Antibiotics: An overview on the environmental occurrence, toxicity, degradation, and removal methods

Effects of four antibiotics on the photosynthetic light reactions in the green alga Chlorella pyrenoidosa

Antibiotics are ubiquitously present in aquatic environments, posing a serious ecological risk to aquatic ecosystems. However, the effects of antibiotics on the photosynthetic light reactions of freshwater algae and the underlying mechanisms are relatively less understood. In this study, the effects of 4 representative antibiotics (clarithromycin, enrofloxacin, tetracycline, and sulfamethazine) on a freshwater alga (Chlorella pyrenoidosa) and the associated mechanisms, primarily focusing on key regulators of the photosynthetic light reactions, were evaluated. Algae were exposed to different concentrations of clarithromycin (0.0-0.3 mg/L), enrofloxacin (0.0-30.0 mg/L), tetracycline (0.0-10.0 mg/L), and sulfamethazine (0.0-50.0 mg/L) for 7 days. The results showed that the 4 antibiotics inhibited the growth, the photosynthetic pigment contents, and the activity of antioxidant enzymes. In addition, exposure to clarithromycin caused a 118.4 % increase in malondialdehyde (MDA) levels at 0.3 mg/L. Furthermore, the transcripts of genes for the adenosine triphosphate (ATP) - dependent chloroplast proteases (ftsH and clpP), genes in photosystem II (psbA, psbB, and psbC), genes related to ATP synthase (atpA, atpB, and atpH), and petA (related to cytochrome b6/f complex) were altered by clarithromycin. This study contributes to a better understanding of the risk of antibiotics on primary producers in aquatic environment.

Hypochlorite-mediated degradation and detoxification of sulfathiazole in aqueous solution and soil slurry

Although various activated sodium hypochlorite (NaClO) systems were proven to be promising strategies for recalcitrant organics treatment, the direct interaction between NaClO and pollutants without explicit activation is quite limited. In this work, a revolutionary approach to degrade sulfathiazole (STZ) in aqueous and soil slurry by single NaClO without any activator was proposed. The results demonstrated that 100% and 94.11% of STZ could be degraded by 0.025 mM and 5 mM NaClO in water and soil slurry, respectively. The elimination of STZ was shown to involve superoxide anion (O2•-), chlorine oxygen radical (ClO•), and hydroxyl radical (•OH), according to quenching experiments and the analysis of electron paramagnetic resonance. The addition of Cl-, HCO3-, SO42-, and humic acid (HA) marginally impeded the decomposition of STZ, while NO3-, Fe3+, and Mn2+ facilitated the process. The NaClO process exhibited significant removal effectiveness at a neutral initial pH. Moreover, the NaClO facilitated application in various soil samples and water matrices, and the procedure was also successful in effectively eliminating a range of sulfonamides. The suggested NaClO degradation mechanism of STZ was based on the observed intermediates, and the majority of the products exhibited lower ecotoxicity than STZ. Besides, the experiment results by using X-ray diffraction (XRD) and a fourier transform infrared spectrometer (FTIR) indicated the negligible effects on the composition and structure of soil by the treatment of NaClO. Simultaneously, the experimental results also illustrated that the bioavailability of heavy metals and the physiochemical characteristics of the soil before and after the remediation did not change to a significant extent. Following the remediation of NaClO, the phytotoxicity tests showed reduced toxicity to wheat and cucumber seeds. As a result, treating soil and water contaminated with STZ by using NaClO was a reasonably practical and eco-friendly method.

Composite RGO/Ag/Nanosponge Materials for the Photodegradation of Emerging Pollutants from Wastewaters

Some composite materials have been prepared, constituted by a cyclodextrin-bis-urethane-based nanosponge matrix in which a reduced graphene oxide/silver nanoparticles photocatalyst has been dispersed. Different chain extenders were employed for designing the nanosponge supports, in such a way as to decorate their hyper-cross-linked structure with diverse functionalities. Moreover, two different strategies were explored to accomplish the silver loading. The obtained systems were successfully tested as catalysts for the photodegradation of emerging pollutants such as model dyes and drugs. Enhancement of the photoactive species performance (up to nine times), due to the synergistic local concentration effect exerted by the nanosponge, could be assessed. Overall, the best performances were shown by polyamine-decorated materials, which were able to promote the degradation of some particularly resistant drugs. Some methodological issues pertaining to data collection are also addressed.

Exploring bacterial diversity and antimicrobial resistance gene on a southern Brazilian swine farm

The bacterial composition of and the circulation of antimicrobial resistance genes (ARGs) in waste from Brazilian swine farms are still poorly understood. Considering that antimicrobial resistance (AMR) is one of the main threats to human, animal, and environmental health, the need to accurately assess the load of ARGs released into the environment is urgent. Therefore, this study aimed to characterize the microbiota in a swine farm in southern Brazil and the resistome in swine farm wastewater treated in a series of waste stabilization ponds (WSPs). Samples were collected from farm facilities and the surrounding environment, representing all levels of swine manure within the treatment system. Total metagenomic sequencing was performed on samples from WSPs, and 16S-rDNA sequencing was performed on all the collected samples. The results showed increased bacterial diversity in WSPs, characterized by the presence of Caldatribacteriota, Cloacimonadota, Desulfobacterota, Spirochaetota, Synergistota, and Verrucomicrobiota. Furthermore, resistance genes to tetracyclines, lincosamides, macrolides, rifamycin, phenicol, and genes conferring multidrug resistance were detected in WSPs samples. Interestingly, the most abundant ARG was linG, which confers resistance to the lincosamides. Notably, genes conferring macrolide (mphG and mefC) and rifamycin (rpoB_RIF) resistance appeared in greater numbers in the late WSPs. These drugs are among the high-priority antibiotic classes for human health. Moreover, certain mobile genetic elements (MGEs) were identified in the samples, notably tnpA, which was found in high abundance. These elements are of particular concern due to their potential to facilitate the dissemination of ARGs among bacteria. In summary, the results indicate that, in the studied farm, the swine manure treatment system could not eliminate ARGs and MGEs. Our results validate concerns about Brazil's swine production system. The misuse and overuse of antimicrobials during animal production must be avoided to mitigate AMR.

Azithromycin removal using pine bark, oak ash and mussel shell

Adsorption is considered an interesting option for removing antibiotics from the environment because of its simple design, low cost, and potential efficiency. In this work we evaluated three by-products (pine bark, oak ash, and mussel shell) as bio-adsorbents for the antibiotic azithromycin (AZM). Furthermore, they were added at doses of 48 t ha-1 to four different soils, then comparing AZM removal for soils with and without bio-adsorbents. Batch-type experiments were used, adding AZM concentrations between 2.5 and 600 μmol L-1 to the different bio-adsorbents and soil + bio-adsorbent mixtures. Regarding the bio-adsorbents, oak ash showed the best adsorption scores (9600 μmol kg-1, meaning >80% retention), followed by pine bark (8280 μmol kg-1, 69%) and mussel shell (between 3000 and 6000 μmol kg-1, 25-50% retention). Adsorption data were adjusted to different models (Linear, Freundlich and Langmuir), showing that just mussel shell presented an acceptable fitting to the Freundlich equation, while pine bark and oak ash did not present a good adjustment to any of the three models. Regarding desorption, the values were always below the detection limit, indicating a rather irreversible adsorption of AZM onto these three by-products. Furthermore, the results showed that when the lowest concentrations of AZM were added to the not amended soils they adsorbed 100% of the antibiotic, whereas when the highest concentrations of AZM were spread, the adsorption decreased to 55%. However, when any of the three bio-adsorbents was added to the soils, AZM adsorption reached 100% for all the antibiotic concentrations used. Desorption was null in all cases for both soils with and without bio-adsorbents. These results, corresponding to an investigation carried out for the first time for the antibiotic AZM, can be seen as relevant in the search of low-cost alternative treatments to face environmental pollution caused by this emerging contaminant.

Natural attenuation of sulfonamides and metabolites in contaminated groundwater - Review, advantages and challenges of current documentation techniques

Sulfonamides are applied worldwide as antibiotics. They are emerging contaminants of concern, as their presence in the environment may lead to the spread of antibiotic resistance genes. Sulfonamides are present in groundwater systems, which suggest their persistence under certain conditions, highlighting the importance of understanding natural attenuation processes in groundwater. Biodegradation is an essential process, as degradation of sulfonamides reduces the risk of antibiotic resistance spreading. In this review, natural attenuation, and in particular assessment of biodegradation, is evaluated for sulfonamides in groundwater systems. The current knowledge level on biodegradation is reviewed, and a scientific foundation is built based on sulfonamide degradation processes, pathways, metabolites and toxicity. An overview of bacterial species and related metabolites is provided. The main research effort has focused on aerobic conditions while investigations under anaerobic conditions are lacking. The level of implementation in research is laboratory scale; here we strived to bridge towards field application and assessment, by assessing approaches commonly used in monitored natural attenuation. Methods to document contaminant mass loss are assessed to be applicable for sulfonamides, while the approach is limited by a lack of reference standards for metabolites. Furthermore, additional information is required on relevant metabolites in order to improve risk assessments. Based on the current knowledge on biodegradation, it is suggested to use the presence of substituent-containing metabolites from breakage of the sulfonamide bridge as specific indicators of degradation. Microbial approaches are currently available for assessment of microbial community's capacities, however, more knowledge is required on indigenous bacteria capable of degrading sulfonamides and on the impact of environmental conditions on biodegradation. Compound specific stable isotope analysis shows great potential as an additional in situ method, but further developments are required to analyse for sulfonamides at environmentally relevant levels. Finally, in a monitored natural attenuation scheme it is assessed that approaches are available that can uncover some processes related to the fate of sulfonamides in groundwater systems. Nevertheless, there are still unknowns related to relevant bacteria and metabolites for risk assessment as well as the effect of environmental settings such as redox conditions. Alongside, uncovering the fate of sulfonamides in future research, the applicability of the natural attenuation documentation approaches will advance, and provide a step towards in situ remedial concepts for the frequently detected sulfonamides.

Photochemical behaviors of sludge extracellular polymeric substances from bio-treated effluents towards antibiotic degradation: Distinguish the main photosensitive active component and its environmental implication

Activated sludge extracellular polymeric substances (ASEPSs) comprise most dissolved organic matters (DOMs) in the tail water. However, the understanding of the link between the photolysis of antibiotic and the photo-reactivity/photo-persistence of ASEPS components is limited. This study first investigated the photochemical behaviors of ASEPS's components (humic acids (HA), hydrophobic substances (HOS) and hydrophilic substances (HIS)) separated from municipal sludge's EPS (M-EPS) and nitrification sludge's EPS (N-EPS) in the photolysis of sulfadiazine (SDZ). The results showed that 60% of SDZ was removed by the M-EPS, but the effect in the separated components was weakened, and only 24% - 39% was degraded. However, 58% of SDZ was cleaned by HOS in N-EPS, which was 23% higher than full N-EPS. M-EPS components had lower steady-state concentrations of triplet intermediates (3EPS*), hydroxyl radicals (·OH) and singlet oxygen (1O2) than M-EPS, but N-EPS components had the highest concentrations (5.96 ×10-15, 8.44 ×10-18, 4.56 ×10-13 M, respectively). The changes of CO, C-O and O-CO groups in HA and HOS potentially correspond to reactive specie's generation. These groups change little in HIS, which may make it have radiation resistance. HCO-3 and NO-3 decreased the indirect photolysis of SDZ, and its by-product N-(2-Pyrimidinyl)1,4-benzenediamine presents high environmental risk.

Comprehensive evaluation of antibiotics pollution the Yangtze River basin, China: Emission, multimedia fate and risk assessment

Antibiotics have attracted global attention because of their potential ecological and health risks. The emission, multimedia fate and risk of 18 selected antibiotics in the entire Yangtze River basin were evaluated by using a level Ⅳ fugacity model. High antibiotic emissions were found in the middle and lower reaches of the Yangtze River basin. The total antibiotic emissions in the Yangtze River basin exceeded 1600 tons per year between 2013 and 2021. The spatial distribution of antibiotics concentration was the upper Yangtze River > middle Yangtze River > lower Yangtze River, which is positively correlated with animal husbandry size in the basin. Temperature and precipitation increases may decrease the antibiotic concentrations in the environment. Transfer fluxes showed that source emission inputs, advection processes, and degradation fluxes contributed more to the total input and output. High ecological risks in the water environment were found in 2018, 2019, 2020, and 2021. The comprehensive health risk assessment through drinking water and fish consumption routes showed that a small part of the Yangtze River basin is at medium risk, and children have a relatively high degree of health risk. This study provides a scientific basis for the pollution control of antibiotics at the basin scale.

Long-term exposure of Allonais inaequalis to a mixture of antibiotics in freshwater and synthetic wastewater matrices: Reproduction, recovery, and swimming responses

Antibiotics from sulfonamide, fluoroquinolone, and diaminopyrimidine classes are widely used in human and veterinary medicine, and their combined occurrence in the aquatic environment is increasing around the world. In parallel, the understanding of how mixtures of these compounds affect non-target species from tropical freshwaters is scarce. Thus, this work aimed to study the long-term reproductive, recovery, and swimming effects of mixtures of 12 antibiotics from three different classes (up to 10 μg L-1 ) added to freshwater (FWM) and synthetic wastewater (SWM) matrices on freshwater worm Allonais inaequalis. Results revealed that at the reproduction level, the exposure to antibiotics in the SWM matrix does not cause a significant toxic effect on species after 10 days. On the other hand, exposures to initial dose mixtures (10 μg L-1 each) in FWM caused a significant reduction of offspring by 19.2%. In addition, recovery bioassays (10 days in an antibiotic-free environment) suggested that A. inaequalis has reduced offspring production due to previous exposure to antibiotic mixtures in both matrices. Furthermore, despite slight variation in swimming speed over treatments, no significant differences were pointed out. Regarding antibiotics in the water matrices after 10-day exposures, the highest concentrations were up to 2.7, 7.8, and 4.2 μg L-1 for antibiotics from sulfonamide, fluoroquinolone, and diaminopyrimidine classes, respectively. These findings suggest that a species positioned between primary producers and secondary consumers may experience late reproductive damage even in an antibiotic-free zone, after previous 10-day exposure to antibiotic mixtures. PRACTITIONER POINTS: A mixture of sulfonamide, fluoroquinolone, and diaminopyrimidine antibiotics in freshwater affects the offspring production of A. inaequalis after 10 days. After the 10-day antibiotic exposure, the reproduction of A. inaequalis remains affected in an antibiotic-free environment over the recovery period. The swimming speed of the worms does not change after 10 days of exposure to the antibiotic mixture. The concentration of dissolved solids can limit the natural degradation of sulfonamide, fluoroquinolone, and diaminopyrimidine antibiotics in the aquatic environment.

Groundwater chlorinated solvent plumes remediation from the past to the future: a scientometric and visualization analysis

Contamination of groundwater with chlorinated hydrocarbons has serious adverse effects on human health. As research efforts in this area have expanded, a large body of literature has accumulated. However, traditional review writing suffers from limitations regarding efficiency, quantity, and timeliness, making it difficult to achieve a comprehensive and up-to-date understanding of developments in the field. There is a critical need for new tools to address emerging research challenges. This study evaluated 1619 publications related to this field using VOSviewer and CiteSpace visual tools. An extensive quantitative analysis and global overview of current research hotspots, as well as potential future research directions, were performed by reviewing publications from 2000 to 2022. Over the last 22 years, the USA has produced the most articles, making it the central country in the international collaboration network, with active cooperation with the other 7 most productive countries. Additionally, institutions have played a positive role in promoting the publication of science and technology research. In analyzing the distribution of institutions, it was found that the University of Waterloo conducted the majority of research in this field. This paper also identified the most productive journals, Environmental Science & Technology and Applied and Environmental Microbiology, which published 11,988 and 3253 scientific articles over the past 22 years, respectively. The main technologies are bioremediation and chemical reduction, which have garnered growing attention in academic publishing. Our findings offer a useful resource and a worldwide perspective for scientists engaged in this field, highlighting both the challenges and the possibilities associated with addressing groundwater chlorinated solvent plumes remediation.

Biodegradation strategies of veterinary medicines in the environment: Enzymatic degradation

One Health closely integrates healthy farming, human medicine, and environmental ecology. Due to the ecotoxicity and risk of transmission of drug resistance, veterinary medicines (VMs) are regarded as emerging environmental pollutants. To reduce or mitigate the environmental risk of VMs, developing friendly, safe, and effective removal technologies is an important means of environmental remediation for VMs. Many previous studies have proved that biodegradation has significant advantages in removing VMs, and biodegradation based on enzyme catalysis presents higher operability and specificity. This review focused on biodegradation strategies of environmental pollutants and reviewed the enzymatic degradation of VMs including antimicrobial drugs, insecticides, and disinfectants. We reviewed the sources and catalytic mechanisms of peroxidase, laccase, and organophosphorus hydrolases, and summarized the latest research status of immobilization methods and bioengineering techniques in improving the performance of degrading enzymes. The mechanism of enzymatic degradation for VMs was elucidated in the current research. Suggestions and prospects for researching and developing enzymatic degradation of VMs were also put forward. This review will offer new ideas for the biodegradation of VMs and have a guide significance for the risk mitigation and detoxification of VMs in the environment.

Occurrence of Trace-Level Antibiotics in the Msunduzi River: An Investigation into South African Environmental Pollution

The presence of antibiotics in the environmental matrix has raised concerns regarding their risk to the aquatic ecosystem and human health. Surface water, such as rivers, plays a pivotal role in the dispersion and transport of antibiotic residues. The effective monitoring of these contaminants requires investigating their sources and distribution. While numerous studies have been conducted globally to comprehend the emergence, prevalence, and management of these substances, the investigation of therapeutic antibiotics in Africa remains notably underrepresented. Consequently, data regarding these emerging contaminants in the African aquatic environments are scarce, warranting further exploration. This study aims to investigate the occurrence of four specific therapeutic antibiotics-tetracycline, sulfathiazole, penicillin g, and erythromycin-across different seasons in the Msunduzi River, Eastern South Africa. Three sampling campaigns were conducted during spring, autumn, and winter to assess the presence of these antibiotics in the river. Analyte extraction from water samples was achieved through solid-phase extraction, and quantification was performed using liquid chromatography-mass spectrometry. The findings reveal notable concentrations of these antibiotics in the river at locations closest to a wastewater treatment discharge point. Among the antibiotics studied, tetracycline (158.42-1290.43 ng/L) and sulfathiazole (112.68-1151.25 ng/L) were the most frequently detected compounds across the majority of the sampling sites and tributaries of the river. Erythromycin was less frequently detected in the surface water and wastewater effluent but was found to be a risk to algal species within the river. While wastewater effluents represent a significant source of antibiotic contamination in the river, tributaries from industrial areas and informal settlements were identified as continuous sources of antibiotic pollution. Thus, it is imperative to implement appropriate monitoring protocols to mitigate antibiotic pollution in the aquatic environment.

Adsorption of clarithromycin on polystyrene nanoplastics surface and its combined adverse effect on serum albumin

Emerging contaminants, such as antibiotics and nanoplastics, have garnered significant attention due to their potential adverse effects on diverse ecosystems. Antibiotic adsorption on the surface of nanoplastics potentially facilitates their long-range transport, leading to the synergistic effects of the complex. This research aims to examine the adsorption behavior of clarithromycin binding with polystyrene nanoplastics surface as well as their interaction between drug adsorbed polystyrene nanoplastics with serum albumin. Different spectroscopic methods were used to find out the interaction between clarithromycin and nanoplastics, under stimulated physiological conditions UV-vis spectroscopy showed a maximum of 22.8% percentage of the drug adsorbed with the polystyrene nanoplastics surface after 6 h of incubation. The fluorescence spectroscopic results demonstrated that the fluorescence intensity of serum albumin was quenched by the clarithromycin-polystyrene nanoplastics (CLA-PSNP) complex through static quenching. We calculated the number of binding stoichiometry, binding constants, and thermodynamic parameters. This study revealed that the CLA-PSNP binds to serum albumin spontaneously and its hydrophobic interactions played a significant role. The conformational changes in the structure of serum albumin were revealed from the findings of synchronous fluorescence spectra, CD spectra, and 3D fluorescence spectra, leading to the disturbance in functional activity. This study focuses valuable insights into the intermolecular interactions between clarithromycin-adsorbed polystyrene nanoplastics and serum albumin and its potential molecular-level biological toxicity.

Antibiotic occurrence, environmental risks, and their removal from aquatic environments using microalgae: Advances and future perspectives

Antibiotic pollution has caused a continuous increase in the development of antibiotic-resistant bacteria and antibiotic-resistant genes (ARGs) in aquatic environments worldwide. Algae-based bioremediation technology is a promising eco-friendly means to remove antibiotics and highly resistant ARGs, and the generated biomass can be utilized to produce value-added products of industrial significance. This review discussed the prevalence of antibiotics and ARGs in aquatic environments and their environmental risks to non-target organisms. The potential of various microalgal species for antibiotic and ARG removal, their mechanisms, strategies for enhanced removal, and future directions were reviewed. Antibiotics can be degraded into non-toxic compounds in microalgal cells through the action of extracellular polymeric substances, glutathione-S-transferase, and cytochrome P450; however, antibiotic stress can alter microalgal gene expression and growth. This review also deciphered the effect of antibiotic stress on microalgal physiology, biomass production, and biochemical composition that can impact their commercial applications.

Characteristics of gut bacterial microbiota of black soldier fly (Diptera: Stratiomyidae) larvae effected by typical antibiotics

As agents in an emerging technology, Hermetia illucens (Linnaeus, 1758) (Diptera: Stratiomyidae) larvae, black soldier fly, have shown exciting potential for degrading antibiotics in organic solid waste, a process for which gut microorganisms play an important role. This study investigated the characteristics of larval gut bacterial communities effected by typical antibiotics. Initially, antibiotics significantly reduced the diversity of gut bacterial species. After 8 days, diversity recovered to similar to that of the control group in the chlortetracycline, tylosin, and sulfamethoxazole groups. Proteobacteria, Firmicutes, and Actinobacteriota were the dominant phyla at the initial BSFL gut. However, after 4 days treatment, the proportion of Actinobacteriota significantly decreased, but Bacteroidota notably increased. During the conversion process, 18, 18, 17, 21, and 19 core genera were present in the chlortetracycline, sulfamethoxazole, tylosin, norfloxacin, and gentamicin groups, respectively. Pseudomonas, Actinomyces, Morganella, Providencia and Klebsiella might be the important genera with extraordinary resistance and degradation to antibiotics. Statistical analyses of COGs showed that antibiotics changed the microbial community functions of BSFL gut. Compared with the control group, (i) the chlortetracycline, sulfamethoxazole, and tylosin groups showed significant increase in the classification functions of transcription, RNA processing and modification，and so on, (ii) the norfloxacin and gentamicin groups showed significant increase in defense mechanisms and other functions. Note that we categorized the response mechanisms of these classification functions to antibiotics into resistance and degradation. This provides a new perspective to deeply understand the joint biodegradation behavior of antibiotics in environments, and serves as an important reference for further development and utilization of microorganisms-assisted larvae for efficient degradation of antibiotics.

Ferrocenylselenoether and its cuprous cluster modified TiO2 as visible-light photocatalyst for the synergistic transformation of N-cyclic organics and Cr(vi)

In this study, fcSe@TiO2 and [Cu2I2(fcSe)2]n@TiO2 nanosystems based on ferrocenylselenoether and its cuprous cluster were developed and characterized by X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HR-TEM), energy dispersive X-ray spectroscopy (EDX), and electron paramagnetic resonance (EPR). Under optimized conditions, 0.2 g L-1 catalyst, 20 mM H2O2, and initial pH 7, good synergistic visible light photocatalytic tetracycline degradation and Cr(vi) reduction were achieved, with 92.1% of tetracycline and 64.5% of Cr(vi) removal efficiency within 30 minutes. Mechanistic studies revealed that the reactive species ˙OH, ˙O2-, and h+ were produced in both systems through the mutual promotion of Fenton reactions and photogenerated charge separation. The [Cu2I2(fcSe)2]n@TiO2 system additionally produced 1O2 from Cu+ and ˙O2-. The advantages of the developed nanosystems include an acidic surface microenvironment provided by Se⋯H+, resourceful product formation, tolerance of complex environments, and excellent adaptability in refractory N-cyclic organics.

The impact of different antibiotic injection regimens on patients with severe infections: A meta-analysis

Severe infection is a critical health threat to humans, and antibiotic treatment is one of the main therapeutic approaches. Nevertheless, the efficacy of various antibiotic injection regimens in severe infection patients remains uncertain. This study aimed to comprehensively evaluate the impact of various antibiotic injection strategies on patients with severe infection through a meta-analysis. Relevant research literature was collected by searching databases such as PubMed, Embase, and Cochrane Library. The retrieved literature was screened according to inclusion and exclusion criteria. Relevant data, including study design, sample size, and antibiotic regimens, were extracted from the included studies. The Cochrane Collaboration's Risk of Bias tool was employed to assess the risk of bias in each study. Statistical analysis was performed based on the results of the included studies. A total of 15 articles were included, covering various types of severe infection patients, including pulmonary and abdominal infections. The analysis provided insights into mortality rates, treatment efficacy, adverse reactions (ARs), Acute Physiology and Chronic Health Evaluation (APACHE) scores, among other outcomes. The results indicated that combination therapy was superior to monotherapy in terms of mortality rate, treatment efficacy, and APACHE scores, while the incidence of ARs was lower in the monotherapy group compared to the combination therapy group (p < 0.05). Combination therapy showed better treatment efficacy compared to monotherapy, although it was associated with a higher incidence of ARs.

Vertical migration and dissipation of oxytetracycline induces the recoverable shift in microbial community and antibiotic resistance

Antibiotic resistance gene (ARG) spread in anthropogenic polluted soils is believed to be accelerated by the incidental inputs of antibiotics via fertilizing and irrigation, and endangering food and human health. However, due to the complex nature of substrates and uncertain microbial responses, the primary drivers of ARG dissemination remain unclear. To address this concern, the effects of antibiotic inputs on soil microbes and antibiotic resistance under simulated natural conditions was investigated in this study. Specifically, four flow-through reactors with gravity flow were established, and the oxytetracycline (OTC) a typical antibiotic in agricultural soils was studied at environmental concentrations (i.e. 0.1, 1 and 10 mg/kg) for 31 days. The vertical distribution and dissipation of OTC were profiled by measuring the residuals in layers over time. Correspondingly, the effects of antibiotic exposure on microbial communities and ARG abundances were studied. The results showed that the average exposure intensity of OTC in different soil layers ranged in 0.03-6.45 mg/kg, and resulted in different dissipation kinetics. In addition, top layer was found to be the main site of OTC reduction, where OTC dissipated at magnitude of 74.0-96.6 %, depending on the initial OTC concentration. OTC migration and dissipation resulted in the shift of community composition to the extent of 0.25-0.33 in terms of Bray-Curtis distance, which partially recovered over time. And the achievement of alternative community compositions was supposed to be largely affected by the microbial interaction. Along with the community changes, a short-term accumulation of resistance genes was detected, while the relative abundance of indicator ARGs, i.e. tetG and mexB, rising up to 10-fold higher than the initial, although eventually decayed. Collective findings of this study indicated that antibiotics at environmental concentrations might trigger extra microbial interactions and thereby reducing the demand for ARGs accumulation. It provided valuable understandings in the risk of antibiotic spillage, especially for the incident exposure at the environmentally relevant concentrations.

Contrasted Antibiotics and Pesticides Occurrence in Fish Exposed In Situ to Urban Effluents: A 20-Day Caging Experiment

Urban freshwater ecosystems receive a wide array of organic pollutants through wastewater-treatment plant (WWTP) discharges and agricultural runoff. Evaluating the fate and effects of antibiotics and pesticides can be a challenging task, especially the effects on freshwater vertebrates because of their abilities to metabolize and excrete these chemicals and because of their high mobility and escape behavior when exposed to stressful environmental conditions. In the present study, 37 wild gudgeons (Gobio gobio) were caged for a period of up to 20 days, upstream and downstream of a WWTP effluent discharge in the Orge River (a tributary of the Seine River, France). Levels of pesticides and antibiotics in fish muscles were monitored weekly and compared with environmental contamination (water and sediments). Our results highlighted a slight bioaccumulation of pesticides in the gudgeon muscles at the downstream site after 20 days of exposure. Concerning antibiotics, ofloxacin was the most detected compound in fish muscles (85% of occurrence) and ranged from undetectable to 8 ng g-1  dry weight. Antibiotic levels in fish muscle were not higher at the downstream site and did not increase with exposure duration, despite high levels in the water (up to 29 times greater than upstream). Potential ecotoxicological effects were also evaluated: Body condition did not differ between the caging location and exposure time. Three oxidative status markers in the fish livers showed significant shifts after 14 days of caging. Our results suggest a high clearance rate of antibiotics and, to a lesser extent, of pesticides in wild gudgeons, which could be explained by changes in xenobiotic metabolism with pollutant exposure. Environ Toxicol Chem 2024;00:1-11. © 2023 SETAC.

Adsorption and photodegradation of organic contaminants by silver nanoparticles: isotherms, kinetics, and computational analysis

In view of the widespread and distribution of several classes and types of organic contaminants, increased efforts are needed to reduce their spread and subsequent environmental contamination. Although several remediation approaches are available, adsorption and photodegradation technologies are presented in this review as one of the best options because of their environmental friendliness, cost-effectiveness, accessibility, less selectivity, and wider scope of applications among others. The bandgap, particle size, surface area, electrical properties, thermal stability, reusability, chemical stability, and other properties of silver nanoparticles (AgNPS) are highlighted to account for their suitability in adsorption and photocatalytic applications, concerning organic contaminants. Literatures have been reviewed on the application of various AgNPS as adsorbent and photocatalyst in the remediation of several classes of organic contaminants. Theories of adsorption have also been outlined while photocatalysis is seen to have adsorption as the initial mechanism. Challenges facing the application of silver nanoparticles have also been highlighted and possible solutions have been presented. However, current information is dominated by applications on dyes and the view of the authors supports the need to strengthen the usefulness of AgNPS in adsorption and photodegradation of more classes of organic contaminants, especially emerging contaminants. We also encourage the simultaneous applications of adsorption and photodegradation to completely convert toxic wastes to harmless forms.

Construction of fluorescent sensor array and three-dimensional microfluidic paper based analytical device for specific identification and visual determination of antibiotics in food

For antibiotics misuse since the global outbreak of COVID 19, a novel strategy for discriminating and detecting antibiotics is proposed based on the graphene quantum dots with multi-doped heteroatoms including F, N and P (M-GQDs), which exhibit blue emission (419.0 nm) under the excitation of 336.0 nm. Specifically, the fluorescence of M-GQDs is quenched by tetracyclines (TCs) owing to inner filter effect (IFE) and enhanced by alkane-modified fluoroquinolones (AFQs), which is attributed to restricted conformational rotation based on π-π stacking, hydrogen-bonding and electrostatic interactions. Meanwhile, the electron-accepting property of oxazine ring in oxazine-modified fluoroquinolones (OFQs) increases emission peak at 498.0 nm and decreases emission peak at 419.0 nm as the color changes from blue to cyan. Moreover, a cascade system integrated with 3D microfluidic paper-based analytical device (3D-μPAD) is applied successfully for visually distinguishing three antibiotics, which shows great potential and versatility of M-GQDs for food safety monitoring.

Unveiling antimicrobial resistance in Chilean fertilized soils: a One Health perspective on environmental AMR surveillance

Antimicrobial resistance (AMR) poses a significant threat to humans and animals as well as the environment. Within agricultural settings, the utilization of antimicrobial agents in animal husbandry can lead to the emergence of antimicrobial resistance. In Chile, the widespread use of animal-derived organic amendments, including manure and compost, requires an examination of the potential emergence of AMR resulting from their application. The aim of this research was to identify and compare AMR genes found in fertilized soils and manure in Los Andes city, Chile. Soil samples were collected from an agricultural field, comprising unamended soils, amended soils, and manure used for crop fertilization. The selected genes (n = 28) included genes associated with resistance to beta-lactams, tetracyclines, sulfonamides, polymyxins, macrolides, quinolones, aminoglycosides, as well as mobile genetic elements and multidrug resistance genes. Twenty genes were successfully identified in the samples. Tetracycline resistance genes displayed the highest prevalence, followed by MGE and sulfonamides, while quinolone resistance genes were comparatively less abundant. Notably, blaOXA, sulA, tetO, tetW, tetM, aac (6) ib., and intI1, exhibited higher frequencies in unamended soils, indicating their potential persistence within the soil microbiome and contribution to the perpetuation of AMR over time. Given the complex nature of AMR, it is crucial to adopt an integrated surveillance framework that embraces the One Health approach, involving multiple sectors, to effectively address this challenge. This study represents the first investigation of antimicrobial resistance genes in agricultural soils in Chile, shedding light on the presence and dynamics of AMR in this context.

Applied potential assisted biodegradation of amoxicillin (AMX) using bacterial consortium isolated from a waste dump site

Antibiotics have revolutionized modern day living with their ability to effectively treat infectious diseases in humans and animals. However, the release of antibiotic compounds into the environment has led to toxic consequences. To reduce this environmental impact, it is important to employ an inexpensive and rational technology to reduce the amount of antibiotics released into the ecosystem. This study aims to explore the potential of using a bio-electrochemical system (BES) to remove Amoxicillin (AMX) from artificially contaminated soil using a microbial consortium and pure culture isolates. Under desired conditions, including an initial AMX concentration of 150 mg/L, 5 mg/L tryptone as the nitrogen source, pH of 7, temperature of 29 °C, an applied potential of 0.8 V, and an inoculum dose of 1% w/v, the BES showed a maximum degradation of 97.9% of AMX with the microbial consortium (HP03, HP09, and HP10). High performance liquid chromatography-mass spectrometry was used to analyse the intermediates formed during the degradation process, and the pathway elucidated revealed complete degradation of AMX. Phytotoxicity studies and degradation efficiency against multiple antibiotics confirmed the environmental significance of the BES with microbial consortium. Overall, this study highlights the potential of BES as a cost-effective and efficient method for reducing the release of antibiotics into the environment and provides valuable insights into the mechanisms and pathways of antibiotic degradation.

Assessing the Ecotoxicity of Eight Widely Used Antibiotics on River Microbial Communities

Global prevalence of antibiotic residues (ABX) in rivers requires ecotoxicological impact assessment. River microbial communities serve as effective bioindicators for this purpose. We quantified the effects of eight commonly used ABXs on a freshwater river microbial community using Biolog EcoPlates™, enabling the assessment of growth and physiological profile changes. Microbial community characterization involved 16S rRNA gene sequencing. The river community structure was representative of aquatic ecosystems, with the prevalence of Cyanobacteria, Proteobacteria, Actinobacteria, and Bacteroidetes. Our findings reveal that all ABXs at 100 µg/mL reduced microbial community growth and metabolic capacity, particularly for polymers, carbohydrates, carboxylic, and ketonic acids. Chloramphenicol, erythromycin, and gentamicin exhibited the highest toxicity, with chloramphenicol notably impairing the metabolism of all studied metabolite groups. At lower concentrations (1 µg/mL), some ABXs slightly enhanced growth and the capacity to metabolize substrates, such as carbohydrates, carboxylic, and ketonic acids, and amines, except for amoxicillin, which decreased the metabolic capacity across all metabolites. We explored potential correlations between physicochemical parameters and drug mechanisms to understand drug bioavailability. Acute toxicity effects at the river-detected low concentrations (ng/L) are unlikely. However, they may disrupt microbial communities in aquatic ecosystems. The utilization of a wide array of genetically characterized microbial communities, as opposed to a single species, enables a better understanding of the impact of ABXs on complex river ecosystems.

Occurrence, Bioaccumulation, Metabolism and Ecotoxicity of Fluoroquinolones in the Aquatic Environment: A Review

In recent years, there has been growing concern about antibiotic contamination in water bodies, particularly the widespread presence of fluoroquinolones (FQs), which pose a serious threat to ecosystems due to their extensive use and the phenomenon of "pseudo-persistence". This article provides a comprehensive review of the literature on FQs in water bodies, summarizing and analyzing contamination levels of FQs in global surface water over the past three years, as well as the bioaccumulation and metabolism patterns of FQs in aquatic organisms, their ecological toxicity, and the influencing factors. The results show that FQs contamination is widespread in surface water across the surveyed 32 countries, with ciprofloxacin and norfloxacin being the most heavy contaminants. Furthermore, contamination levels are generally higher in developing and developed countries. It has been observed that compound types, species, and environmental factors influence the bioaccumulation, metabolism, and toxicity of FQs in aquatic organisms. FQs tend to accumulate more in organisms with higher lipid content, and toxicity experiments have shown that FQs exhibit the highest toxicity to bacteria and the weakest toxicity to mollusk. This article summarizes and analyzes the current research status and shortcomings of FQs, providing guidance and theoretical support for future research directions.

Investigating sulfonamides - Human serum albumin interactions: A comprehensive approach using multi-spectroscopy, DFT calculations, and molecular docking

The environmental and health risks associated with sulfonamide antibiotics (SAs) are receiving increasing attention. Through multi-spectroscopy, density functional theory (DFT), and molecular docking, this study investigated the interaction features and mechanisms between six representative SAs and human serum albumin (HSA). Multi-spectroscopy analysis showed that the six SAs had significant binding capabilities with HSA. The order of binding constants at 298 K was as follows: sulfadoxine (SDX): 7.18 × 105 L mol-1 > sulfamethizole (SMT): 6.28 × 105 L mol-1 > sulfamerazine (SMR): 2.70 × 104 L mol-1 > sulfamonomethoxine (SMM): 2.54 × 104 L mol-1 > sulfamethazine (SMZ): 3.06 × 104 L mol-1 > sulfadimethoxine (SDM): 2.50 × 104 L mol-1. During the molecular docking process of the six SAs with HSA, the binding affinity range is from -7.4 kcal mol-1 to -8.6 kcal mol-1. Notably, the docking result of HSA-SDX reached the maximum of -8.6 kcal mol-1, indicating that SDX may possess the highest binding capacity to HSA. HSA-SDX binding, identified as a static quenching and exothermic process, is primarily driven by hydrogen bonds (H bonds) or van der Waals (vdW) interactions. The quenching processes of SMR/SMZ/SMM/SDX/SMT to HSA are a combination of dynamic and static quenching, indicating an endothermic reaction. Hydrophobic interactions are primarily accountable for SMR/SMZ/SMM/SDX/SMT and HSA binding. Competition binding results revealed that the primary HSA-SAs binding sites are in the subdomain IB of the HAS structure, consistent with the results of molecule docking. The correlation analysis based on DFT calculations revealed an inherent relationship between the structural chemical features of SAs and the binding performance of HSA-SAs. The dual descriptor (DD) and the electrophilic Fukui function were found to have a significant relationship (0.71 and -0.71, respectively) with the binding constants of HSA-SAs, predicting the binding performance of SAs and HSA. These insights have substantial scientific value for evaluating the environmental risks of SAs as well as understanding their impact on biological life activities.

Regulation and role of extracellular polymeric substances in the defensive responses of Dictyosphaerium sp. to enrofloxacin stress

Algae are susceptible to enrofloxacin (ENR), an antibiotic frequently detected in aquatic environments. However, algal responses, especially the secretion and roles of extracellular polymeric substances (EPS), under ENR exposure remain unknown. This study is the first to elucidate the variation in algal EPS triggered by ENR at both the physiological and molecular levels. The results showed that EPS were significantly (P < 0.05) overproduced along with increased polysaccharide and protein contents in algae exposed to 0.05, 0.5, and 5 mg/L ENR. Secretion of aromatic proteins, especially tryptophan-like substances with more functional groups or aromatic rings, was specifically stimulated. Furthermore, the genes with upregulated expression related to carbon fixation, aromatic protein biosynthesis, and carbohydrate metabolism are direct causes of enhanced EPS secretion. Improved EPS levels increased the cell surface hydrophobicity and provided more adsorption sites for ENR, which strengthened the van der Waals interaction and reduced ENR internalization. The hormesis effects of ENR were alleviated, as illustrated by the less affected cell density, chlorophyll a/b, and carotenoids biosynthesis in algae with EPS. These findings demonstrate the involvement of EPS in algal ENR resistance and promote a deeper understanding of the ecological effects of ENR in aquatic environments.

A pilot-scale study on the removal of binary mixture (ciprofloxacin and norfloxacin) by Scenedesmus obliquus: Optimization, biotransformation, and biofuel profile

Ciprofloxacin (CIP) and norfloxacin (NOR) belong to the organic contaminants of emerging concern (OCECs) that are frequently detected in wastewater matrices at ng/L to mg/L concentrations. This study investigates the potential of Scenedesmus obliquus in the treatment of CIP and NOR as a binary mixture from raw wastewater. Optimization of inoculum was done to find the required cell density concentration that has less inhibition and high removal. The optimum inoculum (cell density: 200 × 105 cells/mL and OD680: 1.0) has shown 75% removal with no inhibition of growth. A pilot scale study was conducted in controlled environment using high-rate algal pond to investigate the contribution of abiotic and biotic removal. Abiotic removal is negligible in comparison with the biotic contribution of removal. The order of removal efficiency is observed as COD (88%) > NOR (84.8%) > CIP (84.6%) > NH4+ (71.7%) with biodegradation as the major removal mechanism. Biotransformed products of CIP + NOR were identified inside the Scenedesmus obliquus. During the pilot-scale study, Biomass (3.70 ± 0.07 g/L) was harvested with carbohydrates (17.85 ± 0.1%), lipids (38.36 ± 0.13%), and proteins (28.18 ± 1.63%). Lipid productivity in binary mixture was 2.6 times higher than the lipid production in control condition. Transesterification of these lipids yielded good biofuel composition of 32.72% of saturated fatty acids and 21.7% of unsaturated fatty acids.

Reduced bacterial resistance antibiotics with improved microbiota tolerance in human intestinal: Molecular design and mechanism analysis

Antibiotic selectivity and bacterial resistance are critical global public health issues. We constructed a multi-class machine learning model to study antibiotic effects on human intestinal microbiota abundance and identified key features. Binding energies of β-lactam antibiotics with Escherichia coli PBP3 mutant protein were calculated, and a 2D-QSAR model for bacterial resistance was established. Sensitivity analysis identified key features affecting bacterial resistance. By coupling key features from the machine learning model and 2D-QSAR model, we designed ten flucloxacillin (FLU) substitutes that improved intestinal microbiota tolerance and reduced antibiotic bacterial resistance. Concurrently, the substitutes exhibited superior degradability in soil, aquatic environments, and under photolytic conditions, coupled with a reduced environmental toxicity compared to the FLU. Evaluations under combined medication revealed significant improvements in functionality and bacterial resistance for 80% of FLU substitutes, with 50% showing more than a twofold increase. Mechanistic analysis demonstrated enhanced binding to target proteins and increased biodegradability for FLU substitutes due to more concentrated surface charges. Reduced solvent hindrance and increased cell membrane permeability of FLU substitutes, mainly due to enhanced interactions with phospholipid bilayers, contributed to their functional selectivity. This study aims to address poor antibiotic selectivity and strong bacterial resistance, providing guidance for designing antibiotic substitutes.

Preparation of Yb-Sb co-doped Ti/SnO2 electrode for electrocatalytic degradation of sulfamethoxazole (SMX)

To efficiently break down residual sulfonamide antibiotics in environmental water, Yb-Sb co-doped Ti/SnO2 electrodes were fabricated using a solvothermal method. The effect of different amounts of Yb doping on the properties of the electrodes was studied. When the atom ratio of Sn: Yb is 100 : 7.5 in the preparation, the as-obtained coral-like electrodes (denoted as Yb 7.5%) possessed the smallest diameter of spherical particles on the surfaces, to result in the denser surface, highest electrocatalytic activity and smallest resistance of the electrode. As anode for electrocatalytic degradation of sulfamethoxazole, the Yb 7.5% electrode showed a degradation rate of 92% in 90 min, which was much higher than that of Yb 0% electrode (62.7% degradation rate). The electrocatalytic degradation of sulfamethoxazole was investigated with varying current densities and initial concentrations. Results indicated that the degradation process followed pseudo-first-order kinetics, and the degradation rate constants for Yb 7.5% and Yb 0% electrodes were 0.0278 min-1 and 0.0114 min-1, respectively. Furthermore, the service life of Ti/SnO2 electrodes was significantly improved after Yb doping, as demonstrated by accelerated life testing. Yb 7.5% exhibited a service life that was 2.7 times longer than that of Yb 0%. This work offers a new approach to construct Yb-Sb co-doped Ti/SnO2 electrodes with excellent electrooxidation activity and high stability for the electrochemical oxidation degradation of sulfamethoxazole.

Photocatalysis-PMS oxidation system based on CQDs-doped carbon nitride nanosheets for degradation of residual drugs in water

Graphite-like carbon nitride (g-C3N4) is favored for its excellent physicochemical properties. However, the high complexation rate of photogenerated carriers greatly limits its practical applications. Based on this, a novel CQDs-doped carbon nitride nanosheets composite (CNS/CQDs) was prepared and applied to the visible light-induced activation of peroxymonosulfate (PMS) for meloxicam (Mel) and tetracycline (TC) degradation. The photocatalytic degradation of Mel and TC were remarkably promoted in the CNS/CQDs+PMS+vis system. Mel photodegradation of 99.90% was achieved over 30 min with 20 mg CNS/CQDs and 20 mg PMS at pH11. And TC photodegradation of 95.97% was achieved over 45 min with 20 mg CNS/CQDs and 20 mg PMS at nature pH6.5. The TOC mineralization rates of Mel and TC were 75.49% and 52.00%, respectively. The transient photocurrent response and electrochemical impedance measurements (EIS) results indicated that the doping of CQDs could improve the charge transfer efficiency of pure g-C3N4, and CNS/CQDs had a low charge transfer resistance. Capture experiments and EPR tests explored the effective actives in the CNS/CQDs+PMS+vis system. Possible degradation pathways of Mel were also analyzed. This study provides valid residual drugs degradation under the dual conditions of visible light catalytic oxidation and persulfate oxidation, which will be a novel perspective for advanced oxidation technology to effectively remove organic pollutants from water.

Enhanced photocatalytic degradation of levofloxacin over heterostructured C3N4/Nb2O5 system under visible light

The growing usage of antibiotics and their subsequent release in water bodies have become a serious environmental concern. In this study, heterostructured photocatalysts C3N4/Nb2O5 have been synthesized using a simple hydrothermal method and applied to facilitate the degradation of the widely used antibiotic levofloxacin. The structural, morphological, and optical properties of the photocatalysts were characterized using XRD, SEM, TEM, UV-Vis and PL to establish the structure-property relationship. The type-II heterojunctions C3N4/Nb2O5 show remarkable activity under visible light irradiation, where Nb2O5 facilitates preferential adsorption of levofloxacin at the catalyst surface while C3N4 extends visible light absorption. This synergy resulted in superior catalytic performance (91%) in the optimized system, exceeding that of individual materials (Nb2O5 30% and C3N4 56%). The effect of catalyst dosage, pH, oxygen and point of zero is also investigated. The process is mainly photo-driven, and the trapping experiments reveal superoxide radicals as key species responsible for the degradation. Additionally, the adsorption behaviour, reformation of the degraded pollutant and reusability factors are evaluated to assess the practical feasibility of the photocatalytic system.

Overview of Direct and Indirect Effects of Antibiotics on Terrestrial Organisms

Antibiotics (ABs) have made it possible to treat bacterial infections, which were in the past untreatable and consequently fatal. Regrettably, their use and abuse among humans and livestock led to antibiotic resistance, which has made them ineffective in many cases. The spread of antibiotic resistance genes (ARGs) and bacteria is not limited to nosocomial environments, but also involves water and soil ecosystems. The environmental presence of ABs and ARGs is a hot topic, and their direct and indirect effects, are still not well known or clarified. A particular concern is the presence of antibiotics in agroecosystems due to the application of agro-zootechnical waste (e.g., manure and biosolids), which can introduce antibiotic residues and ARGs to soils. This review provides an insight of recent findings of AB direct and indirect effects on terrestrial organisms, focusing on plant and invertebrates. Possible changing in viability and organism growth, AB bioaccumulation, and shifts in associated microbiome composition are reported. Oxidative stress responses of plants (such as reactive oxygen species production) to antibiotics are also described.

Clarithromycin as soil and environmental pollutant: Adsorption-desorption processes and influence of pH

Antibiotics pollution is a growing environmental issue, as high amounts of these compounds are found in soil, water and sediments. This work studies the adsorption/desorption of the macrolide antibiotic clarithromycin (CLA) for 17 agricultural soils with different edaphic characteristics. The research was carried out using batch-type experiments, with an additional assessment of the specific influence of pH for 6 of the soils. The results show that CLA adsorption reaches between 26 and 95%. In addition, the fit of the experimental data to adsorption models provided values between 1.9 and 19.7 Ln μmol1-n kg-1 for the KF, Freundlich affinity coefficient, and between 2.5 and 10.5 L kg-1 for Kd, distribution constant of Linear model. Regarding the linearity index, n, it varied between 0.56 and 1.34. Desorption showed lower scores than adsorption, with an average of 20%, and with values of 3.1 and 93.0 Ln μmol1-n kg-1 for KF(des) and 4.4 and 95.0 L kg-1 for Kd(des). The edaphic characteristics with the highest influence on adsorption were the silt fraction content and the exchangeable Ca content, while in the case of desorption, they were the total nitrogen, organic carbon, and exchangeable Ca and Mg contents. Regarding the pH, within the range studied (between 3 and 10), its value did not decisively affect the adsorption/desorption process. Overall, the set of these results could be of help to program appropriate measures leading to the retention/elimination of this antibiotic when it reaches the environment as a pollutant.

In situ preparation of MOF-199 into the carrageenan-grafted-polyacrylamide@Fe3O4 matrix for enhanced adsorption of levofloxacin and cefixime antibiotics from water

In this research study, a novel method, an in-situ growth approach, to incorporate metal-organic framework (MOF) into carrageenan-grafted- polyacrylamide-Fe3O4 substrate was introduced. Carrageenan-grafted-polyacrylamide-Fe3O4/MOF nanocomposite (kC-g-PAAm@Fe3O4-MOF-199) was fabricated utilizing three stages. In this way, the polyacrylamide (PAAm) was grafted onto the carrageenan (kC) backbone via free radical polymerization in the presence of methylene bisacrylamide (MBA) as cross-linker and Fe3O4 magnetic nanoparticles. Next, the kC-g-PAAm@Fe3O4 was modified by MOF-199 via an in-situ solvothermal approach. Several analyses such as Fourier transform infrared spectroscopy (FT-IR), X-Ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy-Dispersive X-ray Spectroscopy (EDX), thermogravimetric analysis (TGA), vibrating sample magnetometer (VSM), Brunauer-Emmett-Teller (BET) demonstrated the successful synthesis of kC-g-PAAm@Fe3O4-MOF-199 magnetic hydrogel nanocomposite. The XRD pattern of magnetic hydrogel nanocomposite illustrated characteristic peaks of Fe3O4, neat kC, and MOF-199 with enhanced crystallinity in comparison with kC-g-PAAm@Fe3O4. TGA showed it has a char yield of 24 wt% at 800 °C. VSM confirmed its superparamagnetic behavior (with Ms of 8.04 emu g-1), and the BET surface area of kC-g-PAAm@Fe3O4-MOF-199 was measured at 64.864 m2 g-1, which was higher than that of kC-g-PAAm@Fe3O4 due to the highly porous MOF-199 incorporation with a BET surface area of 905.12 m2 g-1). The adsorption effectiveness of kC-g-PAAm@Fe3O4-MOF-199 for eliminating cephalosporin and quinolones antibiotics, i.e., Cefixime (CFX) and Levofloxacin (LEV) from the aquatic area was considered. Several experimental setups were used to evaluate the efficacy of adsorption, such as solution pH, amount of adsorbent, contact duration, and initial concentration. The maximum adsorption capacity (Qmax) of the prepared magnetic hydrogel nanocomposite was found to be 2000 and 1666.667 mg-1 for LEV and CFX using employing 0.0025 g of adsorbent. The Freundlich isotherm model well described the experimental adsorption data with R2CFX = 0.9986, and R2LEV = 0.9939. And the adsorption kinetic data were successfully represented by the pseudo-second-order model with R2LEV = 0.9949 and R2CFX = 0.9906. Hydrogen bonding, π-π interaction, diffusion, and entrapment in the hydrogel network all contributed to the successful adsorption of both antibiotics onto the kC-g-PAAm@Fe3O4-MOF-199 adsorbent. Other notable physicochemical properties include the three-dimensional structure and availability of the reactive adsorption sites. Moreover, the adsorption/desorption efficacy of magnetic hydrogel nanocomposites was not significantly diminished after four cycles of recovery.

An investigation on removal of ciprofloxacin and norfloxacin by phycoremediation with an emphasis on acute toxicity and biochemical composition

Ciprofloxacin (CIP) and norfloxacin (NOR) belong to the class of emerging contaminants that are frequently detected in the aquatic environment as a binary mixture, responsible for the development of antibiotic-resistant genes and antibiotic-resistant bacteria. This study aims to investigate five different algal species Chlorella vulgaris (Cv), Chlorella pyrenoidosa (Cp), Scenedesmus obliquus (So), Tetradesmus sp (T) and Monoraphidium sp (M) for their tolerance and removal of binary mixture. The effects on biochemical composition in the algal species concerning the binary mixture and its removal efficiency are first reported in this study. The acute toxicity (96 h EC50) values are in the order of So > Cp > T > M > Cv, Chlorella vulgaris is the most sensitive algal species with 17.73 ± 0.24 mg/L and Scenedesmus obliquus is the least sensitive algal species with 39.19 ± 0.79 mg/L. The removal efficiency of the binary mixture was found to be in the order of So > Cp > T > M > Cv, Scenedesmus obliquus removed CIP (52.4%) and NOR (87.5%) with biodegradation as the major contributing removal mechanism. Furthermore, less toxic biotransformed products were detected in Scenedesmus obliquus and the biochemical characterization revealed that the growth-stimulating effect is higher with lipid (35%), carbohydrate (18%), and protein (33%) providing an advantage in the production of valuable biomass.

Deciphering and investigating fragment mechanism of quinolones using multi-collision energy mass spectrometry and computational chemistry strategy

RATIONALE

Quinolones show characteristic fragments in mass spectrometry (MS) analysis due to their common core structures, and energy-dependent differences among these fragments are generated through the same fragmentation pathway of different molecules. Computational chemistry, which provides quantitative results of molecule parameters, is helpful for investigating the mechanisms of chemistry.

METHODS

MS/MS spectra of five quinolones, namely norfloxacin (NOR), enoxacin (ENO), enrofloxacin (ENR), gatifloxacin (GAT), and lomefloxacin (LOM), were acquired for deciphering fragmentation pathways under multi-collision energy (CE). Computational methods were used for excluding little possibility pathways from the point of view of energy and stable conformations, whereas optimized collision energy (OCE) and maximum relative intensity (MRI) of major competitive fragments were investigated and confirmed using computational results.

RESULTS

Fragmentation results of NOR, ENO, ENR, and GAT were deciphered using experimental and computational data, of which fragmentation regularities were summarized. Fragmentation pathways of LOM were deciphered under the guidance of foregoing regularities. Meanwhile, the whole process was validated by comparing OCE and MRI and computational energy results, which showed good agreement.

CONCLUSIONS

A strategy for explaining quinolone fragmentation results of multi-CE values and deciphering fragment mechanism using computational methods was developed. Relevant data and strategy may provide ideas for how to design and decipher new drug molecules with similar structures.

Efficient activation of ferrate by Ru(III): Insights into the major reactive species and the multiple roles of Ru(III)

Ferrate (Fe(VI)) has aroused great research interest in recent years due to its environmental benignancy and lower potential in disinfection by-product generation. However, the inevitable self-decomposition and lower reactivity under alkaline conditions severely restrict the utilization and decontamination efficiency of Fe(VI). Here, we discovered that Ru(III), a representative transition metal, could effectively activate Fe(VI) to degrade organic micropollutants, and its performance on Fe(VI) activation exceeded that of previously reported metal activators. The high-valent metal species (i.e., Fe(IV)/Fe(V) and high-valent Ru species) made a major contribution to SMX removal by Fe(VI)-Ru(III). Density functional theory calculations indicated the function of Ru(III) as a two-electron reductant, leading to the production of Ru(V) and Fe(IV) as the predominant active species. The characterization analyses proved that Ru species was deposited on ferric (hydr)oxides as Ru(III), indicating the possibility of Ru(III) as an electron shuttle with the rapid valence circulation between Ru(V) and Ru(III). This study not only develops an efficient way to activate Fe(VI) but also offers a thorough understanding of Fe(VI) activation induced by transition metals.

Type-1 α-Fe2O3/TiO2 photocatalytic degradation of tetracycline from wastewater using CCD-based RSM optimization

Antibiotic pollution in water is a growing threat to public health and the environment, leading to the spread of antimicrobial-resistant bacteria. While photocatalysis has emerged as a promising technology for removing antibiotics from water, its limited efficiency in the visible light range remains a challenge. In this study, we present a novel method for the photocatalytic degradation of tetracycline, the second most commonly used antibiotic worldwide, using α-Fe₂O₃/TiO₂ nanocomposites synthesized via rapid sonochemical and wet impregnation methods. The nanocomposites were characterised and tested using a range of techniques, including BET, TEM, FTIR, XRD, FESEM, EDS, and UV-Vis. The RSM-CCD method was also used to optimize the degradation process by varying four key variables (initial concentration, photocatalyst quantity, irradiation time, and pH). The resulting optimized conditions achieved a remarkable degradation rate of 97.5%. We also investigated the mechanism of photodegradation and the reusability of the photocatalysts, as well as the effect of light source operating conditions. Overall, the results demonstrate the effectiveness of the proposed approach in degrading tetracycline in water and suggest that it may be a promising, eco-friendly technology for the treatment of water contaminated with antibiotics.

Elucidating microalgae-mediated metabolism for sulfadiazine removal mechanism and transformation pathways

Sulfadiazine (SDZ) as a typical sulfonamide antibiotic is commonly detected in wastewater, and its removal mechanism and transformation pathways in microalgae-mediated system remain unclear. In this study, the SDZ removal through hydrolysis, photodegradation, and biodegradation by Chlorella pyrenoidosa was investigated. Higher superoxide dismutase activity and biochemical components accumulation were obtained under SDZ stress. The SDZ removal efficiencies at different initial concentrations were 65.9-67.6%, and the removal rate followed pseudo first-order kinetic model. Batch tests and HPLC-MS/MS analyses suggested that biodegradation and photodegradation through the reactions of amine group oxidation, ring opening, hydroxylation, and the cleavage of S-N, C-N, C-S bond were dominant removal mechanisms and pathways. Characteristics of transformation products were evaluated to analyze their environmental impacts. High-value products of lipid, carbohydrate, and protein in microalgae biomass presented economic potential of microalgae-mediated metabolism for SDZ removal. The findings of this study broadened the knowledge for the microalgae self-protection from SDZ stress and provided a deep insight into SDZ removal mechanism and transformation pathways.

Antibiotic pollution of the Yellow River in China and its relationship with dissolved organic matter: Distribution and Source identification

Understanding the sources of antibiotics is important for managing antibiotic contamination and preventing environmental risks in the aquatic environment. In this study, the distribution of dissolved organic matter (DOM) and 24 antibiotics from four typical classes (quinolones, macrolides, sulfonamides and tetracyclines) in the Yellow River basin containing distinct sources of pollution was investigated. In particular, relationships between the antibiotic concentrations and fluorescent properties of DOM were to be established to identify antibiotic sources. A total of 22 antibiotics were detected, with maximum concentrations ranging from 0.27 to 30.14 ng/L in the mainstream of the Yellow River. Of these antibiotics, only erythromycin (ERY) and sulfamethoxazole (SMX) posed potential risks to aquatic organisms. Spatially, tetracyclines were mainly distributed in the upstream reaches of the river, and quinolones were largely distributed in the midstream. High levels of sulfonamides were present downstream of the investigated river. Only EYR belonging to the macrolide group was detected and had a high downstream concentration. EEM-PARAFAC analysis showed that DOM was composed of visible fulvic acid-like fluorescence fraction (C1), ultraviolet fulvic acid-like fluorescence fraction (C2) and protein-like fraction (C3). Using Pearson correlation analysis, this study demonstrated a close relationship between DOM spectral parameters and antibiotic concentrations in the Yellow River basin. Specifically, r (C3, C2) was significantly and positively correlated with the concentrations of SMX, sulfadoxine (SDX), and ERY, while humification index (HIX) had an opposite relationship with these antibiotics. These results suggested that SMX, SDX and ERY were mainly discharged from wastewater treatment plants into the mainstream of the Yellow River. This work provides a powerful demonstration that DOM plays an important role in indicating the occurrence and sources of antibiotics in the aquatic environment.

Impact of antibiotics on microbial community in aquatic environment and biodegradation mechanism: a review and bibliometric analysis

Antibiotic residues in aquatic environments pose a potential hazard, and microbes, which play important roles in aquatic ecosystems, are vulnerable to the impacts of antibiotics. This study aimed to analyze the research progress, trends, and hot topics of the impact of antibiotics on microbial community and biodegradation mechanism using bibliometric analysis. An in-depth analysis of the publication characteristics of 6143 articles published between 1990 and 2021 revealed that the number of articles published increased exponentially. The research sites have been mainly concentrated in the Yamuna River, Pearl River, Lake Taihu, Lake Michigan, Danjiangkou Reservoir, etc., illustrating that research around the world is not even. Antibiotics could change the diversity, structure, and ecological functions of bacterial communities, stimulate a widespread abundance of antibiotic-resistant bacteria and antibiotic-resistant genes, and increase the diversity of eukaryotes, thus triggering the shift of food web structure to predatory and pathogenic. Latent Dirichlet allocation theme model analysis showed three clusters, and the research hotspots mainly included the effect of antibiotics on the denitrification process, microplastics combined with antibiotics, and methods for removing antibiotics. Furthermore, the mechanisms of microbe-mediated antibiotic degradation were unraveled, and importantly, we provided bottlenecks and future research perspectives on antibiotics and microbial diversity research.

Novel Non-Toxic Highly Antibacterial Chitosan/Fe(III)-Based Nanoparticles That Contain a Deferoxamine—Trojan Horse Ligands: Combined Synthetic and Biological Studies

In this study, we prepared chitosan/Fe(III)/deferoxamine nanoparticles with unimodal size distribution (hydrodynamic diameter ca. 250 nm, zeta potential ca. 32 mV). The elaborated nanoparticles are characterized by outstanding in vitro and in vivo antibacterial activity, which exceeds even that of commercial antibiotics ampicillin and gentamicin. Moreover, the nanoparticles are non-toxic. We found that the introduction of iron ions into the chitosan matrix increases the ability of the resulting nanoparticles to disrupt the integrity of the membranes of microorganisms in comparison with pure chitosan. The introduction of deferoxamine into the obtained nanoparticles sharply expands their effect of destruction the bacterial membrane. The obtained antibacterial nanoparticles are promising for further preclinical studies.

Effects of Single and Combined Ciprofloxacin and Lead Treatments on Zebrafish Behavior, Oxidative Stress, and Elements Content

Even though the toxic effects of antibiotics and heavy metals have been extensively studied in the last decades, their combined adverse impact on aquatic organisms is poorly understood. Therefore, the objective of this study was to assess the acute effects of a ciprofloxacin (Cipro) and lead (Pb) mixture on the 3D swimming behavior, acetylcholinesterase (AChE) activity, lipid peroxidation level (MDA-malondialdehyde), activity of some oxidative stress markers (SOD-superoxide dismutase and GPx-glutathione peroxidase), and the essential elements content (Cu-copper, Zn-zinc, Fe-iron, Ca-calcium, Mg-magnesium, Na-sodium and K-potassium) in the body of zebrafish (Danio rerio). For this purpose, zebrafish were exposed to environmentally relevant concentrations of Cipro, Pb, and a mixture for 96 h. The results revealed that acute exposure to Pb alone and in mixture with Cipro impaired zebrafish exploratory behavior by decreasing swimming activity and elevating freezing duration. Moreover, significant deficiencies of Ca, K, Mg, and Na contents, as well as an excess of Zn level, were observed in fish tissues after exposure to the binary mixture. Likewise, the combined treatment with Pb and Cipro inhibited the activity of AChE and increased the GPx activity and MDA level. The mixture produced more damage in all studied endpoints, while Cipro had no significant effect. The findings highlight that the simultaneous presence of antibiotics and heavy metals in the environment can pose a threat to the health of living organisms.

The Use of Antibiotics and Antimicrobial Resistance in Veterinary Medicine, a Complex Phenomenon: A Narrative Review

As warned by Sir Alexander Fleming in his Nobel Prize address: “the use of antimicrobials can, and will, lead to resistance”. Antimicrobial resistance (AMR) has recently increased due to the overuse and misuse of antibiotics, and their use in animals (food-producing and companion) has also resulted in the selection and transmission of resistant bacteria. The epidemiology of resistance is complex, and factors other than the overall quantity of antibiotics consumed may influence it. Nowadays, AMR has a serious impact on society, both economically and in terms of healthcare. This narrative review aimed to provide a scenario of the state of the AMR phenomenon in veterinary medicine related to the use of antibiotics in different animal species; the impact that it can have on animals, as well as humans and the environment, was considered. Providing some particular instances, the authors tried to explain the vastness of the phenomenon of AMR in veterinary medicine due to many and diverse aspects that cannot always be controlled. The veterinarian is the main reference point here and has a high responsibility towards the human–animal–environment triad. Sharing such a burden with human medicine and cooperating together for the same purpose (fighting and containing AMR) represents an effective example of the application of the One Health approach.

Methods involved in the treatment of four representative pharmaceuticals in hospital wastewater using sonochemical and biological processes

A primary pollution source by pharmaceuticals is hospital wastewater (HWW). Herein, the methods involved in the action of a biological system (BS, aerobic activated sludge) or a sonochemical treatment (US, 375 kHz and 30.8 W), for degrading four relevant pharmaceuticals (azithromycin, ciprofloxacin, paracetamol, and valsartan) in HWW, are shown. Before treatment of HWW, the correct performance of BS was assessed using glucose as a reference substance, monitoring oxygen consumption, and organic carbon removal. Meanwhile, for US, a preliminary test using ciprofloxacin in distilled water was carried out. The determination of risk quotients (RQ) and theoretical analyses about reactive moieties on these target substances are also presented. For both, the degradation of the pharmaceuticals and the calculation of RQ, analyses were performed by LC-MS/MS. The BS action decreased the concentration of paracetamol and valsartan by ∼96 and 86%, respectively. However, a poor action on azithromycin (2% removal) was found, whereas ciprofloxacin concentration increased ∼20%; leading to an RQ value of 1.61 (high risk) for the pharmaceuticals mixture. The analyses using a biodegradation pathway predictor (EAWAG-BDD methodology) revealed that the amide group on paracetamol and alkyl moieties on valsartan could experience aerobic biotransformations. In turn, US action decreased the concentration of the four pharmaceuticals (removals > 60% for azithromycin, ciprofloxacin, and paracetamol), diminishing the environmental risk (RQ: 0.51 for the target pharmaceuticals mixture). Atomic charge analyses (based on the electronegativity equalization method) were performed, showing that the amino-sugar on azithromycin; piperazyl ring, and double bond close to the two carbonyls on ciprofloxacin, acetamide group on paracetamol, and the alkyl moieties bonded to the amide group of valsartan are the most susceptible moieties to attacks by sonogenerated radicals. The LC-MS/MS analytical methodology, RQ calculations, and theoretical analyses allowed for determining the degrading performance of BS and US toward the target pollutants in HWW.•Biological and sonochemical treatments as useful methods for degrading 4 representative pharmaceuticals are presented.•Sonochemical treatment had higher degrading action than the biological one on the target pharmaceuticals.•Methodologies for risk environmental calculation and identification of moieties on the pharmaceuticals susceptible to radical attacks are shown.

Versatility of Stenotrophomonas maltophilia: Ecological roles of RND efflux pumps

S. maltophilia is a widely distributed bacterium found in natural, anthropized and clinical environments. The genome of this opportunistic pathogen of environmental origin includes a large number of genes encoding RND efflux pumps independently of the clinical or environmental origin of the strains. These pumps have been historically associated with the uptake of antibiotics and clinically relevant molecules because they confer resistance to many antibiotics. However, considering the environmental origin of S. maltophilia, the ecological role of these pumps needs to be clarified. RND efflux systems are highly conserved within bacteria and encountered both in pathogenic and non-pathogenic species. Moreover, their evolutionary origin, conservation and multiple copies in bacterial genomes suggest a primordial role in cellular functions and environmental adaptation. This review is aimed at elucidating the ecological role of S. maltophilia RND efflux pumps in the environmental context and providing an exhaustive description of the environmental niches of S. maltophilia. By looking at the substrates and functions of the pumps, we propose different involvements and roles according to the adaptation of the bacterium to various niches. We highlight that i°) regulatory mechanisms and inducer molecules help to understand the conditions leading to their expression, and ii°) association and functional redundancy of RND pumps and other efflux systems demonstrate their complex role within S. maltophilia cells. These observations emphasize that RND efflux pumps play a role in the versatility of S. maltophilia.

The Source and Distribution of Tetracycline Antibiotics in China: A Review

In recent years, antibiotics have been listed as a new class of environmental pollutants. Tetracycline antibiotics (TCs) used in human medical treatment, animal husbandry and agricultural production are the most widely used antibiotics. Due to their wide range of activities and low cost, their annual consumption is increasing. TCs cannot be completely metabolized by humans and animals. They can be abused or overused, causing the continuous accumulation of TCs in the ecological environment and potential negative effects on non-target organisms. These TCs may spread into the food chain and pose a serious threat to human health and the ecology. Based on the Chinese environment, the residues of TCs in feces, sewage, sludge, soil and water were comprehensively summarized, as well as the potential transmission capacity of air. This paper collected the concentrations of TCs in different media in the Chinese environment, contributing to the collection of a TC pollutant database in China, and facilitating the monitoring and treatment of pollutants in the future.

The Antimicrobial Activity of Micron-Thin Sol-Gel Films Loaded with Linezolid and Cefoxitin for Local Prevention of Orthopedic Prosthesis-Related Infections

Orthopedic prosthesis-related infections (OPRI) are an essential health concern. OPRI prevention is a priority and a preferred option over dealing with poor prognosis and high-cost treatments. Micron-thin sol-gel films have been noted for a continuous and effective local delivery system. This study aimed to perform a comprehensive in vitro evaluation of a novel hybrid organic-inorganic sol-gel coating developed from a mixture of organopolysiloxanes and organophosphite and loaded with different concentrations of linezolid and/or cefoxitin. The kinetics of degradation and antibiotics release from the coatings were measured. The inhibition of biofilm formation of the coatings against Staphylococcus aureus, S. epidermidis, and Escherichia coli strains was studied, as well as the cell viability and proliferation of MC3T3-E1 osteoblasts. The microbiological assays demonstrated that sol-gel coatings inhibited the biofilm formation of the evaluated Staphylococcus species; however, no inhibition of the E. coli strain was achieved. A synergistic effect of the coating loaded with both antibiotics was observed against S. aureus. The cell studies showed that the sol-gels did not compromise cell viability and proliferation. In conclusion, these coatings represent an innovative therapeutic strategy with potential clinical use to prevent staphylococcal OPRI.

Anchoring black phosphorous quantum dots on Bi2WO6 porous hollow spheres: A novel 0D/3D S-scheme photocatalyst for efficient degradation of amoxicillin under visible light

Reasonable regulation of the micro-morphology of material can significantly enhance the related performance. Herein, bismuth tungstate (Bi₂WO₆, simplified as BWO) porous hollow spheres with flower-like surface were prepared successfully, and this unique morphology endowed BWO with improved photocatalytic performance by reflecting and absorbing the light multiple times inside the cavity. To inhibit the rapid recombination of photogenerated e^--h⁺ pairs within BWO itself, black phosphorous quantum dots (BPQDs) were anchored onto the nanosheets of BWO sphere closely by a facile self-assembly process, which will not shade the pores of BWO owing to the small size of BPQDs, but the BP nanosheets have the chance to do that. The band gap of BPQDs expanded much after exfoliation due to the quantum confinement effects, which matched the energy band of BWO well to form S-scheme heterojunction, achieving more efficient separation of photogenerated charges. As a result, the BPQDs/BWO exhibited attractive photocatalytic performance in the degradation of amoxicillin (AMX) and other antibiotics. Besides, the operation conditions were optimized, specifically, 94.5 % of AMX (20 mg/L, 200 mL) can be removed in 60 min when 50 mg of 2BPQDs/BWO was used as catalyst with solution pH = 11. Moreover, a possible degradation pathway of AMX was proposed based on the detected intermediates.