The main objective of this study was to investigate the antibiotic resistance (AR) levels in wastewater (WW) and the impact on the receiving river. Samples were collected once per season over one ...year in the WW of a hospital, in the raw and treated WW of two wastewater treatment plants (WWTPs), as well as upstream and downstream from the release of WWTPs effluents into the Zenne River (Belgium). Culture-dependent methods were used to quantify Escherichia coli and heterotrophic bacteria resistant to amoxicillin, sulfamethoxazole, nalidixic acid and tetracycline. Six antibiotic resistance genes (ARGs) were quantified in both particle-attached (PAB) and free-living (FLB) bacteria. Our results showed that WWTPs efficiently removed antibiotic resistant bacteria (ARB) regardless of its AR profile. The ARGs levels were the highest in the hospital WW and were significantly reduced in both WWTPs. However, ARB and ARGs abundances significantly increased into the Zenne River downstream from the WWTPs outfalls. The variation in the relative abundance of ARGs through WW treatment differed depending on the WWTP, fraction, and gene considered. The sul1 and sul2 genes in PAB fraction showed significantly higher relative abundances in the effluent compared to the influent of both WWTPs. This study demonstrated that WWTPs could be hotspots for AR spread with significant impacts on receiving freshwater ecosystems. This was the first comprehensive study investigating at the same time antibiotics occurrence, fecal bacteria indicators, heterotrophic bacterial communities, and ARGs (distinguishing PAB and FLB) to assess AR levels in WW and impacts on the receiving river.
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•Brussels WWTPs efficiently remove antibiotic resistant bacteria (ARB).•Significant increase of ARB was found downstream from the WWTPs outfalls.•Absolute ARGs abundances are reduced from influents to effluents of both WWTPs.•Significant increase of ARGs was found downstream from the WWTPs outfalls.•Some ARGs relative abundance significantly increased in the effluent of WWTPs.
The ubiquity of antibiotic-resistance bacteria (ARB) and antibiotic-resistance genes (ARGs) in various environmental matrices is a potential threat to human and ecological health. Therefore, the ...inactivation of ARB E. coli S1-23 and the elimination of its associated ARGs, blaTEM-1 and aac(3)-II, were investigated using the photoelectrocatalytic (PEC) process. Results indicate that the ARB E. coli S1-23 (1 × 108 cfu mL−1) and its ARGs (extracellular and intracellular) could be fully inactivated within 10 and 16 h PEC treatment, respectively. In contrast, photocatalytic (PC) and electrochemical (EC) treatments displayed no obvious effect; however, ARG-containing DNA extracted from E. coli S1-23, which was used as a model for dissociative naked ARGs, could be completely decomposed within a few minutes through these three treatments. Further analyses, including PCR, AFM and HPLC, proved that the structural integrity and surface topography of naked ARGs are damaged during treatment and can be completely eliminated. Furthermore, there is no generation of cytosine, guanine, adenine or thymine intermediates during the PEC, PC, and EC treatments. This study is the first report to propose the PEC treatment as a promising method for complete decomposition of ARB and ARGs in aqueous systems.
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•PEC treatment can effectively inactivate ARB and intracellular ARGs can leak out.•Leaked ARGs can be fully destroyed with prolonging treatment time after killing ARB.•Dissociative naked ARG-containing DNA could also be fully destroyed by PEC treatment.
Infectious diseases are the second most important cause of human death worldwide;
is a very common human pathogenic microorganism that can trigger a variety of infectious diseases, such as skin and ...soft tissue infections, endocarditis, osteomyelitis, bacteremia, and lethal pneumonia. Moreover, according to the sensitivity to antibiotic drugs,
can be divided into methicillin-sensitive
(MSSA) and methicillin-resistant
(MRSA). In recent decades, due to the evolution of bacteria and the abuse of antibiotics, the drug resistance of
has gradually increased, the infection rate of MRSA has increased worldwide, and the clinical anti-infective treatment for MRSA has become more difficult. Accumulating evidence has demonstrated that the resistance mechanisms of
are very complex, especially for MRSA, which is resistant to many kinds of antibiotics. Therefore, understanding the drug resistance of MRSA in a timely manner and elucidating its drug resistance mechanism at the molecular level are of great significance for the treatment of
infection. A large number of researchers believe that analyzing the molecular characteristics of
can help provide a basis for designing effective prevention and treatment measures against hospital infections caused by
and further monitor the evolution of
. This paper reviews the research status of MSSA and MRSA, the detailed mechanisms of the intrinsic antibiotic resistance and the acquired antibiotic resistance, the advanced research on anti-MRSA antibiotics and novel therapeutic strategies for MRSA treatment.
This Special Issue on Antimicrobial Resistance in Environmental Waters features 11 articles on the monitoring and surveillance of antimicrobial resistance (AMR) in natural aquatic systems (i.e., ...reservoirs, rivers), and effluent discharge from water treatment plants to assess the effectiveness of AMR removal and resulting loads in treated waters. Some of the key elements of AMR studies presented in this Special Issue highlight the underlying drivers of AMR contamination in the environment and the evaluation of the hazard imposed on aquatic organisms in receiving environments through ecological risk assessments. As described in this Issue, screening antimicrobial peptide (AMP) libraries for biofilm disruption and antimicrobial candidates are promising avenues for the development of new treatment options to eradicate resistance.
The growing antibiotic resistance of microorganisms is an increasingly important challenge for modern medicine. In the next few decades, the so-called post antibiotic era is likely to begin. For this ...reason, the search for new solutions using PACT seems particularly promising.
Four new chlorin compounds were tested and photochemically characterized for singlet oxygen generation efficiency and photostability. They have been evaluated for bactericidal properties against MRSA, E. coli (ESBL+) and C. albicans. Their synergism with antibiotics from the group of cephalosporins and carbapenems was evaluated.
A reduction of approximately 3 logs or more was achieved for each of the bacterial strains. A decrease in MIC values was observed for all bacteria, the greatest for ceftriaxone.
Combining traditional antibiotic therapy with PACT may be a promising route in the case of antibiotic-resistant infections, but requires further in-depth research.
Swine wastewater treatment plant has become one of the main sources of antibiotic resistance genes (ARGs). Membrane treatment processes are promising solutions for removal of the emerging ...contaminants. However, limited studies have investigated the effects of nanofiltration and reverse osmosis treatment in removing ARGs in swine wastewater. In this study, the presence and the fate of common ARGs including sul1, sul2, tetA, tetM and tetW, as well as intI1 and 16S rRNA gene, were investigated in a medium-sized (6500) pig farm wastewater treatment plant (WWTP) equipped with conventional biological treatment and advanced membrane processing system. All of the genes were detected with highly abundance in the raw sewage. The biological treatments of the swine wastewater treatment plant did not reduce the quantity of the ARGs. As expected, nanofiltration and reverse osmosis treatment reduced the absolute gene copy number of ARGs efficiently (4.98–9.52 logs removal compared to raw sewage). Compared to the reverse osmosis effluent, however, the absolute abundance of ARGs in the artificial wetland increased by 1.00–2.06 logs. Meanwhile, the relative abundance of sulfonamide resistant genes were basically unchanged, while tetracycline resistance genes (tetA, tetM and tetW) decreased by 0.88, 3.47, 2.51 log, respectively. The results demonstrated that advanced membrane treatments are capable of removing various kinds of ARGs efficiently, as well as some common nitrogen and phosphorus contaminants. This study suggested a mature alternative method for the removal of ARGs from livestock wastewater.
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•Swine sewage presents high content of ARGs.•Nanofiltration and reverse osmosis reduces ARGs, nitrogen and phosphorus contaminants.•The abundance of ARGs in artificial wetland increased.
This study assessed the inactivation efficiency of plasmid-encoded antibiotic resistance genes (ARGs) both in extracellular form (e-ARG) and present within Escherichia coli (intracellular form, ...i-ARG) during water treatment with chlorine, UV (254 nm), and UV/H2O2. A quantitative real-time PCR (qPCR) method was used to quantify the ARG damage to ampR (850 bp) and kanR (806 bp) amplicons, both of which are located in the pUC4K plasmid. The plate count and flow cytometry methods were also used to determine the bacterial inactivation parameters, such as culturability and membrane damage, respectively. In the first part of the study, the kinetics of E. coli inactivation and ARG damage were determined in phosphate buffered solutions. The ARG damage occurred much more slowly than E. coli inactivation in all cases. To achieve 4-log reduction of ARG concentration at pH 7, the required chlorine exposure and UV fluence were 33–72 (mg × min)/L for chlorine and 50–130 mJ/cm2 for UV and UV/H2O2. After increasing pH from 7 to 8, the rates of ARG damage decreased for chlorine, while they did not vary for UV and UV/H2O2. The i-ARGs mostly showed lower rates of damage compared to the e-ARGs due to the protective roles of cellular components against oxidants and UV. The contribution of OH radicals to i-ARG damage was negligible in UV/H2O2 due to significant OH radical scavenging by cellular components. In all cases, the ARG damage rates were similar for ampR versus kanR, except for the chlorination of e-ARGs, in which the damage to ampR occurred faster than that to kanR. Chlorine and UV dose-dependent ARG inactivation levels determined in a wastewater effluent matrix could be reasonably explained by the kinetic data obtained from the phosphate buffered solutions and the expected oxidant (chlorine and OH radicals) demands by water matrix components. These results can be useful in optimizing chlorine and UV-based disinfection systems to achieve ARG inactivation.
•Inactivation kinetics of ARB, e- and i-ARGs by chlorine, UV, UV/H2O2 were determined.•Damages of ARGs occurred much more slowly than the inactivation of ARB (E. coli).•Damages of i-ARGs were slower than e-ARGs due to protections by cellular components.•4-log ARG reductions require 40–70 (mg × min)/L for chlorine and 50–130 mJ/cm2 for UV.•ARG removals in a wastewater effluent were predictable from the ARG damage kinetics.
Antibiotic resistance genes (ARGs) are a growing problem that is widespread in river–lake ecosystems, where they pose a threat to the aquatic environment's health and public safety. These systems ...serve as critical nodes in water management, as they facilitate the equitable allocation of water resources through long-term and frequent water diversions. However, hydrological disturbances associated with water-regulation practices can influence the dynamics of their potential host microorganisms and associated resistance genes. Consequently, identifying the key ARGs and their resistance mechanisms in heavily regulated waters is vital for safeguarding human health and that of river–lake ecosystems. In this study, we examined the impact of water-regulation factors on ARGs and their hosts within a river–lake continuum using 16S rRNA and metagenomic sequencing. We found that a significant increase in ARG abundance during regulation periods (p < 0.05), especially in the aquatic environment. Key resistance genes were macB, tetA, evgS, novA, and msbA, with increased efflux pinpointed as their principal resistance mechanism. Network analysis identified Flavobacteriales, Acinetobacter, Pseudomonas, Burkholderiaceae, and Erythrobacter as key potential host microorganisms, which showed increased abundance within the water column during regulation periods (p < 0.05). Flow velocity and water depth both drove the host microorganisms and critical ARGs. Our findings underscore the importance of monitoring and mitigating the antibiotic resistance risk during water transfers in river–lake systems, thereby supporting informed management and conservation strategies.
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•Antibiotic resistance gene (ARG) abundance increased during regulation periods.•The key ARGs identified in microbes were macB, tetA, evgS, novA, and msbA.•Increased antibiotic efflux was the dominant antibiotic resistance mechanism.•Hosts were Flavobacteriales, Acinetobacter, Pseudomonas and Burkholderiaceae.•Increased flow velocity promoted gene exchange within microbial communities.
With an increase of diverse contaminants in the environment, particularly antibiotics, the maintenance and propagation of antibiotic resistance genes (ARGs) are promoted by co-selection mechanisms. ...ARGs are difficult to degrade, cause long-lasting pollution, and are widely transmitted in aquatic environments. Biochar is frequently used to remove various pollutants during environmental remediation. Thus, this review provides a thorough analysis of the current state of ARGs in the aquatic environment as well as their removal by using biochar. This article summarizes the research and application of biochar and modified biochar to remove ARGs in aquatic environments, in order to refine the following contents: 1) fill gaps in the research on the various ARG behaviors mediated by biochar and some influence factors, 2) further investigate the mechanisms involved in effects of biochar on extracellular ARGs (eARGs) and intracellular ARGs (iARGs) in aquatic environments, including direct and the indirect effects, 3) describe the propagation process and resistance mechanisms of ARGs, 4) propose the challenges and prospects of feasibility of application and subsequent treatment in actual aquatic environment. Here we highlight the most recent research on the use of biochar to remove ARGs from aquatic environments and suggest future directions for optimization, as well as current perspectives to guide future studies on the removal of ARGs from aquatic environments.
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•The numerous ways that biochar affects ARGs in aquatic environments were analyzed.•The different mediating effects of biochar on the lowering of iARGs and eARGs were discussed.•The inhibitory effect of biochar on HGT at the gene level was illustrated.•The application of different biochars for removing ARGs was summarized.
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