Occurrences and Characterization of Antibiotic-Resistant Bacteria and Genetic Determinants of Hospital Wastewater in a Tropical Country

Multi-drug resistant (MDR) Gram-negative pathogenic bacteria isolated from poultry in the Noakhali region of Bangladesh

Rapidly increasing antibiotic-resistant bacterial strains in Bangladesh's food and farm animals stem from the excessive and inappropriate use of antibiotics. To assess the prevalence of multi-drug resistant (MDR) Gram-negative bacteria in poultry chicks, we sought to isolate and identify strains carrying antimicrobial resistance genes. Isolation and identification involved biochemical tests, 16S rRNA sequencing, and PCR screening of species-specific genes. MDR patterns were evaluated using CLSI guidelines with seventeen antibiotics across twelve classes. Targeted gene sequences were amplified for the detection of Extended-spectrum β-Lactamase (ESBL), carbapenem, tetracycline, sulfonamide, and colistin resistance genes. Common isolates, such as Escherichia coli, Klebsiella pneumoniae, Proteus penneri, and Enterobacter hormaechei, exhibited average Multiple Antimicrobial Resistance (MAR) indices of 0.66, 0.76, 0.8, 0.84, and 0.81, 0.76, 0.84, 0.41 for broiler and layer chicken, respectively. Providencia stuartii and Salmonella enterica, exclusive to broiler samples, had MAR indices of 0.82 and 0.84, respectively. Additional isolates Morganella morganii, Aeromonas spp., and Wohlfahrtiimonas chitiniclastica were found in layers (Average MAR indices: 0.73, 0.71, and 0.91). Notably, M. morganii, E. hormaechei and W. chitiniclastica were identified for the first time in Bangladeshi poultry chicken, although their evolution is yet to be understood. In this study, Pan-drug resistance was observed in one P. stuartii (broiler) and one Aeromonas spp. (layer) with a MAR index 1, while all isolates exhibited MAR indices >0.2, indicating MDR. Antimicrobial resistance (AMR) gene screening identified blaTEM, blaSHV, tetA, and sul1 in a majority of the MDR strains. Interestingly, E. coli (lactose positive and negative) and E. hormaechei were exclusively found to possess the tetB gene. In addition, E. coli (lactose negative), Klebsiella pneumoniae, Enterobacter hormaechei, M. morganii, and P. stuartii were observed to carry the colistin-resistant mcr-1 gene, whereas sul2 was detected in E. coli (lactose positive and negative), E. hormaechei, P. stuartii, and P. penneri. These findings emphasize the health risk of our consumers of both broiler and layer chickens as they have turned into a potent reservoir of various AMR gene carrying MDR and Pan-drug resistant bacteria.

Pharmaceutical industrial wastewater exhibiting the co-occurrence of biofilm-forming genes in the multidrug-resistant bacterial community poses a novel environmental threat

The interaction of the environment with the effluent of wastewater treatment plants, having antibiotics, multidrug-resistant (MDR) bacteria, and biofilm-forming genes (BFGs), has vast environmental risks. Antibiotic pollution bottlenecks environmental bacteria and has the potential to significantly lower the biodiversity of environmental bacteria, causing an alteration in ecological equilibrium. It can induce selective pressure for antibiotic resistance (AR) and can transform the non-resistant environmental bacteria into a resistant form through HGT. This study investigated the occurrence of MDR bacteria, showing phenotypic and genotypic characteristics of biofilm. The bacteria were isolated from the pharmaceutical wastewater treatment plants (WWTPs) of Dehradun and Haridwar (India), located in the pharmaceutical areas. The findings of this study demonstrate the coexistence of BFGs and MDR clinical bacteria in the vicinity of pharmaceutical industrial wastewater treatment plants. A total of 47 bacteria were isolated from both WWTPs and tested for antibiotic resistance to 13 different antibiotics; 16 isolates (34.04 %) tested positive for MDR. 5 (31.25 %) of these 16 MDR isolates were producing biofilm and identified as Pseudomonas aeruginosa, Acinetobacter baumannii, Escherichia coli, Klebsiella pneumoniae, and Burkholderia cepacia. The targeted BFGs in this study were ompA, bap and pslA. The most common co-occurring gene was ompA (80 %), with pslA (40 %) being the least common. A. baumannii contains all three targeted genes, whereas B. cepacia only has bap. Except for B. cepacia, all the biofilm-forming MDR isolates show AR to all the tested antibiotics and prove that the biofilm enhances the AR potential. The samples of both wastewater treatment plants also showed the occurrence of tetracycline, ampicillin, erythromycin and chloramphenicol, along with high levels of BOD, COD, PO4-3, NO3-, heavy metals and organic pollutants. The co-occurrence of MDR and biofilm-forming tendency in the clinical strain of bacteria and its environmental dissemination may have an array of hazardous impacts on human and environmental health.

Complete genome sequence of carbapenem-resistant pathogenic Klebsiella aerogenes strain CH7 isolated from vermicompost

We announce the complete genome of Klebsiella aerogenes strain CH7, isolated from a vermicompost sample. A total of 9.14131 million high-quality reads comprised 96 contigs with 5,273 genes and 5,038 protein-coding genes.

Removal efficiency of antibiotic residues, antibiotic resistant bacteria, and genes across parallel secondary settling tank and membrane bioreactor treatment trains in a water reclamation plant

Antimicrobial resistance is recognized as a potent threat to human health. Wastewater treatment facilities are viewed as hotspots for the spread of antimicrobial resistance. This study provides comprehensive data on the occurrences of 3 different antibiotic resistant opportunistic pathogens (with resistance to up to 5 antibiotics), 13 antibiotic resistant genes and intI1, and 22 different antimicrobial residues in a large water reclamation plant (176 million gallons per day) that runs a conventional Modified Ludzack-Ettinger (MLE) reactor followed by a secondary settling tank (SST) and membrane bioreactor (MBR) in parallel. All the antibiotic resistant bacteria and most of the antibiotic resistance genes were present in the raw influent, ranging from 2.5 × 102-3.7 × 106 CFU/mL and 1.2× 10-1-6.5 × 1010 GCN/mL, respectively. MBR outperformed the SST system in terms of ARB removal as the ARB targets were largely undetected in MBR effluent, with log removals ranging from 2.7 to 6.8, while SST only had log removals ranging from 0.27 to 4.6. Most of the ARG concentrations were found to have significantly higher in SST effluent than MBR permeate, and MBR had significantly higher removal efficiency for most targets (p < 0.05) except for sul1, sul2, blaOXA48, intI1 and 16S rRNA genes (p > 0.05). As for the antibiotic residues (AR), there was no significant removal from the start to the end of the treatment process, although MBR had higher removal efficiencies for azithromycin, chloramphenicol, erythromycin, erythromycin-H2O, lincomycin, sulfamethoxazole and triclosan, compared to the SST system. In conclusion, MBR outperformed SST in terms of ARB and ARGs removal. However low removal efficiencies of most AR targets were apparent.

Activated sludge and UV-C254 for Sapovirus, Aichivirus, Astrovirus, and Adenovirus processing

In this study, the detection rates of four enteric viruses, Human Astrovirus (HAstVs), Aichivirus (AiVs), Human Adenovirus (HAdVs), and Sapovirus (SaVs) are carried out to assess the virological quality of the treated wastewater. A total of 140 samples was collected from wastewater treatment plant WWTP of Tunis-City. Real-time RT-PCR and conventional RT-PCR results showed high frequencies of detection of the four enteric viruses investigated at the entry and exit of the biological activated sludge procedure and a significant reduction in viral titers after tertiary treatment with UV-C254 irradiation. These results revealed the ineffectiveness of the biological activated sludge treatment in removing viruses and the poor quality of the treated wastewater intended for recycling, agricultural reuse, and safe discharge into the natural environment. The UV-C254 irradiation, selected while considering the non-release of known disinfection by-products because of eventual reactions with the large organic and mineral load commonly present in the wastewater.

Protecting the Last Line of Defense: Analytical Approaches for Sample Preparation and Determination of the Reserve Group of Antibiotics in the Environment

Drug resistance in microorganisms is a serious threat to life and health due to the limited number of antibiotics that show efficacy in treating infections and the difficulty in discovering new compounds with antibacterial activity. To address this issue, the World Health Organization created the AWaRe classification, a tool to support global and national antimicrobial stewardship programs. The AWaRe list categorizes antimicrobials into three groups - Access, Watch, and Reserve - according to their intended use. The Reserve group comprises "last resort" medicines used solely for treating infections caused by bacterial strains that are resistant to other treatments. It is therefore necessary to protect them, not only by using them as prudently as possible in humans and animals, but also by monitoring their subsequent fate. Unmetabolized antibiotics enter the environment through hospital and municipal wastewater or from manure, subsequently contaminating bodies of water and soils, thus contributing to the emergence and spread of antibiotic resistance. This article presents a review of determination methods for the Reserve group of antimicrobials in water, wastewater, and manure. Procedures for extracting and determining these substances in environmental samples are described, showing the limited research available, which is typically on a local level.

Fate and transport modelling for evaluating antibiotic resistance in aquatic environments: Current knowledge and research priorities

Antibiotics have revolutionised medicine in the last century and enabled the prevention of bacterial infections that were previously deemed untreatable. However, in parallel, bacteria have increasingly developed resistance to antibiotics through various mechanisms. When resistant bacteria find their way into terrestrial and aquatic environments, animal and human exposures increase, e.g., via polluted soil, food, and water, and health risks multiply. Understanding the fate and transport of antibiotic resistant bacteria (ARB) and the transfer mechanisms of antibiotic resistance genes (ARGs) in aquatic environments is critical for evaluating and mitigating the risks of resistant-induced infections. The conceptual understanding of sources and pathways of antibiotics, ARB, and ARGs from society to the water environments is essential for setting the scene and developing an appropriate framework for modelling. Various factors and processes associated with hydrology, ecology, and climate change can significantly affect the fate and transport of ARB and ARGs in natural environments. This article reviews current knowledge, research gaps, and priorities for developing water quality models to assess the fate and transport of ARB and ARGs. The paper also provides inputs on future research needs, especially the need for new predictive models to guide risk assessment on AR transmission and spread in aquatic environments.

Pharmaceuticals and personal care products in Tunisian hospital wastewater: occurrence and environmental risk

Despite concerns about the potential risk associated with the environmental occurrence of pharmaceuticals and personal care products (PPCPs), few studies address the emissions of hospitals to aquatic compartments. We examined within a 3-month sampling period the occurrence and environmental risk of PPCPs in seven Tunisian hospital wastewaters. From personal care products, UV filters, main metabolites, and benzotriazoles were quantified, with benzophenone 3 (oxybenzone, BP3) and benzotriazole (BZT) the most frequently found (71%) at median concentrations in the range 2.43 ± 0.87 ngL-1-64.05 ± 6.82 ngL-1 for BP3 and 51.67 ± 1.67 ngL-1-254 ± 9.9 ngL-1 for BZT. High concentrations were also found for 4-hydroxybenzophenone (4HB) (221 ± 6.22 ngL-1), one of the main metabolites of BP3. The antibiotics ofloxacin and trimethoprim, the anti-inflammatory acetaminophen, the antiepileptic carbamazepine, and the stimulant caffeine were present in all the wastewaters. The highest median concentration corresponded to acetaminophen, with 1240 ± 94 mgL-1 in Tunis Hospital, followed by ofloxacin with 78850 ± 39 μgL-1 in Sousse Hospital. For ecotoxicity assessment, acute toxicity was observed for Daphnia magna and Vibrio fischeri. The toxicity data were used in a hazard quotient (HQ) approach to evaluate the risk posed by the target PPCPs to aquatic organisms. The calculated HQs revealed that marbofloxacin (234 for V. fischeri), enrofloxacin (121 for D. magna), and BZT (82.2 for D. magna and 83.7 for V. fischeri) posed the highest risk, concluding that potential risk exists toward aquatic microorganisms. This study constitutes the first monitoring of UV filters in Tunisian hospital effluents and provides occurrence and toxicity data of PPCPs for reference in further surveys in the country.

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.

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

BACKGROUND

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

RESULTS

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

CONCLUSIONS

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

The occurrence and abundance of antibiotic resistance genes in rivers of tropical islands: a case of Hainan Island, China

In this study, the occurrence and distribution of 49 antibiotic resistance genes (ARGs) and two integrase genes (intl1, intl2) in three major rivers of Hainan Island, China, were investigated in July 2021, and to explore the spatial distribution of the target genes in the three rivers with the potential influencing factors such as regional characteristics and environmental factors. The results showed that a total of 46 ARGs and two integrase genes were detected in water and sediment, and the absolute abundance of ARGs ranged from 1.16 × 103 to 2.97 × 107 copies/L and 3.34 × 103-1.55 × 107 copies/g. ARGs of macrolides, aminoglycosides, and sulfonamides were this study's main types of ARGs. The aadA2, tetE, ermF, tetX, aac(6')-Ib, tetW, and qnrS genes are predominant ARGs in the water and sediment of the three rivers. The relative abundance of ARGs shows higher abundance in the midstream and downstream and lower abundance in the upstream and estuarine. After conducting a correlation analysis, it was found that there was a significant positive correlation between the ARGs detected in the water of the three main rivers. However, in sediment, tetC was negatively correlated with tetQ, macB was negatively correlated with ermF and ereA (p < 0.05), while the remaining ARGs showed positive correlations. Specifically, there was no significant positive correlation between tetQ and tetC, macB and ereA, and ermF in the sediments. Among the nine environmental factors studied, pH was found to be the main factor associated with the occurrence of ARGs in the aquatic environment, but it was also significantly associated with only nine ARGs. Among the detected heavy metals, only Cd and Zn showed significant correlations with the two ARGs in the water bodies of the three main rivers. It indicated that the pollution of ARGs in the three major rivers was in the initial stage, the detection abundance was low, the influence of environmental factors was small, and the interaction between ARGs seemed to be the main driving force. This study provides a scientific basis for further understanding the occurrence of ARGs and their influencing factors in a tropical island environment, and lays a foundation for subsequent management.

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.

A Review of Antibiotics, Antibiotic Resistant Bacteria, and Resistance Genes in Aquaculture: Occurrence, Contamination, and Transmission

Antibiotics are commonly used to prevent and control diseases in aquaculture. However, long-term/overuse of antibiotics not only leaves residues but results in the development of antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs). Antibiotics, ARB, and ARGs are widespread in aquaculture ecosystems. However, their impacts and interaction mechanisms in biotic and abiotic media remain to be clarified. In this paper, we summarized the detection methods, present status, and transfer mechanisms of antibiotics, ARB, and ARGs in water, sediment, and aquaculture organisms. Currently, the dominant methods of detecting antibiotics, ARB, and ARGs are UPLC-MS/MS, 16S rRNA sequencing, and metagenomics, respectively. Tetracyclines, macrolides, fluoroquinolones, and sulfonamides are most frequently detected in aquaculture. Generally, antibiotic concentrations and ARG abundance in sediment are much higher than those in water. Yet, no obvious patterns in the category of antibiotics or ARB are present in organisms or the environment. The key mechanisms of resistance to antibiotics in bacteria include reducing the cell membrane permeability, enhancing antibiotic efflux, and structural changes in antibiotic target proteins. Moreover, horizontal transfer is a major pathway for ARGs transfer, including conjugation, transformation, transduction, and vesiculation. Identifying, quantifying, and summarizing the interactions and transmission mechanisms of antibiotics, ARGs, and ARB would provide useful information for future disease diagnosis and scientific management in aquaculture.

Prevalence and Abundance of Beta-Lactam Resistance Genes in Hospital Wastewater and Enterobacterales Wastewater Isolates

Antimicrobial resistance may develop in nature including in hospital wastewater through horizontal genetic transfer. Few studies were conducted on the antimicrobial resistance genes in hospital wastewater and wastewater isolates in Indonesia. The prevalence and abundance of beta-lactam resistance genes in hospital wastewater and Enterobacterales wastewater isolates were investigated. Twelve wastewater samples were collected from an influent wastewater treatment plant. Escherichia coli and Klebsiella pneumoniae were isolated from the wastewater samples by culture-based methods. DNA was extracted from wastewater samples and the isolates. Nineteen beta-lactam resistance genes were tested by a high throughput qRT-PCR method. blaGES and blaTEM were the most abundant genes detected in hospital wastewater and Escherichia coli, respectively (p < 0.001). The relative abundance of blaCMY_2, blaCTX-M5, blaCTX-M8, blaGES, blaNDM, and blaSHV11 in Klebsiella pneumoniae was higher than in the wastewater and Escherichia coli (p < 0.001; p = 0.006; p = 0.012; p < 0.001; p = 0.005; p < 0.001). Klebsiella pneumoniae might be associated with resistance to piperacillin/tazobactam, ceftriaxone, and cefepime (p < 0.001; p = 0.001; p < 0.001). In conclusion, ESBL genes showed higher abundance than carbapenemase genes in hospital wastewater samples. The ESBL-producing bacteria that were predominantly found in hospital wastewater may originate from clinical specimens. The culture-independent antibiotic resistance monitoring system might be developed as an early warning system for the increasing beta-lactam resistance level in clinical settings.

A new class A beta-lactamase gene blaCAE-1 coexists with blaAFM-1 in a novel untypable plasmid in Comamonas aquatica

Antimicrobial resistance, especially carbapenem resistance, poses a serious threat to global public health. Here, a carbapenem-resistant Comamonas aquatica isolate SCLZS63 was recovered from hospital sewage. Whole-genome sequencing showed that SCLZS63 has a 4,048,791-bp circular chromosome and three plasmids. The carbapenemase gene bla_AFM-1 is located on the 143,067-bp untypable plasmid p1_SCLZS63, which is a novel type of plasmid with two multidrug-resistant (MDR) regions. Notably, a novel class A serine β-lactamase gene, bla_CAE-1, coexists with bla_AFM-1 in the mosaic MDR2 region. Cloning assay showed that CAE-1 confers resistance to ampicillin, piperacillin, cefazolin, cefuroxime, and ceftriaxone, and elevates the MIC of ampicillin-sulbactam two-fold in Escherichia coli DH5α, suggesting that CAE-1 functions as a broad-spectrum β-lactamase. Amino acid sequences analysis suggested that bla_CAE-1 may originate from Comamonadaceae. The bla_AFM-1 in p1_SCLZS63 is located in a conserved structure of ISCR29-ΔgroL-bla_AFM-1-ble-ΔtrpF-ΔISCR27-msrB-msrA-yfcG-corA. Comprehensive analysis of the bla_AFM-bearing sequences revealed important roles of ISCR29 and ΔISCR27 in the mobilization and truncation of the core module of bla_AFM alleles, respectively. The diverse passenger contents of class 1 integrons flanking the bla_AFM core module make the complexity of genetic contexts for bla_AFM. In conclusion, this study reveals that Comamonas may act as an important reservoir for antibiotics-resistance genes and plasmids in the environment. Continuous monitoring for the environmental emergence of antimicrobial-resistant bacteria is needed to control the spread of antimicrobial 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.

Genotypic Diversity, Antibiotic Resistance, and Virulence Phenotypes of Stenotrophomonas maltophilia Clinical Isolates from a Thai University Hospital Setting

Stenotrophomonas maltophilia is a multidrug-resistant organism that is emerging as an important opportunistic pathogen. Despite this, information on the epidemiology and characteristics of this bacterium, especially in Thailand, is rarely found. This study aimed to determine the demographic, genotypic, and phenotypic characteristics of S. maltophilia isolates from Maharaj Nakorn Chiang Mai Hospital, Thailand. A total of 200 S. maltophilia isolates were collected from four types of clinical specimens from 2015 to 2016 and most of the isolates were from sputum. In terms of clinical characteristics, male and aged patients were more susceptible to an S. maltophilia infection. The majority of included patients had underlying diseases and were hospitalized with associated invasive procedures. The antimicrobial resistance profiles of S. maltophilia isolates showed the highest frequency of resistance to ceftazidime and the lower frequency of resistance to chloramphenicol, levofloxacin, trimethoprim/sulfamethoxazole (TMP/SMX), and no resistance to minocycline. The predominant antibiotic resistance genes among the 200 isolates were the smeF gene (91.5%), followed by bla_L1 and bla_L2 genes (43% and 10%), respectively. Other antibiotic resistance genes detected were floR (8.5%), intI1 (7%), sul1 (6%), mfsA (4%) and sul2 (2%). Most S. maltophilia isolates could produce biofilm and could swim in a semisolid medium, however, none of the isolates could swarm. All isolates were positive for hemolysin production, whereas 91.5% and 22.5% of isolates could release protease and lipase enzymes, respectively. In MLST analysis, a high degree of genetic diversity was observed among the 200 S. maltophilia isolates. One hundred and forty-one sequence types (STs), including 130 novel STs, were identified and categorized into six different clonal complex groups. The differences in drug resistance patterns and genetic profiles exhibited various phenotypes of biofilm formation, motility, toxin, and enzymes production which support this bacterium in its virulence and pathogenicity. This study reviewed the characteristics of genotypes and phenotypes of S. maltophilia from Thailand which is necessary for the control and prevention of S. maltophilia local spreading.

Research of Antibiotic Residues and Bacterial Strain's Antibiotic Resistance Profile in the Liquid Effluents Evacuated in Nature by Two CHUs and a Mixed WWTP of Ouagadougou (Burkina Faso)

Background

In Burkina Faso, suspicions have been raised that hospital liquid effluents are a source of microbiological contaminants in surface waters of urban and peri-urban areas. This study aimed to determine the antibiotic residues and the antibiotic resistance phenotype of potential pathogenic bacteria in the hospital liquid effluents discharged into nature by the CHUs Bogodogo, Yalgado Ouédraogo and the WWTS of Kossodo.

Methods

Fifteen samples of liquid effluents discharged into nature were collected. Antibiotic residues were identified by HPLC. A wavelength of 254 nm for the UV detector was set. Antibiotic testing was realized according to CASFM 2019 recommendations.

Results

Three molecules including Amoxicillin, Chloramphenicol and Ceftriaxone were detected in 13 samples. The strains characterized were 06 E. coli, 09 Pseudomonas spp, 05 Staphylococcus aureus and 04 Salmonella spp. Thus, none of the strains was resistant to Imipenem, but they were resistant to Amoxiclav with rates of 83.33% (E. coli), 88.88% (Pseudomonas spp) and 100% (Staphylococcus aureus and Salmonella spp).

Conclusion

Ouagadougou hospital liquid effluents discharged into nature are contaminated with antibiotic residues and potential pathogenic bacteria.

Stress-responses of microbes in oil reservoir under high tetracycline exposure and their environmental risks

As the groundwater ecosystem is connected with surface, antibiotics and antibiotic resistance genes (ARGs) in aquatic environments will gradually infiltrate into the deep environment, posing a potential threat to groundwater ecosystem. However, knowledge on the environmental risk of antibiotics and ARGs in groundwater ecosystem and their ecological process still remains unexplored. In this study, lab-scale oil reservoirs under high tetracycline stress were performed to evaluate the dynamics of microbial communities, ARGs and potential functions by using 16S rRNA gene sequencing and metagenomics analysis. Although the presence of antibiotics remarkably reduced the microbial abundance and diversity in a short term, but remain stable or even increased after a long-term incubation. Antibiotic stress caused a greater diversity and abundance of ARGs, and higher numbers of ARGs-related species with the capacity to transfer ARGs to other microbes through horizontal gene transfer. Thus, a much more frequent associations of microbial community at both node- and network-level and a selective pressure on enrichment of antibiotic resistant bacteria related to "anaerobic n-alkane degradation" and "methylotrophic methanogenesis" were observed. It is important to emphasize that high antibiotic stress could also prevent some microbes related to "Sulfate reduction", "Fe(II) oxidation", "Nitrate reduction", and "Xylene and Toluene degradation". This study provides an insight into the long-term stress-responses of microbial communities and functions in oil reservoir under tetracycline exposure, which may help to elucidate the effect of antibiotic stress on biogeochemical cycling with microbial involvement in groundwater ecosystem.

Multidrug-Resistant Bacteria in Hospital Wastewater of the Korle Bu Teaching Hospital in Accra, Ghana

BACKGROUND

Antimicrobial resistance (AMR) is one of the top 10 public health threats. One approach to tackling the AMR menace could involve expanding the range of AMR surveillance domains to include hospital wastewater (HWW), a domain that has largely been overlooked by researchers.

AIM

To evaluate the occurrence of multidrug-resistant bacteria in hospital wastewater of the Korle Bu Teaching Hospital (KBTH).

METHODOLOGY

This was a longitudinal study involving 288 HWW samples consecutively collected across 12 weeks from the pool of wastewater emanating from 2 critical care units of KBTH-The Child Health Unit and the Maternity Unit-on Mondays and Thursdays, each week. The samples were cultured for bacteria, which were identified using the Matrix-Assisted Laser Desorption/Ionization-Time of Flight (MALDI-TOF) technique and subjected to antimicrobial susceptibility testing via the Kirby-Bauer method.

RESULTS

In total, 294 bacteria of 23 different types, all being Gram-negative, were isolated from the 288 samples. The predominant ones were Escherichia coli (30.6%, n = 90), Klebsiella pneumoniae (11.2%, n = 33), Citrobacter freundii (10.9%, n = 32), Alcaligenes faecalis (5.8%, n = 17), and Pseudomonas mendocina (5.4%, n = 16). The prevalence of multidrug resistance among the isolates was 55.4% (n = 163). Moreover, the prevalence of extended-spectrum beta-lactamase (ESBL) producers was 15.6% (n = 46). E. coli accounted for the most ESBL-producing organisms (28.9%, n = 26).

CONCLUSION

The wastewater generated by the Maternity and Child Health Units of KBTH harbored a wide range of multidrug resistant bacteria, with a good proportion of these being ESBL producers, and the predominant one being E. coli. The study thus identifies the wastewater of KBTH as an important source of multidrug resistant organisms, and underscores the significance of appropriate treatment of wastewater of the hospital and other clinical, and related settings prior to its discharge.

Impact of Anthropogenic Activities on the Dissemination of ARGs in the Environment-A Review

Over the past few decades, due to the excessive consumption of drugs in human and veterinary medicine, the antimicrobial resistance (AR) of microorganisms has risen considerably across the world, and this trend is predicted to intensify. Many worrying research results indicate the occurrence of pools of AR, both directly related to human activity and environmental factors. The increase of AR in the natural environment is mainly associated with the anthropogenic activity. The dissemination of AR is significantly stimulated by the operation of municipal facilities, such as wastewater treatment plants (WWTPs) or landfills, as well as biogas plants, agriculture and farming practices, including animal production and land application of manure. These activities entail a risk to public health by spreading bacteria resistant to antimicrobial products (ARB) and antibiotic resistance genes (ARGs). Furthermore, subinhibitory concentrations of antimicrobial substances additionally predispose microbial consortia and resistomes to changes in particular environments that are permeated by these micropollutants. The current state of knowledge on the fate of ARGs, their dissemination and the complexity of the AR phenomenon in relation to anthropogenic activity is inadequate. This review summarizes the state-of-the-art knowledge on AR in the environment, in particular focusing on AR spread in an anthropogenically altered environment and related environmental consequences.

Evaluation of culturable 'last-resort' antibiotic resistant pathogens in hospital wastewater and implications on the risks of nosocomial antimicrobial resistance prevalence

Antimicrobial resistance has been recognized as an important emerging environmental pollutant. 'Last-resort' antibiotics including tigecycline, polymyxin E, daptomycin, vancomycin and linezolid are the 'last line of defence' for antibiotic resistant pathogen infections. Therefore, the presence of 'last-resort' antibiotic resistant pathogens in hospital environments and the nosocomial transmission of 'last-resort' antibiotic resistance poses a grave threat to the well-being of patients. In this work, the extent of resistance to 'last-resort' antibiotics in culturable pathogens in hospital wastewater was investigated. Resistance to 'last-resort' antibiotics were quantified for 1384 culturable Enterobacteriaceae, Enterococcus, Staphylococcus, and Pseudomonas strains. With these investigations, several significant findings were made: (1) a very high level of resistance to 'last-resort' antibiotics was found; (2) multiple resistance to antibiotics, including 'last-resort' antibiotics, was prevalent; (3) a high level of 'last-resort' antibiotic resistance phenotype-genotype inconsistency was found, suggesting knowledge gap for resistance mechanisms; 4) tet(X4)-containing tigecycline-resistant Gram-positive pathogens were found for the first time; 5) wastewater treatment processes are effective in preventing the release of 'last-resort' antibiotic resistant pathogens to the environment. This investigation reveals the severe situation on 'last-resort' resistance in the hospital environment, and implies high risk for nosocomial transmission of 'last-resort' antibiotic resistant pathogens.

Solar-light driven photodegradation of antimicrobials, their transformation by-products and antibiotic resistance determinants in treated wastewater

This study aimed to assess the possibility of using solar light-driven photolysis and TiO₂-based photocatalysis to remove (1) antibiotic residues, (2) their transformation products (TPs), (3) antibiotic resistance determinants, and (4) genes identifying the indicator bacteria in a treated wastewater (secondary effluent). 16 antimicrobials belonging to the different classes and 45 their transformation by-products were selected for the study. The most susceptible to photochemical decomposition was tetracycline, which was completely removed in the photocatalysis process and in more than 80% in the solar light-driven photolysis. 83.8% removal (on average) was observed using photolysis and 89.9% using photocatalysis in the case of the tested genes, among which the genes sul1, uidA, and intI1 showed the highest degree of removal by both methods. The study revealed that applied methods promisingly remove the tested antibiotics, their TPs and genes even in such a complex matrix including treated wastewater and photocatalysis process had a higher removal efficiency of antibiotics, TPs and genes tested. Moreover, the high percentage removal of the intI1 gene (>93%) indicates the possibilities of use of the solar light-driven photolysis and TiO₂-based photocatalysis in minimizing the antibiotic resistance genes transfer by mobile genetic elements.

Metagenomic profiling and transfer dynamics of antibiotic resistance determinants in a full-scale granular sludge wastewater treatment plant

In the One Health context, wastewater treatment plants (WWTPs) are central to safeguarding water resources. Nonetheless, many questions remain about their effectiveness in preventing antimicrobial resistance (AMR) dissemination. Most surveillance studies monitor the levels and removal of selected antibiotic resistance genes (ARGs) and mobile genetic elements (MGEs) in intracellular DNA (iDNA) extracted from WWTP influents and effluents. The role of extracellular free DNA (exDNA) in wastewater is mostly overlooked. This study analyzed the transfer of ARGs and MGEs in a full-scale Nereda® reactor removing nutrients with aerobic granular sludge. We tracked the composition and fate of the iDNA and exDNA pools of influent, sludge, and effluent samples. Metagenomics was used to profile the microbiome, resistome, and mobilome signatures of iDNA and exDNA extracts. Selected ARGs and MGEs were analyzed by qPCR. From 2,840 ARGs identified, the genes arr-3 (2%), tetC (1.6%), sul1 (1.5%), oqxB (1.2%), and aph(3")-Ib (1.2%) were the most abundant among all sampling points and bioaggregates. Pseudomonas, Acinetobacter, Aeromonas, Acidovorax, Rhodoferax, and Streptomyces populations were the main potential hosts of ARGs in the sludge. In the effluent, 478 resistance determinants were detected, of which 89% were from exDNA potentially released by cell lysis during aeration in the reactor. MGEs and multiple ARGs were co-localized on the same extracellular genetic contigs. Total intracellular ARGs decreased 3-42% due to wastewater treatment. However, the ermB and sul1 genes increased by 2 and 1 log gene copies mL^-1, respectively, in exDNA from influent to effluent. The exDNA fractions need to be considered in AMR surveillance, risk assessment, and mitigation strategies.

Influences of anthropogenic activities on water quality in the Saigon River, Ho Chi Minh City

Water quality for the surface water along the Saigon River in Ho Chi Minh City was assessed for four groups of water samples collected at the agricultural, industrial, residential, and less impacted areas. A variety of parameters indicating water quality including physicochemical parameters, nutrients, heavy metals, and antibiotic residues were measured for both the rainy and dry seasons, two main tropical seasons in HCM City using the standard methods. The results showed that the river water in the rainy season was detected with significantly higher values of turbidity, BOD5, PO₄-P, NH₄-N, NO₃-N; and lower values of pH, temperature, conductivity, DO, salinity, Cu, Zn, As, Ni, Hg compared to that in the dry season. Sulfamethoxazole and trimethoprim were highly detected in the industrial areas compared to the agricultural and residential areas. Multivariate analyses suggested that the industrial and residential activities were more important contributors to the pollution of the Saigon River than the agricultural activities in HCM City.

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

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

Isolation and Characterization of Endophytes Bacterial Strains of Momordica charantia L. and Their Possible Approach in Stress Management

In the present study, eight endophytic bacterial strains, namely Bacillus licheniformis R1, Bacillus sp. R2, Agrobacterium tumefaciens R6, uncultured bacterium R11, Bacillus subtilis RS3, Bacillus subtilis RS6, uncultured bacterium RS8 and Lysinibacillus fusiformis RS9, were isolated from the root of Momordica charantia L. All the strains, except R6 exhibited positive for IAA production, siderophore production, and phosphate solubilization during plant growth-promoting traits analysis. Strains invariably utilized glucose and sucrose as a carbon source during substrate utilization, while yeast extract, ammonium sulphate, ammonium chloride, glycine, glutamine, and isoleucine as nitrogen sources. In addition, Spectinomycin was found as the most effective during antibiotic sensitivity TEST, followed by Chloramphenicol, Erythromycin, Rifampicin and Kanamycin, while Polymixin B was found least effective, while strains R1, R6, and RS8 were sensitive to all the antibiotics. Strains R1 and RS6 were able to withstand tolerance up to 10% of NaCl. The strains showing resistance against broad-spectrum antibiotics, especially chloramphenicol, can be used in hospital waste management. In addition, strains with a tolerance of 10 % of NaCl can improve plant growth in the saline affected area.

Comprehensive Genomic Survey of Antimicrobial-Resistance Bacteria in the Sewage Tank Replacement with Hospital Relocation

Background

Excrement containing antimicrobial-resistant bacteria (ARB) is discharged from the hospital sewage through wastewater treatment plants (WWTP) into rivers, increasing the antimicrobial resistance (AMR) burden on the environment.

Purpose

We illustrate the contamination of hospital sewage tanks with ARB harboring antimicrobial resistance genes (ARGs) using comprehensive metagenomic sequencing. During the study period, we moved to a new hospital building constructed for renovation. Therefore, we investigated the difference in bacterial flora in the sewage tanks for each building with different departments, and the change in bacterial flora over time in new sewage tanks. Furthermore, we performed a comparative genome analysis of extended spectrum β-lactamase (ESBL)-producing organisms (EPOs) from hospital sewage and clinical samples. Residual antibiotics in the sewage tank were also measured.

Methods

Metagenomic analysis was performed on the hospital sewage samples, followed by whole genome sequencing of EPOs.

Results

The bacterial composition of new sewage tanks was comparable with that of old tanks within 1 month after relocation and was instantly affected by excrement. The bacterial composition of sewage tanks in the old and new buildings, containing rooms where seriously ill patients were treated, was similar. Selection on CHROMagar ESBL allowed detection of EPOs harboring bla_CTX-M and carbapenemase genes in all sewage tanks. One of the sewage Escherichia coli strain comprising ST393 harboring bla_CTX-M-27 corresponded to the clinical isolates based on core genome analysis. Moreover, the levels of levofloxacin and clarithromycin in the hospital sewage were 0.0325 and 0.0135 µg/mL, respectively.

Conclusion

Hospital sewage was contaminated with many ARB species, ARGs and residual antibiotics, which can cause a burden on WWTP sewage treatment. The bacterial flora in the sewage tank was rapidly affected, especially by the ward with seriously ill patients. AMR monitoring of hospital sewage may help detect carriers prior to nosocomial ARB-associated outbreaks and control the outbreaks.

Occurrence and removal of antibiotics, antibiotic resistance genes, and bacterial communities in hospital wastewater

Hospital wastewater contains a variety of human antibiotics and pathogens, which makes the treatment of hospital wastewater essential. However, there is a lack of research on these pollutants at hospital wastewater treatment plants. In this study, the characteristics and removal of antibiotics and antibiotic resistance genes (ARGs) in the independent treatment processes of hospitals of different scales (primary hospital, H1; secondary hospital, H2; and tertiary hospital, H3) were investigated. The occurrence of antibiotics and ARGs in wastewater from three hospitals varied greatly. The first-generation cephalosporin cefradine was detected at a concentration of 2.38 μg/L in untreated wastewater from H1, while the fourth-generation cephalosporin cefepime had the highest concentration, 540.39 μg/L, at H3. Ofloxacin was detected at a frequency of 100% and had removal efficiencies of 44.2%, 51.5%, and 81.6% at H1, H2, and H3, respectively. The highest relative abundances of the β-lactam resistance gene bla_GES-1 (1.77×10^-3 copies/16S rRNA), the quinolone resistance gene qnrA (8.81×10^-6 copies/16S rRNA), and the integron intI1 (1.86×10^-4 copies/16S rRNA) were detected in the treated wastewater. The concentrations of several ARGs were increased in the treated wastewater (e.g. bla_OXA-1, bla_OXA-10, and bla_TEM-1). Several pathogenic or opportunistic bacteria (e.g. Acinetobacter, Klebsiella, Aeromonas, and Pseudomonas) were observed at high relative abundances in the treated wastewater. These results suggested the co-occurrence of antibiotics, ARGs, and antibiotic-resistant pathogens in hospital wastewater, and these factors may spread into the receiving aquatic environment.

Routine wastewater-based monitoring of antibiotic resistance in two Finnish hospitals: focus on carbapenem resistance genes and genes associated with bacteria causing hospital-acquired infections

BACKGROUND

Wastewater-based monitoring represents a useful tool for antibiotic resistance surveillance.

AIM

To investigate the prevalence and abundance of antibiotic resistance genes (ARGs) in hospital wastewater over time.

METHODS

Wastewater from two hospitals in Finland (HUS1 and HUS2) was monitored weekly for nine weeks (weeks 25-33) in summer 2020. A high-throughput real-time polymerization chain reaction (HT-qPCR) system was used to detect and quantify 216 ARGs and genes associated with mobile genetic elements (MGEs), integrons, and bacteria causing hospital-acquired infections (HAIs), as well as the 16S rRNA gene. Data from HT-qPCR were analysed and visualized using a novel digital platform, ResistApp. Eight carbapenem resistance genes (blaGES, blaKPC, blaVIM, blaNDM, blaCMY, blaMOX, blaOXA48, and blaOXA51) and three genes associated with bacteria causing HAIs (Acinetobacter baumannii, Klebsiella pneumoniae, and Pseudomonas aeruginosa) were studied.

FINDINGS

There was a significantly higher number of ARGs at both hospitals in weeks 27-30 (174-191 genes) compared to other sampling weeks (151-171 genes). Our analyses also indicated that the two hospitals, which used different amounts of antibiotics, had significantly different resistance gene profiles. Carbapenem resistance genes were more prevalent and abundant in HUS1 than HUS2. Across both hospitals, blaGES and blaVIM were the most prevalent and abundant. There was also a strong positive association between blaKPC and K. pneumoniae in HUS1 wastewater.

CONCLUSION

Routine wastewater-based monitoring using ResistApp can provide valuable information on the prevalence and abundance of ARGs in hospitals. This helps hospitals understand the spread of antibiotic resistance in hospitals and identify potential areas for intervention.

Hospital Wastewater-Source of Specific Micropollutants, Antibiotic-Resistant Microorganisms, Viruses, and Their Elimination

Municipal wastewaters can generally provide real-time information on drug consumption, the incidence of specific diseases, or establish exposure to certain agents and determine some lifestyle consequences. From this point of view, wastewater-based epidemiology represents a modern diagnostic tool for describing the health status of a certain part of the population in a specific region. Hospital wastewater is a complex mixture of pharmaceuticals, illegal drugs, and their metabolites as well as different susceptible and antibiotic-resistant microorganisms, including viruses. Many studies pointed out that wastewater from healthcare facilities (including hospital wastewater), significantly contributes to higher loads of micropollutants, including bacteria and viruses, in municipal wastewater. In addition, such a mixture can increase the selective pressure on bacteria, thus contributing to the development and dissemination of antimicrobial resistance. Because many pharmaceuticals, drugs, and microorganisms can pass through wastewater treatment plants without any significant change in their structure and toxicity and enter surface waters, treatment technologies need to be improved. This short review summarizes the recent knowledge from studies on micropollutants, pathogens, antibiotic-resistant bacteria, and viruses (including SARS-CoV-2) in wastewater from healthcare facilities. It also proposes several possibilities for improving the wastewater treatment process in terms of efficiency as well as economy.

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

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

Taxonomic and Functional Distribution of Bacterial Communities in Domestic and Hospital Wastewater System: Implications for Public and Environmental Health

The discharge of untreated hospital and domestic wastewater into receiving water bodies is still a prevalent practice in developing countries. Unfortunately, because of an ever-increasing population of people who are perennially under medication, these wastewaters contain residues of antibiotics and other antimicrobials as well as microbial shedding, the direct and indirect effects of which include the dissemination of antibiotic resistance genes and an increase in the evolution of antibiotic-resistant bacteria that pose a threat to public and environmental health. This study assessed the taxonomic and functional profiles of bacterial communities, as well as the antibiotic concentrations in untreated domestic wastewater (DWW) and hospital wastewater (HWW), using high-throughput sequencing analysis and solid-phase extraction coupled to Ultra-high-performance liquid chromatography Mass Spectrometry (UHPLC–MS/MS) analysis, respectively. The physicochemical qualities of both wastewater systems were also determined. The mean concentration of antibiotics and the concentrations of Cl⁻, F⁻ and PO₄³ were higher in HWW samples than in DWW samples. The phylum Firmicutes was dominant in DWW with a sequence coverage of 59.61% while Proteobacteria was dominant in HWW samples with a sequence coverage of 86.32%. At genus level, the genus Exiguobacterium (20.65%) and Roseomonas (67.41%) were predominant in DWW and HWW samples, respectively. Several pathogenic or opportunistic bacterial genera were detected in HWW (Enterococcus, Pseudomonas and Vibrio) and DWW (Clostridium, Klebsiella, Corynebacterium, Bordetella, Staphylocccus and Rhodococcus) samples. Functional prediction analysis indicated the presence of beta-lactam resistance, cationic antimicrobial peptide (CAMP) resistance and vancomycin resistance genes in HWW samples. The presence of these antibiotic resistance genes and cassettes were positively correlated with the presence of pathogens. These findings show the risk posed to public and environmental health by the discharge of untreated domestic and hospital wastewaters into environmental water bodies.

Industrialization as a source of heavy metals and antibiotics which can enhance the antibiotic resistance in wastewater, sewage sludge and river water

The spread of antibiotic resistance is closely related with selective pressure in the environment. Wastewater from industrialized regions is characterized by higher concentrations of these pollutants than sewage from less industrialized areas. The aim of this study was to compare the concentrations of contaminants such as antibiotics and heavy metals (HMs), and to evaluate their impact on the spread of genes encoding resistance to antimicrobial drugs in samples of wastewater, sewage sludge and river water in two regions with different levels of industrialization. The factors exerting selective pressure, which significantly contributed to the occurrence of the examined antibiotic resistance genes (ARGs), were identified. The concentrations of selected gene copy numbers conferring resistance to four groups of antibiotics as well as class 1 and 2 integron-integrase genes were determined in the analyzed samples. The concentrations of six HMs and antibiotics corresponding to genes mediated resistance from 3 classes were determined. Based on network analysis, only some of the analyzed antibiotics correlated with ARGs, while HM levels were correlated with ARG concentrations, which can confirm the important role of HMs in promoting drug resistance. The samples from a wastewater treatment plant (WWTP) located an industrialized region were characterized by higher HM contamination and a higher number of significant correlations between the analyzed variables than the samples collected from a WWTP located in a less industrialized region. These results indicated that treated wastewater released into the natural environment can pose a continuous threat to human health by transferring ARGs, antibiotics and HMs to the environment. These findings shed light on the impact of industrialization on antibiotic resistance dissemination.

Antibiotics in surface water of East and Southeast Asian countries: A focused review on contamination status, pollution sources, potential risks, and future perspectives

This review provides focused insights into the contamination status, sources, and ecological risks associated with multiple classes of antibiotics in surface water from the East and Southeast Asia based on publications over the period 2007 to 2020. Antibiotics are ubiquitous in surface water of these countries with concentrations ranging from <1 ng/L to hundreds μg/L and median values from 10 to 100 ng/L. Wider ranges and higher maximum concentrations of certain antibiotics were found in surface water of the East Asian countries like China and South Korea than in the Southeast Asian nations. Environmental behavior and fate of antibiotics in surface water is discussed. The reviewed occurrence of antibiotics in their sources suggests that effluent from wastewater treatment plants, wastewater from aquaculture and livestock production activities, and untreated urban sewage are principal sources of antibiotics in surface water. Ecological risks associated with antibiotic residues were estimated for aquatic organisms and the prevalence of antibiotic resistance genes and antibiotic-resistant bacteria were reviewed. 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 antibiotics and antibiotic resistance in water bodies of East and Southeast Asian countries.

Occurrence and quantification of prevalent antibiotics in wastewater samples from Rawalpindi and Islamabad, Pakistan

Release of emerging pollutants including antibiotics to the environment is a serious concern for environmentalist as well as policy makers. To explore the presence and real situation analysis, a study was conducted focusing on detection and quantification of selected antibiotics in wastewater channels of Rawalpindi/Islamabad, Pakistan along with development of a simple High-Performance Liquid Chromatography (HPLC) based method. The samples were collected in triplicates from all the main wastewater streams of the study area with potential presence of antibiotics in the wastewater coming from the surrounding industries, hospitals, drug formulation units and residential localities. Optimized method for detection and quantification was established and validated through spiked as well as real samples. The highest concentration was of Ciprofloxacin 332.154 μg mL^-1 followed by Ofloxacin > Ampicillin > Levofloxacin > Sulfamethoxazole. The results showed the presence of antibiotics due to indiscriminate use that could lead to presence of resistant strains and thus ultimately causing the spread of antibiotic resistance.

A metagenomic-based method to study hospital air dust resistome

As a symbol of the defense mechanisms that bacteria have evolved over time, the genes that make bacteria resist antibiotics are overwhelmingly present in the environment. Currently, bacterial antibiotic resistance genes (ARGs) in the air are a serious concern. Previous studies have identified bacterial communities and summarized putative routes of transmissions for some dominant hospital-associated pathogens from hospital indoor samples. However, little is known about the possible indoor air ARG transportation. In this study, we mainly surveyed air-conditioner air dust samples under different airflow conditions and analyzed these samples using a metagenomic-based method. The results show air dust samples exhibited a complex resistome, and the average concentration is 0.00042 copies/16S rRNA gene, which is comparable to some other environments. The hospital air-conditioners can form resistome over time and accumulate pathogens. In addition, our results indicate that the Outpatient hall is one of the main ARG transmission sources, which can distribute ARGs to other departments (explains >80% resistome). We believe that the management should focus on ARG carrier genera such as Staphylococcus, Micrococcus, Streptococcus, and Enterococcus in this hospital and our novel evidence-based network strategy proves that plasmid-mediated ARG transfer can occur frequently. Overall, these results provide insights into the characteristics of air dust resistome and possible route for how ARGs are spread in air.

Free-floating extracellular DNA: Systematic profiling of mobile genetic elements and antibiotic resistance from wastewater

The free-floating extracellular DNA (exDNA) fraction of microbial ecosystems harbors antibiotic resistance genes (ARGs) and mobile genetic elements (MGEs). Natural transformation of these xenogenetic elements can generate microbial cells resistant to one or more antibiotics. Isolating and obtaining a high yield of exDNA is challenging due to its low concentration in wastewater environments. Profiling exDNA is crucial to unravel the ecology of free-floating ARGs and MGEs and their contribution to horizontal genetransfer. We developed a method using chromatography to isolate and enrich exDNA without causing cell lysis from complex wastewater matrices like influent (9 µg exDNA out of 1 L), activated sludge (5.6 µg out of 1 L), and treated effluent (4.3 µg out of 1 L). ARGs and MGEs were metagenomically profiled for both the exDNA and intracellular DNA (iDNA) of activated sludge, and quantified by qPCR in effluent water. qPCR revealed that ARGs and MGEs are more abundant in the iDNA fraction while still significant on exDNA (100-1000 gene copies mL^-1) in effluent water. The metagenome highlighted that exDNA is mainly composed of MGEs (65%). According to their relatively low abundance in the resistome of exDNA, ARGs uptake by natural transformation is likely not the main transfer mechanism. Although ARGs are not highly abundant in exDNA, the prevalence of MGEs in the exDNA fraction can indirectly promote antibiotic resistance development. The combination of this method with functional metagenomics can help to elucidate the transfer and development of resistances in microbial communities. A systematic profiling of the different DNA fractions will foster microbial risk assessments across water systems, supporting water authorities to delineate measures to safeguard environmental and public health.

intI1 Type Mobile Genetic Elements Co-selected Antibiotic-Resistant Genes in Untreated Hospital Wastewaters

Dissemination of antibiotic-resistant genes (ARGs) from hospital wastewaters (HWWs) is facilitated by the horizontal gene transfer (HGT) and involves association of ARGs with mobile genetic elements (MGEs). In our previous study, HWWs were found to have relatively high copy numbers of ARGs aadA, tetA, cmlA, sul1, and qnrS. In this study, therefore, the same HWWs were also monitored for 3 MGEs class 1 integron (intI1), insertion sequence common region 1 (ISCR1) and conjugative transposon Tn916/Tn1545 by using quantitative polymerase chain reaction. The gene intI1 with 7.4 × 10² average copy number/mL was found to be the most prevalent MGE and was up to two orders of magnitude higher than ISCR1 (5.5 × 10⁰ average copy number/mL, p < 0.05) and Tn916/Tn1545 (2.3 × 10⁰ average copy number/mL, p < 0.05) in all HWWs tested. Positive correlation between intI1 and the aadA, tetA, cmlA and sul1 genes indicated that the MGEs harbouring class1 integron most likely played major role in co-selecting all these ARGs together.

Nanotechnology as a viable alternative for the removal of antimicrobial resistance determinants from discharged municipal effluents and associated watersheds: A review

Effective and efficient utilization of antimicrobial drugs has been one of the important cornerstone of modern medicine. However, since antibiotics were first discovered by Alexander Fleming about a century ago, the time clock of antimicrobial resistance (AMR) started ticking somewhat leading to a global fear of a possible "post-antimicrobial era". Antibiotic resistance (AR) remains a serious challenge causing global outcry in both the clinical setting and the environment. The huge influence of municipal wastewater effluent discharges on the aquatic environment has made the niche a hotspot of research interest in the study of emergence and spread of AMR microbes and their resistance determinants/genes. The current review adopted a holistic approach in studying the proliferation of antibiotic resistance determinants (ARDs) as well as their impacts and fate in municipal wastewater effluents and the receiving aquatic environments. The various strategies deployed hitherto for the removal of resistance determinants in municipal effluents were carefully reviewed, while the potential for the use of nanotechnology as a viable alternative is explicitly explored. Also, highlighted in this review are the knowledge gaps to be filled in order to curtail the spread of AMR in aquatic environment and lastly, suggestions on the applicability of nanotechnology in eliminating AMR determinants in municipal wastewater treatment facilities are proffered.

Hospital Wastewater as a Reservoir for Antibiotic Resistance Genes: A Meta-Analysis

Background: The emergence and dissemination of antibiotic resistance genes (ARGs) in the environment poses a huge global health hazard. Hospital wastewater (HWW), in which a high density of antibiotic residues and antibiotic-resistant bacteria are present, may be a reservoir of ARGs dissemination into the environment. Our meta-analysis comprehensively analyzes the prevalence of ARGs in HWW, as well as the influencing factors in ARGs distribution.

Methods: Online databases were used to search for literature using the subject terms: “Drug Resistance” AND “Genes” AND “Hospitals” AND “Wastewater.” Two reviewers independently applied predefined criteria to assess the literature and extract data including “relative abundance of ARGs,” “title,” “authors,” “country,” “location,” “sampling year,” and “sampling seasons.” The median values and 95% confidence intervals of ARGs abundance were calculated by Wilcox.test function in R. Temporal trends, spatial differences, seasonal variations and removal efficiency of ARGs were analyzed by Pearson correlation analysis and Kruskal-Wallis H test.

Results: Resistance genes to carbapenems, sulfonamides, tetracyclines and mobile genetic elements were found at high relative abundance (>10⁻⁴ gene copies/16S rRNA gene copies) in HWW. The abundance of resistance genes to extended-spectrum β-lactams, carbapenems, sulfonamides and glycopeptide significantly decreased, while tetracycline resistance genes abundance increased from 2014 to 2018. The abundance of ARGs was significantly different by country but not by season. ARGs could not be completely removed by on-site HWW treatments and the removal efficiency varies for different ARGs.

Conclusions: HWW presents more types of ARGs, and their abundance is higher than those in most wastewater systems. HWW may be a reservoir of ARGs and play an important role in the dissemination of ARGs.

Hospital Wastewater-Important Source of Multidrug Resistant Coliform Bacteria with ESBL-Production

This work compares the prevalence of antibiotic resistant coliform bacteria in hospital wastewater effluents in Slovak (SR) and Czech Republic (ČR). It also describes selected antibiotic resistant isolates in view of resistance mechanism and virulence factor. The highest number of multidrug resistant bacteria was detected in samples from the hospital in Valašské Meziříčí (ČR). More than half of resistant isolates showed multidrug resistance phenotype as well as strong ability to form biofilm. In 42% of isolates efflux pump overproduction was detected together with tetA and tetE genes. The production of extended-spectrum β-lactamases in coliform isolates was encoded mainly by bla_TEM, bla_CTX-M-2 and bla_CTX-M-8/25 genes. About 62% of resistants contained a combination of two or more extended spectrum beta-lactamases (ESBL) genes. Our results strengthen the fact that hospital effluents are a source of multidrug resistant bacteria which can spread their resistance genes to other bacteria in wastewater treatment plants (WWTPs). Accordingly, hospital wastewater should be better treated before it enters urban sewerage.

Detection of New Delhi Metallo-β-lactamase 1 and Cephalosporin Resistance Genes Among Carbapenem-Resistant Enterobacteriaceae in Water Bodies Adjacent to Hospitals in India

The prevalence of carbapenem resistance among bacterial isolates from selected water bodies receiving hospital effluents and adjoining aquaculture farms in Kerala, India, was studied. Klebsiella pneumoniae followed by Escherichia coli, Klebsiella oxytoca, Enterobacter aerogenes and Acinetobacter baumannii were the predominant isolates. Antibiotic sensitivity of these isolates was determined by Kirby-Bauer disc diffusion method. Nearly 60% of the Enterobacteriaceae isolates screened were multidrug resistant of which 16.6% were carbapenem resistant. The carbapenem-resistant Enterobacteriaceae were further screened for the presence of New Delhi metallo β-lactamase-1 and cephalosporin resistance encoding genes. All NDM-1 isolates were highly resistant to carbapenem, cephalosporin, aminoglycosides, quinolones, tetracycline, and sulphonamides. K. pneumoniae harboring bla_NDM-1 gene and E. coli isolates with bla_CTX-M-15 and bla_SHV-11 genes were detected in hospital discharge points. In aquaculture farms too, carbapenem-resistant K. pneumoniae with bla_NDM-1 gene and E. coli isolates with bla_CTX-M-15 were observed, although there was no use of antibiotics in these farms. However, other carbapenemase genes such as bla_TEM, bla_VIM, bla_IMP and bla_GIM were not detected in any of these isolates. The results suggest the increased prevalence of carbapenem-resistant Enterobacteriaceae in the water bodies receiving hospital effluent and its dissemination to adjacent aquaculture farms, posing a serious threat to public health.

Retrospective suspect screening reveals previously ignored antibiotics, antifungal compounds, and metabolites in Bangladesh surface waters

Densely populated countries in Asia, such as Bangladesh, are considered to be major contributors to the increased occurrence of global antimicrobial resistance (AMR). Several factors make low-and middle-income countries vulnerable to increased emergence and spread of AMR in the environment including limited regulations on antimicrobial drug use, high volume of antimicrobials used in human medicine and agricultural production, and poor wastewater management. Previous monitoring campaigns to investigate the presence of antibiotics in the aquatic environment have employed targeted analysis in which selected antibiotics are measured using liquid chromatography with tandem mass spectrometry (LC/MS/MS). However, this approach can miss several important contaminants that can contribute to the selective pressure that promotes maintenance and dissemination of antibiotic resistance genes (ARGs) in the environment. Nontarget analysis by suspect screening and reanalysis of stored digital data of previously ran samples can provide information on analytes that were formerly uncharacterized and may be chemicals of emerging concern (CECs). In this study, surface waters in both urban and rural sites in Bangladesh were collected and analyzed for the presence of antibiotic residues and other pharmaceuticals. Utilizing targeted analysis, the antibiotics with the highest concentrations detected were ciprofloxacin (1407 ng/L) and clarithromycin (909 ng/L). In addition, using high-resolution LC/MS/MS in the first ever application of retrospective analysis in samples from Bangladesh, additional antibiotics clindamycin, lincomycin, linezolid, metronidazole, moxifloxacin, nalidixic acid, and sulfapyridine were detected. Prevalence of amoxicillin transformation products in surface waters was also confirmed. In addition, medicinal and agricultural antifungal compounds were frequently found in Bangladeshi surface waters. This later finding - the near ubiquity of antifungal agents in environmental samples - is of particular concern, as it may be contributing to the alarming rise of multi-drug resistant fungal (e.g. Candida auris) disease recently seen in humans throughout the world.

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

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

Prevalence of Colistin-Resistant, Carbapenem-Hydrolyzing Proteobacteria in Hospital Water Bodies and Out-Falls of West Bengal, India

Indiscriminate use of antibiotics has resulted in a catastrophic increase in the levels of antibiotic resistance in India. Hospitals treat critical bacterial infections and thus can serve as reservoirs of multidrug resistant (MDR) bacteria. Hence, this study was conducted to gauge the prevalence patterns of MDR bacteria in hospital wastewater. Water samples collected from 11 hospitals and 4 environmental sources belonging to 5 most-densely populated districts of West Bengal, India were grown on MacConkey and Eosin Methylene Blue agar. A total of 84 (hospital-associated = 70, environmental water sources = 14) isolates were characterized. The predominant species found in water from hospital-associated areas (HAA) were Acinetobacter baumannii (22.9%), Escherichia coli (28.6 %), and Klebsiella pneumoniae (25.7%). Greater than 75% of the HAA isolates were found to be mcr-1 gene negative and colistinresistant. Meropenem non-susceptibility was also high among the HAA isolates at 58.6%, with the presence of the carbapenemase gene and bla_NDM in 67.1% of the non-susceptible isolates. Among the three predominant species, significantly higher numbers of E. coli isolates were found to be non-susceptible to meropenem ((80%), p-value = 0.00432) and amikacin (AK (90%), p-value = 0.00037). This study provides evidence for the presence of high numbers of colistin-resistant and carbapenem-hydrolyzing Proteobacteriain hospital wastewater.

Occurrence of antibiotics residues in hospital wastewater, wastewater treatment plant, and in surface water in Nairobi County, Kenya

The occurrence of 17 antibiotics belonging to sulfonamides, β-lactams, macrolides and aminoglycosides classes, and trimethoprim in raw hospital wastewater, wastewater treatment plant (WWTP), and surface water was determined. Residual antibiotics were quantified by LC/MS/MS. Residues of antibiotics in hospital wastewater were 3-10 times higher than that detected in WWTP and surface water. Trimethoprim, spectinomycin, ampicillin, and oxacillin were detected in all the sampled water. Sulfamethoxazole was detected at the highest concentration of 20.6, 7.8, and 6.8 μg L^-1 in hospital wastewater, WWTP and in surface water, respectively. Other detected sulfonamides were sulfamethazine, sulfadiazine, and sulfanilamide at a concentration range of 0.4-15.7 μg L^-1. Detected trimethoprim ranged from 0.4-6.6 μg L^-1, the rest of the detected antibiotics were up to 1.0 μg L^-1. The speciation of the sulfonamides at pH values relevant to sampled water was evaluated by use of pKa values. These compounds existed largely as anionic and neutral species indicating high mobility as these speciation forms are less sorbed in environmental matrices. Continuous monitoring of antibiotics residues in wastewater, surface water, and other environmental matrices is very important due to their adverse health and environmental effects. The information is useful in designing strategies for antibiotics pollution control and also in policy formulation.

Detection of Sapoviruses in two biological lines of Tunisian hospital wastewater treatment

The efficiency of rotating biodisks and natural oxidizing lagoon procedures is investigated at a Tunisian semi-industrial pilot plant, El Menzeh I, where the wastewater is mainly provided by three different neighbouring hospital clinics. Throughout 2011, 102 wastewater samples were collected from the two mentioned wastewater treatment procedures. Results showed that the Sapovirus (SaV) frequency was approximately 29.4% using the real-time reverse transcription polymerase chain reaction (RT-PCR) technique, and about 16.6% using the conventional RT-PCR. Also, the SaV genogroups and genotypes were identified and genotyping revealed that all of the four Tunisian SaV strains obtained belonged to the two genogroups GIV.1 and GGI.3. In addition, two new genotypes, D and C, were detected. A moderate decrease in the SaV frequencies was observed at the exit of the two treatment processes and the SaV removal rate was around 90% in the natural oxidizing lagoons and 94% in the rotating biodisks procedure showing the temperate sensitivity of these viruses to the implemented biological wastewater. Therefore, an urgent disinfection process should be implemented downstream of the two biological treatment procedures for safe release of treated effluent in the different natural environments. Abbreviations: NoV: Noroviruses; SaV: Sapoviruses; EC: Electrical Conductivity; COD: Chemical Oxygen Demand; BOD5: Biological Oxygen Demand; SS: Suspended Solids; NH4-N: Ammonium Nitrogen; P-PO4: Ortho-Phosphate; AlCl3: aluminum chloride.