Antimicrobial resistance in southeast Asian water environments: A systematic review of current evidence and future research directions

Protective masks reduced gastrointestinal risks of antibiotic-resistant E. coli for hospital wastewater treatment plant workers: A quantitative microbial risk assessment

Antibiotic-resistant bacteria (ARB) in hospital wastewater present significant but under-researched risks for wastewater treatment plant (WWTP) workers. This study evaluated annual infection risks (Py) from exposure to ESBL-producing Escherichia coli (ESBL E. coli) and the effectiveness of protective masks. Wastewater samples from 25 hospitals in Thailand revealed 88 % of untreated samples were positive for ESBL E. coli (6.25 × 102 to 1.83 × 107 CFU/100 mL, mean 2.22 × 106), while 40 % of treated samples tested positive (1.00 × 102 to 1.97 × 105 CFU/100 mL, mean 2.45 × 104). Using quantitative microbial risk assessment and data from 917 workers, risks were calculated under three scenarios: non-resistant, antibiotic-resistant, and highly virulent E. coli. Ingestion of aerosols and droplets posed a higher infection risk than hand-to-mouth contact, with Py often exceeding the U.S. EPA benchmark of 10-4 per person per year. Mask use, particularly surgical and FFP2 masks, significantly reduced risks, bringing treated wastewater exposure below the benchmark. However, highly virulent E. coli risks remained high across all mask types. These findings highlight the need for effective protective measures and disinfection strategies to safeguard WWTP workers and mitigate ARB dissemination, protecting public health and environmental safety.

Evaluation of public health impact risks associated with bacterial antimicrobial resistome in tropical coastal environments

This study investigated antimicrobial resistance genes (ARGs) and microbial communities in Singapore's tropical coastal environments, comparing natural marine waters with aquaculture sites using metagenomic analysis. Results show consistently low ARG levels in natural ecosystems, whereas aquaculture sites exhibit elevated ARG concentrations, particularly those relevant to human pathogens, with considerably temporal fluctuations likely driven by human activities and seasonal factors. Additionally, aquaculture sites were found to host mobile genetic elements (MGEs) that may facilitate ARG spread, identifying aquaculture as a key reservoir of resistance genes with potential public health implications. These findings underscore distinct prevalence of ARG between natural and managed marine environments and highlight the need for continued surveillance to monitor ARG dynamics in coastal areas. By elucidating the potential for ARGs to transfer from aquaculture environments to the human food chain, this research emphasizes the importance of sustainable aquaculture practices and proactive ARG management strategies to mitigate antimicrobial resistance risks posed by tropical coastal ecosystem.

The Interactive Dynamics of Pseudomonas aeruginosa in Global Ecology

Pseudomonas aeruginosa is an opportunistic bacterium widely distributed in both natural and urban environments, playing a crucial role in global microbial ecology. This article reviews the interactive dynamics of P. aeruginosa across different ecosystems, highlighting its capacity for adaptation and resistance in response to environmental and therapeutic pressures. We analyze the mechanisms of antibiotic resistance, including the presence of resistance genes and efflux systems, which contribute to its persistence in both clinical and nonclinical settings. The interconnection between human, animal, and environmental health, within the context of the One Health concept, is discussed, emphasizing the importance of monitoring and sustainable management practices to mitigate the spread of resistance. Through a holistic approach, this work offers insights into the influence of P. aeruginosa on public health and biodiversity.

Antibiotic Resistance Dissemination and Mapping in the Environment Through Surveillance of Wastewater

Antibiotic resistance is one of the major health threat for humans, animals, and the environment, according to the World Health Organization (WHO) and the Global Antibiotic-Resistance Surveillance System (GLASS). In the last several years, wastewater/sewage has been identified as potential hotspots for the dissemination of antibiotic resistance and transfer of resistance genes. However, systematic approaches for mapping the antibiotic resistance situation in sewage are limited and underdeveloped. The present review has highlighted all possible perspectives by which the dynamics of ARBs/ARGs in the environment may be tracked, quantified and assessed spatio-temporally through surveillance of wastewater. Moreover, application of advanced methods like wastewater metagenomics for determining the community distribution of resistance at large has appeared to be promising. In addition, monitoring wastewater for antibiotic pollution at various levels, may serve as an early warning system and enable policymakers to take timely measures and build infrastructure to mitigate health crises. Thus, by understanding the alarming presence of antibiotic resistance in wastewater, effective action plans may be developed to address this global health challenge and its associated environmental risks.

Single-chain antibody gene therapy strategy based on high-throughput screening triggers sustained antiviral activity in the body

The occurrence of viral diseases poses a huge threat and impact on human public health safety and the development of the animal and fishery industry. Here, a strain of single-chain antibody fragment, scFv-1, was isolated from the phage antibody display library construct by immunizing New Zealand white rabbits with rhabdovirus. In vitro analysis showed that the single-chain antibody could inhibit the infection of the virus in multiple pathways, including adsorption, fusion, and release. In vivo analysis revealed scFv-1 had a preventive and protective effect against the infection of virus. In addition, we describe that transposon-based transport of neutralizing genes allows for long-term, continuous expression, avoiding the need for lifelong, repeated passive immunization for treatment. In sum, high-throughput screening of neutralization genes based on phage display technology and transposon vector-based gene transfer provides effective methods for treating and preventing diseases and avoiding repetitive passive immunotherapy. This study also provides a reference for the prevention and treatment of unknown pathogens.IMPORTANCELivestock and fisheries play an important role in economic development and food security. The frequent outbreaks of viral diseases have caused great losses to the livestock industry, while the increase in drug resistance caused by the use of antibiotics as well as the potential risks to human health have raised serious concerns. Here, we constructed a phage display antibody library by immunizing New Zealand white rabbits with purified rhabdovirus and selected a single-chain antibody, scFv-1, with good neutralizing activity, which was validated and found to be able to block multiple phases of the virus and thus play a neutralizing role. In addition, we describe that transposon-based transport of neutralizing genes allows for long-term, continuous expression, reducing the need for lifelong, repeated passive immunization for treatment. Our work not only provides methods for the prevention and treatment of viral diseases but also provides the body with long-lasting and even permanent protection against repeated passive immunization.

Chlorine and UV combination sequence: Effects on antibiotic resistance control and health risks of ARGs

The effective control of antibiotic resistance in aquatic environments is urgent. The combined chlorine and UV processes (Cl2-UV, UV/Cl2, and UV-Cl2) are considered potential control processes for controlling antibiotic resistance. This study compared the effectiveness of these three processes in real water bodies and the potential health risks associated with antibiotic resistance genes (ARGs) after treatments. The removal of various antibiotic-resistant bacteria (ARB) and ARGs by the combined processes was analysed. The UV/Cl2 process was less effective than the others in inactivating β-lactam-resistant bacteria (BRB) and sulfamethoxazole-resistant bacteria (SRB), which are more challenging to remove, though its performance might improve with increased UV fluence. Nevertheless, the UV/Cl2 process showed an advantage in removing ARGs. The absolute abundance of aminoglycoside resistance genes (AmRGs), sulfonamide resistance genes (SRGs), macrolide resistance genes (MRGs), and multidrug efflux-associated ARGs detected after the UV/Cl2 process was relatively low, and this process outperformed the others in removing a greater number of ARGs. Additionally, certain ARGs and bacterial genera were found to be enriched after the combined processes, with lower and more similar abundance levels of ARGs and genera observed after UV/Cl2 and UV-Cl2 processes compared to the Cl2-UV process. Health risk assessments indicated that the Cl2-UV process posed the highest risk, followed by UV/Cl2 and UV-Cl2 processes. Overall, the UV/Cl2 process may offer the most practical advantages for controlling antibiotic resistance.

A systematic scoping review of antibiotic-resistance in drinking tap water

Environmental matrices have been considered of paramount importance in the spread of antibiotic-resistance; however, the role of drinking waters is still underexplored. Therefore, a scoping review was performed using a systematic approach based on PRISMA guidelines, with the aim of identifying and characterizing antibiotic-resistance in tap water, specifically, water treated at a potabilization plant and provided for drinking use through a water distribution system. The review included 45 studies, the majority of which were conducted in upper-middle-income economies (42.2%), mainly from the Western Pacific region (26.7%), followed by Europe (24.4%). Most of the papers focused on detecting antibiotic-resistant bacteria (ARB), either alone (37.8%) or in combination with antibiotic-resistant genes (ARGs) (26.7%). Multidrug-resistance profile was often identified in heterotrophic bacteria, including various species of nontuberculous mycobacteria, Pseudomonas spp., and Aeromonas spp., which were especially resistant to penicillins, cephalosporins (including 3rd-generation), and also to macrolides (erythromycin) and tetracyclines. Resistance to a wide range of antibiotics was also prevalent in fecal bacteria, e.g., the Enterobacteriaceae family, with common resistance to (fluoro)quinolones and sulfonamide groups. ARGs were investigated either in bacterial strains isolated from tap waters or directly in water samples, and the most frequently detected ARGs belonged to β-lactam, sulfonamide, and tetracycline types. Additionally, mobile genetic elements were found (i.e., int1 and tnpA). Sulfonamides and macrolides were the most frequently detected antibiotics across countries, although their concentrations were generally low (<10 ng/L) in Europe and the United States. From a health perspective, tap water hosted ARB of health concern based on the 2024 WHO bacterial priority pathogens list, mainly Enterobacteriaceae resistant to 3rd-generation cephalosporin and/or carbapenem. Despite the fact that tap water is treated to meet chemical and microbiological quality standards, current evidence suggests that it can harbor antibiotic-resistance determinants, thus supporting its potential role in environmental pathways contributing to antibiotic resistance.

Quantitative distribution of antibiotic resistance genes and crAssphage in a tropical urbanized watershed

As antimicrobial resistance continues to pose a significant threat to global health, this study provided a focused examination of the prevalence and behavior of key antibiotic resistance genes in aquatic environments. We investigated the quantitative distribution of intI1, sul1, blaTEM, blaNDM, blaVIM, mcr-1, tetQ, and crAssphage within wastewater influents (n = 12), effluents (n = 12) and river water samples (n = 12), from three municipal wastewater treatment plants and three river locations in an urbanized watershed in Central Thailand over dry and wet seasons. The qPCR method demonstrated that intI1, sul1, blaTEM, and tetQ were the most abundant in all samples (2.71-7.89 mean log10 copies/100 mL), with all genes exhibiting consistently uniform levels across diverse locations, suggesting the potential for any site to act as a monitoring sentinel. Although there is a significant reduction of ARG concentrations by WWTPs (0.62 - >4.05 LRV), the persistence of these genes in effluents points to the limited effectiveness of existing treatment methodologies. Temporal data indicated stable ARG concentrations over time, but tetQ levels rose during the wet season, in alignment with the monsoonal climate in Thailand. Additionally, we identified crAssphage, a marker of human sewage contamination, exhibited strong correlations with the more abundant ARGs (rho 0.65 - 0.81), implying that human waste contributes significantly to the environmental burden of ARGs. The results of this research highlight the widespread nature of ARGs in water systems and the need for improved treatment and sanitation strategies to mitigate the public health threat posed by antimicrobial resistance.

Antibiotic resistance genes and crAssphage in hospital wastewater and a canal receiving the treatment effluent

Hospital wastewater is a major hotspot for the spread of antimicrobial resistance (AMR) in aquatic ecosystems. This study aimed to investigate the prevalence of antibiotic resistance genes (ARGs) and their correlation with crAssphage in a hospital wastewater treatment plant (HWWTP) and a receiving canal. Water samples were analyzed for 94 ARGs and crAssphage relative to the 16S rRNA using high-throughput quantitative polymerase chain reaction (HT-qPCR). Subsequently, 7 ARGs and crAssphage were selected and quantified using qPCR. The results showed that the detected genes ranged from 79 to 93 out of 95 genes. The raw wastewater (WW) samples had the highest gene diversity compared to the upstream canal, which had less diversity than downstream samples, as determined by HT-qPCR. The blaGES was the most abundant in WW samples, while qacEΔ1, merA, IS6100, tnpA, and IS26 showed high prevalence throughout the treatment processes. The concentrations of intI1, sul1, blaTEM,blaNDM,blaVIM,tetQ, mcr-1, crAssphage, and 16S rRNA, measured using qPCR, were the highest in WW and significantly reduced in treated water samples. Although some water quality parameters, such as total suspended solids and dissolved oxygen, did not significantly differ before and after treatment, removal efficiency ranged from 0.60 to 3.23 log reduction values (LRV). The highest LRV was observed for the tetQ, whereas the mcr-1 had the lowest LRV. Strong positive correlations among the absolute concentrations of ARGs and crAssphage were observed (Spearman's rho = 0.6-1.0), and biochemical oxygen demand correlated with blaTEM and blaVIM (Spearman's rho = 0.6). These results indicate that crAssphage and water quality could reflect the distribution of other ARGs throughout the HWWTP. Further studies are needed to underscore the importance of monitoring ARGs and genetic markers such as crAssphage in HWWTPs and their receiving waters to enhance our understanding of ARG distribution.

A multi-pronged approach to assessing antimicrobial resistance risks in coastal waters and aquaculture systems

Antimicrobial resistance (AMR) is a global challenge that has impacted aquaculture and surrounding marine environments. In this study, a year-long monitoring program was implemented to evaluate AMR in two different aquaculture settings (i.e., open cage farming, recirculating aquaculture system (RAS)) and surrounding marine environment within a tropical coastal region. The objectives of this study are to (i) investigate the prevalence and co-occurrence of antibiotic-resistant bacteria (ARB), antibiotic resistance genes (ARGs), antibiotics (AB) and various associated chemical compounds at these study sites; (ii) explore the contributing factors to development and propagation of AMR in the coastal environment; and (iii) assess the AMR risks from different perspectives based on the three AMR determinants (i.e., ARB, ARGs and AB). Key findings revealed a distinct pattern of AMR across the different aquaculture settings, notably a higher prevalence of antibiotic-resistant Vibrio at RAS outfalls, suggesting a potential accumulation of microorganisms within the treatment system. Despite the relative uniform distribution of ARGs across marine sites, specific genes such as qepA, blaCTX-M and bacA, were found to be abundant in fish samples, especially from the RAS. Variations in chemical contaminant prevalence across sites highlighted possible anthropogenic impacts. Moreover, environmental and seasonal variations were found to significantly influence the distribution of ARGs and chemical compounds in the coastal waters. Hierarchical cluster analysis that was based on ARGs, chemical compounds and environmental data, categorized the sites into three distinct clusters which reflected strong association with location, seasonality and aquaculture activities. The observed weak correlations between ARGs and chemical compounds imply that low environmental concentrations may be insufficient for resistance selection. A comprehensive risk assessment using methodologies such as the multiple antibiotic resistance (MAR) index, comparative AMR risk index (CAMRI) and Risk quotient (RQ) underscored the complexity of AMR risks. This research significantly contributes to the understanding of AMR dynamics in natural aquatic systems and provides valuable insights for managing and mitigating AMR risks in coastal environments.

High throughput qPCR unveils shared antibiotic resistance genes in tropical wastewater and river water

The global challenge posed by rising antimicrobial resistance, and the adoption of a One Health approach, has led to the prioritisation of surveillance for antibiotic resistance genes (ARGs) in various environments. Herein lies an information gap, particularly in the context of Thailand, where there is scarce data on ARG prevalence across diverse environmental matrices and throughout different seasons. This study aimed to fill this void, analysing ARG prevalence by high-throughput qPCR in influent (n = 12) and effluent wastewater (n = 12) and river water (n = 12). The study reveals a substantial and largely uniform presence of ARGs across all water sample types (87 % similarity). Intriguingly, no ARGs were exclusive to specific water types, indicating an extensive circulation of resistance determinants across the aquatic environment. The genes intI1, tnpA, and intI3, part of the integrons and mobile genetic elements group, were detected in high relative abundance in both wastewater and river water samples, suggesting widespread pollution of rivers with wastewater. Additional high-prevalence ARGs across all water types included qepA, aadA2, merA, sul1, qacF/H, sul2, aadB, and ereA. More alarmingly, several ARGs (e.g., blaVIM, intI3, mcr-1, mexB, qepA, vanA, and vanB) showed higher relative abundance in effluent and river water than in influents, which suggests malfunctioning or inadequate wastewater treatment works and implicates this as a possible mechanism for environmental contamination. Nine genes (i.e., blaCTX-M, blaVIM, emrD, ermX, intI1, mphA, qepA, vanA, and vanB) were recovered in greater relative abundance during the dry season in river water samples as compared to the wet season, suggesting there are seasonal impacts on the efficacy of wastewater treatment practices and pollution patterns into receiving waters. This study highlights the urgency for more effective measures to reduce antibiotic resistance dissemination in water systems.

Multidrug antibiotic resistance in hospital wastewater as a reflection of antibiotic prescription and infection cases

Antimicrobial resistance (AMR) is an escalating issue that can render illnesses more difficult to treat if effective antibiotics become resistant. Many studies have explored antibiotic resistance in bacteria (ARB) in wastewater, comparing results with clinical data to ascertain the public health risk. However, few investigations have linked the prevalence of ARB in hospital wastewater (HWW) with these outcomes. This study aimed to bridge this gap by assessing the prevalence of ARB in HWW and its receiving waters. Among the 144 isolates examined, 24 were obtained from each of the six sites (untreated wastewater, aeration tank, sedimentation tank, effluent after disinfection, upstream canal, and downstream canal). A significant portion (87.5 %) belonged to the Enterobacteriaceae family, with Klebsiella pneumoniae as the predominant species (47.9 %). The antimicrobial sensitivity testing (AST) showed that 57.6 % of the isolates were resistant to amoxicillin/clavulanic acid (AMX), the most prevalent antibiotic used within the studied hospital. The total resistance rate before and after treatment was 27.7 % and 28.0 %, respectively, with an overall multi-drug resistance (MDR) rate of 33.3 %. The multiple antibiotic resistance index (MARI) range varied between 0.0 and 0.9. The outpatient ward's three-day mean bacterial infection cases showed a significant association (Spearman's rho = 0.98) with the MARI in the sedimentation tank. Moreover, a strong correlation (Spearman's rho = 0.88) was found between hospital effluent's MARI and the seven-day mean inpatient ward case. These findings indicate that applying wastewater-based epidemiology (WBE) to hospital wastewater could provide valuable insights into understanding ARB contamination across human domains and water cycles. Future studies, including more comprehensive collection data on symptomatic patients and asymptomatic carriers, will be crucial in fully unravelling the complexities between human health and environmental impacts related to AMR.

Antimicrobial resistance in aquaculture: Occurrence and strategies in Southeast Asia

Aquaculture is a highly important and expanding industry in Southeast Asia (SEA). An upcoming problem is the emergence of antibiotic resistant pathogens due to the unchecked use of antibiotics and human clinical practices. This review focused insight into the occurrence of antimicrobial resistance (AMR) and strategies from SEA aquaculture based on the original research publication over the period 2002 to 2023. Amongst the 11 SEA countries, the most AMR report has come from Vietnam, Malaysia, and Thailand, respectively. The AMR found in SEA aquaculture were classified into 17 drug classes. The most reported AMR are aminoglycosides, beta-lactams, (fluoro)quinolones, tetracycline, sulpha group and multi-drug. Beta-lactams, tetracycline, sulpha group are reported in each country with the reported frequencies higher than 40 %. Escherichia coli, Aeromonas and Vibrio are the most widely and frequently reported ARB in SEA aquaculture. Multiple antibiotic resistance (MAR) indexes for the sample containing multiple bacterial isolates were generally low, while the medium numbers of MAR indexes for the typical bacteria species were higher than 0.2 and showed higher MAR levels than the global mean. Most of the detected ARGs are related to beta-lactams, tetracycline, sulpha group, and aminoglycosides. Amongst the beta-lactam resistance genes, blaTEM, and blaSHV are the most frequently detected. Almost all the available information of antibiotics, ARB and ARGs in SEA aquaculture was consistent with the global scale analysis. In addition, factors that contribute to the development and spread of AMR in SEA aquaculture were discussed. Moreover, the national action plan to combat AMR in SEA countries and the available technologies that already applied in the SEA aquaculture are also included in this review. Such findings underline the need for synergistic efforts from scientists, engineers, policy makers, government managers, entrepreneurs, and communities to manage and reduce the burden of AMR in aquaculture of SEA countries.

Micro/nanorobots for remediation of water resources and aquatic life

Nowadays, global water scarcity is becoming a pressing issue, and the discharge of various pollutants leads to the biological pollution of water bodies, which further leads to the poisoning of living organisms. Consequently, traditional water treatment methods are proving inadequate in addressing the growing demands of various industries. As an effective and eco-friendly water treatment method, micro/nanorobots is making significant advancements. Based on researches conducted between 2019 and 2023 in the field of water pollution using micro/nanorobots, this paper comprehensively reviews the development of micro/nanorobots in water pollution control from multiple perspectives, including propulsion methods, decontamination mechanisms, experimental techniques, and water monitoring. Furthermore, this paper highlights current challenges and provides insights into the future development of the industry, providing guidance on biological water pollution control.