Antibiotic Pollution in the Environment: From Microbial Ecology to Public Policy

Challenges & Solutions for Recent Advancements in Multi-Drugs Resistance Tuberculosis: A Review

In MDR-TB, mycobacterium is resistant to battlefront drugs like rifampicin and isoniazid. Now it's an urgent global challenge for treatment & diagnosis because more than 50% of drugs are resistant. Till today's information, 5 reasons are liable for MDR: (1) Errors of physicians/patients in therapy management, (2) Complexity and poor vascularization of granulomatous lesions, which obstruct drug distribution to some sites, leading to resistance development, (3) Intrinsic drug resistance of tubercle bacilli, (4) Formation of non-replicating, drug-tolerant bacilli inside the granulomas, (5) Development of mutations in Mtb genes, which are the foremost important molecular mechanisms of resistance. the most contribution of this work is a brief & clear explanation of things chargeable for resistant development, and recent diagnostic & treatment methods for MDR-TB. This study shall help researchers & scientists to develop replacement rapid diagnostic tools, drugs, and treatment protocols.

Antimicrobial Resistance and Recent Alternatives to Antibiotics for the Control of Bacterial Pathogens with an Emphasis on Foodborne Pathogens

Antimicrobial resistance (AMR) is one of the most important global public health problems. The imprudent use of antibiotics in humans and animals has resulted in the emergence of antibiotic-resistant bacteria. The dissemination of these strains and their resistant determinants could endanger antibiotic efficacy. Therefore, there is an urgent need to identify and develop novel strategies to combat antibiotic resistance. This review provides insights into the evolution and the mechanisms of AMR. Additionally, it discusses alternative approaches that might be used to control AMR, including probiotics, prebiotics, antimicrobial peptides, small molecules, organic acids, essential oils, bacteriophage, fecal transplants, and nanoparticles.

Preparation of entrapment-based microcolumns for analysis of drug-humic acid interactions by high-performance affinity chromatography

Reversible interactions between drugs and humic acid in water can be an important factor in determining the bioavailability and effects of these pharmaceuticals as micropollutants in the environment. In this study, microcolumns containing entrapped humic acid were used in high-performance affinity chromatography (HPAC) to examine the binding of this agent with the drugs tetracycline, carbamazepine, ciprofloxacin, and norfloxacin. Parameters that were varied to optimize the entrapment of humic acid within HPLC-grade porous silica included the starting concentration of humic acid, the mass ratio of humic acid vs silica, and the method of mixing the reagents with the support for the entrapment process. The highest retention for the tested drugs was obtained when using supports that were prepared using an initial humic acid concentration of 80 mg mL^-1 and a humic acid vs silica mass ratio of 600 mg per g silica, along with preincubation of the humic acid with hydrazide-activated silica before the addition of a capping agent (i.e., oxidized glycogen). Characterization of the humic acid support was also carried out by means of TGA, FTIR, SEM, and energy-dispersive X-ray spectroscopy. The binding constants measured by HPAC for the given drugs with entrapped Aldrich humic acid gave good agreement with values reported in the literature under similar pH and temperature conditions for this and other forms of humic acid. Besides providing valuable data on the binding strength of various drugs with humic acid, this work illustrates how HPAC may be used as an analytical tool for screening and characterizing the interactions of drugs and man-made contaminants with humic acid or related binding agents in water and the environment.

Effects of population age structure on parenteral antimicrobial use estimations

Antimicrobial use (AMU) is conventionally reported as unadjusted defined daily doses (DDDs) or population-adjusted DDDs per 1000 inhabitants per day (DID). DID is frequently used to monitor national AMU trends, this metric does not intrinsically take temporal changes in population age structure into account. We examined the effects of population age structure on DID estimates of parenteral AMU in Japan, and predicted future trends in DDDs based on population projections. Parenteral AMU data from 2013 to 2018 were acquired from a national claims database. We assessed temporal trends in parenteral AMU by age group (children aged < 15 years, working-age persons aged 15-64 years, and older persons aged ≥ 65 years) using both DID and DDDs. In addition, we modeled DDD predictions based on age-specific population projections from 2019 to 2030. DID values for older persons were 8.08-10.15 times and 5.43-5.63 times higher than in children and working-age persons, respectively. DID was stable, but DDDs increased in older persons. The prediction models showed that DDDs will continue to increase until 2030 if DID remains steady or decreases. DID estimates were skewed by the older population. More rigorous antimicrobial stewardship efforts targeting geriatric care are needed to counter the aging-associated increase in AMU.

Influences of Bacillus subtilis and fructooligosaccharide on growth performances, immune responses, and disease resistance of Nile tilapia, Oreochromis niloticus

The present study investigated the effects of Bacillus subtilis and fructooligosaccharide (FOS) on growth performances, immunity improvement, and disease resistance of Nile tilapia (Oreochromis niloticus). The fish (24.5 ± 1.6 g) were fed a basal diet (G1), diets supplemented with 1 g/kg (G2), 3 g/kg (G3) and 5 g/kg (G4) of FOS as well as diets supplemented with 1 × 10⁹ CFU/g (G5), 3 × 10⁹ CFU/g (G6) and 5 × 10⁹ CFU/g (G7) of B. subtilis for 56 days. After the feeding trial, the complement C3, IL-1β, TNF-α, IFN-γ, hsp70 gene expression in the liver was then analyzed by a quantitative Real-time PCR. Then, fish were infected with Streptococcus agalactiae, and the survival rate was recorded. The results showed that FOS and B. subtilis had no significant effect (P > 0.05) on growth performances and survival rate. Lysozyme activity was significantly greater in the G4, G5, G6, and G7 groups. Also, all fish fed FOS and B. subtilis showed significantly (P < 0.05) higher respiratory burst activity than other groups. The expressions of complement C3, IL-1β, TNF-α, IFN-γ, and hsp-70 in the liver were significantly higher for fish fed 5 g/kg of FOS as well as for fish that received any concentration level of B. subtilis (P < 0.05) used in the study. After the S. agalactiae challenge test, the survival rate of fish-fed diets supplemented with FOS and B. subtilis was slightly higher than for the control group. The results indicated that FOS and B. subtilis could stimulate immune responses and immune-related genes in tilapia. However, further investigation of other prebiotics or herbs in combination with B. subtilis is encouraged at molecular levels and screening for beneficial metabolites that may increasingly improve digestive enzymes, growth performances, and health benefits in tilapia. In addition, on-farm experiments are needed.

An environmentally relevant concentration of antibiotics impairs the immune system of zebrafish (Danio rerio) and increases susceptibility to virus infection

In this work, we analysed the transcriptome and metatranscriptome profiles of zebrafish exposed to an environmental concentration of the two antibiotics most frequently detected in European inland surface water, sulfamethoxazole (SMX) and clarithromycin (CLA). We found that those animals exposed to antibiotics (SMX+CLA) for two weeks showed a higher bacterial load in both the intestine and kidney; however, significant differences in the relative abundance of certain bacterial classes were found only in the intestine, which also showed an altered fungal profile. RNA-Seq analysis revealed that the complement/coagulation system is likely the most altered immune mechanism, although not the only one, in the intestine of fish exposed to antibiotics, with numerous genes inhibited compared to the control fish. On the other hand, the effect of SMX+CLA in the kidney was more modest, and an evident impact on the immune system was not observed. However, infection of both groups with spring viremia of carp virus (SVCV) revealed a completely different response to the virus and an inability of the fish exposed to antibiotics to respond with an increase in the transcription of complement-related genes, a process that was highly activated in the kidney of the untreated zebrafish after SVCV challenge. Together with the higher susceptibility to SVCV of zebrafish treated with SMX+CLA, this suggests that complement system impairment is one of the most important mechanisms involved in antibiotic-mediated immunosuppression. We also observed that zebrafish larvae exposed to SMX+CLA for 7 days showed a lower number of macrophages and neutrophils.

Factors affecting the hydrolysis of the antibiotic amoxicillin in the aquatic environment

The environmental fate of the frequently used broad-spectrum β-lactam antibiotic amoxicillin (AMX) is of high concern regarding the potential evolution of antimicrobial resistance (AMR). Moreover, it is known that AMX is prone to hydrolysis, yielding a variety of hydrolysis products (HPs) with yet unknown effects. Studies to identify those HPs and investigate their formation mechanisms have been reported but a long-term study on their stability in real water samples was missing. In this regard, we investigated the hydrolysis of AMX at two concentration levels in four distinct water types under three different storage conditions over two months. Concentrations of AMX and four relevant HPs were monitored by an LC-MS/MS method revealing pronounced differences in the hydrolysis rate of AMX in tap water and mineral water on the one hand (fast) and surface water on the other (slow). In this context, the occurrence, relative intensities, and stability of certain HPs are more dependent on the water type than on the storage condition. As clarified by ICP-MS, the main difference between the water types was the content of the metals copper and zinc which are supposed to catalyze AMX hydrolysis demonstrating an effective method to degrade AMX at ambient conditions.

The Phenomenon of Antibiotic Resistance in the Polar Regions: An Overview of the Global Problem

The increasing prevalence of antibiotic resistance is a global problem in human and animal health. This leads to a reduction in the therapeutic effectiveness of the measures used so far and to the limitation of treatment options, which may pose a threat to human health and life. The problem of phenomenon of antibiotic resistance affects more and more the polar regions. This is due to the increase in tourist traffic and the number of people staying at research stations, unmodernised sewage systems in inhabited areas, as well as the migration of animals or the movement of microplastics, which may contain resistant bacteria. Research shows that the presence of antibiotic resistance genes is more dominant in zones of human and wildlife influence than in remote areas. In a polluted environment, there is evidence of a direct correlation between human activity and the spread and survival of antibiotic-resistant bacteria. Attention should be paid to the presence of resistance to synthetic and semi-synthetic antibiotics in the polar regions, which is likely to be correlated with human presence and activity, and possible steps to be taken. We need to understand many more aspects of this, such as bacterial epigenetics and environmental stress, in order to develop effective strategies for minimizing the spread of antibiotic resistance genes. Studying the diversity and abundance of antibiotic resistance genes in regions with less anthropogenic activity could provide insight into the diversity of primary genes and explain the historical evolution of antibiotic resistance.

End-of-life management strategies of pharmaceuticals in Portuguese households

The end of life of pharmaceutical products through environmentally unsafe routes is a growing concern in our society. However, the studies reported so far, apart from being limited in number, do not reflect the current management practices for the end-of-life management of pharmaceuticals. Published work lacks an in-depth analysis in focusing on the pharmaceutical waste in households. The present work focused on (1) performing a state-of-the art overview to compare worldwide studies and the results and (2) implementing a comprehensive survey in Portugal (n = 454 respondents). The results showed that the delivery to pharmacies was used by the majority of the respondents (72%), indicating a good awareness of pharmaceutical waste management issues, when compared to the reviewed studies. Statistically significant variables for the destination of end-of-use pharmaceuticals include gender, age and distance from the residence to the pharmacy (p < 0.05). Most participants believe that educating the population on existing structures of medication and packaging management is of the utmost importance to improve the national managing system. This is the first study conducted in Portugal; it includes statistical analysis of the data and reflects on the practices that should be adopted to reduce incorrect pharmaceutical waste disposal. These findings call upon the strategies to strengthen the pharmaceutical waste management programme.

Leave No Trace? Ecological and anthropogenic determinants of antibiotic resistant bacteria in a recreational alpine environment

Antibiotic resistant bacteria (ARB) have been detected in remote environments, but the degree to which their presence is due to anthropogenic contamination remains unclear. Here, anthropogenic and ecological determinants of ARB were characterized in remote and highly visited areas of Rocky Mountain National Park in the United States. Soil and water samples were collected from 29 sites once a month for three months and measured for bacteria resistant to seven antibiotics with flow cytometry. A novel index of the likelihood of human presence (HPI) was generated for estimating human impact on ARB abundance. The HPI accounted for 44% of variation in ARB abundance in water samples (p < 0.0001) and 51% of variation in soil samples (p < 0.00001). Human presence index was illustrated as a reliable predictor of ARB abundance despite a tendency to underpredict at higher levels of human impact. Ecological determinants such as temperature, elevation, slope, and aspect were also found to be significantly associated with ARB abundance. These findings suggest that human presence drives the abundance of ARB in Rocky Mountain National Park, but ecological variables play a significant role in their presence and dispersal.

Evidence of Antimicrobial Resistance in Bats and Its Planetary Health Impact for Surveillance of Zoonotic Spillover Events: A Scoping Review

As a result of the COVID-19 pandemic, as well as other outbreaks, such as SARS and Ebola, bats are recognized as a critical species for mediating zoonotic infectious disease spillover events. While there is a growing concern of increased antimicrobial resistance (AMR) globally during this pandemic, knowledge of AMR circulating between bats and humans is limited. In this paper, we have reviewed the evidence of AMR in bats and discussed the planetary health aspect of AMR to elucidate how this is associated with the emergence, spread, and persistence of AMR at the human-animal interface. The presence of clinically significant resistant bacteria in bats and wildlife has important implications for zoonotic pandemic surveillance, disease transmission, and treatment modalities. We searched MEDLINE through PubMed and Google Scholar to retrieve relevant studies (n = 38) that provided data on resistant bacteria in bats prior to 30 September 2022. There is substantial variability in the results from studies measuring the prevalence of AMR based on geographic location, bat types, and time. We found all major groups of Gram-positive and Gram-negative bacteria in bats, which are resistant to commonly used antibiotics. The most alarming issue is that recent studies have increasingly identified clinically significant multi-drug resistant bacteria such as Methicillin Resistant Staphylococcus aureus (MRSA), ESBL producing, and Colistin resistant Enterobacterales in samples from bats. This evidence of superbugs abundant in both humans and wild mammals, such as bats, could facilitate a greater understanding of which specific pathways of exposure should be targeted. We believe that these data will also facilitate future pandemic preparedness as well as global AMR containment during pandemic events and beyond.

Integrated Adsorption-Photocatalytic Decontamination of Oxytetracycline from Wastewater Using S-Doped TiO2/WS2/Calcium Alginate Beads

Integrated wastewater treatment processes are needed due to the inefficient removal of emerging pharmaceuticals by single methods. Herein, an adsorbent-photocatalyst integrated material was fabricated by coupling calcium alginate with sulfur-doped TiO2/tungsten disulfide (S-TiO2/WS2/alginate beads) for the removal of oxytetracycline (OTC) from aqueous solution by an integrated adsorption-photocatalysis process. The semiconductor S-TiO2/WS2 hybrid photocatalyst was synthesized with a hydrothermal method, while the integrated adsorbent-photocatalyst S-TiO2/WS2/alginate beads were synthesized by blending S-TiO2/WS2 with sodium alginate using calcium chloride as a precipitating agent. The physicochemical characteristics of S-TiO2/WS2/alginate beads were analyzed using X-ray diffraction , scanning electron microscopy, elemental mapping, X-ray photoelectron spectroscopy, and photoluminescence spectroscopy. The integrated adsorption-photocatalysis process showed enhanced removal from 92.5 to 72%, with a rise in the OTC concentration from 10 to 75 mg/L respectively. The results demonstrated that the adsorption of OTC onto S-TiO2/WS2/alginate beads followed the Elovich kinetic model and Redlich–Peterson isotherm models. The formations of H-bonds, cation bridge bonding, and n-π electron donor-acceptor forces were involved in the adsorption of OCT onto S-TiO2/WS2/alginate beads. In the integrated adsorption-photocatalysis, surface-adsorbed OTC molecules were readily decomposed by the photogenerated active radical species (h⁺, O2•−, and HO•). The persulfate addition to the OTC solution further increased the photocatalysis efficacy due to the formation of additional oxidizing species (SO4•⁻, SO4⁻). Moreover, S-TiO2/WS2/alginate beads showed favorable efficiency and sustainability in OTC removal, approaching 78.6% after five cycles. This integrated adsorption-photocatalysis process offered significant insight into improving efficiency and reusability in water treatment.

Growth productivity as a determinant of the inoculum effect for bactericidal antibiotics

Understanding the mechanisms by which populations of bacteria resist antibiotics has implications in evolution, microbial ecology, and public health. The inoculum effect (IE), where antibiotic efficacy declines as the density of a bacterial population increases, has been observed for multiple bacterial species and antibiotics. Several mechanisms to account for IE have been proposed, but most lack experimental evidence or cannot explain IE for multiple antibiotics. We show that growth productivity, the combined effect of growth and metabolism, can account for IE for multiple bactericidal antibiotics and bacterial species. Guided by flux balance analysis and whole-genome modeling, we show that the carbon source supplied in the growth medium determines growth productivity. If growth productivity is sufficiently high, IE is eliminated. Our results may lead to approaches to reduce IE in the clinic, help standardize the analysis of antibiotics, and further our understanding of how bacteria evolve resistance.

Bacterial Communities and Antibiotic Resistance of Potential Pathogens Involved in Food Safety and Public Health in Fish and Water of Lake Karla, Thessaly, Greece

Bacterial communities, microbial populations, and antibiotic resistance of potential pathogens in the water and fish (Cyprinus carpio, flesh and gut) from different areas (A1, A2 and A3-A1 was linked with river water, A2 with cattle activity, and A3 with waters of a spring after heavy rains) of Lake Karla (Thessaly, Central Greece) were investigated. The isolated bacteria were identified using Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) and were tested for resistance in 21 antibiotics. The microbiota composition of fish flesh was also studied using 16S amplicon-based sequencing Serratia fonticola and several species of Aeromonas (e.g., Aeromonas salmonicida, Aeromonas bestiarium, Aeromonas veronii, etc.) exhibited the highest abundances in all studied samples, while the microbiota profile between the three studied areas was similar, according to the culture-dependent analysis. Of them, S. fonticola was found to be resistant in the majority of the antibiotics for the water and fish (gut and flesh), mainly of the areas A1 and A2. Regarding 16S metabarcoding, the presence of Serratia and Aeromonas at genus level was confirmed, but they found at very lower abundances than those reported using the culture-dependent analysis. Finally, the TVC and the rest of the studied microbiological parameters were found at acceptable levels (4 log cfu/mL or cfu/g and 2-4 log cfu/mL or cfu/g, extremely low levels of E. coli/coliforms) in both water and fish flesh. Based on our findings, the water of Lake Karla would be used for activities such as irrigation, recreation and fishing, however, the development and implementation of a quality management tool for Lake Karla, to ensure environmental hygiene and prevention of zoonosis during the whole year, is imperative.

Metagenomic-based surveillance systems for antibiotic resistance in non-clinical settings

The success of antibiotics as a therapeutic agent has led to their ineffectiveness. The continuous use and misuse in clinical and non-clinical areas have led to the emergence and spread of antibiotic-resistant bacteria and its genetic determinants. This is a multi-dimensional problem that has now become a global health crisis. Antibiotic resistance research has primarily focused on the clinical healthcare sectors while overlooking the non-clinical sectors. The increasing antibiotic usage in the environment - including animals, plants, soil, and water - are drivers of antibiotic resistance and function as a transmission route for antibiotic resistant pathogens and is a source for resistance genes. These natural compartments are interconnected with each other and humans, allowing the spread of antibiotic resistance via horizontal gene transfer between commensal and pathogenic bacteria. Identifying and understanding genetic exchange within and between natural compartments can provide insight into the transmission, dissemination, and emergence mechanisms. The development of high-throughput DNA sequencing technologies has made antibiotic resistance research more accessible and feasible. In particular, the combination of metagenomics and powerful bioinformatic tools and platforms have facilitated the identification of microbial communities and has allowed access to genomic data by bypassing the need for isolating and culturing microorganisms. This review aimed to reflect on the different sequencing techniques, metagenomic approaches, and bioinformatics tools and pipelines with their respective advantages and limitations for antibiotic resistance research. These approaches can provide insight into resistance mechanisms, the microbial population, emerging pathogens, resistance genes, and their dissemination. This information can influence policies, develop preventative measures and alleviate the burden caused by antibiotic resistance.

In-situ degradation of Amphotericin B in a microbial electrochemical cell containing wastewater

Antimicrobial resistance raises serious medical implications and is primarily caused by indiscriminate usage and environmental contamination with antimicrobial agents. To prevent microbes from developing resistance against antimicrobial agents, they must be effectively degraded. This is the first study that investigates the degradation of Amphotericin B(AmB) with simultaneous wastewater treatment in a Microbial Peroxide producing cell (MPPC). Two sets of MPPCs (A and B) were used to degrade AmB oxidatively, one with H₂O₂ and the other with the microbial electro Fenton process in a catholyte containing 0.1% AmB. MPPC A and B had voltage outputs of 0.356 ± 3 V and 0.411 ± 2 V, producing 26 ± 0.04 mM and 44 ± 0.8 mM of H₂O₂ respectively. The structural changes of treated samples were analyzed using Fourier Transformed Infrared Spectroscopy, which revealed the disappearance of major characteristic bands such as the NH band (1556 cm^-1), the CH band Polyene ring (3358 cm^-1), and others, implying the disruption of multiple double bonds in polyene, resulting in the structure's lactone ring breakdown. Liquid chromatography quadrupole time-of-flight revealed the changes in retention time and peak area of treated samples in comparison to native AmB which also confirmed its structural changes. Such structural disruption induced the drug to lose its antifungal action since no zones of inhibition were detected in an antimicrobial susceptibility test against Candida albicans. The degradation of 57.05% and 69.83% of AmB by H₂O₂ and the Fenton process was also correlated with a reduction in COD. Simultaneously the anodic wastewater treatment in both the MPPCs had COD removal efficiency of 78% and 82% and the BOD removal efficiency was 75.38% and 90% respectively. The MPPC system's process conditions and reactor design could be optimized further to enhance antimicrobial degradation and wastewater treatment. This research offers a sustainable and efficient method for expediting antimicrobial degradation while simultaneously treating wastewater.

High interfacial charge separation in visible-light active Z- scheme g-C3N4/MoS2 heterojunction: Mechanism and degradation of sulfasalazine

Examination of highly proficient photoactive materials for the degradation of antibiotics from the aqueous solution is the need of the hour. In the present study, a 2D/2D binary junction GCM, formed between graphitic-carbon nitride (g-C3N4) and molybdenum disulphide (MoS2), was synthesized using facile hydrothermal method and its photo-efficacy was tested for the degradation of sulfasalazine (SUL) from aqueous solution under visible-light irradiation. Morphological analysis indicated the nanosheets arrangement of MoS2 and g-C3N4. The visible-light driven experiments indicated that 97% antibiotic was degraded by GCM-30% within 90 min which was found to be quite high than pristine g-C3N4 and MoS2 at solution pH of 6, GCM-30% dose of 20 mg, and SUL concentration of 20 mgL-1. The degradation performance of GCM-30% was selectively improved due to enhanced visible-light absorption, high charge carrier separation, and high redox ability of the photogenerated charges which was induced by the effective Z-scheme 2D/2D heterojunction formed between g-C3N4 and MoS2. The reactive radicals as determined by the scavenging study were •O2-, and h+. A detailed degradation mechanism of SUL by GCM-30% was also predicted based on the detailed examination of the band gaps of g-C3N4 and MoS2.

Experimental inheritance of antibiotic acquired dysbiosis affects host phenotypes across generations

Microbiomes can enhance the health, fitness and even evolutionary potential of their hosts. Many organisms propagate favorable microbiomes fully or partially via vertical transmission. In the long term, such co-propagation can lead to the evolution of specialized microbiomes and functional interdependencies with the host. However, microbiomes are vulnerable to environmental stressors, particularly anthropogenic disturbance such as antibiotics, resulting in dysbiosis. In cases where microbiome transmission occurs, a disrupted microbiome may then become a contagious pathology causing harm to the host across generations. We tested this hypothesis using the specialized socially transmitted gut microbiome of honey bees as a model system. By experimentally passaging tetracycline-treated microbiomes across worker 'generations' we found that an environmentally acquired dysbiotic phenotype is heritable. As expected, the antibiotic treatment disrupted the microbiome, eliminating several common and functionally important taxa and strains. When transmitted, the dysbiotic microbiome harmed the host in subsequent generations. Particularly, naïve bees receiving antibiotic-altered microbiomes died at higher rates when challenged with further antibiotic stress. Bees with inherited dysbiotic microbiomes showed alterations in gene expression linked to metabolism and immunity, among other pathways, suggesting effects on host physiology. These results indicate that there is a possibility that sublethal exposure to chemical stressors, such as antibiotics, may cause long-lasting changes to functional host-microbiome relationships, possibly weakening the host's progeny in the face of future ecological challenges. Future studies under natural conditions would be important to examine the extent to which negative microbiome-mediated phenotypes could indeed be heritable and what role this may play in the ongoing loss of biodiversity.

Interaction of Antibiotics and Humic Substances: Environmental Consequences and Remediation Prospects

The occurrence and distribution of antibiotics in the environment has received increasing attention due to their potential adverse effects on human health and ecosystems. Humic substances (HS) influence the mobility, reactivity, and bioavailability of antibiotics in the environment significantly due to their interaction. As a result, HS can affect the dissemination of antibiotic-resistance genes, which is one of the main problems arising from contamination with antibiotics. The review provides quantitative data on the binding of HS with fluoroquinolones, macrolides, sulfonamides, and tetracyclines and reports the proposed mechanisms of their interaction. The main issues of the quantification of antibiotic-HS interaction are discussed, which are a development of standard approaches and the accumulation of a dataset using a standard methodology. This would allow the implementation of a meta-analysis of data to reveal the patterns of the binding of antibiotics to HS. Examples of successful development of humic-based sorbents for fluoroquinolone and tetracycline removal from environmental water systems or polluted wastewaters were given. Data on the various effects of HS on the dissemination of antibiotic-resistance genes (ARGs) were summarized. The detailed characterization of HS properties as a key point of assessing the environmental consequences of the formation of antibiotic-HS complexes, such as the dissemination of antibiotic resistance, was proposed.

Mobile resistome of microbial communities and antimicrobial residues from drinking water supply systems in Rio de Janeiro, Brazil

Antibiotic resistance genes (ARGs) are widespread in the environment due to the overuse of antibiotics and other pollutants, posing a threat to human and animal health. In this study, we evaluated antimicrobial residues, bacterial diversity and ARGs in two important watersheds, Guandu and São João, that supply drinking water to Rio de Janeiro city, Brazil. In addition, tap water samples were collected from three different cities in Rio de Janeiro State, including the metropolitan area of Rio de Janeiro city. Clarithromycin, sulfamethoxazole and azithromycin were found in untreated water and drinking water in all samples. A greater abundance of Proteobacteria was observed in Guandu and São João watersheds, with most of the sequences belonging to the Gammaproteobacteria class. A plasmidome-focused metagenomics approach revealed 4881 (Guandu), 3705 (São João) and 3385 (drinking water) ARGs mainly associated with efflux systems. The genes encoding metallo-β-lactamase enzymes (blaAIM, blaGIM, blaIMP, and blaVIM) were detected in the two watersheds and in drinking water samples. Moreover, we demonstrated the presence of the colistin resistance genes mcr-3 and mcr-4 (both watersheds) and mcr-9 (drinking water and Guandu) for the first time in Brazil. Our data emphasize the importance of introducing measures to reduce the disposal of antibiotics and other pollutants capable of promoting the occurrence and spread of the microbial resistome on aquatic environments and predicting possible negative impacts on human health.

Abundant bacteria shaped by deterministic processes have a high abundance of potential antibiotic resistance genes in a plateau river sediment

Recent research on abundant and rare bacteria has expanded our understanding of bacterial community assembly. However, the relationships of abundant and rare bacteria with antibiotic resistance genes (ARGs) remain largely unclear. Here, we investigated the biogeographical patterns and assembly processes of the abundant and rare bacteria from river sediment at high altitudes (Lhasa River, China) and their potential association with the ARGs. The results showed that the abundant bacteria were dominated by Proteobacteria (55.4%) and Cyanobacteria (13.9%), while the Proteobacteria (33.6%) and Bacteroidetes (18.8%) were the main components of rare bacteria. Rare bacteria with a large taxonomic pool can provide function insurance in bacterial communities. Spatial distribution of persistent abundant and rare bacteria also exhibited striking differences. Strong selection of environmental heterogeneity may lead to deterministic processes, which were the main assembly processes of abundant bacteria. In contrast, the assembly processes of rare bacteria affected by latitude were dominated by stochastic processes. Abundant bacteria had the highest abundance of metabolic pathways of potential drug resistance in all predicted functional genes and a high abundance of potential ARGs. There was a strong potential connection between these ARGs and mobile genetic elements, which could increase the ecological risk of abundant taxa and human disease. These results provide insights into sedimental bacterial communities and ARGs in river ecosystems.

Integrative analysis of GWAS and transcriptome reveals p53 signaling pathway mediates resistance to visceral white-nodules disease in large yellow croaker

Visceral white-nodules disease (VWND), caused by Pseudomonas plecoglossicida, is one of the primary causes of morbidity and mortality in large yellow croaker aquaculture. Host disease resistance is a heritable trait that involves complex regulatory processes. However, the regulatory mechanism of bacterial resistance in large yellow croaker is still unclear. This study attempted to systematically evaluate the major genetic loci and transcriptional regulatory mechanisms associated with the resistance to VWND in large yellow croaker by crossover method studies. A large population of large yellow croaker was challenged with P. plecoglossicida, with survival time recorded and samples were taken for genotyping. Meanwhile, spleen samples that were used for RNA-seq to compare their transcriptomic profiles before and after infection were taken from resistant populations (RS) and susceptible control populations (CS) bred using the genomic selection (GS) technique. Genome-wide association analyses using 46 K imputed SNP genotypes highlighted that resistance is a polygenic trait. The integrative analysis results show the co-localization of the cd82a gene between disease resistance-related genetic loci and comparative transcriptional analysis. And functional enrichment analysis showed differential enrichment of the p53 signaling pathway in RS and CS groups, suggesting that there may be cd82a-mediated p53 signaling pathway activation for VWND resistance. This large-scale study provides further evidence for the heritability and transcriptional regulatory mechanisms of host inheritance of VWND resistance.

Trace Metal Concentrations in Surface Water Along the Yangtze River in Chongqing, China: Urban Discharge Impacts

Urban rivers are suffering from a significant anthropogenic impact. In this study, eight trace metals were investigated in surface water along the Yangtze River in Chongqing, China. The decreasing trend of trace metals was observed in water as Sr > Li > Mo > As > Cu > Ni > Cr > Co. Multivariate statistical analysis identified two source types that accounted for 77.17% of the total variance. As, Co, Mo, and Sr were mainly originated from geological sources, while Cr, Cu, and Ni were influenced by anthropogenic activities. Moreover, the average contents of Cr, Cu, and Ni exhibited a significant increase close to the city compared to the sites that are far away from the city, which was identified by various urban rivers. This study suggested that Cr, Cu, and Ni could be regarded as anthropophile elements, which could be a promising indicator for tracing the urban activities.

A review on synthesis methods and recent applications of nanomaterial in wastewater treatment: Challenges and future perspectives

Freshwater has been incessantly polluted by various activities such as rapid industrialization, fast growth of population and agricultural activities. Water pollution is considered as one the major threatens to human health and aquatic bodies which causes various severe harmful diseases including gastrointestinal disorders, asthma, cancer, etc. The polluted wastewater could be treated by different conventional and advanced methodologies. Amongst them, adsorption is the most utilized low cost, efficient technique to treat and remove the harmful pollutants from the wastewater. The efficiency of adsorption mainly depends on the surface properties such as functional group availability and surface area of the adsorbents used. Since various waste-based carbon derivatives are utilized as adsorbents for harmful pollutants removal; nanomaterials are employed as effective adsorbents in recent times due to its excellent surface properties. This review presents an overview of the different types of nanomaterials such as nano-particles, nanotubes, nano-sheets, nano-rods, nano-spheres, quantum dots, etc. which have been synthesized by different chemical and green synthesis methodologies using plants, microorganisms, biomolecules and carbon derivatives, metals and metal oxides and polymers. By concentrating on potential research difficulties, this study offers a new viewpoint on fundamental field of nanotechnology for wastewater treatment applications. This review paper critically reviewed the synthesis of nanomaterials more importantly green synthesis and their applications in wastewater treatment to remove the harmful pollutants such as heavy metals, dyes, pesticides, polycyclic aromatic hydrocarbons, etc.

Antibiotic resistance in the aquatic environment: Analytical techniques and interactive impact of emerging contaminants

Antibiotic pollution is becoming an increasingly severe threat globally. Antibiotics have emerged as a new class of environmental pollutants due to their expanding usage and indiscriminate application in animal husbandry as growth boosters. Contamination of aquatic ecosystems by antibiotics can have a variety of negative impacts on the microbial flora of these water bodies, as well as lead to the development and spread of antibiotic-resistant genes. Various strategies for removing antibiotics from aqueous systems and environments have been developed. Many of these approaches, however, are constrained by their high operating costs and the generation of secondary pollutants. This review aims to summarize research on the distribution and effects of antibiotics in aquatic environments, their interaction with other emerging contaminants, and their remediation strategy. The ecological risks associated with antibiotics in aquatic ecosystems and the need for more effective monitoring and detection system are also highlighted.

High Frequency of Antibiotic Resistance Genes (ARGs) in the Lerma River Basin, Mexico

The spread of beta-lactamase-producing bacteria is of great concern and the environment has been found to be a main source of contamination. Herein, it was proposed to determine the frequency of antimicrobial-resistant-Gram-negative bacteria throughout the Lerma River basin using phenotypic and molecular methods. Resistant bacteria were isolated with chromogenic media and antimicrobial susceptibility tests were used to characterize their resistance. ARGs for beta-lactams, aminoglycosides, and quinolones were detected by PCR. Species were identified by Sanger sequencing the 16S rRNA gene and the representative genomes of MDR strains were sequenced by NGS. A high variation in the number of isolates was observed in the 20 sampled sites, while observing a low diversity among the resistant bacteria. Of the 12 identified bacterial groups, C. freundii, E. coli, and S. marcescens were more predominant. A high frequency of resistance to beta-lactams, quinolones, and aminoglycosides was evidenced, where the bla_CTX,qnrB, qnrS y, and aac(6')lb-cr genes were the most prevalent. C. freundii showed the highest frequency of MDR strains. Whole genome sequencing revealed that S. marcescens and K. pneumoniae showed a high number of shared virulence and antimicrobial resistance genes, while E. coli showed the highest number of unique genes. The contamination of the Lerma River with MDR strains carrying various ARGs should raise awareness among environmental authorities to assess the risks and regulations regarding the optimal hygienic and sanitary conditions for this important river that supports economic activities in the different communities in Mexico.

Electro-Chemical Degradation of Norfloxacin Using a PbO2-NF Anode Prepared by the Electrodeposition of PbO2 onto the Substrate of Nickel Foam

A novel three-dimensional network nickel foam/PbO2 combination electrode (PbO2-NF) with high electrochemical degradation efficiency to norfloxacin was successfully fabricated through the electrodeposition of PbO2 on the substrate of nickel foam. The characterization of an PbO2-NF electrode, including surface morphology, elemental components, electrochemical performance, and stability was performed. In electrochemical oxidation tests, the removal efficiency of norfloxacin (initial concentration for 50 mg/L) on PbO2-NF reached 88.64% within 60 min of electrolysis, whereas that of pure nickel foam was only 30%. In the presence of PbO2-NF, the optimum current density, solution pH, electrode spacing for norfloxacin degradation were 30 mA/cm2, 11, and 3 cm, respectively. The electric energy consumption for 80% norfloxacin was approximately 5 Wh/L. Therefore, these results provide a new anode to improve the removal of norfloxacin in the wastewater with high efficiency and low energy consumption.

Ecological Responses of Maize Rhizosphere to Antibiotics Entering the Agricultural System in an Area with High Arsenicals Geological Background

Metal(loid)s can promote the spread and enrichment of antibiotic resistance in the environmental ecosystem through a co-selection effect. Little is known about the ecological effects of entering antibiotics into the environment with long-term metal(loid)s' resistance profiles. Here, cow manure containing oxytetracycline (OTC) or sulfadiazine (SA) at four concentrations (0 (as control), 1, 10, and 100 mg/kg) was loaded to a maize cropping system in an area with high a arsenicals geological background. Results showed that exogenous antibiotics entering significantly changed the nutrient conditions, such as the concentration of nitrate nitrogen, ammonium nitrogen, and available phosphorus in the maize rhizosphere soil, while total arsenic and metals did not display any differences in antibiotic treatments compared with control. Antibiotics exposure significantly influenced nitrate and nitrite reductase activities to reflect the inhibition of denitrification rates but did not affect the soil urease and acid phosphatase activities. OTC treatment also did not change soil dehydrogenase activities, while SA treatment posed promotion effects, showing a tendency to increase with exposure concentration. Both the tested antibiotics (OTC and SA) decreased the concentration of arsenite and arsenate in rhizosphere soil, but the inhibition effects of the former were higher than that of the latter. Moreover, antibiotic treatment impacted arsenite and arsenate levels in maize root tissue, with positive effects on arsenite and negative effects on arsenate. As a result, both OTC and SA treatments significantly increased bioconcentration factors and showed a tendency to first increase and then decrease with increasing concentration. In addition, the treatments decreased translocation capacity of arsenic from roots to shoots and showed a tendency to increase translocation factors with increasing concentration. Microbial communities with arsenic-resistance profiles may also be resistant to antibiotics entering.

Biodegradation of tylosin in swine wastewater by Providencia stuartii TYL-Y13: Performance, pathway, genetic background, and risk assessment

Microbial bioremediation offers a solution to the problem of residual antibiotics in wastewater associated with animal farms. Efficient degradation of antibiotic residues depends upon the genetic make-up of microbial degraders, which requires a comprehensive understanding of the degradation mechanisms. In this study, a novel, efficient tylosin (TYL)-degrading bacterium, Providencia stuartii TYL-Y13 (Y13) was isolated, which could completely degrade 100 mg/L TYL within 15 h under optimal operating conditions at 40 ℃, pH 7.0 %, and 1 % (v/v) bacterial inoculation rate. Whole genome sequencing revealed that strain Y13 consists of a circular chromosome and two plasmids. A new biodegradation pathway of TYL including desugarification, hydrolysis, and reduction reactions was proposed through the analysis of biodegradation products. It was demonstrated that strain Y13 gradually decreased the biotoxicity of TYL and its metabolites based on the results of the ecological structural activity relationships (ECOSAR) model analysis and toxicity assessment. Moreover, Y13 promoted the reduction of the target macrolide resistance genes in wastewater and disappeared within 84 h. These results shed new light on the mechanism of TYL biodegradation and better utilization of microbes to remediate TYL contamination.

Pan-Genome Analysis Reveals Functional Divergences in Gut-Restricted Gilliamella and Snodgrassella

Gilliamella and Snodgrassella, members of core gut microbiota in corbiculate bees, have high species diversity and adaptability to a wide range of hosts. In this study, we performed species taxonomy and phylogenetic analysis for Gilliamella and Snodgrassella strains that we isolated in our laboratory, in combination with published whole-genome. Functional effects of accessory and unique genes were investigated by KEGG category and pathway annotation in pan-genome analysis. Consequently, in Gilliamella, we inferred the importance of carbohydrate metabolism, amino acid metabolism, membrane transport, energy metabolism, and metabolism of cofactors and vitamins in accessory or unique genes. The pathway mentioned above, plus infectious disease, lipid metabolism, nucleotide metabolism as well as replication and repair exert a pivotal role in accessory or unique genes of Snodgrassella. Further analysis revealed the existence of functional differentiation of accessory and unique genes among Apis-derived genomes and Bombus-derived genomes. We also identified eight and four biosynthetic gene clusters in all Gilliamella and Snodgrassella genomes, respectively. Our study provides a good insight to better understand how host heterogeneity influences the bacterial speciation and affects the versatility of the genome of the gut bacteria.

A resistome survey across hundreds of freshwater bacterial communities reveals the impacts of veterinary and human antibiotics use

Our decreasing ability to fight bacterial infections is a major health concern. It is arising due to the evolution of antimicrobial resistance (AMR) in response to the mis- and overuse of antibiotics in both human and veterinary medicine. Lakes integrate watershed processes and thus may act as receptors and reservoirs of antibiotic resistance genes (ARGs) introduced into the watershed by human activities. The resistome – the diversity of ARGs – under varying anthropogenic watershed pressures has been previously studied either focused on few select genes or few lakes. Here, we link the resistome of ~350 lakes sampled across Canada to human watershed activity, trophic status, as well as point sources of ARG pollution including wastewater treatment plants and hospitals in the watershed. A high percentage of the resistance genes detected was either unimpacted by human activity or highly prevalent in pristine lakes, highlighting the role of AMR in microbial ecology in aquatic systems, as well as a pool of genes available for potential horizontal gene transfer to pathogenic species. Nonetheless, watershed agricultural and pasture area significantly impacted the resistome. Moreover, the number of hospitals and the population density in a watershed, the volume of wastewater entering the lake, as well as the fraction of manure applied in the watershed as fertilizer significantly impacted ARG diversity. Together, these findings indicate that lake resistomes are regularly stocked with resistance genes evolved in the context of both veterinary and human antibiotics use and represent reservoirs of ARGs that require further monitoring.

Antibiotic resistance in aquaculture and aquatic organisms: a review of current nanotechnology applications for sustainable management

Aquaculture has emerged as one of the world's fastest-growing food industries in recent years, helping food security and boosting global economic status. The indiscriminate disposal of untreated or improperly managed waste and effluents from different sources including production plants, food processing sectors, and healthcare sectors release various contaminants such as bioactive compounds and unmetabolized antibiotics, and antibiotic-resistant organisms into the environment. These emerging contaminants (ECs), especially antibiotics, have the potential to pollute the environment, particularly the aquatic ecosystem due to their widespread use in aquaculture, leading to various toxicological effects on aquatic organisms as well as long-term persistence in the environment. However, various forms of nanotechnology-based technologies are now being explored to assist other remediation technologies to boost productivity, efficiency, and sustainability. In this review, we critically highlighted several ecofriendly nanotechnological methods including nanodrug and vaccine delivery, nanoformulations, and nanosensor for their antimicrobial effects in aquaculture and aquatic organisms, potential public health risks associated with nanoparticles, and their mitigation measures for sustainable management.

Antimicrobial resistance genes in microbiota associated with sediments and water from the Akaki river in Ethiopia

The spread of antimicrobial-resistant pathogens is a global health concern. Most studies report high levels of antimicrobial resistance genes (ARGs) in the aquatic environment; however, levels associated with sediments are limited. This study aimed to investigate the distribution of ARGs in the sediments and water of the Akaki river in Addis Ababa, Ethiopia. The diversity and abundance of 84 ARGs and 116 clinically important bacteria were evaluated from the sediments and water collected from five sites in the Akaki river. Most of the ARGs were found in the city close to anthropogenic activities. Water samples collected in the middle catchment of the river contained 71-75% of targeted ARGs, with genes encoding aminoglycoside acetyltransferase (aac(6)-Ib-cr), aminoglycoside adenylyl transferase (aadA1), β-lactamase (bla_OXA-10)_, quinolone resistance S (qnrS), macrolide efflux protein A (mefA), and tetracycline resistance (tetA), were detected at all sampling sites. Much fewer ARGs were detected in all sediments, and those near the hospitals had the highest diversity and level. Despite the lower levels and diversity, there were no unique ARGs detected in the sediments that were also not detected in the waters. A wide range of clinically relevant pathogens were also detected in the Akaki river. The findings suggest that the water phase, rather than the sediments in the Akaki river, is a potential conduit for the spread of ARGs and antibiotic-resistant bacteria.

Computational and experimental elucidation of the boosted stability and antibacterial activity of ZIF-67 upon optimized encapsulation with polyoxometalates

Water microbial purification is one of the hottest topics that threats human morbidity and mortality. It is indispensable to purify water using antimicrobial agents combined with several technologies and systems. Herein, we introduce a class of nanosized metal organic framework; Zeolitic imidazolate framework (ZIF-67) cages encapsulated with polyoxometalates synthesized via facile one-step co-precipitation method. We employed two types of polyoxometalates bioactive agents; phosphotungstic acid (PTA) and phosphomolybdic acid (PMA) that act as novel antibacterial purification agents. Several characterization techniques were utilized to investigate the morphological, structural, chemical, and physical properties such as FESEM, EDS, FTIR, XRD, and N₂ adsorption/desorption isotherms techniques. The antibacterial assessment was evaluated using colony forming unit (CFU) against both Escherichia coli and Staphylococcus aureus as models of Gram-negative and Gram-positive bacteria, respectively. The PTA@ZIF-67 showed higher microbial inhibition against both Gram-positive and Gram-negative bacteria by 98.8% and 84.6%, respectively. Furthermore, computational modeling using density functional theory was conducted to evaluate the antibacterial efficacy of PTA when compared to PMA. The computational and experimental findings demonstrate that the fabricated POM@ZIF-67 materials exhibited outstanding bactericidal effect against both Gram-negative and Gram-positive bacteria and effectively purify contaminated water.

Bacteria communities and water quality parameters in riverine water and sediments near wastewater discharges

Wastewater treatment plant (WWTP) discharges alter water quality and microbial communities by introducing human-associated bacteria in the environment and by altering microbial communities. To fully understand this impact, it is crucial to study whether WWTP discharges affect water and sediments microbial communities in comparable ways and whether such effects depend on specific environmental variables. Here, we present a dataset investigating the impact of a WWTP on water quality and bacterial communities by comparing samples collected directly from the WWTP outflow to surface waters and sediments at two sites above and two sites below it over a period of five months. When possible, we measured five physicochemical variables (e.g., temperature, turbidity, conductivity, dissolved oxygen, and salinity), four bioindicators (e.g., Escherichia coli, total coliforms, Enterococcus sp., and endotoxins), and two molecular indicators (e.g., intI1’s relative abundance, and 16S rRNA gene profiling). Preliminary results suggest that bioindicators correlate with environmental variables and that bacterial communities present in the water tables, sediments, and treated water differ greatly in composition and structure.

Measurement(s)	temperature of water • conductivity of water • dissolved oxygen in water • salinity of water • Concentration of Escherichia coli in water • Concentration of total coliforms in water • Concentration of Enterococcus sp. • Concentration of endotoxins in water • Relative abundance of integron 1 in water • Bacterial 16S RNA
Technology Type(s)	YSI field probe • Colilert dection system • Enterolert dection system • Charles River Endosafe system • quantitative PCR • Illumina Sequencing
Sample Characteristic - Organism	Bacteria
Sample Characteristic - Environment	Fresh water river
Sample Characteristic - Location	United States

Antimicrobial resistance: new insights and therapeutic implications

Antimicrobial resistance has not been a new phenomenon. Still, the number of resistant organisms, the geographic areas affected by emerging drug resistance, and the magnitude of resistance in a single organism are enormous and mounting. Disease and disease-causing agents formerly thought to be contained by antibiotics are now returning in new forms resistant to existing therapies. Antimicrobial resistance is one of the most severe and complicated health issues globally, driven by interrelated dynamics in humans, animals, and environmental health sectors. Coupled with various epidemiological factors and a limited pipeline for new antimicrobials, all these misappropriations allow the transmission of drug-resistant organisms. The problem is likely to worsen soon. Antimicrobial resistance in general and antibiotic resistance in particular is a shared global problem. Actions taken by any single country can adversely or positively affect the other country. Targeted coordination and prevention strategies are critical in stopping the spread of antibiotic-resistant organisms and hence its overall management. This article has provided in-depth knowledge about various methods that can help mitigate the emergence and spread of antimicrobial resistance globally. KEY POINTS: • Overview of antimicrobial resistance as a global challenge and explain various reasons for its rapid progression. • Brief about the intrinsic and acquired resistance to antimicrobials and development of antibiotic resistance in bacteria. • Systematically organized information is provided on different strategies for tackling antimicrobial resistance for the welfare of human health.

Metagenomic insights into the antibiotic resistome in freshwater and seawater from an Antarctic ice-free area

The comprehensive profiles of antibiotic resistance genes (ARGs) in the Antarctic water environments and their potential health risks are not well understood. The present study characterized the bacterial community compositions and ARG profiles of freshwater (11 samples) and seawater (28 samples) around the Fildes Region (an ice-free area in Antarctica) using a shotgun metagenomic sequencing approach for the first time. There were significant differences in the compositions of the bacterial community and ARG profiles between freshwater and seawater. In the 39 water samples, 114 ARG subtypes belonging to 15 ARG types were detectable. In freshwater, the dominant ARGs were related to multidrug and rifamycin resistance. In seawater, the dominant ARGs were related to peptide, multidrug, and beta-lactam resistance. Both the bacterial community compositions and ARG profiles were significantly related to certain physicochemical properties (e.g., pH, salinity, NO₃^-). Procrustes analysis revealed a significant correlation between the bacterial community compositions and ARG profiles of freshwater and seawater samples. A total of 31 metagenome-assembled genomes (MAGs) carrying 35 ARG subtypes were obtained and identified. The results will contribute to a better evaluation of the ARG contamination in relation to human health in the Antarctic aquatic environments.

Diversity of lytic bacteriophages against XDR Klebsiella pneumoniae sequence type 16 recovered from sewage samples in different parts of the world

Bacteriophages (phages) are viruses considered to be natural bacterial predators and widely detected in aquatic environments. Sewage samples are an important source of phage isolation since high density and diversity of bacterial cells are present, due to human, animal and household fluids. This study aims to investigate and characterise phages against an extremely drug-resistant (XDR) lineage, Klebsiella pneumoniae ST16, using sewage samples from different parts of the World. Sewage samples from Brazil, Bangladesh, Saudi Arabia, Thailand and the United Kingdom were collected and used to investigate phages against ten K. pneumoniae ST16 (hosts) recovered from infection sites. The phages were microbiological and genetically characterised by double-agar overlay (DLA), transmission electron microscopy and Illumina WGS. The host range against K. pneumoniae belonging to different sequence types was evaluated at different temperatures by spot test. Further phage characterisation, such as efficiency of plating, optimal phage temperature, and pH/temperature susceptibility, were conducted. Fourteen lytic phages were isolated, belonging to Autographiviridae, Ackermannviridae, Demerecviridae, Drexlerviridae, and Myoviridae families, from Brazil, Bangladesh, Saudi Arabia and Thailand and demonstrated a great genetic diversity. The viruses had good activity against our collection of clinical K. pneumoniae ST16 at room temperature and 37 °C, but also against other important Klebsiella clones such as ST11, ST15, and ST258. Temperature assays showed lytic activity in different temperatures, except for PWKp18 which only had activity at room temperature. Phages were stable between pH 5 and 10 with minor changes in phage activity, and 70 °C was the temperature able to kill all phages in this study. Using sewage from different parts of the World allowed us to have a set of highly efficient phages against an K. pneumoniae ST16 that can be used in the future to develop new tools to combat infections in humans or animals caused by this pathogen.

Novel Effective Fluorinated Benzothiophene-Indole Hybrid Antibacterials against S. aureus and MRSA Strains

Increasing antibacterial drug resistance threatens global health, unfortunately, however, efforts to find novel antibacterial agents have been scaled back by the pharmaceutical industry due to concerns about a poor return on investment. Nevertheless, there is an urgent need to find novel antibacterial compounds to combat antibacterial drug resistance. The synthesis of novel drugs from natural sources is mostly cost-intensive due to those drugs’ complicated structures. Therefore, it is necessary to find novel antibacterials by simple synthesis to become more attractive for industrial production. We succeeded in the discovery of four antibacterial compound (sub)classes accessible in a simple one-pot reaction based on fluorinated benzothiophene-indole hybrids. They have been evaluated against various S. aureus and MRSA strains. Structure- and substituent-dependent activities have been found within the (sub)classes and promising lead compounds have been identified. In addition, bacterial pyruvate kinase was found to be the molecular target of the active compounds. In conclusion, simple one-pot synthesis of benzothiophene-indoles represents a promising strategy for the search of novel antimicrobial compounds.

Evolutionary history and strength of selection determine the rate of antibiotic resistance adaptation

Bacterial adaptation to stressful environments often produces evolutionary constraints whereby increases in resistance are associated with reduced fitness in a different environment. The exploitation of this resistance-cost trade-off has been proposed as the basis of rational antimicrobial treatment strategies designed to limit the evolution of drug resistance in bacterial pathogens. Recent theoretical, laboratory, and clinical studies have shown that fluctuating selection can maintain drug efficacy and even restore drug susceptibility, but can also increase the rate of adaptation and promote cross-resistance to other antibiotics. In this paper, we combine mathematical modeling, experimental evolution, and whole-genome sequencing to follow evolutionary trajectories towards β-lactam resistance under fluctuating selective conditions. Our experimental model system consists of eight populations of Escherichia coli K12 evolving in parallel to a serial dilution protocol designed to dynamically control the strength of selection for resistance. We implemented adaptive ramps with mild and strong selection, resulting in evolved populations with similar levels of resistance, but with different evolutionary dynamics and diverging genotypic profiles. We found that mutations that emerged under strong selection are unstable in the absence of selection, in contrast to resistance mutations previously selected in the mild selection regime that were stably maintained in drug-free environments and positively selected for when antibiotics were reintroduced. Altogether, our population dynamics model and the phenotypic and genomic analysis of the evolved populations show that the rate of resistance adaptation is contingent upon the strength of selection, but also on evolutionary constraints imposed by prior drug exposures.

Evaluating the Role of Wastewaters as Reservoirs of Antibiotic-Resistant ESKAPEE Bacteria Using Phenotypic and Molecular Methods

Introduction

Methodology

Results

Conclusion

Combination of Paraconiothyrium brasiliense fabricated titanium dioxide nanoparticle and antibiotics enhanced antibacterial and antibiofilm properties: A toxicity evaluation

Antimicrobial resistance (AMR) causes global consequences through increased mortality and economic loss. Antimicrobial drugs including nanomaterials are an emerging environmental impact. Hence, this work aimed to synthesize and characterize the titanium dioxide nanoparticles (TiO₂ NPs) using the aqueous extract of endophytic fungus Paraconiothyrium brasiliense (Pb) for enhancing the antibacterial efficiency of existing standard antibiotics at minimum concentration. The FTIR and XRD results confirmed the capping of functional molecules and the crystalline nature of Pb-TiO2 NPs. The spherical-shaped TiO2 NPs with the size of 57.39 ± 13.65 nm were found in TEM analysis. The average hydrodynamic size (68.43 ± 1.49 d. nm) and the zeta potential (-19.6 ± 1.49 mV) was confirmed the stability of Pb-TiO2 NPs. Antibacterial studies revealed that bare Pb-TiO2 NPs (20 μg/mL) did not exhibit significant antibacterial activity while combination of TCH + Pb-TiO2 NPs considerably increased the inhibition of E. coli biofilm evidenced by CLSM and SEM analysis. Further, Pb-TiO₂ NPs (100 μg/mL) were found to be moderately toxic to cell line (NIH3T3), red blood cells (RBC), and egg embryos. Hence, this study concluded that <50 μg/mL of TiO₂ NPs can be mixed with antibiotics for enhanced antibacterial application thereby minimizing the AMR and the environmental toxicity.

Sub-lethal concentration of sulfamethoxazole affects the growth performance of milkfish (Chanos chanos), the microbial composition of antibiotic-resistant bacteria and the prevalence of sulfonamide-resistance genes in mariculture

To investigate the impacts of sub-lethal concentrations of antibiotic agents in mariculture, culturable approach and DNA based detection were employed to isolate and analyse resistant bacteria and resistant genes in this study. Milkfish (Chanos chanos), the target rearing animal was exposed to sulfamethoxazole (SMX; 2 mg/L) for 8 weeks and resulted in reduced survival rate and weight gain to 61.9 % and 28.4 %, respectively compared to control milkfish (p < 0.001). The composition of SMX-resistant bacteria isolated from the culture water and the gastrointestinal tracts of milkfish underwent changes in response to SMX treatment with a reduced diversity. The prevalence of SMX resistant genes sul in bacterial isolates was elevated from 2.8 % of control to 100 % of SMX-administrated water. Exposure to SMX at a sub-lethal dosage enhanced the prevalence of resistance genes sul1 and sul2 in resistant bacteria, thus implying high frequency of resistance dissemination in the marine environment and surrounding ecosystems.

Gut microbiome and metabolome of sea cucumber (Stichopus ocellatus) as putative markers for monitoring the marine sediment pollution in Pahang, Malaysia

Antibiotic contamination in the marine environment forms an emerging threat to marine ecosystems. This study aimed to compare the gut and coelomic microbiota of Stichopus ocellatus with sediments between two coastal districts of Pahang, which potentially conferring as putative biomarkers for sediment pollution monitoring. The composition of the bacteria communities was determined using 16S rRNA V3-region gene amplicon sequencing, while hybrid whole-genome sequencing was employed to analyze the genome of Vibrio parahaemolyticus. The trace elements and antibiotic compositions were access using high-throughput spectrometry. The alpha- and beta-diversity of bacteria in gut and sediment samples from Kuantan differed substantially within (p-value = 0.017604) and between samples (p-value <0.007), respectively. Vibrio genera predominated in Kuantan samples, while Flavobacterium and Synechococcus_E genera predominated in Pekan samples. Vibrio parahaemolyticus revealed the presence of tet(35) and bla_CARB-33 genes that conceived resistance towards tetracycline and beta-lactam antibiotics, respectively, which were detected in sediment and gut samples.