Occurrence of antibiotics in the aquatic environment

Treatment of simulated industrial pharmaceutical wastewater containing amoxicillin antibiotic via advanced oxidation processes

The treatment of pharmaceutical industrial wastewaters, containing the antibiotic amoxicillin (218.29 mg L^-1), via some advanced oxidation processes (POA), was studied. The H₂O₂ photolysis process presented the highest percentage of mineralization (97%), after the total reaction time (180 min). However, the photo-Fenton process showed the highest organic carbon removal rate, mineralizing 65% of the initial concentration, in 30 min. Because of this fact, this process was studied in more detail. The initial concentration of ferrous ions (0.03-1.00 mmol L^-1) did not affect the performance of the photo-Fenton process, possibly operating using concentrations of below 15 mg L^-1 (0.27 mmol L^-1), that is the iron content limit for discharging wastewaters established in the Brazilian environmental legislation. Furthermore, experiments were performed according to the composite experimental design technique (Doehlert matrix), analyzing the following variables: (i) the inlet molar flow rate of H₂O₂ (F_H2O2 ) and (ii) the initial concentration of ferrous ions ([Fe²⁺]). Besides that, the initial mineralization rate and the total organic carbon removal percentages, measured at 5, 10, 15 and 30 min of reaction, were chosen as the response variables. It was observed that F_H2O2 was the most important variable in relation to the initial degradation rate. In the optimal conditions (F_H2O2  = 3.27 mmol min^-1 and [Fe²⁺] = 0.27 mmol L^-1), the photo-Fenton process achieved a percentage of organic carbon removal of 84%, in only 30 min of reaction, presenting an interesting potential for real industrial applications, combined, or not, with conventional technologies (as biological treatments, for example).

First insight into the occurrence, spatial distribution, sources, and risks assessment of antibiotics in groundwater from major urban-rural settings of Pakistan

Antibiotics contamination in the water environment is a high priority global concern. Growing levels of antibiotics in freshwater resources, especially groundwater, due to anthropogenic sources such as pharmaceutical and veterinary applications, are alarming. The present study aims to investigate the occurrence, spatial distribution, source apportionment, ecological, and human health risks of antibiotics (n = 23) in groundwater samples (n = 144) of highly populated cities of Pakistan. The elevated level of antibiotics was detected in Faisalabad with the mean concentrations of 13.8 ng/L, followed by Gujrat (7.8 ng/L), Lahore (4.04 ng/L), Quetta 3.9 ng/L, Rawalpindi/Islamabad (2.29 ng/L), and Peshawar (2.03 ng/L), respectively. Out of 23 investigated antibiotics, tigecycline and ciprofloxacin were predominantly present in groundwater with average concentrations of 21.3 ng/L and 18.2 ng/L, respectively. The spatial distribution analyses revealed that among the targeted cities, Faisalabad, an industrial hub of the country, had the most polluted groundwater with dominant classes of antibiotics including quinolones (except flumequine), β-Lactams, tetracyclines, sulfonamides, and amphenicols, implying an elevated consumption of human and veterinary drugs in the city. The occurrence of targeted antibiotics varied greatly among cities (p < 0.05). PCA-MLR analysis confirmed domestic discharge (31%), animal husbandry (19%), and pharmaceutical/hospital discharge (48%) as the chief contributors to antibiotics contamination in groundwater of Faisalabad. The risk quotient (RQ) values of targeted antibiotics were reported as 1.16E-07 to 1.03E-02, and demonstrated that antibiotics pose no risks to human health, while hazard quotient (HQ) values were observed as 09.5E-05 to 6.6E-01, and only ciprofloxacin, flumequine, oxytetracycline, and sulfamethoxazole revealed moderate to low ecological risks to water species (0.1 < HQ < 1). Since, no detailed study has been conducted to evaluate the antibiotics' contamination in groundwater of Pakistan, this robust investigation provides a way forward to further explore the environmental and human health implications of antibiotics in major urban-rural settings in the region.

Molecularly Imprinted Polymers (MIPs) in Sensors for Environmental and Biomedical Applications: A Review

Molecular imprinted polymers are custom made materials with specific recognition sites for a target molecule. Their specificity and the variety of materials and physical shapes in which they can be fabricated make them ideal components for sensing platforms. Despite their excellent properties, MIP-based sensors have rarely left the academic laboratory environment. This work presents a comprehensive review of recent reports in the environmental and biomedical fields, with a focus on electrochemical and optical signaling mechanisms. The discussion aims to identify knowledge gaps that hinder the translation of MIP-based technology from research laboratories to commercialization.

Removal and transformation of sulfamethoxazole in acclimated biofilters with various operation modes - Implications for full-scale application

The knowledge gaps regarding the degradation of sulfamethoxazole (SMX) in biofilters include the effect of aeration, constant feeding with readily biodegradable organic carbon and the presence of reactive media such as manganese oxides (MnOx). Thus, the goal of this study was to assess the removal of SMX in lab-scale biofilters with various operation variables: aeration, presence of MnOx as an amendment of filtering medium and the presence of readily biodegradable organic carbon (acetate). The sand used in the experiment as a filtering medium was previously exposed to the presence of SMX and acetate, which provided acclimation of the biomass. The removal of SMX was complete (>99%) with the exception of the unaerated columns fed with the influent containing acetate, due to apparent slower rate of SMX degradation. The obtained results suggest that bacteria were able to degrade SMX as a primary substrate and the degradation of this compound was subsequent to the depletion of acetate. The LC-MS/MS analysis of the effluents indicated several biotransformation reactions for SMX: (di)hydroxylation, acetylation, nitrosation, deamonification, S-N bond cleavage and isoxazole-ring cleavage. The relative abundance of transformation products was decreased in the presence of MnOx or acetate. Based on the Microtox assay, only the effluents from the unaerated columns filled with MnOx were classified as non-toxic. The results offer important implications for the design of biofilters for the elimination of SMX, namely that biofilters offer the greatest performance when fed with secondary wastewater and operated as non-aerated systems with a filtering medium containing MnOx.

A Review on the Application of Zeolites and Mesoporous Silica Materials in the Removal of Non-Steroidal Anti-Inflammatory Drugs and Antibiotics from Water

Zeolites and mesoporous silica materials are effective adsorbents that can be useful for the removal of various pharmaceuticals including non-steroidal anti-inflammatory drugs and antibiotics from low-quality water. This paper summarizes the properties and basic characteristics of zeolites and mesoporous silica materials and reviews the recent studies on the efficacy of the adsorption of selected non-steroidal medicinal products and antibiotics by these adsorbents to assess the potential opportunities and challenges of using them in water treatment. It was found that the adsorption capacity of sorbents with high silica content is related to their surface hydrophobicity (hydrophilicity) and structural features, such as micropore volume and pore size, as well as the properties of the studied medicinal products. This review can be of help to scientists to develop an effective strategy for reducing the amount of these two groups of pharmaceuticals in wastewater.

Phytoextraction of ciprofloxacin and sulfamethoxaxole by cattail and switchgrass

Cattail (Typha latifolia L.) and switchgrass (Panicum virgatum L.) can effectively remove inorganic contaminants from soils and biosolids, but their role in the attenuation of organic contaminants, such as antimicrobials, is currently poorly understood. Uptake by plants is one of several mechanisms by which plant-assisted attenuation of antimicrobials can be achieved. The objectives of this growth room study were to evaluate the plant uptake of ciprofloxacin (CIP) and sulfamethoxazole (SMX) and examine their partitioning between plant roots and aboveground biomass (AGB). Plant uptake of the two ¹⁴C labeled antimicrobials was studied at two environmentally relevant concentrations (5 and 10 μg L^-1). Plants were destructively sampled every 3-4 d during the 21-d growth period. Accumulation of CIP and SMX in both plant species was greater in the roots than in the AGB. The percentage uptake values of the two antimicrobials were significantly greater for cattail (34% for CIP, 20% for SMX) than for switchgrass (10% for both CIP and SMX). Translocation factors of the two antimicrobials were <1 for both plants, indicating slow movement of the antimicrobials from the roots to the shoots. For cattail roots, the BCF for CIP (1.58 L g^-1) was significantly greater than that for SMX (0.8 L g^-1). By comparison, BCFs for switchgrass roots did not differ significantly between CIP (0.88 L g^-1) and SMX (1.13 L g^-1). These results indicate greater potential for cattail to phytoextract CIP and SMX and significantly contribute to the attenuation of these antimicrobials in systems designed for the phytoremediation of contaminated wastewater.

Molybdenum disulfide (MoS2): A novel activator of peracetic acid for the degradation of sulfonamide antibiotics

Sulfonamide antibiotics (SAs) are typical antibiotics and have attracted increasing concerns about their wide occurrence in environment as well as potential risk for human health. In this study, we applied a novel advanced oxidation process in SAs degradation by combining molybdenum sulfide and peracetic acid (MoS₂/PAA). Reactive oxygen species (ROS) including HO^●, CH₃C(O)O^●, CH₃C(O)OO^●, and ¹O₂ were generated from PAA by MoS₂ activation and contributed to SAs degradation. The effects of initial pH, the dosages of PAA and MoS₂, and humic acid for SAs degradation were further evaluated by selecting sulfamethoxazole (SMX) as a target SA in the MoS₂/PAA process. Results suggested that the optimum pH for SMX removal was 3, where the degradation efficiency of SMX was higher than 80% after reaction for 15 min. Increasing PAA (0.075-0.45 mM) or MoS₂ (0.1-0.4 g/L) dosages facilitated the SMX degradation, while the presence of humic acids retarded the SMX removal. This MoS₂/PAA process also showed good efficiencies in removing other SAs including sulfaguanidine, sulfamonomethoxine and sulfamerazine. Their possible degradation pathways were proposed based on the products identification and DFT calculation, showing that apart from the oxidation of amine groups to nitro groups in SAs, MoS₂/PAA induced SO₂ extrusion reaction for SAs that contained six-membered heterocyclic moieties.

Spread of antibiotic resistance genes and microbiota in airborne particulate matter, dust, and human airways in the urban hospital

Antimicrobial resistance is an increasingly serious threat to public health worldwide. The presence of antibiotic resistance genes (ARGs) in human airways and relevant environments has not received significant attention. In this study, abundances of ARGs and microbes from airborne particulate matter, dust, and human airways in a hospital were profiled using high-throughput qPCR and 16S rRNA gene sequencing. More diverse ARGs and microbes in indoor dust and higher levels of ARGs in particulate matter PM₁₀ and PM_2.5 were observed. Macrolides and aminoglycoside resistance genes were the most abundant ARGs in the airway and environmental samples, respectively. Moreover, the co-occurrences of priority pathogens, ARGs, and mobile genetic elements (MGEs) were shown by the Network analysis. Campylobacter spp. and Staphylococcus spp. positively correlated with fluoroquinolone (vatC-02, mexD) and β-lactams (blaZ, mecA) resistance genes, respectively. In this regard, based on SourceTracker analysis, inhalable particles contributed to 4.0% to 5.5% of ARGs in human airway samples, suggesting an important exchange between airborne inhalable particles and human commensals. This study may advance knowledge about ARGs in airborne particulate matter and dust associated environments, reveal their potential link between environments and humans, and provide a new sight and fundamental data for ARG risk assessment.

Occurrence and bioaccumulation of sulfonamide antibiotics in different fish species from Hangbu-Fengle River, Southeast China

As a class of synthetic sulfur drugs, sulfonamides (SAs) have been used to treat diseases and promote organism growth. Different concentrations of SAs have been detected in the water environment, which has threatened the ecological environment. In this study, the contamination of 9 SAs in water, sediments, and 8 fish species from the Hangbu-Fengle River, China, were analyzed using UPLC-MS/MS. The total SA concentrations in surface water, sediments, and fish were ND-5.064 ng/L, ND-5.052 ng/g dry weight (d.w.), and ND-1.42 ng/g wet weight (w.w.), respectively. The major compounds were sulfadiazine (SDZ), sulfamerazine (SMZ), and sulfamethoxazole (SMX) in water and fish. The SA levels of in fish from different habitat preferences revealed a spatial difference, with the order of demersal species > pelagic species. Moreover, the SA concentrations were affected by trophic guilds, indicating their decrease in the order of piscivorous fish > omnivorous fish > planktivorous fish > herbivorous fish. The obtained bioaccumulation factors showed that SMZ and SMX have strong bioenrichments in Ophiocephalus argus Cantor and Pelteobagrus fulvidraco. The risk assessment indicated that SAs did not pose significant health threats to the organisms. This research is the first report of SA contamination in the Hangbu-Fenle River, which can provide an important scientific basis for their pollution prevention and ecological risk assessment in the aquatic environment.

Identification of Antibiotics in Surface-Groundwater. A Tool towards the Ecopharmacovigilance Approach: A Portuguese Case-Study

Environmental monitoring, particularly of water, is crucial to screen and preselect potential hazardous substances for policy guidance and risk minimisation strategies. In Portugal, extensive data are missing. This work aimed to perform a qualitative survey of antibiotics in surface- groundwater, reflecting demographic, spatial, consumption and drug profiles during an observational period of three years. A passive sampling technique (POCIS) and high-resolution chromatographic system were used to monitor and analyse the antibiotics. The most frequently detected antibiotics were enrofloxacin/ciprofloxacin and tetracycline in surface-groundwater, while clarithromycin/erythromycin and sulfamethoxazole were identified only in surface water. The detection of enzyme inhibitors (e.g., tazobactam/cilastatin) used exclusively in hospitals and abacavir, a specific human medicine was also noteworthy. North (Guimarães, Santo Tirso and Porto) and South (Faro, Olhão and Portimão) Portugal were the regions with the most significant frequency of substances in surface water. The relatively higher detection downstream of the effluent discharge points compared with a low detection upstream could be attributed to a low efficiency in urban wastewater treatment plants and an increased agricultural pressure. This screening approach is essential to identify substances in order to perform future quantitative risk assessment and establishing water quality standards. The greatest challenge of this survey data is to promote an ecopharmacovigilance framework, implement measures to avoid misuse/overuse of antibiotics and slow down emission and antibiotic resistance.

Petrel Probe: An Integrated In Situ Sampling and Injection Interface for Fast, High-Efficiency Liquid Chromatography-Mass Spectrometry Analysis

Herein, we describe an in situ analysis probe, Petrel probe, highly integrating multiple functions of in situ sampling, in situ sample injection, high-performance liquid chromatography (HPLC) separation, and mass spectrometry (MS) electrospray. The Petrel probe was fabricated based on a single capillary, which consists of a micrometer-sized hole for sampling, a packed column for LC separation, and a tapered tip for MS electrospray. The design of the Petrel probe was optimized to obtain higher structural strength, and a polytetrafluoroethylene (PTFE) chip was used for sealing the probe-sampling hole to meet the high-pressure (∼30 MPa) requirement of LC manifold. On the basis of the Petrel probe, we developed a novel valveless LC injection method, that is, the probe pressing microamount in situ (PPMI) injection method, which performs sample injection by pressing the probe-sampling hole on the PTFE chip, using the mobile phase to dissolve the sample dry spot in the sampling area on the chip, and injecting it into the LC column under high-pressure conditions for separation and subsequent MS analysis. The LC-MS system with the PPMI injection method exhibits rapid injection and separation speed, as well as minimum injection dead volume. It can yield a high separation efficiency comparable to those of conventional HPLC systems. The present system was optimized using standard peptide samples, and four peptides were separated within 11 min in a probe with an effective column length of 5 cm, achieving the highest theoretical plate number up to ∼5,500,000/m. The system was also applied in the separation of cytochrome C digest to demonstrate its separation ability for complex samples, and 21 peptides were detected in 8 min with an amino-acid coverage of 83%.

Sample preparation optimization by central composite design for multi class determination of 172 emerging contaminants in wastewaters and tap water using liquid chromatography high-resolution mass spectrometry

Multi-residue analysis is highly desirable for water quality control. To this end, a comprehensive workflow for the quantitative analysis of 172 anthropogenic organic compounds belonging to emerging contaminants (pharmaceuticals and personal care products, illicit drugs, organophosphate flame retardants and perfluoroalkyl substances) has been developed for application to wastewater and tap water, based on solid phase extraction (SPE) and Orbitrap high resolution mass spectrometry (HRMS). Due to the large number of analytes with various physicochemical characteristics that should be efficiently extracted, the response surface methodology (RSM) employing a central composite design (CCD) and desirability function (DF) approach was exploited to optimize the sample preparation process, instead of the conventional single-factor analysis. The factors included in the design of experiments (DoE) were sample pH, eluent solvents composition and volume. Statistical analysis (ANOVA) proved the adequacy of the proposed model (2- factor interaction) as p-value < 0.05 followed by different diagnostic tests confirmed the good fitting. The best values to acquire DF close to 1 were pH 3.5, methanol/ethyl acetate ratio 87:13 and eluent volume 6 mL. The streamlined method was validated in terms of accuracy, linearity, method limits, reproducibility, and matrix effect. The proposed workflow combines sensitivity and robustness, with recoveries over 70%, method quantification limits <1 ng/L, and relative standard deviations <20% for most of the compounds. Slight matrix effect (ME) was observed for most of PPCPs, IDs and PFAs, in contrast with most of the OPFRs, for which strong ME was calculated. Method applicability was tested over wastewater collected from a municipal wastewater treatment plant in Thessaloniki (Greece), revealing the presence of 69 and 40 compounds in influents and effluents, respectively, at varying concentrations.

Recent trends in advanced oxidation process-based degradation of erythromycin: Pollution status, eco-toxicity and degradation mechanism in aquatic ecosystems

Wide spread documentation of antibiotic pollution is becoming a threat to aquatic environment. Erythromycin (ERY), a macrolide belonging antibiotic is at the top of this list with its concentrations ranging between ng/L to a few μg/L in various global waterbodies giving rise to ERY-resistance genes (ERY-RGs) and ERY- resistance bacteria (ERY-RBs) posing serious threat to the aquatic organisms. ERY seems resistant to various conventional water treatments, remained intact and even increased in terms of mass loads after treatment. Enhanced oxidation potential, wide pH range, elevated selectivity, adaptability and greater efficiency makes advance oxidation processes (AOPs) top priority for degrading pollutants with aromatic rings and unsaturated bonds like ERY. In this manuscript, recent developments in AOPs for ERY degradation are reported along with the factors that affect the degradation mechanism. ERY, marked as a risk prioritized macrolide antibiotic by 2015 released European Union watch list, most probably due to its protein inhibition capability considered third most widely used antibiotic. The current review provides a complete ERY overview including the environmental entry sources, concentration in global waters, ERY status in STPs, as well as factors affecting their functionality. Along with that this study presents complete outlook regarding ERY-RGs and provides an in depth detail regarding ERY's potential threats to aquatic biota. This study helps in figuring out the best possible strategy to tackle antibiotic pollution keeping ERY as a model antibiotic because of extreme toxicity records.

Occurrence and fate of antibiotics and heavy metals in sewage treatment plants and risk assessment of reclaimed water in Chengdu, China

Aim of this study was to provide an up-to-date assessment of the heavy metals and antibiotics in reclaimed water in Chengdu, China. 3 sewage treatment plants (STPs) and 1 constructed wetland (CW) were first taken as the research objects. The total concentration and reduction change rule of heavy metals and antibiotics in the process of reclaimed water production were investigated. The possible health risks to ecological environment and human body were evaluated. For the treatment process, the Cyclic Activated Sludge System (CASS) used in A sewage treatment plant (STP A) had the best removal effect for heavy metals. When the proportion of industrial wastewater in the influent was relatively high, the heavy metal pollution level was alert. Ofloxacin (OFX) and roxithromycin (ROX) were the most abundant antibiotics in reclaimed water. After being removed by the sewage treatment system, OFX concentrations changed, but several of them remained in reclaimed water. Negative removal of ROX occurred. This is because macrolides were wrapped in human feces, whose concentration increased as feces disperse and hydrolyze. Compared with CASS (20.02%) and Anaerobic-Anoxic-Oxic process (A²/O 34.16%), the average removal rate of antibiotics from the A²/O accompanied by Membrane Bio-Reactor (71.1%) and CW (54.95%) was higher. When the proportion of domestic sewage in wastewater was high, antibiotics in reclaimed water had higher ecological risk. OFX had the highest ecological risk for non-target aquatic organisms. It was assessed that the heavy metals and antibiotics studied did not pose a carcinogenic or non-carcinogenic risk to human health.

Chemical and toxicological evaluation along with unprecedented transformation products during photolysis and heterogeneous photocatalysis of chloramphenicol in different aqueous matrices

As the presence of antibiotics in environmental waters enhances antimicrobial resistance, photolysis and heterogeneous photocatalysis of chloramphenicol (CAP) were evaluated in deionized water (DW) and in sewage treatment plant (STP) effluent under black light and solar irradiation. Processes were compared in terms of CAP degradation, reaction kinetics, and electrical energy per order, as well as regarding theoretical toxicity, biodegradability, carcinogenicity, and mutagenicity of transformation products (TPs). Rate constants obtained under photolysis (0.008 min^-1) and heterogeneous photocatalysis (0.18 min^-1) only differed in DW. This is due to the generation of photo-active reactive oxygen species (HO^· and HO₂^·-/O₂^·-) under photolysis in STP effluent, as verified by experiments in the presence of 2-propanol and chloroform. Natural organic matter and HCO₃^- were the main responsible for reducing CAP degradation in STP effluent. Fifteen TPs were identified during both processes in DW, 13 of which are unprecedented. TPs were formed mainly via HO^· preferential attack on the aromatic ring and on the α-carbon, and some of them were classified as persistent and toxic, genotoxic, or carcinogenic by Toxtree software. Results confirm that solar photocatalysis is less costly than to photocatalysis under black light for wastewater treatment.

Residues of selected sulfonamides, non-steroidal anti-inflammatory drugs and analgesics-antipyretics in surface water of the Elbe river basin (Czech Republic)

The occurrence of human as well as veterinary drug residues in surface water is caused by their insufficient removal ability from wastewater. Drug residues disturb the natural balance of water ecosystem, have a negative effect on non-target organisms and pose a significant risk for human health. The main aim of this study was to determine the concentration of residues of eight drugs from the group of sulfonamides (sulfathiazole, sulfadiazine, sulfamethazine, sulfamethoxazole, sulfadimethoxine, sulfadoxine, sulfamerazine, sulfachlorpyridazine), four drugs from the non-steroidal anti-inflammatory drug group (ibuprofen, ketoprofen, naproxen, diclofenac) and one representative of the analgesics-antipyretics group [paracetamol (acetaminophen)] in the surface water of the Elbe river basin. A total of 65 samples of surface water from the Elbe river basin were taken during August 2018 when the weather was constant without any significant fluctuations. The analysis was performed by means of liquid chromatography with tandem mass spectrometry (LC-MS/MS). The results have shown the numerous occurrences of sulfamethoxazole, ibuprofen, naproxen, diclofenac and paracetamol (acetaminophen). A statistically significant negative correlation between the river flow rate in the monitored locations and the residue concentration was found for ibuprofen, naproxen, diclofenac and paracetamol (acetaminophen). The most significant findings of the monitored drug residues were mostly determined in samples from small streams below larger urban settlements with a hospital or other health facilities.

Pharmaceutical effluent: a critical link in the interconnected ecosystem promoting antimicrobial resistance

Antimicrobial resistance (AMR) is a complex global health issue and will push twenty-four million people into extreme poverty by 2030, risking the sustainable development goals (SDGs) 2, 3, 6, 9, 12, and 17 if not addressed immediately. Humans, animals, and the environment are the reservoirs that contribute and allow AMR to propagate in interconnected ecosystems. The emergence of antibiotic-resistant bacteria and antibiotic-resistant genes in the water environment has become an important environmental health issue. One of the major influencers from environment sector is the pharmaceutical industry which is growing globally to meet the ever-increasing demand of antibiotics, especially in low- and middle-income countries. The pharmaceutical effluent has a mix of large concentrations of antibiotics and antibiotic resistance genes, and these sites act as hotspots for environmental contamination and the spread of AMR. Inadequate treatment of the effluent and its irresponsible disposal leads to unprecedented antibiotic contamination in the environment and their persistent presence in the environment significantly modulates the bacterial genomes' expression that is responsible for increase and spread of AMR. However, not much interventions are suggested in the National Action Plan developed on AMR by many countries. There are no regulations across the globe till date for the level of antibiotic residues in pharmaceutical effluent for the growing pharmaceutical industry. This review put together the work done showing several detrimental effects of the antimicrobial residues in the pharmaceutical effluent which leads to rise in development of AMR. The environment risk approach and need to have indicators to measure environment risk is a way forward for all countries engage in antibiotic manufacturing. Overall, efforts to address the problem are isolated and fragmented. Policymakers, regulators, manufacturers, researchers, civil society, and the community need to collaborate so that antibiotics are produced sustainably and continue to stay effective in treating bacterial infections.

Stereoselective Bacterial Metabolism of Antibiotics in Environmental Bacteria - A Novel Biochemical Workflow

Although molecular genetic approaches have greatly increased our understanding of the evolution and spread of antibiotic resistance genes, there are fewer studies on the dynamics of antibiotic - bacterial (A-B) interactions, especially with respect to stereochemistry. Addressing this knowledge gap requires an interdisciplinary synthesis, and the development of sensitive and selective analytical tools. Here we describe SAM (stereoselective antimicrobial metabolism) workflow, a novel interdisciplinary approach for assessing bacterial resistance mechanisms in the context of A-B interactions that utilise a combination of whole genome sequencing and mass spectrometry. Chloramphenicol was used to provide proof-of-concept to demonstrate the importance of stereoselective metabolism by resistant environmental bacteria. Our data shows that chloramphenicol can be stereoselectively transformed via microbial metabolism with R,R-(-)-CAP being subject to extensive metabolic transformation by an environmental bacterial strain. In contrast S,S-(+)-CAP is not metabolised by this bacterial strain, possibly due to the lack of previous exposure to this isomer in the absence of historical selective pressure to evolve metabolic capacity.

Preparation and characterization of DNA aptamers against roxithromycin

Roxithromycin is a broad-spectrum antibiotic widely used in human and livestock. It is continually released and accumulated in our natural environment. It exhibited an extreme resistance to microbial biodegradation and has a serious impact on ecosystem and human health. It is in urgent need of establishing a rapid and efficient method for the detection of environmental roxithromycin. This study was based on capture-SELEX to select aptamers against roxithromycin from an initial library containing randomized ssDNA sequences. Candidate aptamers were obtained by 16 rounds of capture-SELEX process. Competent clones were prepared for sequencing. Clone Ap01 was chosen for further characterization. SYBR Green I fluorescence assays showed high affinity with roxithromycin. The dissociation constant of Ap01 was 0.46 ± 0.08 μM. Ap01 bound specifically to roxithromycin with capable of distinguish from non-roxithromycin macrolides. There was no cross reaction with the detected non-macrolide compounds. Accordingly, a colorimetric aptasensor has been developed. It has been demonstrated that the detection limit achieved 0.077 μM. To proof the concept, detections of roxithromycin contained in tap water and lake water were evaluated. It laid a foundation for further study on the detection of roxithromycin in actual aquatic environments.

Occurrence, Distribution, and Ecological Risk Assessment of Antibiotics in Selected Urban Lakes of Hanoi, Vietnam

Residue concentrations of fifteen antibiotics including sulfonamides, quinolones, macrolides, β-lactams, and trimethoprim in lakes from Hanoi metropolitan area, Vietnam, were analyzed using ultra-performance liquid chromatography coupled with tandem mass spectrometry (UPLC/MS-MS) to elucidate their occurrence and behavior in urban environment. For surface water, the average concentrations of five antibiotic classes decreased in the order: sulfonamides (117.9 ng/L) > β-lactams (31.28 ng/L) > quinolones (20.19 ng/L) > macrolides (17.74 ng/L) > trimethoprim (8.93 ng/L). While the highest concentration of SMX was detected at 806.5 ng/L in surface water, those obtained in sediment were only at 1.35 ng/g because of their high solubility in water. Quinolones were found at a maximal concentration of 158.7 ng/L for OFL in water phase whereas those in sediment phase were 4,017 ng/g due to their great affinity in sediment. These findings revealed the different fate and release mechanisms of each antibiotic group in the environment. The ecological risk assessment implied some targeted compounds, and in particular, OFL and AZM could pose high risks to algae in the aquatic ecosystem.

The Role of Aquatic Ecosystems (River Tua, Portugal) as Reservoirs of Multidrug-Resistant Aeromonas spp

The inappropriate use of antibiotics, one of the causes of the high incidence of antimicrobial-resistant bacteria isolated from aquatic ecosystems, represents a risk for aquatic organisms and the welfare of humans. This study aimed to determine the antimicrobial resistance rates among riverine Aeromonas spp., taken as representative of the autochthonous microbiota, to evaluate the level of antibacterial resistance in the Tua River (Douro basin). The prevalence and degree of antibiotic resistance was examined using motile aeromonads as a potential indicator of antimicrobial susceptibility for the aquatic environment. Water samples were collected from the middle sector of the river, which is most impacted area by several anthropogenic pressures. Water samples were plated on an Aeromonas-selective agar, with and without antibiotics. The activity of 19 antibiotics was studied against 30 isolates of Aeromonas spp. using the standard agar dilution susceptibility test. Antibiotic resistance rates were fosfomycin (FOS) 83.33%, nalidixic acid (NA) 60%, cefotaxime (CTX) 40%, gentamicin (CN) 26.67%, tobramycin (TOB) 26.67%, cotrimoxazole (SXT) 26.67%, chloramphenicol (C) 16.67%, and tetracycline (TE) 13.33%. Some of the nalidixic acid-resistant strains were susceptible to fluoroquinolones. Multiple resistance was also observed (83.33%). The environmental ubiquity, the natural susceptibility to antimicrobials and the zoonotic potential of Aeromonas spp. make them optimal candidates for studying antimicrobial resistance (AMR) in aquatic ecosystems. Aquatic environments may provide an ideal setting for the acquisition and dissemination of antibiotic resistance because anthropogenic activities frequently impact them. The potential risk of multi- and pan-resistant bacteria transmission between animals and humans should be considered in a “One Health—One World” concept.

Visible-light harvesting innovative W6+/Yb3+/TiO2 materials as a green methodology photocatalyst for the photodegradation of pharmaceutical pollutants

In this work, we report on the synthesis of a new-age reusable visible-light photocatalyst using a heterojunction nanocomposite of W⁶⁺/Yb³⁺ on a mixed-phase mesoporous network of monolithic TiO₂. The structural properties of the monolithic photocatalysts are characterized using p-XRD, SEM-EDAX, TEM-SAED, XPS, PLS, UV-Vis-DRS, FT-IR, micro-Raman, TG-DTA, and N₂ isotherm analysis. The electron microscopic analysis reveals a mesoporous network of ordered worm-like monolithic design, with a polycrystalline mixed-phase (anatase/rutile) TiO₂ composite, as indicated by diffraction studies. The UV-Vis-DRS analysis reveals a redshift in the light absorption characteristics of the mixed-phase TiO₂ monolith as a function of W⁶⁺/Yb³⁺ co-doping. It is observed that the use of (8.0 mol%)W⁶⁺/0.4 (mole%)Yb³⁺ co-doped monolithic TiO₂ photocatalyst, with an energy bandgap of 2.77 eV demonstrates superior visible-light photocatalysis, which corroborates with the PLS studies in terms of voluminous e^-/h⁺ pair formation. The practical application of the photocatalyst has been investigated through a time-dependent dissipation of enrofloxacin, a widely employed antimicrobial drug, and its degradation pathway has been monitored by LC-MS-ESI and TOC analysis. The impact of physio-chemical parameters such as solution pH, sensitizers, drug concentration, dopant/codopant stoichiometry, catalyst quantity, and light intensity has been comprehensively studied to monitor the process efficiency.

Hydrometeorological Influence on Antibiotic-Resistance Genes (ARGs) and Bacterial Community at a Recreational Beach in Korea

We investigated the occurrence and distribution of antibiotic-resistance genes (ARGs) and the composition of a bacterial community under conditions of rainfall on a recreational beach in Korea. Seawater samples, collected every 1‒5 hours in June 2018 and May 2019, were analyzed using quantitative real-time polymerase chain reaction and next-generation sequencing. We found a substantial influence of rainfall and tidal levels on the relative abundance of total ARGs and bacterial operational taxonomic units (OTUs), which showed 1.9 × 10³ and 1.1 × 10¹ fold increases, respectively. In particular, the elevated levels of ARGs were maintained for up to 32 hours after rainfall. An increased abundance of sewage-related ARGs and bacterial OTUs suggested that combined sewer overflow (CSO) may be the major factor contributing to the increase in the number and diversity of ARGs and related bacterial communities. Network analysis of ARGs and OTUs indicated that, at the genus level, Acinetobacter, Pseudomonas, and Prevotella were the main potential pathogens carrying the observed ARGs in the recreational seawater. Overall, these findings highlight the potential threat to public health on beaches, and indicate the requirement for more adequate monitoring, with greater efforts to mitigate the propagation of ARGs arising from CSOs.

Perspectives on the antibiotic contamination, resistance, metabolomics, and systemic remediation

Antibiotics have been regarded as the emerging contaminants because of their massive use in humans and veterinary medicines and their persistence in the environment. The global concern of antibiotic contamination to different environmental matrices and the emergence of antibiotic resistance has posed a severe impact on the environment. Different mass-spectrometry-based techniques confirm their presence in the environment. Antibiotics are released into the environment through the wastewater steams and runoff from land application of manure. The microorganisms get exposed to the antibiotics resulting in the development of antimicrobial resistance. Consistent release of the antibiotics, even in trace amount into the soil and water ecosystem, is the major concern because the antibiotics can lead to multi-resistance in bacteria which can cause hazardous effects on agriculture, aquaculture, human, and livestock. A better understanding of the correlation between the antibiotic use and occurrence of antibiotic resistance can help in the development of policies to promote the judicious use of antibiotics. The present review puts a light on the remediation, transportation, uptake, and antibiotic resistance in the environment along with a novel approach of creating a database for systemic remediation, and metabolomics for the cleaner and safer environment.

Quaternary enteric solid dispersion prepared by hot-melt extrusion to mask the bitter taste and enhance drug stability

To mask the bitterness of drug is profoundly important especially in children's medication. This study designed and investigated a quaternary enteric solid dispersion (QESD) by secondary hot-melt-extrusion. Erythromycin (EM) was chosen as a model drug. The optimal QESD contained enteric polymer HPMCP-55, plasticizer and water-soluble polymer copovidone VA64. Raman and Atomic force microscope has exploited that majority EM was distributed in VA64 matrix, nanometer-sized EM-VA64 system was entrapped within enteric continuous phase to form a solid emulsion-like structure. For the prepared QESD, EM released concentration was far less than bitterness threshold (7 μg/mL to 20 μg/mL) in artificial saliva within the first 30 s. And dissolution rate was increased by 10% in article intestine fluid, which dominated by water-soluble VA64. Stress testing after two months at high-humidity (75% RH) and high-temperature (60 °C) revealed, compared with traditional enteric SDs, the chemical degradation of EM was slowed down in QESD. Furthermore, hydrogen and salt bonds were respectively formed between EM and VA64 and between leaking EM and HPMCP-55, which increasing the system stability and taste-masking. The effect of masking bitter taste can be satisfied as well as enhance drug dissolution rate in the intestine, and formulation physicochemical stability during storage.

Emerging contaminants in the water bodies of the Middle East and North Africa (MENA): A critical review

Many emerging contaminants (ECs) are not currently removed by conventional water treatment methods and consequently, often reach the aquatic environment. In the absence of proper management strategies, ECs can accumulate in water bodies, which poses potential environmental and health risks. This paper critically reviews, for the first time, the reported occurrence and treatment of ECs in the Middle Eastern and North Africa (MENA) region. The paper also provides recommendations to properly manage EC risks. In the MENA region, pharmaceuticals and personal care products (PPCPs) have been detected in surface water, seawater, groundwater, and wastewater treatment plants. A focus on surface water in the published literature suggests that studies are skewed towards worldwide trends, whereas studies on ECs in seawater are of great importance in the study region. The types of PPCPs detected in the MENA region vary, but anti-inflammatories and antibiotics dominate. In comparison, microplastics have mainly been studied in surface waters and seawater with much less focus on drinking water. The majority of microplastics in the region are secondary types resulting from the degradation of larger plastic debris; polyethylene (PE) and polypropylene (PP) fibers are the most frequently detected polymers, which are indicative of local anthropogenic sources. Research progress on ECs varies between countries, having received more attention in Iran and Tunisia. Most MENA countries have now begun monitoring water bodies for ECs; however, studies are still lacking in some countries including Sudan, Djibouti, Syria, Ethiopia, and Bahrain. Based on this review, critical knowledge gaps and research needs are identified. Countries in the MENA region require further research on a broader range of EC types. Overall, water pollution due to the use and release of ECs can be tackled by improving public awareness, public campaigns, government intervention, and advanced monitoring and treatment methods.

Statistical approach reveals tidal effect on the antibiotics and environmental relationship with the case study of Yongjiang Estuary, China

We used statistical approach by coupling redundancy analysis with linear regression analysis, which is useful to understand potential sources of antibiotics in the tide rising and ebbing of surface water in the Yongjiang Estuary, China. This study aimed to investigate the relationship between 29 antibiotics at five sites over four seasons and 13 environmental parameters during the tide rising and ebbing durations. The results found that dissolved organic carbon (DOC), salinity, temperature and chlorophyll a (Chla) were the main factors to impact antibiotics. The concentrations of macrolides were increasing with DOC, suggesting DOC may influence the adsorption capacity of antibiotics. The concentrations of tetracyclines had significant correlation with temperature and Chla during the tide rising period. This study demonstrated a method of exploring the relationship between the concentrations of antibiotics and environmental parameters, which is beneficial to future antibiotics research in estuaries.

Occurrence, fate, and risk assessment of typical tetracycline antibiotics in the aquatic environment: A review

Tetracyclines (TCs), used as human and veterinary medicines, are the most widely used antibiotics. More than 75% of TCs are excreted in an active form and released into the environment through human and animal urine and feces, causing adverse effects on the ecological system and human health. Few articles review the environmental occurrence and behaviors of TCs, as well as their risks and toxicities. Here, we comprehensively summarized the recent advances on the following important issues: (1) Environmental occurrence of TCs. TCs are used globally and their occurrence in the aquatic environment has been documented, including surface water, groundwater, drinking water, wastewater, sediment, and sludge. (2) Environmental behaviors of TCs, particularly the fate of TCs in wastewater treatment plants (WWTPs). Most WWTPs cannot effectively remove TCs from wastewater, so alternative methods for efficient removal of TCs need to be developed. The latest degradation methods of TCs are summarized, including adsorption, photocatalytic, photochemical and electrochemical, and biological degradations. (3) Toxicities and possible risks of TCs. The toxicological data of TCs indicate that several TCs are more toxic to algae than fish and daphnia. Risk assessments based on individual compound exposure indicate that the risks arising from the current concentrations of TCs in the aquatic environment cannot be ignored.

Determination of antimicrobial concentration and associated risk in water sources in West Bengal state of India

The presence of antimicrobials in wastewater (WW), surface water (SW), groundwater (GW), and even in potable water from treatment plants has been reported from many countries. Their presence in the water sources is causing the rise and spread of antimicrobial resistance (AMR), thereby threatening our public health, global economy, and development. This necessitates the constant monitoring of these compounds along with the evaluation of their associated risk to aquatic organisms. In this study, GW, WW, and SW samples from different parts of West Bengal (India) were analyzed using the SPE-HPLC-DAD method for detecting two frequently used fluoroquinolones (ciprofloxacin, CIP and ofloxacin, OFL). The highest concentration of CIP and OFL was 5.75 μg/L (GW) and 17.84 μg/L (WW), respectively. The antimicrobial activity was determined against Escherichia coli and Staphylococcus aureus isolates from WW against CIP, which showed that Escherichia coli and Staphylococcus aureus had developed ~ 69 and ~ 12 times resistance compared to their respective pure strains. The risk assessment showed that CIP poses an insignificant threat to fish and Daphnia (RQ < 1) but a significant threat to green algae and Microcystis aeruginosa (RQ> > 1). OFL concentration also poses a great threat to all the organisms for which the assessment was made (RQ> > 1). Moreover, risk assessment in terms of AMR showed that the present level of these antimicrobials in different water sources could cause the development of resistance among the microbial community (RQ > 1). These results emphasize the need for constant monitoring of pharmaceutical compounds, especially antimicrobials, to be kept under check.

Erythromycin in the aquatic environment: deleterious effects on the initial development of zebrafish

Due to the large volume of erythromycin continuously reaching waterbodies and its high persistence, this antibiotic drug has been detected in the aquatic environment at elevated concentrations. Although the problem of the presence of erythromycin in the environment is evident due to its influence in development of antimicrobial resistance, the toxicological consequences on non-target organisms remain to be determined. There are no apparent data on the impact of environmentally relevant concentrations of erythromycin on developing fish. Data on toxic effects during development are essential for evaluation of environmental risk to organisms. Therefore, the aim of this study was to investigate the effects of exposure to erythromycin on certain parameters including hatchability, survival rate, heart rate, and behavior in developing zebrafish. Zebrafish were exposed to a range of environmentally relevant concentrations of antibiotic (0.001, 0.01, 0.1, 1 μg/L) and one concentration 10-fold higher (10 μg/L). Exposure to erythromycin at 0.1 μg/L delayed hatching and decreased survival rate. Exposure to all tested concentrations increased heart rate. Further, exposure to erythromycin at 1 or 10 μg/L enhanced swimming activity. Our results indicated that erythromycin present in the aquatic environment might lead to disabling consequences in developing fish organisms and subsequently may result in ecological imbalance in the natural environment.

Development of an electrochemical sensor based on a cobalt oxide/tin oxide composite for determination of antibiotic drug ornidazole

A schematic illustration of the electrochemical performance towards sensing of ODZ at the Co₃O₄/SnO₂/GCE.

Preliminary assessment of antimicrobial activity and acute toxicity of norfloxacin chlorination by-product mixture

Among drugs and personal care products, antibiotics arouse interest since they are widely used in human and veterinary medicine and can lead to the development of bacterial resistance. Usually, sewage treatment does not remove most of these compounds. So, these drugs can reach water treatment plants (WTP), where disinfection with chlorine compounds is common. This work aimed to evaluate the antimicrobial activity and preliminary toxicity of the mix of by-products forming due to the chlorination of norfloxacin. This is a fluoroquinolone antibiotic indicated for the treatment of urinary infection and gonorrhea, with sodium hypochlorite (NaClO). The drug was subjected to chlorination tests, on a bench scale, with several reaction times (from 5 min to 24 h). Analyses of high-resolution mass spectrometry (MS) were performed for the characterization of the by-products. The MS results showed five peaks attributed to the by-products' formation, of which four were identified. The antibiogram results indicated that the solution that contained the mixture of the by-products lost antibacterial activity against the E. coli strain studied. The acute toxicity tests for the Artemia salina microcrustacean showed that the blend of the by-products exhibited higher toxicity than pure norfloxacin.

Indirect photodegradation of sulfathiazole and sulfamerazine: Influence of the CDOM components and seawater factors (salinity, pH, nitrate and bicarbonate)

Sulfonamides (SAs) are ubiquitous antibiotics that are increasingly detected in the aquatic environment, and may cause potential harm to the environment and humans. Indirect photodegradation has been considered to be a promising natural degradation process for antibiotics in the environment. Chromophoric dissolved organic matter (CDOM) is an important participant in the indirect photodegradation of antibiotics. Indirect photodegradation of sulfathiazole (ST) and sulfamerazine (SM) were studied in the presence of CDOM and marine factors (salinity, pH, nitrate (NO₃^-) and bicarbonate (HCO₃^-)) to simulate photodegradation of these compounds in the coastal seawater environment. The main findings are as follows. First, the indirect photodegradation rates of ST and SM in the presence of CDOM were significantly increased and followed the pseudofirst order kinetics. Second, ¹O₂ played a critical role in the indirect photodegradation of ST and its contribution rate was 54.2%; ³CDOM^⁎ performed similarly in the case of SM with a 58.0% contribution rate. Third, CDOM was divided into four fluorescent components by excitation-emission matrix spectroscopy and parallel factor analysis (EEMs-PARAFAC), including three exogenous components and an autochthonous component. The exogenous components with high molecular weight and higher number of aromatic groups played a decisive role in the indirect photodegradation of ST and SM due to their ability to generate higher levels of reactive intermediates (RIs). Finally, seawater factors (salinity, pH, NO₃^- and HCO₃^-) influenced the indirect photodegradation of ST and SM by influencing the steady-state concentrations of RIs. This report is the first study of indirect photodegradation of ST and SM from the perspective of the CDOM components and simulated coastal waters.

Occurrence of organic micropollutants in an urbanized sub-basin and ecological risk assessment

The João Mendes River - an important contributor to the Piratininga/Itaipu lagoon system in Rio de Janeiro State, Brazil - receives untreated sewage from the population occupying the drainage basin with no proper sanitation infrastructure. The present study assessed the ecological risk resulting from the presence of five organic micropollutants (17α-ethynylestradiol, ibuprofen, trimethoprim, sulfamethoxazole, bisphenol A) based on four monitoring campaigns which included three sampling points and one reference area. Chronic ecotoxicity assays were conducted with the bioindicators R. subcapitata, C. dubia and O. niloticus. Estrogenicity was assessed with genetically modified S. cerevisiae based on YES protocol. The Ecological Risk Assessment was conducted based on the Chemical and the Ecotoxicological Lines of Evidence (LoE). In order to analyse the results from different sampling points, principal component analysis (PCA) was performed using a correlation matrix. Micropollutants below limit of detection or in very low concentrations were detected in the reference area; no significant differences were observed when samples from the reference area were compared to the negative controls for the ecotoxicity assays. A PCA including selected variables revealed the latent relationships among the three sampling points (not verified for the reference area), which confirmed the analytical results. An extreme ecological risk index was estimated for all sampling points in all campaigns. The extreme ecological risk index was mostly associated to the high concentrations of 17α-ethynylestradiol and the antibiotic sulfamethoxazole.

Investigating the impact of hospital antibiotic usage on aquatic environment and aquaculture systems: A molecular study of quinolone resistance in Escherichia coli

Quinolones are one of the most important classes of antibacterials available for the treatment of infectious diseases in humans. However, there is a growing concern about bacterial resistance to antimicrobials including quinolones. The spread of antibiotic-resistant bacteria in the aquatic environment has been recognized as a growing threat to public health and hospitals appear to be a major contributor to this. The objective of this study was to investigate the prevalence of quinolone resistance in Escherichia coli from selected water bodies receiving direct hospital effluents in Kerala, India. Standard disc diffusion and E-test were used for antibiotic susceptibility testing. As antibiotic resistance can develop in bacterial isolates by different means, EtBr Agar Cartwheel method was used to detect the efflux pump activity and presence of resistant genes was detected by PCR. The mechanism of transfer of plasmid mediated resistance was confirmed by conjugation experiments. A total of 209 multidrug-resistant Escherichia coli were isolated from different hospital effluent discharge sites and aquaculture farms located in their vicinity. Among them, qnrB was found to be most prevalent followed by qnrS, OqxAB, qnrA and aac (6')-Ib-cr. The results suggested that the antibiotics present at sub-inhibitory concentrations in direct hospital effluents increases the selection pressure impacting the cell function of even normal microorganisms in the aquatic environment to change the genetic expression of virulence factors or acquire resistance genes by different transfer mechanisms, posing a serious threat to public health.

Effects of prescription antibiotics on soil- and root-associated microbiomes and resistomes in an agricultural context

The use of treated wastewater for crop irrigation is rapidly increasing to respond to the ever-growing demands for water and food resources. However, this practice may contribute to the spread of antibiotic resistant bacteria (ARB) and antibiotic resistant genes (ARGs) in agricultural settings. To evaluate this potential risk, we analyzed microbiomes and resistomes of soil and Lactuca sativa L. (lettuce) root samples from pots irrigated with tap water spiked with 0, 20, or 100 μg L^-1 of a mixture of three antibiotics (Trimethoprim, Ofloxacin, Sulfamethoxazole). The presence of antibiotics induced changes in bacterial populations, particularly in soil, as revealed by 16S rDNA sequence analysis. Parallel shotgun sequencing identified a total of 56 different ARGs conferring resistance against 14 antibiotic families. Antibiotic -treated samples showed increased loads of ARGs implicated in mutidrug resistance or in both direct and indirect acquired resistance. These changes correlated with the prevalence of Xantomonadales species in the root microbiomes. We interpret these data as indicating different strategies of soil and root microbiomes to cope with the presence of antibiotics, and as a warning that their presence may increase the loads of ARBs and ARGs in edible plant parts, therefore constituting a potential risk for human consumers.

Occurrence, spatiotemporal distribution and potential ecological risks of antibiotics in Dongting Lake, China

We investigated the occurrence and distribution of 18 antibiotics in surface water from Dongting Lake, as well as in influents and effluents from a municipal wastewater treatment plant (WWTP) and a swine farm. The total concentrations of target antibiotics in surface water ranged from limit of quantification to 3107 and 5.32-107 ng L^-1 in the dry season and wet season, respectively. Among these studied antibiotics, ciprofloxacin (CIP) and lomefloxacin were as the main components in the dry season, while CIP, oxytetracycline, and chlortetracycline were the main components in the wet season. The concentrations of target compounds exhibited obvious temporal-spatial variation characteristic in the studied region, suggesting their different emission sources related to pig breeding, aquaculture, and human activities, as well as possible degradation in the aquatic system. We estimated that the daily total input and output masses of antibiotics in the influent and effluent from the swine farm were 12.1 mg d^-1 pig^-1 and 7.49 μg d^-1 pig^-1, while they were 103 μg d^-1 inhabitant^-1 and 22.9 μg d^-1 inhabitant^-1 in the WWTP. The risk assessment results indicated that CIP posed a moderate or high risk to algae in most locations in Dongting Lake.

Pharmaceuticals and personal care products in water and wastewater: a review of treatment processes and use of photocatalyst immobilized on functionalized carbon in AOP degradation

The presence of emerging contaminants such as pharmaceutical and personal care products in many aqueous matrices have been reported. One of such matrix is streams of wastewater, including wastewater treatment plants inflows and outflows and wastewater flow by-passing wastewater treatment plants. Their persistence arises from their resistant to breakdown, hence they may remain in the environment over long time, with a potential to cause adverse effects including endocrine disruption, gene toxicity, the imposition of sex organs, antibiotic resistance and many others in some aquatic organisms exposed to arrays of residues of pharmaceutical and personal care products. Among the treatment techniques, advanced oxidation processes have been reported to be a better technique through which these PPCPs can be degraded in the WWTPs. Heterogeneous photocatalysis using various photocatalyst immobilized on solid support such as activated carbon, graphene and carbon nanotubes in AOPs have been shown to be a viable and efficient method of PPCPs degradation. This is because, the performance of most WWTPs is limited since they were not designed to degrade toxic and recalcitrant PPCPs. This review highlight the occurrence, concentration of PPCPs in wastewater and the removal efficiency of heterogeneous photocatalysis of TiO2 immobilized on solid supports.

Effect of sludge recirculation on removal of antibiotics in two-stage membrane bioreactor (MBR) treating livestock wastewater

Two-stage MBR consisting of anaerobic and aerobic reactors was operated at total hydraulic retention time (HRT) of 48 h for the treatment of livestock wastewater containing antibiotics, i.e. amoxicillin (AMX), tiamulin (TIA), and chlortetracycline (CTC), under the (1st) absence and (2nd) presence of sludge recirculation between the reactors. During the operation with sludge recirculation, the removals of organic and nitrogen were enhanced. Meanwhile, the removals of TIA and CTC were found to decrease by 9% and 20% in the aerobic reactor but increased by 5% to 7% in the anaerobic reactor due to the relocation of biomass from the aerobic to the anaerobic reactor. A high degree of AMX biodegradation under both anaerobic and aerobic conditions and partial biodegradation of TIA and CTC under aerobic conditions were confirmed in batch experiments. Moreover, the effect of sludge recirculation on biomass and pollutant removal efficiencies in the 2-stage MBR was revealed using microbial community analyses. Membrane filtration also helped to retain the adsorbed antibiotics associated with small colloidal particles in the system.

Erythromycin Treatment of Brassica campestris Seedlings Impacts the Photosynthetic and Protein Synthesis Pathways

Erythromycin (Ery) is a commonly used veterinary drug that prevents infections and promotes the growth of farm animals. Ery is often detected in agricultural fields due to the effects of manure application in the ecosystem. However, there is a lack of information on Ery toxicity in crops. In this study, we performed a comparative proteomic analysis to identify the molecular mechanisms of Ery toxicity during seedling growth based on our observation of a decrease in chlorophyll (Chl) contents using Brassica campestris. A total of 452 differentially abundant proteins (DAPs) were identified including a ribulose-1,5-bisphosphate carboxylase (RuBisCO). The proteomic analysis according to gene ontology (GO) classification revealed that many of these DAPs responding to Ery treatment functioned in a cellular process and a metabolic process. The molecular function analysis showed that DAPs classified within catalytic activity were predominantly changed by Ery, including metabolite interconversion enzyme and protein modifying enzyme. An analysis of functional pathways using MapMan revealed that many photosynthesis components were downregulated, whereas many protein biosynthesis components were upregulated. A good relationship was observed between protein and transcript abundance in a photosynthetic pathway, as determined by qPCR analysis. These combined results suggest that Ery affects plant physiological activity by downregulating protein abundance in the photosynthetic pathway.

Antimicrobial Resistance Patterns in Organic and Conventional Dairy Herds in Sweden

Monitoring antimicrobial resistance (AMR) and use (AMU) is important for control. We used Escherichia coli from healthy young calves as an indicator to evaluate whether AMR patterns differ between Swedish organic and conventional dairy herds and whether the patterns could be related to AMU data. Samples were taken twice, in 30 organic and 30 conventional dairy herds. Selective culturing for Escherichia coli, without antibiotics and with nalidixic acid or tetracycline, was used to estimate the proportions of resistant isolates. Microdilution was used to determine the minimum inhibitory concentrations (MICs) for thirteen antimicrobial substances. AMU data were based on collection of empty drug packages. Less than 8% of the bacterial growth on non-selective plates was also found on selective plates with tetracycline, and 1% on plates with nalidixic acid. Despite some MIC variations, resistance patterns were largely similar in both periods, and between organic and conventional herds. For most substances, only a few isolates were classified as resistant. The most common resistances were against ampicillin, streptomycin, sulfamethoxazole, and tetracycline. No clear association with AMU could be found. The lack of difference between organic and conventional herds is likely due to a generally good animal health status and consequent low AMU in both categories.

Occurrence and fate of antibiotics, antibiotic resistant genes (ARGs) and antibiotic resistant bacteria (ARB) in municipal wastewater treatment plant: An overview

The occurrence and fate of antibiotics and antibiotic resistant genes (ARGs) and antibiotic resistant bacteria (ARB) in Municipal Wastewater Treatment Plants (WWTPs) worldwide were reviewed. The prevalence of antibiotics in WWTPs among different periods (1999-2009 and 2010-2019) and geographical areas (Europe, America, Asia and Africa) was summarized, analyzed and evaluated. The classes of macrolides (clarithromycin, erythromycin/erythromycin-H₂O, azithromycin, roxithromycin), sulfonamides (sulfamethoxazole), trimethoprim, quinolones (ofloxacin, ciprofloxacin, norfloxacin) and tetracyclines (tetracycline) were the antibiotics most frequently detected, while bla (bla_CTXM, bla_TEM), sul (sul1, sul2), tet (tetO, tetQ, tetW) and ermB genes were the ARGs commonly reported in WWTPs. There was a positive correlation between antibiotics and ARGs commonly detected in WWTPs, except for β-lactam antibiotics and bla genes. The genes bla were found frequently, despite β-lactam antibiotics were seldom detected owing to the hydrolysis. Most of antibiotics had lower levels in the period 2010-2019 in Asian countries than that in period 1999-2009 in North American and European countries. In the effluent of secondary treatment, the concentration of trimethoprim was the highest (138 ng/L in median) and the concentration of other antibiotics remained at lower than 80 ng/L, while the relative abundance of ARGs ranged 2.9-4.6 logs (copies/mL, in median). Future researches on the development of effective antibiotic removal technologies, such as advanced oxidation processes, are suggested to focus on antibiotics frequently detected and their corresponding ARGs in WWTPs.

Effects of erythromycin and sulfamethoxazole on Microcystis aeruginosa: Cytotoxic endpoints, production and release of microcystin-LR

Antibiotics can cause severe ecological problems for aquatic ecosystems due to their wide use and incomplete removal. Microcystis aeruginosa was exposed to different levels of erythromycin (ERY) and sulfamethoxazole (SMX) separately to assess their cytotoxic effects on harmful cyanobacteria. The production and release of the toxin MC-LR was measured, and several endpoints were investigated using flow cytometry (FCM) for 7 d. ERY resulted in cell membrane hyperpolarization and a hormesis effect on growth rate and chlorophyll a fluorescence at environmentally relevant concentrations (0.5 and 5 μg/L). Microcystis exhibited elevated photosynthesis and hyperpolarization at 50 and 125 μg/L of SMX. An increase of metabolically non-active cells was observed in either ERY or SMX cultures while stimulation of esterase activity was also found at 7 d. ERY and SMX caused damage of membrane integrity due to the overproduction of ROS, which led to increased release of MC-LR. MC-LR production apparently was induced by ERY (0.5-500 μg/L) and SMX (50 and 125 μg/L). In conclusion, ERY and SMX can disrupt the physiological status of Microcystis cells and stimulate the production and release of MC-LR, which can exacerbate potential risks to water systems.

Research on the Impact and Mechanism for the Inhibition of Micrococcus Catalase Activity by Typical Tetracyclines

As potential inhibitors target to biological enzymes, antibiotics may have certain impacts on the biochemical treatment process. With micrococcus catalase (CAT) served as the target molecule, the impact and inhibition mechanism for typical tetracyclines (TCs) were evaluated. Toxicity experiments showed that TCs had significant inhibition on CAT in the sequence of tetracycline>chlortetracycline>oxytetracycline>doxycycline. To clarify the inhibition mechanism between TCs and CAT which was explored with the assistance of fluorescence spectroscopy and MOE molecule simulation. According to fluorescence analysis, TCs quenched the fluorescence signal of CAT by the mode of static quenching. Combined with toxicity data, it could be presumed that TCs combined with the catalytic active center and thus inhibited CAT. Above presumption was further verified by the molecular simulation data. When TCs combined with the catalytic center of CAT, the compounds have increased combination areas and prominent energy change (compared with the compounds formed by TCs and noncatalytic center recommend by MOE software). IBM SPSS statistics showed that TC toxicity positively correlated with the hydrogen bonds such as O¹³→Glu₂₅₂, O¹←Arg₁₉₅, and O⁶→Asp₂₄₉, but negatively correlated with the hydrogen bonds such as O¹⁰→Pro₃₆₃, O¹⁰→Lys₄₅₅, and O¹² → Asn₁₂₇. TC toxicity also positively correlated with the ion bonds ofN⁴-Glu₂₅₂, but negatively correlated with the ion bonds of N⁴-Asp₃₇₉. Hydrogen bonds and ion bonds for above key sites were closely related to the inhibition effect of TCs on CAT.

Chloramphenicol and sulfonamide residues in sea bream (Sparus aurata) and sea bass (Dicentrarchus labrax) fish from aquaculture farm

There are many worries about the food safety of seafood contaminated with antibiotic residues. These residues can be potentially dangerous for public health owing to the causation of allergic reactions, toxic effects, and serious health problems. This study was planned to search the occurrence of chloramphenicol (CAP) and sulfonamide residue in sea bream and sea bass. A total of 82 fish samples were collected from 14 different sales points in Afyonkarahisar. The samples were analyzed for CAP and sulfonamide residues using the ELISA method. Results showed that up to 18.3% of the samples were contaminated with CAP. In the positive fish meat samples, the CAP residue concentrations ranged within 0.54-10.6 ng kg^-1. The mean CAP residue concentration in positive samples was 4.25 ± 2.78 ng kg^-1. No sulfonamide residue was detected from the samples. Despite the prohibition of CAP application in aquaculture, detectable CAP residues in fish meat samples indicate an illegal use of this antibiotic. Therefore, the results obtained in the study are negative signs for food safety. Official controls must be performed rigorously in accordance with the national residue monitoring plan especially for the illegal antibiotics.