress for mitigating MGEs and ARGs in the environment.

Recovery and genetic characterization of clinically-relevant ST2 carbapenem-resistant Acinetobacter baumannii isolates from untreated hospital sewage in Zhejiang Province, China

The global transmission of carbapenem-resistant Acinetobacter baumannii (CRAB) poses a significant and grave threat to human health. To investigate the potential relationship between hospital sewage and the transmission of CRAB within healthcare facilities, isolates of Acinetobacter spp. obtained from untreated hospital sewage samples were subjected to antimicrobial susceptibility tests, genome sequencing, and bioinformatic and phylogenetic tree analysis, and that data were matched with those of the clinical isolates. Among the 70 Acinetobacter spp. sewage isolates tested, A. baumannii was the most prevalent and detectable in 5 hospitals, followed by A. nosocomialis and A. gerneri. Worryingly, 57.14 % (40/70) of the isolates were MDR, with 25.71 % (18/70) being resistant to carbapenem. When utilizing the Pasteur scheme, ST2 was the predominant type among these CRAB isolates, with Tn2006 (ΔISAba1-blaOXA-23-ATPase-yeeB-yeeA-ΔISAba1) and Tn2009 (ΔISAba1-blaOXA-23-ATPase-hp-parA-yeeC-hp-yeeB-ΔISAba1) being the key mobile genetic elements that encode carbapenem resistance. Seven A. gerneri isolates which harbored Tn2008 (ISAba1-blaOXA-23 -ATPase) and the blaPER-1 gene were also identified. Besides, an A. soil isolate was found to exhibit high-level of meropenem resistance (MIC ≥128 mg/L) and harbor a blaNDM-1 gene located in a core genetic structure of ISAba125-blaNDM-1-ble-trpF-dsbC-cutA. To investigate the genetic relatedness between isolates recovered from hospital sewage and those collected from ICUs, a phylogenetic tree was constructed for 242 clinical isolates and 9 sewage isolates. The results revealed the presence of two evolutionary clades, each containing isolates from both ICU and sewage water, suggesting that CRAB isolates in untreated sewage water were also the transmission clones or closely related evolutionary isolates recoverable in hospital settings. Findings in this work confirm that hospital sewage is a potential reservoir of CRAB.

Efficacy of new generation biosorbents for the sustainable treatment of antibiotic residues and antibiotic resistance genes from polluted waste effluent

Antimicrobials are frequently used in both humans and animals for the treatment of bacterially-generated illnesses. Antibiotic usage has increased for more than 40% from last 15 years globally per day in both human populations and farm animals leading to the large-scale discharge of antibiotic residues into wastewater. Most antibiotics end up in sewer systems, either directly from industry or healthcare systems, or indirectly from humans and animals after being partially metabolized or broken down following consumption. To prevent additional antibiotic compound pollution, which eventually impacts on the spread of antibiotic resistance, it is crucial to remove antibiotic residues from wastewater. Antibiotic accumulation and antibiotic resistance genes cannot be effectively and efficiently eliminated by conventional sewage treatment plants. Because of their high energy requirements and operating costs, many of the available technologies are not feasible. However, the biosorption method, which uses low-cost biomass as the biosorbent, is an alternative technique to potentially address these problems. An extensive literature survey focusing on developments in the field was conducted using English language electronic databases, such as PubMed, Google Scholar, Pubag, Google books, and ResearchGate, to understand the relative value of the available antibiotic removal methods. The predominant techniques for eliminating antibiotic residues from wastewater were categorized and defined by example. The approaches were contrasted, and the benefits and drawbacks were highlighted. Additionally, we included a few antibiotics whose removal from aquatic environments has been the subject of extensive research. Lastly, a few representative publications were identified that provide specific information on the removal rates attained by each technique. This review provides evidence that biosorption of antibiotic residues from biological waste using natural biosorbent materials is an affordable and effective technique for eliminating antibiotic residues from wastewater.

Safe Disposal of Accident Wastewater in Chemical Industrial Parks Using Non-Thermal Plasma with ZnO-Fe3O4 Composites

Chemical wastewater has a high concentration of toxic and hazardous antibiotic pollutants, which not only devastates the ecological environment and disrupts the ecological balance, but also endangers human health. This research proposed a non-thermal plasma (NTP) combined with a ZnO-Fe3O4 nano-catalyst system to achieve the efficient degradation of ciprofloxacin (CIP) in chemical wastewater. Firstly, ZnO-Fe3O4 composite materials were prepared using hydrothermal method and characterized with scanning electron microscopy (SEM), transmission electron microscope (TEM), X-ray diffractometer (XRD), X-ray photoelectron spectroscopy (XPS), etc. With the sole NTP, NTP/ZnO, and NTP/ZnO-Fe3O4 systems, the removal efficiency of CIP can reach 80.1%, 88.2%, and 99.6%, respectively. The optimal doping amount of Fe3O4 is 14%. Secondly, the capture agent experiment verified that ·OH, ·O2-, and 1O2 all have a certain effect on CIP degradation. Then, liquid chromatography-mass spectrometry (LC-MS) was used to detect the intermediate and speculate its degradation pathway, which mainly included hydroxyl addition, hydroxyl substitution, and piperazine ring destruction. After treatment with the NTP/ZnO-Fe3O4 system, the overall toxicity of the product was reduced. Finally, a cyclic experiment was conducted, and it was found that the prepared ZnO-Fe3O4 catalyst has good reusability. The NTP/ZnO-Fe3O4 was also applied in practical pharmaceutical wastewater treatment and has practical applicability.

A comprehensive review on the application of semiconducting materials in the degradation of effluents and water splitting

In this comprehensive review article, we delve into the critical intersection of environmental science and materials science. The introduction sets the stage by emphasizing the global water shortage crisis and the dire consequences of untreated effluents on ecosystems and human health. As we progress into the second section, we embark on an intricate exploration of piezoelectric and photocatalytic principles, illuminating their significance in wastewater treatment and sustainable energy production. The heart of our review is dedicated to a detailed analysis of the detrimental impacts of effluents on human health, underscoring the urgency of effective treatment methods. We dissected three key materials in the realm of piezo-photocatalysis: ZnO-based materials, BaTiO3-based materials, and bismuth-doped materials. Each material is scrutinized for its unique properties and applications in the removal of pollutants from wastewater, offering a comprehensive understanding of their potential to address this critical issue. Furthermore, our exploration extends to the realm of hydrogen production, where we discuss various types of hydrogen and the role of piezo-photocatalysis in generating clean and sustainable hydrogen. By illuminating the synergistic potential of these advanced materials and technologies, we pave the way for innovative solutions to the pressing challenges of water pollution and renewable energy production. This review article not only serves as a valuable resource for researchers and scholars in the fields of material science and environmental engineering but also underscores the pivotal role of interdisciplinary approaches in addressing complex global issues.

Insights into the circular: The cryptic plasmidome and its derived antibiotic resistome in the urban water systems

Plasmids have been a concern in the dissemination and evolution of antibiotic resistance in the environment. In this study, we investigated the total pool of plasmids (plasmidome) and its derived antibiotic resistance genes (ARGs) in different compartments of urban water systems (UWSs) in three European countries representing different antibiotic usage regimes. We applied a direct plasmidome approach using wet-lab methods to enrich circular DNA in the samples, followed by shotgun sequencing and in silico contig circularisation. We identified 9538 novel sequences in a total of 10,942 recovered circular plasmids. Of these, 66 were identified as conjugative, 1896 mobilisable and 8970 non-mobilisable plasmids. The UWSs' plasmidome was dominated by small plasmids (≤10 Kbp) representing a broad diversity of mobility (MOB) types and incompatibility (Inc) groups. A shared collection of plasmids from different countries was detected in all treatment compartments, and plasmids could be source-tracked in the UWSs. More than half of the ARGs-encoding plasmids carried mobility genes for mobilisation/conjugation. The richness and abundance of ARGs-encoding plasmids generally decreased with the flow, while we observed that non-mobilisable ARGs-harbouring plasmids maintained their abundance in the Spanish wastewater treatment plant. Overall, our work unravels that the UWS plasmidome is dominated by cryptic (i.e., non-mobilisable, non-typeable and previously unknown) plasmids. Considering that some of these plasmids carried ARGs, were prevalent across three countries and could persist throughout the UWSs compartments, these results should alarm and call for attention.

Characterization of urban sources of antibiotics and antibiotic-resistance genes in a Dutch sewer catchment

A one year study was conducted in the city of Nijmegen, The Netherlands, to characterize various urban sources of antibiotics and antibiotic resistant genes (ARGs) in wastewater within a single sewer catchment. Prevalence of ermB, tet(W), sul1, sul2, intl1, and 16S rRNA gene was determined at 10 locations within the city. Sampling locations included a nursing home, a student residence, a hospital and an industrial area, among others. Wastewater concentrations of 23 antibiotics were measured using passive sampling. Additionally, excreted loads of 22 antibiotics were estimated based on ambulatory prescription and clinical usage data. Genes sul1 and intl1 were most abundant across most locations. Ciprofloxacin and amoxicillin together contributed over 92 % of the total estimated antibiotic selective pressure at all sampling points. The present study highlights the prominent role that hospitals can have in the prevalence and proliferation of ARGs in urban wastewater. Furthermore, results suggest that even short-term changes in the therapeutic regimen prescribed in hospitals may translate into shifting ARG abundance patterns in hospital wastewater. The methods applied present an opportunity to identify emission hotspots and prioritize intervention options to limit ARG spread from urban wastewater to the environment.

Mapping the spread and mobility of antibiotic resistance in wastewater due to COVID-19 surge

Large amounts of antibiotics have been discharged into wastewater during the COVID-19 pandemic due to overuse and misuse of antibiotics to treat patients. Wastewater-based surveillance can be used as an early warning for antibiotic resistance (AR) emergence. The present study analyzed municipal wastewater corresponding to the major pandemic waves (WW1, WW2, and WW3) in India along with hospital wastewater (Ho) taken as a benchmark for AR. Commonly prescribed antibiotics during a pandemic, azithromycin and cefixime residues, were found in the range of 2.1-2.6 μg/L in Ho and WW2. Total residual antibiotic concentration was less in WW2; however, the total antibiotic resistance gene (ARG) count was 1065.6 ppm compared to 85.2 ppm in Ho. Metagenome and RT-qPCR analysis indicated a positive correlation between antibiotics and non-corresponding ARGs (blaOXA, aadA, cat, aph3, and ere), where 7.2-7.5% was carried by plasmid in the bacterial community of WW1 and WW2. Moreover, as the abundance of the dfrA and int1 genes varied most among municipal wastewater, they can be suggested as AR markers for the pandemic. The common pathogens Streptococcus, Escherichia, Shigella, and Aeromonas were putative ARG hosts in metagenome-assembled genomes. The ARG profile and antibiotic levels varied between municipal wastewaters but were fairly similar for WW2 and Ho, suggesting the impact of the pandemic in shaping the resistome pattern. The study provides insights into the resistome dynamic, AR markers, and host-ARG association in wastewater during the COVID-19 surge. Continued surveillance and identification of intervention points for AR beyond the pandemic are essential to curbing the environmental spread of ARGs in the near future.

Occurrence and Removal of Antibiotic Resistance in Nationwide Hospital Wastewater Deciphered by Metagenomics Approach - China, 2018-2022

What is already known about this topic?

Hospital wastewater represents a significant conduit for the dissemination of antibiotic resistance genes (ARGs), including those that are of clinical importance. Yet, the variation in antibiotic resistance on a national level, which can be influenced by regional differences, has not been thoroughly elucidated.

What is added by this report?

Uniform methodologies were employed to analyze data from various provincial-level administrative divisions in China, aiming to investigate the patterns of antibiotic resistance across these regions. This analysis illuminated the location preferences of clinically ARGs on plasmids. Additionally, our study uncovered regional variations in the presumed bacterial hosts of ARGs at the genus level.

What are the implications for public health practice?

This investigation has shed light on the nationwide prevalence of ARGs in hospital wastewater in China, uncovering the significant ecological and public health risks associated with the disposal of such effluents.

Large-scale characterization of hospital wastewater system microbiomes and clinical isolates from infected patients: profiling of multi-drug-resistant microbial species

BACKGROUND

Hospital-acquired infections (HAIs) and infectious agents exhibiting antimicrobial resistance (AMR) are challenges globally. Environmental patient-facing wastewater apparatus including handwashing sinks, showers and toilets are increasingly identified as sources of infectious agents and AMR genes.

AIM

To provide large-scale metagenomics analysis of wastewater systems in a large teaching hospital in the Republic of Ireland experiencing multi-drug-resistant HAI outbreaks.

METHODS

Wastewater pipe sections (N=20) were removed immediately prior to refurbishment of a medical ward where HAIs had been endemic. These comprised toilet U-bends, and sink and shower drains. Following DNA extraction, each pipe section underwent metagenomic analysis.

FINDINGS

Diverse taxonomic and resistome profiles were observed, with members of phyla Proteobacteria and Actinobacteria dominating (38.23 ± 5.68% and 15.78 ± 3.53%, respectively). Genomes of five clinical isolates were analysed. These AMR bacterial isolates were from patients >48 h post-admission to the ward. Genomic analysis determined that the isolates bore a high number of antimicrobial resistance genes (ARGs).

CONCLUSION

Comparison of resistome profiles of isolates and wastewater metagenomes revealed high degrees of similarity, with many identical ARGs shared, suggesting probable acquisition post-admission. The highest numbers of ARGs observed were those encoding resistance to clinically significant and commonly used antibiotic classes. Average nucleotide identity analysis confirmed the presence of highly similar or identical genomes in clinical isolates and wastewater pipes. These unique large-scale analyses reinforce the need for regular cleaning and decontamination of patient-facing hospital wastewater pipes and effective infection control policies to prevent transmission of nosocomial infection and emergence of AMR within potential wastewater reservoirs.

Chlorine disinfection modifies the microbiome, resistome and mobilome of hospital wastewater - A nanopore long-read metagenomic approach

The aim of the present study was to analyze changes in the microbiome, resistome, and mobilome of hospital wastewater (HWW) induced by disinfection with chlorine compounds. Changes in bacterial communities and specific antibiotic resistance genes (ARGs) in HWW were determined with the use of a nanopore long-read metagenomic approach. The main hosts of ARGs in HWW were identified, and the mobility of resistance mechanisms was analyzed. Special attention was paid to the prevalence of critical-priority pathogens in the HWW microbiome, which pose the greatest threat to human health. The results of this study indicate that chlorine disinfection of HWW can induce significant changes in the structure of the total bacterial population and antibiotic resistant bacteria (ARB) communities, and that it can modify the resistome and mobilome of HWW. Disinfection favored the selection of ARGs, decreased their prevalence in HWW, while increasing their diversity. The mobility of the HWW resistome increased after disinfection. Disinfection led to the emergence of new drug resistance mechanisms in previously sensitive bacterial taxa. In conclusion, this study demonstrated that HWW disinfected with low (sublethal) concentrations of free chlorine significantly contributes to the mobility and transfer of drug resistance mechanisms (including critical mechanisms) between bacteria (including pathogens).

Impact of the antibiotic doxycycline on the D. magna reproduction, associated microbiome and antibiotic resistance genes in treated wastewater conditions

Wastewater Treatment Plant (WWTP) effluents are important sources of antibiotics, antibiotic resistance genes (ARGs) and resistant bacteria that threaten aquatic biota and human heath. Antibiotic effects on host-associated microbiomes, spread of ARGs and the consequences for host health are still poorly described. This study investigated changes of the Daphnia magna associated microbiome exposed to the recalcitrant antibiotic doxycycline under artificial reconstituted lab water media (lab water) and treated wastewater media. D. magna individual juveniles were exposed for 10 days to treated wastewater with and without doxycycline, and similarly in lab water. We analysed 16 S rRNA gene sequences to assess changes in community structure, monitored Daphnia offspring production and quantified ARGs abundances by qPCR from both Daphnia and water (before and after the exposure). Results showed that doxycycline and media (lab water or wastewater) had a significant effect modulating Daphnia-associated microbiome composition and one of the most discriminant taxa was Enterococcus spp. Moreover, in lab water, doxycycline reduced the presence of Limnohabitans sp., which are dominant bacteria of the D. magna-associated microbiome and impaired Daphnia reproduction. Contrarily, treated wastewater increased diversity and richness of Daphnia-associated microbiome and promoted fecundity. In addition, the detected ARG genes in both lab water and treated wastewater medium included the qnrS1, sul1, and blaTEM, and the integron-related intI1 gene. The treated wastewater contained about 10 times more ARGs than lab water alone. Furthermore, there was an increase of sul1 in Daphnia cultured in treated wastewater compared to lab water. In addition, there were signs of a higher biodegradation of doxycycline by microbiomes of treated wastewater in comparison to lab water. Thus, results suggest that Daphnia-associated microbiomes are influenced by their environment, and that bacterial communities present in treated wastewater are better suited to cope with the effects of antibiotics.

Streptomyces argyrophyllae sp. nov., isolated from the rhizosphere soil of Cathaya argyrophylla

Strain Jing01T, a novel actinomycete from rhizosphere soil of Cathaya argyrophylla, was identified using a polyphasic approach. 16S rRNA gene sequence analysis of strain Jing01T revealed that it was a member of the genus Streptomyces and shared 99.03%, 99.03%, 98.96%, 98.89%, 98.83%, 98.82%, 98.76%, 98.74%, 98.73%, 98.69% and 98.68% similarities to Streptomyces rochei NRRL B-2410T, Streptomyces naganishii NBRC 12892T, Streptomyces rubradiris JCM 4955T, Streptomyces anandii NRRL B-3590T, Streptomyces aurantiogriseus NBRC 12842T, Streptomyces mutabilis NBRC 12800T, Streptomyces rameus LMG 20326T, Streptomyces djakartensis NBRC 15409T, Streptomyces bangladeshensis JCM 14924T, Streptomyces andamanensis KCTC 29502T and Streptomyces tuirus NBRC 15617T, respectively. In phylogenetic trees constructed based on 16S rRNA gene sequences, strain Jing01T generated a separate branch at the middle of the clade, suggesting it could be a potential novel species. In phylogenomic tree, strain Jing01T was related to S. rubradiris JCM 4955T. In phylogenetic trees based on the gene sequences of atpD, gyrB, recA, rpoB and trpB, strain Jing01T was related to S. bangladeshensis JCM 14924T and S. rubradiris JCM 4955T. Whereas, the multilocus sequence analysis distance, average nucleotide identity and DNA-DNA hybridization values between them were much less than the species-level thresholds. This conclusion was further supported by phenotypic and chemotaxonomic analysis. Consequently, strain Jing01T represents a new Streptomyces species, for which the proposed name is Streptomyces argyrophyllae sp. nov. The type strain is Jing01T (= MCCC 1K05707T = JCM 35923T).

Experimental and numerical elucidation of the fate and transport of antibiotics in aquatic environment: A review

This review highlights various experimental and mathematical modeling strategies to investigate the fate and transport of antibiotics that elucidate antimicrobial selective pressure in aquatic environments. Globally, the residual antibiotic concentrations in effluents from bulk drug manufacturing industries were 30- and 1500-fold greater than values reported in municipal and hospital effluents, respectively. The antibiotic concentration from different effluents enters the waterbodies that usually get diluted as they go downstream and undergo various abiotic and biotic reactive processes. In aquatic systems, photolysis is the predominant process for antibiotic reduction in the water matrix, while hydrolysis and sorption are frequently reported in the sediment compartment. The rate of antibiotic reduction varies widely with influencing factors such as the chemical properties of the antibiotics and hydrodynamic conditions of river streams. Among all, tetracycline was found to more unstable (log Kow =  - 0.62 to - 1.12) that can readily undergo photolysis and hydrolysis; whereas macrolides were more stable (log Kow = 3.06 to 4.02) that are prone to biodegradation. The processes like photolysis, hydrolysis, and biodegradation followed first-order reaction kinetics while the sorption followed a second-order kinetics for most antibiotic classes with reaction rates occurring in the decreasing order of Fluoroquinolones and Sulphonamides. The reports from various experiments on abiotic and biotic processes serve as input parameters for an integrated mathematical modeling to predict the fate of the antibiotics in the aquatic environment. Various mathematical models viz. Fugacity level IV, RSEMM, OTIS, GREAT-ER, SWAT, QWASI, and STREAM-EU are discussed for their potential capabilities. However, these models do not account for microscale interactions of the antibiotics and microbial community under real-field conditions. Also, the seasonal variations for contaminant concentrations that exert selective pressure for antimicrobial resistance has not been accounted. Addressing these aspects collectively is the key to exploring the emergence of antimicrobial resistance. Therefore, a comprehensive model involving antimicrobial resistance parameters like fitness cost, bacterial population dynamics, conjugation transfer efficiency, etc. is required to predict the fate of antibiotics.

Metagenomic analysis reveals the short-term influences on conjugation of blaNDM-1 and microbiome in hospital wastewater by silver nanoparticles at environmental-related concentration

Hospital wastewater contains large amounts of antibiotic-resistant bacteria and serves as an important reservoir for horizontal gene transfer (HGT). However, the response of the microbiome in hospital wastewater to silver remains unclear. In this study, the short-term impacts of silver on the microbiome in hospital wastewater were investigated by metagenome next-generation sequencing. The influence of silver on the conjugation of plasmid carrying bla_NDM-1 was further examined. Our results showed that in hospital wastewater, high abundances of antibiotic resistance genes (ARGs) were detected. The distribution tendencies of certain ARG types on chromosomes or plasmids were different. Clinically important ARGs were identified in phage-like contigs, indicating potential transmission via transduction. Pseudomonadales, Enterobacterales, and Bacteroidales were the major ARG hosts. Mobile genetic elements were mainly detected in plasmids and associated with various types of ARGs. The binning approach identified 29 bins that were assigned to three phyla. Various ARGs and virulence factors were identified in 14 and 11 bins, respectively. MetaCHIP identified 49 HGT events. The transferred genes were annotated as ARGs, mobile genetic elements, and functional genes, and they mainly originated from donors belonging to Bacteroides and Pseudomonadales. In addition, 20 nm AgNPs reduced microbial diversity and enhanced the relative abundance of Acinetobacter. The changes induced by 20 nm AgNPs included increases in the abundances of ARGs and genes involved lipid metabolism pathway. Conjugation experiments showed that Ag⁺ and 20 nm AgNPs caused 2.38-, 3.31-, 4.72-, and 4.57-fold and 1.46-, 1.61-, 3.86-, and 2.16-fold increases in conjugation frequencies of plasmid with bla_NDM-1 at 0.1, 1, 10, and 100 μg/L, respectively. Our findings provide insight into the response of the microbiome in hospital wastewater to silver, emphasize the adaptation capability of Acinetobacter inhabiting hospitals against adverse environments, and highlight the promotion of silver for antibiotic resistance.

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.

Quantification and antibiotic resistance risk assessment of chlorination-residual viable/VBNC Escherichia coli and Enterococcus in on-site hospital wastewater treatment system

On-site hospital wastewater treatment system widely applying chlorination has been regarded as an important barrier to curb the dissemination of antibiotic resistance. Chlorination-residual viable and viable but non-culturable (VBNC) bacteria probably lead to overestimate the effect of disinfection, while their antibiotic resistance risks imported from hospital effluents to municipal pipe network may be ignored. In this study, we quantified viable/VBNC Escherichia coli and Enterococcus in chlorination of an on-site hospital wastewater treatment system and assessed their antibiotic resistance risks. The numbers of viable/VBNC Escherichia coli and Enterococcus in raw wastewater were detected as high as 5.76-6.34/5.76-6.33 and 5.44-5.76/5.44-5.75 log₁₀(cells/mL). Meanwhile, high proportions of antibiotic-resistant Escherichia coli and Enterococcus to culturable Escherichia coli and Enterococcus were observed, especially carrying ampicillin resistance (22.25-41.70 % and 28.09-54.05 %). Chlorination could remove 0.44-1.88-/0.43-1.88- and 0.29-1.29-/0.28-1.28-log of viable/VBNC and complete culturable Escherichia coli and Enterococcus, but cause antibiotic resistance genes (ARGs) and mobile genetic elements (MGEs) to be released outside cells, and possibly further enhance the antibiotic resistance of viable bacteria. Low detections of antibiotics suggested that the occurrence of antibiotic-resistant bacteria (ARB) may not be accompanied by the corresponding antibiotics. Different sampling months had some impacts on above results, while the results were basically stable at different sampling times of hospital daily working period. The high release rates (11.26-13.02 and 11.59-12.98 log₁₀(cells/h)) and cumulative amounts (15.41-16.12 and 15.75-16.14 log₁₀(cells)) of chlorination-residual viable/VBNC Escherichia coli and Enterococcus indirectly assessed the potential risks of bacterial antibiotic resistance entering municipal pipe network. Additionally, the contributions from the corresponding antibiotic ceftazidime, ciprofloxacin, and vancomycin with the cumulative amounts of 2.57-4.85, 5.73-7.50, and 5.21-7.14 kg should also be taken seriously. Residual chlorine could serve as an important signal indicator for the risk assessment.

A case series and literature review of infections due to Myroides spp.: identification of contributing factors and emerging antibiotic susceptibility trends

Introduction

Infections forby Myroides spp. can lead to significant morbidity and mortality, particularly in immunocompromised patients with underlying co-morbidities. Recent reports have highlighted its intrinsic and acquired drug resistance, making it a particularly challenging infectious agent to combat.

Methods

Myroides spp. isolated and reported in clinically significant urine samples were considered for the study. Identification of the organism was done via the VITEK 2C system. Antibiotic susceptibility testing was done using both manual and automated methods following Clinical and Laboratory Standards Institute (CLSI) guidelines. Existing literature was searched on MEDLINE using PubMed.

Results

We present a series of five catheter-associated urinary tract infections due to Myroides odoratimimus , with sensitivity to only minocycline. This is the first case from Western India, and the third case in the existing literature that shows Myroides sensitivity only to minocycline. Our literature review is the first to systematically describe contributory factors to infection, allowing us to devise a clinically relevant tool that delineates contributory factors and efficacious drugs in Myroides spp. infection.

Conclusion

Myroides spp. infections, previously considered rare and opportunistic, need cognizance and diagnostic suspicion especially in particular associated conditions.

Viability and transcriptional responses of multidrug resistant E. coli to chromium stress

The viability of multidrug resistant (MDR) bacteria in environment is critical for the spread of antimicrobial resistance. In this study, two Escherichia coli strains, MDR LM13 and susceptible ATCC25922, were used to elucidate differences in their viability and transcriptional responses to hexavalent chromium (Cr(VI)) stress. The results show that the viability of LM13 was notably higher than that of ATCC25922 under 2-20 mg/L Cr(VI) exposure with bacteriostatic rates of 3.1%-57%, respectively, for LM13 and 0.9%-93.1%, respectively, for ATCC25922. The levels of reactive oxygen species and superoxide dismutase in ATCC25922 were much higher than those in LM13 under Cr(VI) exposure. Additionally, 514 and 765 differentially expressed genes were identified from the transcriptomes of the two strains (log₂|FC| > 1, p < 0.05). Among them, 134 up-regulated genes were enriched in LM13 in response to external pressure, but only 48 genes were annotated in ATCC25922. Furthermore, the expression levels of antibiotic resistance genes, insertion sequences, DNA and RNA methyltransferases, and toxin-antitoxin systems were generally higher in LM13 than in ATCC25922. This work shows that MDR LM13 has a stronger viability under Cr(VI) stress, and therefore may promote the dissemination of MDR bacteria in environment.

Seasonal analysis of commonly prescribed antibiotics in Istanbul city

Antibiotics are among the most common medicine groups since they are used to treat infectious diseases, as nutritional supplements in livestock breeding, and for preservation in the food industry. Turkey is among the highest antibiotic consumers in the world. In the present study, the most popular 14 antibiotics available in Turkey were monitored in one hospital sewage and two urban wastewater treatment plant influents and effluents seasonally in Istanbul province, the largest metropolitan center in Turkey. The present research aimed to develop a robust analytical method to determine 14 antibiotics, including six chemical groups, in environmental matrices which are considered significant antibiotic pollution sources, namely hospital sewage and urban wastewater. Solid-phase extraction (SPE) and UPLC-MS/MS analysis parameters included optimized column temperature, eluent, mobile phase, and flow rate. Three SPE cartridges were employed in recovery studies. The antibiotic recovery rates varied between 40 and 100%, and all analytes were identified within 3 min with UPLC-MS/MS under optimal conditions. It was determined that method detection limits (MDLs) varied between 0.07 and 2.72 µg/L for the antibiotics. In all seasons, the highest beta-lactam group antibiotic concentrations were identified in hospital sewage. The season with the greatest variety of antibiotics in urban wastewater was spring. Clarithromycin and ciprofloxacin were the antibiotics determined at the highest concentration in the influent and effluent of the wastewater treatment plant in all seasons. This study showed that the most widely used beta-lactam group antibiotics were found in high amounts in hospital sewage wastewater but in low concentrations in the treatment plants, and hence, it is seen that the degradability of beta-lactam group antibiotics was high. The presence of clarithromycin, ciprofloxacin, lincomycin, levofloxacin, and trimethoprim antibiotics in hospital sewage in higher amounts and also in inlet and outlet of wastewater treatment plants proves that those are resistant antibiotics.

Insight into the dynamics of drinking water resistome in China

Antibiotic resistance (AR) is a serious environmental hazard of the current age. Antibiotic resistance genes (ARGs) are the fundamental entities that spread AR in the environment. ARGs are likely to be transferred from the non-pathogenic to pathogenic microbes that might ultimately be responsible for the AR in humans and other organisms. Drinking water (DW) is the primary interaction route between ARGs and humans. Being the highest producer and consumer of antibiotics China poses a potential threat to developing superbugs and ARGs dissemination. Herein, we comprehensively seek to review the ARGs from dominant DW sources in China. Furthermore, the origin and influencing factors of the ARGs to the DW in China have been evaluated. Commonly used methods, both classical and modern, are being compiled. In addition, the risk posed and mitigation strategies of DW ARGs in China have been outlined. Overall, we believe this review would contribute to the assessment of ARGs in DW of China and their dissemination to humans and other animals and ultimately help the policymakers and scientists in the field to counteract this problem on an emergency basis.

Antimicrobial Resistance and β-Lactamase Production in Clinically Significant Gram-Negative Bacteria Isolated from Hospital and Municipal Wastewater

Hospital and municipal wastewater contribute to the spread of antibiotic-resistant bacteria and genes in the environment. This study aimed to examine the antibiotic resistance and β-lactamase production in clinically significant Gram-negative bacteria isolated from hospital and municipal wastewater. The susceptibility of bacteria to antibiotics was tested using the disk diffusion method, and the presence of extended-spectrum β-lactamases (ESBL) and carbapenemases was determined using an enzyme inhibitor and standard multiplex PCR. Analysis of antimicrobial resistance of total bacterial strains (n = 23) revealed that most of them were resistant to cefotaxime (69.56%), imipenem (43.47%), meropenem (47.82%) and amoxicillin-clavulanate (43.47%), gentamicin (39.13%), cefepime and ciprofloxacin (34.78%), trimethoprim-sulfamethoxazole (30.43%). A total of 8 of 11 phenotypically confirmed isolates were found to have ESBL genes. The blaTEM gene was present in 2 of the isolates, while the blaSHV gene was found in 2 of the isolates. Furthermore, the blaCTX-M gene was found in 3 of the isolates. In one isolate, both the blaTEM and blaSHV genes were identified. Furthermore, of the 9 isolates that have been phenotypically confirmed to have carbapenemase, 3 were confirmed by PCR. Specifically, 2 isolates have the blaOXA-48 type gene and 1 have the blaNDM-1 gene. In conclusion, our investigation shows that there is a significant rate of bacteria that produce ESBL and carbapenemase, which can promote the spread of bacterial resistance. Identifying ESBL and carbapenemase production genes in wastewater samples and their resistance patterns can provide valuable data and guide the development of pathogen management strategies that could potentially help reduce the occurrence of multidrug resistance.

Global Increase of Antibiotic Resistance Genes in Conjugative Plasmids

Antibiotic resistance is propagating worldwide, but the predominant dissemination mechanisms are not fully understood. Here, we report that antibiotic resistance gene (ARG) abundance in conjugative plasmids that are recorded in the National Center for Biotechnology Information (NCBI) RefSeq plasmid database is increasing globally, which is likely a key factor in the propagation of resistance. ARG abundance in plasmids increased by 10-fold on a global scale from the year 2000 to the year 2020 (from 0.25 to 2.93 ARG copies/plasmid), with a more pronounced increase being observed in low-to-middle income countries. This increasing trend of plasmid-borne ARGs was corroborated by bootstrap resampling from each year of the NCBI RefSeq plasmid database. The results of a correlation analysis imply that if antibiotic consumption keeps growing at the current rates, a 2.7-fold global increase in the ARG abundance of clinically relevant plasmids may be reached by 2030. High sequence similarities of clinically relevant, conjugative plasmids that are isolated both from clinics and from the environment raise concerns about the environmental resistome serving as a potential ARG maintenance reservoir that facilitates transmission across these ecological boundaries. IMPORTANCE Antibiotic resistance propagation is a significant concern due to its projected impacts on both global health and the economy. However, global propagation mechanisms are not fully understood, including regional and temporal trends in the abundance of resistance plasmids that facilitate antibiotic resistance gene (ARG) dissemination. This unprecedented study reports that ARG abundance in the conjugative plasmids that are recorded in the National Center for Biotechnology Information (NCBI) database and harbor ARGs is increasing globally with antibiotic consumption, especially in low-to-medium income countries. Through network and comparative genomic analyses, we also found high sequence similarities of clinically relevant conjugative resistance plasmids that were isolated from clinical and environmental sources, suggesting transmission between these ecological boundaries. Therefore, this study informs the One Health perspective to develop effective strategies by which to curtail the propagation of plasmid-borne antibiotic resistance.

Profile and actual transmissibility of Carbapenem resistance genes: Intracellular and extracellular DNA in hospital wastewater

The current worldwide spread of carbapenem resistance genes (CRGs) has posed a major public health threat, which continues to grow in severity. Hospital wastewaters (HWWs) are major reservoirs for antibiotic resistance genes, while resistomes in HWWs are still poorly characterized when it comes to CRGs. We comprehensively characterized the profile and actual transmissibility of extracellular CRGs (eCRGs) and intracellular CRGs (iCRGs) in HWWs for the first time. In this study, CRGs showed similar relative abundance in treated and untreated HWWs. Meanwhile, HWWs treatments led to the enrichment of bla_IMP-8, probably attributed to the promotion of Novosphingobium and Prosthecobacter after treatment. To evaluate the transmission potential of CRGs, extracellular and intracellular carbapenem-resistant plasmids were captured from HWWs by transformation and conjugation, respectively. We found an interesting phenomenon regarding the transmission characteristics of CRGs: bla_KPC-carrying plasmids could only be captured by transformation, while bla_NDM-carrying plasmids were captured by conjugation. Further experiments showed that HWW treatments increased the conjugation ability of bla_NDM. In conclusion, our study demonstrated that HWWs are significant reservoirs of CRGs and various CRGs exhibit different modes of transmission in HWWs. CRGs cannot be removed by membrane bioreactor and chlorine disinfection. An urgent need is to develop more efficient wastewater treatments to limit CRG dissemination.

Antimicrobial and the Resistances in the Environment: Ecological and Health Risks, Influencing Factors, and Mitigation Strategies

Antimicrobial contamination and antimicrobial resistance have become global environmental and health problems. A large number of antimicrobials are used in medical and animal husbandry, leading to the continuous release of residual antimicrobials into the environment. It not only causes ecological harm, but also promotes the occurrence and spread of antimicrobial resistance. The role of environmental factors in antimicrobial contamination and the spread of antimicrobial resistance is often overlooked. There are a large number of antimicrobial-resistant bacteria and antimicrobial resistance genes in human beings, which increases the likelihood that pathogenic bacteria acquire resistance, and also adds opportunities for human contact with antimicrobial-resistant pathogens. In this paper, we review the fate of antimicrobials and antimicrobial resistance in the environment, including the occurrence, spread, and impact on ecological and human health. More importantly, this review emphasizes a number of environmental factors that can exacerbate antimicrobial contamination and the spread of antimicrobial resistance. In the future, the timely removal of antimicrobials and antimicrobial resistance genes in the environment will be more effective in alleviating antimicrobial contamination and antimicrobial resistance.

Chronic intake of an enriched diet with spirulina (Arthrospira maxima) alleviates the embryotoxic effects produced by realistic concentrations of tetracycline in Danio rerio

Tetracycline (TC) is one of the most consumed antibiotics worldwide. Due to its high consumption, recent studies have reported its presence in aquatic environments and have assessed its effects on fish, algae, and daphniids. However, in most of those works, authors have tested TC toxicity at concentrations higher than the ones reported in the water matrix. Herein, we aimed to assess the likely embryotoxic and oxidative damage induced by environmentally relevant concentrations of TC in embryos of Danio rerio. Moreover, we seek to determine whether or not an enriched diet with spirulina can alleviate the embryotoxic damage produced by TC. Our findings indicated that TC at concentrations of 50 to 500 ng/L induced pericardial edema, tail deformities, and absence of head and fin in embryos after 96 h of exposure. Moreover, this antibiotic prompted the death of embryos in a concentration-dependent manner. According to our integrated biomarker response index, TC induced oxidative damage on Danio rerio embryos, as star plots showed a tendency to lipoperoxidation, hydroperoxides, and protein carbonyl content. Spirulina reduced the toxicity of TC by diminishing the levels of oxidative damage biomarkers, which resulted in a decrease in the rate of death and malformed embryos. Overall, TC at concentrations of ng/L prompted oxidative stress and embryotoxicity in the early life stages of Danio rerio; nonetheless, the algae spirulina was able to reduce the severity of those effects.

Unveiling the dynamics of antibiotic resistome, bacterial communities, and metals from the feces of patients in a typical hospital wastewater treatment system

Bacterial pathogens and antibiotic resistance genes (ARGs) are extensively disseminated into the environment via hospital wastewater (HWW), as it contains large quantities of feces from resident patients. However, studies on the antibiotic resistome and pathogenic bacteria from the gut of resident patients within the hospital wastewater treatment plant (hWWTP) are limited. Here, we examined and compared the occurrence and abundance of ARGs, mobile genetic elements (MGEs), metals, and bacterial communities from the feces of patients in a typical hWWTP system and determined the pathogenic hosts responsible for transferring ARGs. There were 176 ARGs and 43 MGEs detected in the feces of hospitalized patients, 129 genes were persistent, and 88 genes were enriched after HWW treatment, particularly for the bla_VEB, bla_NDM, and class 1 integron (intI1), with an average of 659-fold, 202-fold, and seven-fold enrichment, respectively. MGEs, especially Is613, in the feces of hospitalized patients were exceptionally abundant and even surpassed the abundance of total ARGs, which explained the persistence of ARGs in hWWTPs due to possible gene mobilization events. Bacteroidetes and Firmicutes were the most abundant phyla in these feces, accounting for 81 % of the total gut microbiota, while Epsilonbacteraeota and Proteobacteria dominated the hWWTPs. Additionally, 54 possible bacterial pathogens were found in the hospital environment, including four "ESKAPE" pathogens and 14 cancer-related pathogens. Many of them were strongly associated with different types of ARGs. Notably, Bacteroides was the major potential ARG-harboring pathogenic genus, as determined by the network analysis, and was highly abundant after the treatment. The altered microbial community was the major contributing factor shaping antibiotic resistome. This study might provide a comprehensive insight into the distribution profiles of ARGs and pathogens from the gut of inpatients throughout the HWW treatment system, which could be used as a reference for optimizing HWW treatment and monitoring public risk.

Antibiotic resistance profile of wastewater treatment plants in Brazil reveals different patterns of resistance and multi resistant bacteria in final effluents

Wastewater treatment plants (WWTPs) are recognized as important sources of Antibiotic Resistant Bacteria (ARBs) and Antibiotic Resistant Genes (ARGs), and might play a role in the removal and dissemination of antimicrobial resistance (AMR) in the environment. Detailed information about AMR removal by the different treatment technologies commonly applied in urban WWTPs is needed. This study investigated the occurrence, removal and characterization of ARBs in WWTPs employing different technologies: WWTP-A (conventional activated sludge-CAS), WWTP-B (UASB reactor followed by biological trickling filter) and WWTP-C (modified activated sludge followed by UV disinfection-MAS/UV). Samples of raw sewage (RI) and treated effluent (TE) were collected and, through the cultivation-based method using 11 antibiotics, the antibiotic resistance profiles were characterized in a one-year period. MAS was effective in reducing ARB counts (2 to 3 log units), compared to CAS (1 log unit) and UASB/BTF (0.5 log unit). The composition of cultivable ARB differed between RI and TE samples. Escherichia was predominant in RI (56/118); whilst in TE Escherichia (31/118) was followed by Bacillus (22/118), Shigella (14/118) and Enterococcus (14/118). Most of the isolates identified (370/394) harboured at least two ARGs and in over 80 % of the isolates, 4 or more ARG (int1, blaTEM, TetA, sul1 and qnrB) were detected. A reduction in the resistance prevalence was observed in effluents after CAS and MAS processes; whilst a slight increase was observed in treated effluents from UASB/BTF and after UV disinfection stage. The multi-drug resistance (MDR) phenotype was attributed to 84.3 % of the isolates from RI (27/32) and 63.6 % from TE (21/33) samples and 52.3 % of the isolates (34/65) were resistant to carbapenems (imipenem, meropenem, ertapenem). The results indicate that treated effluents are still a source for MDR bacteria and ARGs dissemination to aquatic environments. The importance of biological sewage treatment was reinforced by the significant reductions in ARB counts observed. However, implementation of additional treatments is needed to mitigate MDR bacteria release into the environment.

Transmission of antibiotic resistance genes through mobile genetic elements in Acinetobacter baumannii and gene-transfer prevention

Antibiotic resistance is a major global public health concern. Acinetobacter baumannii is a nosocomial pathogen that has emerged as a global threat because of its high levels of resistance to many antibiotics, particularly those considered as last-resort antibiotics, such as carbapenems. Mobile genetic elements (MGEs) play an important role in the dissemination and expression of antibiotic resistance genes (ARGs), including the mobilization of ARGs within and between species. We conducted an in-depth, systematic investigation of the occurrence and dissemination of ARGs associated with MGEs in A. baumannii. We focused on a cross-sectoral approach that integrates humans, animals, and environments. Four strategies for the prevention of ARG dissemination through MGEs have been discussed: prevention of airborne transmission of ARGs using semi-permeable membrane-covered thermophilic composting; application of nanomaterials for the removal of emerging pollutants (antibiotics) and pathogens; tertiary treatment technologies for controlling ARGs and MGEs in wastewater treatment plants; and the removal of ARGs by advanced oxidation techniques. This review contemplates and evaluates the major drivers involved in the transmission of ARGs from the cross-sectoral perspective and ARG-transfer prevention processes.