Evaluation of food chain transfer of the antibiotic oxytetracycline and human risk assessment

Effect of UV pretreatment on the source control of floR during subsequent biotreatment of florfenicol wastewater

UV photolysis has been recommended as an alternative pretreatment method for the elimination of antibacterial activity of antibiotics against the indicator strain, but the pretreated antibiotic intermediates might not lose their potential to induce antibiotic resistance genes (ARGs) proliferation during subsequent biotreatment processes. The presence of florfenicol (FLO) in wastewater seriously inhibits the metabolic performance of anaerobic sludge microorganisms, especially the positive correlation between UV irradiation doses and ATP content, while it did not significantly affect the organics utilization ability and protein biosynthetic process of aerobic microorganisms. After sufficient UV pretreatment, the relative abundances of floR from genomic or plasmid DNA in subsequent aerobic and anaerobic biotreatment processes both decreased by two orders of magnitude, maintained at the level of the groups without FLO selective pressure. Meanwhile, the abundances of floR under anaerobic condition were always lower than that under aerobic condition, suggesting that anaerobic biotreatment systems might be more suitable for the effective control of target ARGs. The higher abundance of floR in plasmid DNA than in genome also indicated that the potential transmission risk of mobile ARGs should not be ignored. In addition, the relative abundance of intI1 was positively correlated with floR in its corresponding genomic or plasmid DNA (p < 0.05), which also increased the potential horizontal transfer risk of target ARGs. This study provides new insights into the effect of preferential UV photolysis as a pretreatment method for the enhancement of metabolic performance and source control of target ARGs in subsequent biotreatment processes. KEY POINTS: • Sufficient UV photolytic pretreatment efficiently controlled the abundance of floR • A synchronous decrease in abundance of intI1 reduced the risk of horizontal transfer • An appreciable abundance of floR in plasmid DNA was a potential source of total ARGs.

Effect of microplastics on oxytetracycline trophic transfer: Immune, gut microbiota and antibiotic resistance gene responses

Microplastics and antibiotics are prevalent and emerging pollutants in aquatic ecosystems, but their interactions in aquatic food chains remain largely unexplored. This study investigated the impact of polypropylene microplastics (PP-MPs) on oxytetracycline (OTC) trophic transfer from the shrimp (Neocaridina denticulate) to crucian carp (Carassius auratus) by metagenomic sequencing. The carrier effects of PP-MPs promoted OTC bioaccumulation and trophic transfer, which exacerbated enterocyte vacuolation and hepatocyte eosinophilic necrosis. PP-MPs enhanced the inhibitory effect of OTC on intestinal lysozyme activities and complement C3 levels in shrimp and fish, and hepatic immunoglobulin M levels in fish (p < 0.05). Co-exposure of MPs and OTC markedly increased the abundance of Actinobacteria in shrimp and Firmicutes in fish, which caused disturbances in carbohydrate, amino acid, and energy metabolism. Moreover, OTC exacerbated the enrichment of antibiotic resistance genes (ARGs) in aquatic animals, and PP-MPs significantly increased the diversity and abundance of ARGs and facilitated the trophic transfer of teta and tetm. Our findings disclosed the impacts of PP-MPs on the mechanism of antibiotic toxicity in aquatic food chains and emphasized the importance of gut microbiota for ARGs trophic transfer, which contributed to a deeper understanding of potential risks posed by complex pollutants on aquatic ecosystems.

Surface functional groups on nanoplastics delay the recovery of gut microbiota after combined exposure to sulfamethazine in marine medaka (Oryzias melastigma)

Nanoplastics can interact with antibiotics, altering their bioavailability and the ensuing toxicity in marine organisms. It is reported that plain polystyrene (PS) nanoplastics decrease the bioavailability and adverse effects of sulfamethazine (SMZ) on the gut microbiota in Oryzias melastigma. However, the influence of surface functional groups on the combined effects with SMZ remains largely unknown. In this study, adult O. melastigma were fed diet amended with 4.62 mg/g SMZ and 3.65 mg/g nanoplastics (i.e., plain PS, PS-COOH and PS-NH2) for 30 days (F0-E), followed by a depuration period of 21 days (F0-D). In addition, the eggs produced on the last day of exposure were cultured under standard protocols without further exposure for 2 months (F1 fish). The results showed that the alpha diversity or the bacterial community of gut microbiota did not differ among the SMZ + PS, SMZ + PS-COOH, and SMZ + PS-NH2 groups in the F0-E and F1 fish. Interestingly, during the depuration, a clear recovery of gut microbiota (e.g., increases in the alpha diversity, beneficial bacteria abundances and network complexity) was found in the SMZ + PS group, but not for the SMZ + PS-COOH and SMZ + PS-NH2 groups, indicating that PS-COOH and PS-NH2 could prolong the toxic effect of SMZ and hinder the recovery of gut microbiota. Compared to plain PS, lower egestion rates of PS-COOH and PS-NH2 were observed in O. melastigma. In addition, under the simulated fish digest conditions, the SMZ-loaded PS-NH2 was found to desorb more SMZ than the loaded PS and PS-COOH. These results suggested that the surface -COOH and -NH2 groups on PS could influence their egestion efficiency and the adsorption/desorption behavior with SMZ, resulting in a long-lasting SMZ stress in the gut during the depuration phase. Our findings highlight the complexity of the carrier effect and ecological risk of surface-charged nanoplastics and the interactions between nanoplastics and antibiotics in natural environments.

The Potential of Wood Vinegar to Replace Antimicrobials Used in Animal Husbandry-A Review

The indiscriminate use of antimicrobials in animal husbandry can result in various types of environmental contamination. Part of the dose of these products is excreted, still active, in the animals' feces and urine. These excreta are widely used as organic fertilizers, which results in contamination with antimicrobial molecules. The impacts can occur in several compartments, such as soil, groundwater, and surface watercourses. Also, contamination by antimicrobials fed or administrated to pigs, chickens, and cattle can reach the meat, milk, and other animal products, which calls into question the sustainability of using these products as part of eco-friendly practices. Therefore, a search for alternative natural products is required to replace the conventional antimicrobials currently used in animal husbandry, aiming to mitigate environmental contamination. We thus carried out a review addressing this issue, highlighting wood vinegar (WV), also known as pyroligneous acid, as an alternative antimicrobial with good potential to replace conventional products. In this regard, many studies have demonstrated that WV is a promising product. WV is a nontoxic additive widely employed in the food industry to impart a smoked flavor to foods. Studies have shown that, depending on the WV concentration, good results can be achieved using it as an antimicrobial against pathogenic bacteria and fungi and a valuable growth promoter for poultry and pigs.

Environmental Sample Stability for Pharmaceutical Compound Analysis: Handling and Preservation Recommendations

Efficient and resilient techniques for handling samples are essential for detecting pharmaceutical compounds in the environment. This study explores a method for preserving water samples during transport before quantitative analysis. The study investigates the stability of 17α-ethynylestradiol (EE2), acetaminophen (ACM), oxytetracycline (OTC), sulfamethoxazole (SMX), and trimethoprim (TMP) after preconcentration within solid-phase extraction (SPE) cartridges. Through various experiments involving different holding times and storage temperatures, it was determined that four pharmaceutical compounds remained stable when stored for a month at 4°C and for six months when stored at -18°C in darkness. Storing these compounds in SPE cartridges at -18°C seemed effective in preserving them for extended periods. In addition, ACM, TMP, OTC, EE2, and SMX remained stable for three days at room temperature. These findings establish guidelines for appropriate storage and handling practices of pharmaceutical compounds preconcentrated from aqueous environmental samples using SPE.

Assessment of Nonalcoholic Fatty Liver Disease Symptoms and Gut-Liver Axis Status in Zebrafish after Exposure to Polystyrene Microplastics and Oxytetracycline, Alone and in Combination

BACKGROUND

Environmental pollution may give rise to the incidence and progression of nonalcoholic fatty liver disease (NAFLD), the most common cause for chronic severe liver lesions. Although knowledge of NAFLD pathogenesis is particularly important for the development of effective prevention, the relationship between NAFLD occurrence and exposure to emerging pollutants, such as microplastics (MPs) and antibiotic residues, awaits assessment.

OBJECTIVES

This study aimed to evaluate the toxicity of MPs and antibiotic residues related to NAFLD occurrence using the zebrafish model species.

METHODS

Taking common polystyrene MPs and oxytetracycline (OTC) as representatives, typical NAFLD symptoms, including lipid accumulation, liver inflammation, and hepatic oxidative stress, were screened after 28-d exposure to environmentally realistic concentrations of MPs (0.69mg/L) and antibiotic residue (3.00μg/L). The impacts of MPs and OTC on gut health, the gut-liver axis, and hepatic lipid metabolism were also investigated to reveal potential affecting mechanisms underpinning the NAFLD symptoms observed.

RESULTS

Compared with the control fish, zebrafish exposed to MPs and OTC exhibited significantly higher levels of lipid accumulation, triglycerides, and cholesterol contents, as well as inflammation, in conjunction with oxidative stress in their livers. In addition, a markedly smaller proportion of Proteobacteria and higher ratios of Firmicutes/Bacteroidetes were detected by microbiome analysis of gut contents in treated samples. After the exposures, the zebrafish also experienced intestinal oxidative injury and yielded significantly fewer numbers of goblet cells. Markedly higher levels of the intestinal bacteria-sourced endotoxin lipopolysaccharide (LPS) were also detected in serum. Animals treated with MPs and OTC exhibited higher expression levels of LPS binding receptor (LBP) and downstream inflammation-related genes while also exhibiting lower activity and gene expression of lipase. Furthermore, MP-OTC coexposure generally exerted more severe effects compared with single MP or OTC exposure.

DISCUSSION

Our results suggested that exposure to MPs and OTC may disrupt the gut-liver axis and be associated with NAFLD occurrence. https://doi.org/10.1289/EHP11600.

Analysis of the multi-media environmental behavior of polycyclic aromatic hydrocarbons (PAHs) within Haizhou Bay using a fugacity model

In this study, we aimed to quantify the transport and fate of PAHs in different environmental phases (air, seawater, soil, sediment and fish), verify application of the Level III fugacity model in a bay simulation, and understand the transport and fate of PAHs in the bay environment on a macroscopic scale. The simulated average concentrations of ∑₁₆PAH in the air and soil (23.8 ng/m³ and 1080.91 ng/g, respectively), which is as a background reference data for the Haizhou Bay. In addition, the soil (307 t), fish (29.4 t), and sediment (9.72 t) phases were found to be important reservoirs in the Haizhou Bay. Emissions from road vehicles (658 t) accounted for the largest share of PAH emissions in the area, and atmospheric deposition contributed most to the input of PAHs to the polluted area in the region. Whereas the contribution of river runoff input was small, and degradation loss was the main output pathway.

Energy transfer mediated rapid and visual discrimination of tetracyclines and quercetin in food by using N, Cu Co-doped carbon dots

The appearance of multi-drug resistant Escherichia coli makes the combination of tetracyclines (TCs) and quercetin (QCT) more common to fight stubborn bacterial infections so that the effective detections of TCs and QCT are essential and necessary. Here, a novel fluorescence probe for differentiating TCs and QCT is developed based on the nitrogen and copper co-doped carbon dots (N, Cu-CDs). The N, Cu-CDs are prepared from ethylene diamine tetraacetic acid (EDTA) and anhydrous copper chloride as precursors through hydrothermal process and exhibit bright blue fluorescence with excellent optical stability. With the presence of four tetracyclines (DOX, TC, CTC and OTC), the fluorescence intensity of N, Cu-CDs is quenched directly due to the internal filtration effect (IFE), and the detection limit obtained through single-signal fluorescence sensing is as low as 23.8 nM for DOX, 37.2 nM for TC, 43.8 nM for OTC and 28.8 nM for CTC. More remarkably, three dimensional ratiometric fluorescence probe for detecting QCT is proposed based on the appearance of another emission at (410 nm, 490 nm) due to electron transform (ET) process. This new method shows a good linear relationship in the range of 10-100 μM with a low detection limit of 59.3 nM. Furthermore, a dual-channel fluorescence sensing platform based on microfluidics paper-based analytical devices (μPADs) is developed for simultaneously visual discrimination of TCs (DOX is chosen as the typical detecting model for TCs) and QCT. This investigation provides a new way for the development of CDs as multifunction fluorescence probes.

Residue, biotransformation, risk assessment and withdrawal time of enrofloxacin in red swamp crayfish (Procambarus clarkii)

Crayfish is a very popular aquatic food in many countries, and enrofloxacin (ENR) and ciprofloxacin (CIP) was the most frequently detected in aquatic products. However, limited information is available on the residue characterization, biotransformation rate and withdrawal period (WT) of ENR and CIP in crayfish and health risk via consumption of ENR and CIP remained crayfish. Herein, a comprehensive investigation was conducted to study residue depletion, biotransformation, ingestion risk, and WT of ENR and its predominate metabolite CIP in crayfish following different routes with repeated doses. The results showed that the elimination half-life (T_1/2) of target compounds in crayfish were all in order of hepatopancreas > muscle > gill, and the order of T_1/2 in different crayfish tissues were intramuscular (IM) route > oral (PO) treatment > immersion (IMMR) administration. The biotransformation rates from ENR to CIP varied from 0.75% to 3.45% in crayfish tissues following different exposure routes. The high dietary risk (RQ > 1) consuming muscle and hepatopancreas of ENR and CIP remained crayfish occurred at early after different administrations. WT is the key to control the drug residue risk, and the longest WT of marker residue of ENR in crayfish was calculated to be 51 d (1275 °C-day).

Quinolone distribution, trophodynamics, and human exposure risk in a transit-station lake for water diversion in east China

Quinolone antibiotics (QNs) pollution in lake environments is increasingly raising public concern due to their potential combined toxicity and associated risks. However, the spatiotemporal distribution and trophodynamics of QNs in transit-station lakes for water diversion are not well documented or understood. In this study, a comprehensive investigation of QNs in water, sediment, and aquatic fauna, including norfloxacin (NOR), ciprofloxacin (CIP), enrofloxacin (ENR), and ofloxacin (OFL), was conducted in Luoma Lake, a major transit station for the eastern route of the South-to-North Water Diversion Project in China. The target QNs were widely distributed in the water (∑QNs: 70.12 ± 62.79 ng/L) and sediment samples (∑QNs: 13.35 ± 10.78 ng/g dw) in both the non-diversion period (NDP) and the diversion period (DP), where NOR and ENR were predominant. All the QNs were detected in all biotic samples in DP (∑QNs: 80.04 ± 20.59 ng/g dw). The concentration of ∑QNs in the water in NDP was significantly higher than those in DP, whereas the concentration in the sediments in NDP was comparable to those in DP. ∑QNs in the water-sediment system exhibited decreasing trends from northwest (NW) to southeast (SE) in both periods; however, the K_oc (organic carbon normalized partition coefficients) of individual QNs in DP sharply rose compared with those in NDP, which indicated that water diversion would alter the environmental fate of QNs in Luoma Lake. In DP, all QNs, excluding NOR, were all biodiluted across the food web; whereas their bioaccumulation potentials in the SE subregion were higher than those in the NW subregion, which was in contrast to the spatial distribution of their exposure concentrations. The estimated daily QN intakes via drinking water and aquatic products suggested that residents in the SE side were exposed to greater health risks, despite less aquatic pollution in the region.

Application of duckweed (Lemna sp.) and water fern (Azolla sp.) in the removal of pharmaceutical residues in water: State of art focus on antibiotics

In recent decades, antibiotic residues in the environment have increased, affecting components of biological communities, from bacteria to plants and animals. Different methods have been used to remove these compounds, including phytoremediation with floating aquatic species such as duckweed and aquatic fern, with positive results. This study analyses information about the removal efficiency of drugs, with a focus on antibiotics, using Lemna and Azolla, which will allow a better understanding of phytoremediation processes from the perspective of plant physiology. The physiological processes of macrophytes in an environment with this type of pollutant and the phytotoxic effects on plants at high concentrations are also analysed. The metabolization of toxic compounds occurs in three phases: phase I begins with the absorption of antibiotics and the secretion of reactive oxygen species (ROS); in phase II, the effects of ROS are neutralized and minimized by conjugation with enzymes such as glutathione transferase or metabolites such as glutathione; and phase III culminates with the storage of the assimilated compounds in the vacuoles, apoplast and cell wall. In this way, plants contribute to the removal of toxic compounds. In summary, there is sufficient scientific evidence on the efficiency of the elimination of pharmaceutical compounds by these floating macrophytes at the laboratory scale, which indicates that their application under real conditions can have good results.

Occurrence and human health risk assessment of antibiotics in cultured fish from 19 provinces in China

The occurrence of antibiotics and potential health risk of 300 cultured fish samples from 19 provinces in China were investigated. The levels of 28 antibiotics (15 fluoroquinolones, 4 tetracyclines, 8 macrolides and rifampin) in 8 fish species were measured through liquid chromatography electrospray tandem mass spectrometry. As a result, 10 antibiotics were detected with an overall detection frequency of 24.3%, and the individual detection frequency of antibiotics ranged from 0.33 to 16.7%. The extremely high concentrations (above 100 µg/kg) of doxycycline and erythromycin were found in the samples. Antibiotics with high detection frequency was noticed in largemouth bass (41.2%), followed by snakehead (34.4%) and bream (31.2%). Specifically, Heilongjiang, Xinjiang, Qinghai and Gansu presented high detection frequency values of more than 60%. Moreover, the highest mean concentration was observed in Shandong, and the concentration covered from 34.8 µg/kg to 410 µg/kg. Despite the high detection frequency and levels of antibiotics were found in samples, ingestion of cultured fish was not significantly related to human health risks in China, according to the calculated estimated daily intakes and hazard quotients. These results provided us the actual levels of antibiotics in cultured fish and human health risk assessment of consuming fishery products.

Occurrence of quinolones in cultured fish from Shandong Province, China and their health risk assessment

The residue levels of 6 quinolones in 160 cultured fish samples from Shandong Province, China were investigated using UPLC-MS/MS. The detection rate was 43.1% and enrofloxacin had the highest detection rate as well as the highest residue concentration. The violation rates were 2.50% for the sum of enrofloxacin and ciprofloxacin and 1.25% for ofloxacin. Among the 9 fish species, quinolone contamination problems should receive more attention in Carp, Grass carp, Crucian and Catfish. The health risk assessment showed that when calculated by the maximum concentration, the estimated daily intakes (EDIs) of Carp, Grass carp and Crucian for the high consumption group accounted for more than 10% of the acceptable daily intakes (ADIs), indicating that a large intake of these fish species might pose a potential health risk and health risk monitoring of quinolones in cultured fish should be continually performed.

Efficient with low-cost removal and adsorption mechanisms of norfloxacin, ciprofloxacin and ofloxacin on modified thermal kaolin: experimental and theoretical studies

Quinolone antibiotics (QNs) can be potential hazard to environment and human. Combination of experimental and theoretical studies was used to analyze the adsorption properties of norfloxacin, ciprofloxacin and ofloxacin on modified thermally activated kaolin (KL). Main factors (calcination temperature, dose, pH, cations and regeneration) affecting the adsorption were discussed. Adsorption processes fit the pseudo-second order kinetic and Langmuir model well. The adsorption removal of norfloxacin, ciprofloxacin and ofloxacin can reach 88.53%, 89.43% and 91.46%, respectively. Cations inhibited adsorption, and AlS-KLB can maintain 80% efficiency in five cycles under optimal conditions. Simulations showed that the materials had good adsorption capacity for QNs, and the "①" of KL had the best capacity. Simulations explain the adsorption mechanism: F, H, O atoms of QNs are covalently bonded to O atoms from KL, Al₂O₃ and Al (OH)₃, C atoms from amorphous carbon and H atoms from C-H and Al (OH)₃. The Al atoms of Al₂O₃ and Al, Si atoms of KL are ionically bonded to F, H, O atoms of QNs. This study shed new light on the removal of QNs by providing low-cost and efficient modified KL and elucidating the adsorption mechanism in conjunction with DFT simulations.

Antibiotics in aquaculture ponds from Guilin, South of China: Occurrence, distribution, and health risk assessment

Antibiotics have been widely used to prevent or treat bacterial infections in aquaculture in the past decades. However, large proportions of these compounds are excreted unchanged in feces and urine of animals, given incomplete metabolism, leading to the residual of unmetabolized compounds, and posing a potential risk to the environment. This study investigated the occurrence and distribution of seven antibiotics in surface water, sediments, fish muscle, and fish feed by high-performance liquid chromatography from the aquaculture areas in Guilin, South of China. The highest concentrations of the target antibiotics in water, sediment, fish muscle, and fish feed were 2047.53 ng/L, 13.32 μg/kg, 35.90 μg/kg, and 2203.97 μg/kg, respectively. In contrast, the most abundant antibiotic was enrofloxacin (ENR), followed by ofloxacin (OFL), sulfadimidine (SMZ), and ciprofloxacin (CIP). In this work, the concentrations of antibiotics were lower than those in other breeding areas. Correlation analyses showed significant relationships between sulfadiazine (SDZ) and TP, TN, and COD_Cr in water. In sediment, the release of SDZ was significantly related to TN, TP, and organic matter. The risk quotient (RQ) results revealed that sulfamethoxazole (SMX), CIP, and ENR were at high risk to microorganisms in water; while, SMX and NOR were at high risk in sediments. The result from the estimated daily intakes (health risk quotient, HQ < 1) suggested that the antibiotics might not pose a risk to human health by dietary exposure assessment; however, sediments may become an accumulation reservoir of antibiotics and cause secondary pollution, of which the local management should raise awareness.

A systematic review on antibiotics misuse in livestock and aquaculture and regulation implications in China

China is one of the largest producers and consumers of antibiotics, and China is a larger producer of livestock farming and aquaculture in the world. The livestock farming and aquaculture industry is a major area of antibiotic misuse, which has caused serious antibiotic residues and environment pollution. The antibiotic residues exceeding the standard may lead to antibiotic resistances in animals or human bodies, which poses a threat to human health. In this context, this study tries to systematically review the current situation of antibiotic misuse in livestock and aquaculture in China, and put forward corresponding regulatiory measures for the central government. Based on the status quo of livestock farming and aquaculture in China, this study reviewed antibiotic misuse in livestock farming and aquaculture and antibiotic resistance in China, introduced China's current policies on antibiotic regulation and the gap between China and developed countries, and analyzed the implications of current regulatory policies on animal health and productivity. At last, we put forward suggestions for the future antibiotic regulation, including strictly implementing the relevant laws and regulations, formulating specific supporting measures, encouraging the research and development of antibiotic substitutes, introducing advanced technologies for supervision and regulation, strengthening the publicity of science popularization and enhancing the public's awareness of the rational use of antibiotics. If these policy recommendations can be implemented, they will significantly promote the regulation of antibiotic abuse.

Exposure of tilapia (Oreochromis niloticus) to the antibiotic florfenicol in water: determination of the bioconcentration factor and the withdrawal period

The demand for healthier foods with high nutritional value has resulted in intensive fish farming. In this production system, high-frequency infections occur, and antibiotics are administrated for control. Only two antibiotics are allowed for use in Brazilian aquaculture, one of which is florfenicol. In this work, a bioconcentration assay was performed to assess the accumulation of florfenicol in the muscle of Nile tilapia (Oreochromis niloticus). Tilapia was evaluated as it is the most produced fish species in Brazil. The fish were exposed to florfenicol at a nominal concentration of 10 mg/L, through the water. Muscle and water were collected at 0, 1.5, 3, 6, 24, and 48 h during the exposure phase and at 1.5, 3, 6, 24, 48, and 120 h during the depuration phase. Quantification was performed using an LC-MS/MS. The results showed rapid absorption and elimination of the antibiotic (half-life, t_1/2 = 5 h), with low potential for accumulation of florfenicol in tilapia muscles. The study was performed to determine the bioconcentration factor (BCF) and withdrawal period of florfenicol, being 0.05 mL/μg and 1.8 h, respectively. The results contribute to set protocols for the safe use of florfenicol in tilapia transport, avoiding residues in fish that may pose risks to human health.

Synthetic musks in surface water and fish from the rivers in India: Seasonal distribution and toxicological risk assessment

Synthetic musks (SMs), a class of organic compounds added to various personal care products (PCPs) to enhance aroma, are increasingly released into the environment and become one emerging contaminants of concern in India. Some SMs like Galaxolide, Tonalide and Musk Ketone (MK) are lipophilic and found ubiquitously in the environment, posing health and ecological risks, especially affecting aquatic organisms. Hence, monitoring the synthetic musks contamination in these rivers become environmentally inevitable. Consequently, three major rivers, the Kaveri (Cauvery), Vellar and Thamirabarani Rivers in Tamil Nadu, India, were investigated to understand the occurrence and fate of SMs. The concentration of Galaxolide, Tonalide and MK in surface water ranged as not detected (ND)-198, ND-77 and ND-62 ng/L, respectively. The levels of SMs in the Kaveri River were comparable with Vellar and Thamirabarani Rivers; however, the detection frequency was low in Thamirabarani river. Fish samples from the Kaveri river had higher concentrations of SMs (galaxolide 36-350 ng/g > MK 2-33 ng/g > Tonalide 1-9 ng/g ww (wet weight)) than in the Vellar River. Based on Hazard Quotient, SMs pose no risks to freshwater systems and the resident organisms in this study. In India, the dry season starts from March to July (35-42 °C) and wet season starts from November to February (25-35 °C). Bioconcentration factor (BCF) values for Galaxolide were found higher during the wet season and lower during the dry season, whereas it is reverse for Tonalide. Among fish Gebilion catla may be a good indicator species for SMs, despite the seasons, it accumulates more. This is the first study of SMs in surface water and fish from the rivers in India.

Unveiling the Impact of Antibiotics and Alternative Methods for Animal Husbandry: A Review

Since the 1950s, antibiotics have been used in the field of animal husbandry for growth promotion, therapy and disease prophylaxis. It is estimated that up to 80% of the antibiotics produced by the pharmaceutical industries are used in food production. Most of the antibiotics are used as feed additives at sub-therapeutic levels to promote growth. However, studies show the indiscriminate use of antibiotics has led to the emergence of multidrug-resistant pathogens that threaten both animal health and human health, including vancomycin-resistant Enterococcus (VRE), Methicillin-resistant Staphylococcus aureus (MRSA) and carbapenem-resistant Enterobacteriaceae (CRE). This scenario is further complicated by the slow progress in achieving scientific breakthroughs in uncovering novel antibiotics following the 1960s. Most of the pharmaceutical industries have long diverted research funds away from the field of antibiotic discovery to more lucrative areas of drug development. If this situation is allowed to continue, humans will return to the pre-antibiotics era and potentially succumb to huge health and economic consequences. Fortunately, studies investigating various alternatives to antibiotics use in livestock show promising results. These alternatives include the application of bacteriophages and phage derived peptidoglycan degrading enzymes, engineered peptides, egg yolk antibodies, probiotics, prebiotics and synbiotics, as well as quorum quenching molecules. Therefore, this review aims to discuss the use of growth-promoting antibiotics and their impact on livestock and provide insights on the alternative approaches for animal husbandry.

The degradation of oxytetracycline with ferrous oxalate under different light irradiation

Degradation of OTC under different light with Fe²⁺/C2O42- was investigated, and the reaction mechanism was also discussed. Although Fe(II/III)-C2O42- complex could weaken the inhibitory effect of Fe(II/III)-OTC complex on the detection of OTC by HPLC, the acidification could make inhibition become minimal. Response surface methodology was used to optimize the Fe²⁺/C2O42- dosage at low concentrations of Fe²⁺ and H₂C₂O₄. When the OTC concentration was 0.04 mM, the optimal dosage was OTC:Fe²⁺:H₂C₂O₄= 1:1.25:2 to attain a removal rate of 80% after 60 min under simulated solar light, and HO^• for degradation of OTC with Fe²⁺/C2O42+ could be 53%, furthermore, removal rate of OTC just increased 3 percentage points at 60 min when the simulated solar light changed into UV-254 nm, however, OTC could also be degraded for 48.89% removal rate after 3 h illumination of simulated visible light. The influence of Cl^-, CO32-, HCO3-, NO3-, NO2-, or H2PO4- on the degradation of OTC with Fe²⁺/C2O42- under simulated solar light was studied. NO2- could inhibit degradation for NO2- could react with free radicals, but the reason of inhibition of degradation by HCO3-, or CO32- was its influence on pH, whereas Cl^-, NO3- and H2PO4- had no influence on degradation. In addition, when the concentration of CO32- was higher than 4 mM, CO32- could promote the degradation for the direct photolysis of OTC at alkaline (pH > 10). Four products were detected by LC-MS, and the OTC degradation pathway was discussed.

High levels of antibiotic resistance genes and opportunistic pathogenic bacteria indicators in urban wild bird feces

This study analyzed fresh feces from three common bird species that live in urban environments and interact with human communities. Antibiotic resistance genes (ARGs) encoding resistance to three major classes of antibiotics (i.e., tetracyclines, β-lactams, and sulfonamides) and the mobile genetic element integrase gene (intI1) were abundant (up to 10⁹, 10⁸, 10⁹, and 10¹⁰ copies/g dry feces for tetW, bla_TEM, sul1, and intI1, respectively), with relative concentrations surprisingly comparable to that in poultry and livestock that are occasionally fed antibiotics. Biomarkers for opportunistic pathogens were also abundant (up to 10⁷ copies/g dry feces) and the dominant isolates (i.e., Enterococcus spp. and Pseudomonas aeruginosa) harbored both ARGs and virulence genes. ARGs in bird feces followed first-order attenuation with half-lives ranging from 1.3 to 11.1 days in impacted soil. Although residual antibiotics were detected in the feces, no significant correlation was observed between fecal antibiotic concentrations and ARG relative abundance. Thus, other unaccounted factors likely contributed selective pressure for ARG maintenance. These findings highlight the contribution of wild urban bird feces to the maintenance and dissemination of ARGs, and the associated health risks.

Antibiotics and Food Safety in Aquaculture

Antibiotics are widely used in aquaculture. Intensive farming drives indiscriminate use of antibiotics, which results in residues of antibiotics in cultured aquatic products and bacterial resistance. This perspective attempts to present a brief update on usage, regulations, residues, and potential human health risk of antibiotics used in aquaculture. Through the comprehensive literature review, we provide a view that the safety of aquatic products still requires further attention and more rigorous risk assessment. Finally, we make a few suggestions for future research directions: reduce the use of antibiotics to bring down the speed of resistance development and monitor resistant pathogens and genes, strictly manage the environmental sanitation of aquaculture and pay attention to the quality of water bodies introduced into aquaculture, seek international cooperation to establish an information bank of antibiotic residues and antibiotic-resistant genes, and set up a quantitative model to assess the risk of antibiotic resistance associated with the antibiotic residues.

Tissue concentrations, trophic transfer and human risks of antibiotics in freshwater food web in Lake Taihu, China

The objective of this study was to evaluate the tissue distributions of antibiotics in the fish, the bioaccumulation and trophic transfer in freshwater food web in Taihu Lake, a large shallow freshwater lake. Twenty four out of 41 antibiotics were detected in the biotas of the food web; and antibiotic concentrations followed the orders: fish plasma ~ fish muscle < fish liver ~ fish bile and fish < invertebrates ~ plankton. Antibiotic concentrations in the liver of piscivores were higher than those in omnivores and planktivores. Most bioaccumulation factors (BAFs) of sulfonamides (SAs), macrolides (MLs), ionophores (IPs) and lincomycin (LIN) were less than 2000 L/kg, indicating low bioaccumulation ability of these compounds in fish. Fluoroquinolones (FQs) were frequently detected in fish liver, invertebrates and plankton with much of BAFs great than 5000 L/kg, indicating that FQs have the potential of bioaccumulation in fish. Relationship analysis between BAFs and physicochemical properties of antibiotics showed that the bioaccumulation of antibiotics in the biota was related with their adsorption ability. Generally, the antibiotics in the food web of Lake Taihu including plankton, invertebrates and fish showed trophic dilution. The normalized estimated daily intake (EDI) values are less than the acceptable daily intake (ADI) values, and then hazard quotients were much less than 1. This result suggests the consumption of fish, crab and shrimp in Lake Taihu would probably not pose direct detrimental effects on humans.

UV photolysis as an efficient pretreatment method for antibiotics decomposition and their antibacterial activity elimination

The biological treatment of antibiotic-containing wastewater is a mainstream process, but the antibacterial activity from the persistence of antibiotics would inhibit the biological activity and function of wastewater treatment plants and lead to the risk of transmission of antibiotic resistant bacteria and genes. In this study, UV photolysis was selected as an appropriate pretreatment technology for antibiotic-containing wastewater. It could decompose many kinds of antibiotics and was not inhibited by the coexisting organics in wastewater. The antibacterial activities of five kinds of antibiotics, which were eliminated with UV irradiation, exhibited a significantly positive correlation with their parent compound concentrations. The photodecomposition of the main functional groups in antibiotics contributed to the elimination of antibacterial activity. Defluorination was the main pathway to eliminate the antibacterial activity of antibiotics containing a fluorine substituent (e.g., florfenicol and ofloxacin), while the photoinduced opening of the β-lactam ring was the most efficient route to eliminate the antibacterial activity of β-lactam antibiotics (e.g. cefalexin, amoxicillin and ampicillin). These results demonstrated that UV photolysis could be adopted as an efficient and promising pretreatment strategy for the source control of antibiotic antibacterial activity by the decomposition of antibiotic functional groups before the biological treatment unit.

Evaluation of factors influencing annual occurrence, bioaccumulation, and biomagnification of antibiotics in planktonic food webs of a large subtropical river in South China

Biological pump is important to control the fate and distribution of organic contaminants, particularly in temperate and cold oligotrophic waters. However, it remains largely unknown how factors affect the long-term occurrence and fate of ionogenic organic compounds in subtropical eutrophic waters. The present study aimed to assess biogeochemical and physical factors affecting the annual occurrence, bioaccumulation, and trophic transfer of 14 antibiotics through planktonic food webs in the Pearl River, a large subtropical eutrophic river in China. This was done by carrying out 1-year simultaneous field observations of antibiotic concentrations in five water column compartments and assessing the variability of bioconcentration (BCF), bioaccumulation (BAF), and biomagnification (BMF) factors, which were influenced by plankton biomass, pH and temperature of water columns. The annual mean antibiotic concentration per site ranged from 1014.66 ± 535.66 ng L^-1 to 1464.63 ± 1075.91 ng L^-1, and was positively correlated with phytoplankton biomass, but independent of the proximity of the sites to urban areas. Antibiotic occurrences in both phytoplankton and zooplankton were greatly influenced by a biodilution effect. The annual occurrence of antibiotics in the water column was modulated by biological pumps as well as their equilibrium partitioning, and indirectly influenced of eutrophication with pH increased with phytoplankton biomass and phytoplankton life cycling. BAF of antibiotics by plankton had biphasic correlations with temperature (n = 150, R² = 0.17-0.60, p < 0.001) and decreased with plankton biomass (n = 105-147, R² = 0.10-0.22, p < 0.001). The trophic transfer of antibiotics from phytoplankton to zooplankton (BMFs) were positively correlated with both phytoplankton biomass (n = 30, R² = 0.58, p < 0.001) and temperature (n = 132-150, R² = 0.12-0.43, p < 0.001). Mean BMFs of ciprofloxacin, lomefloxacin, ofloxacin, oxytetracycline, and tetracycline ranged between 0.18 and 2.25, implying these chemicals can undergo biomagnification along planktonic food webs. The present research demonstrates the important role of biogeochemical and physical factors in the environmental fate of antibiotics at large spatiotemporal scales.

Antibiotics in wastewater from multiple sources and surface water of the Yangtze River in Chongqing in China

Antibiotic contamination attracts growing concerns because of their deleterious effects on the ecosystem and human health. In this study, 43 antibiotics in wastewater from a variety of sources and water of the Yangtze River in Chongqing City in western China were measured. Thirty compounds were detected, and their concentrations were highest in leachates from the municipal solid waste treatment facilities (landfills and incineration plants) with total concentrations of 3584-57,106 ng/L. The total concentrations in influents of municipal and industrial wastewater treatment plants (WWTPs) were comparable (401-7994 ng/L versus 640-8945 ng/L). The concentrations in raw sewage from swine farms (with a total of 10,219-39,195 ng/L) and poultry farms (1419-36,027 ng/L) were noticeably higher than those from other farms (54.0-5516 ng/L). Fluoroquinolones were the dominant antibiotics contributing over 50% in all the sources, and sulfonamides and imidazole fungicides contributed 3.2-34%, whereas tetracyclines and macrolides had minor contributions. The overall antibiotic removal rates were highest in solid waste treatment facilities (88% on average), comparable between municipal and industrial WWTPs (61%), and lowest in animal farms (39%). The mass loads to the investigated municipal WWTPs via influent wastewater ranged from 7.80 to 1531 kg/year (53.2-2482 μg/day per capital). The influent mass loads to the industrial WWTPs and farms were 3.7-50 kg/year and 0.9-5437 g/year, respectively. We estimated that the mass inventories of antibiotics from these sources to the environment via effluent discharges were approximately 2044 kg for municipal WWTPs, 61 kg for industrial WWTPs, and 34 kg for animal farms in the whole city. Antibiotic concentrations in the Yangtze River water were substantially low (< 492 ng/L, with a mean of 57.8 ng/L) suggesting dissipation during the movement.

Bioaccumulation, metabolism, and risk assessment of phenolic endocrine disrupting chemicals in specific tissues of wild fish

Phenolic endocrine disrupting chemicals (EDCs) may pose a great hazard to wildlife and humans, owing to their ubiquitous presence in the environment and potential bioaccumulation ability. We investigated the bioaccumulation, metabolism, and human health risks of six phenolic EDCs, including bisphenol A (BPA), 4-tert-octylphenol (4-t-OP), 4-nonylphenol (4-NP), estrone (E1), 17β-estradiol (E2), and 17α-ethinylestradiol (EE2), in wild fish from the Pearl River system, South China. Except EE2, the other five EDCs were detected in at least one of the four fish tissues (bile, liver, plasma, and muscle). The concentrations of BPA and 4-NP were greater than those of 4-t-OP, E1, and E2 in all tissues. The median values of log bioaccumulation factors for EDCs at the range of 3.86-4.52 in bile, 2.06-3.16 in liver, 2.69-3.87 in plasma, and 1.34-2.30 in muscle, indicating a higher bioaccumulation potential in fish bile than in other tissues. Greater levels of glucuronide/sulfate conjugated EDCs were found in fish bile and liver than in the plasma and muscle, suggesting that the liver and bile played an important role in the metabolism and excretion of phenolic EDCs in fish. The calculated hazard quotient values were below 1 for each compound, implying low risk to human health by intake of edible fish.

Distribution and relationship between antimicrobial resistance genes and heavy metals in surface sediments of Taihu Lake, China

Heavy metals, pharmaceuticals, and other wastes released into the environment can significantly influence environmental antibiotic resistance. We investigated the occurrence of 22 antimicrobial resistance genes (ARGs) and 10 heavy metal concentrations, and the relationship between ARGs and heavy metals in surface sediment from seven sites of Lake Taihu. The results showed significant correlations (p < 0.05) between sediment ARG levels, especially for tetracycline and sulfonamides (e.g., tet(A), tet(D), tet(E), tet(O), sul1, sul2 and int-1) and specific heavy metals (Fe, Mn, Cr, Cu, Zn, among others) in the Lake. In the surface sediments, heavy metals showed an interaction with resistance genes, but the strength of interaction was diminished with increasing depth. For most of the heavy metals, the concentration of elements in the top sediments was higher than that in other depths. Tetracycline resistance genes (tet(A), tet(B), tet(D), tet(E) and tet(O), β-lactam resistance genes (SHV, TEM, CTX, OXA and OXY) and sulfonamide resistance genes (sulA, sul1, sul2, sul3 and int-1) were detected. They showed a trend which inferred a statistically significant increase followed by decreases in the relative abundance of these ARGs (normalized to 16S rRNA genes) with increasing depth. This study revealed that tet(A), tet(O), TEM, OXY, int-1, sul1 and sul3 were widespread in surface sediments with high abundance, indicating that these genes deserve more attention in future work.

The biodegradation of cefuroxime, cefotaxime and cefpirome by the synthetic consortium with probiotic Bacillus clausii and investigation of their potential biodegradation pathways

Cephalosporin residues in the environment are a great concern, but bioremediation options do exist. Bacillus clausii T reached a removal rate of 100% within 8 h when challenged with a mixture of cefuroxime (CFX), cefotaxime (CTX), and cefpirome (CPR). The co-culture of B. clausii T and B. clausii O/C displayed a higher removal efficiency for the mixture of CFX, CTX and CPR than a pure culture of B. clausii O/C. B. clausii T alleviated the biotoxicity of CFX and CPR. What's more, the biotoxicity of for CFX and CPR transformation products released by the co-culture of B. clausii T and B. clausii O/C was lower than that in pure cultures. Real-time PCR was applied to detect the changes in the expression levels of the relevant antibiotic-resistance genes of B. clausii T during CFX and CPR degradation. The results indicated that CFX and CPR enhanced the expression of the β-lactamase gene bcl1. Hydrolysis, deacetylation and decarboxylation are likely the major mechanisms of CTX biodegradation by B. clausii. These results demonstrate that B. clausii T is a promising strain for the bioremediation of environmental contamination by CFX, CTX, and CPR.

Bio-hybrid inorganic microparticles derived from CO2 for highly efficient and selective removal of antibiotics

BACKGROUND

Antibiotics, which are the most important medication in human history, have brought global concerns due to their potential risk to human health and environment by accelerating the development of drug-resistant bacteria, and accumulating in the food chain system. Among antibiotics, oxytetracycline (OTC) is widely used in aquaculture, and its potential risk of toxicity to human by bioaccumulation has been reported. Therefore, the effective removal of OTC is highly needed.

RESULTS

In this study, we report bio-hybrid inorganic microparticles (apt-mag-SiCC) for efficient capturing and facile magnet-based separation of oxytetracycline (OTC). These bio-hybrid inorganic microparticles are composed of magnetic separable silica coated calcium carbonate microparticles (mag-SiCC) derived from CO2, conjugated with oxytetracycline binding aptamers (OBA). These bio-hybrid inorganic microparticles were successfully synthesized, based on the characterization data obtained by SEM, FT-IR, EDAX, BET, and CLSM. About 6 μm sized bio-hybrid inorganic microparticles showed low non-specific adsorption to OTC and other molecules, and the selective capturing towards to the OTC in both buffer and tap water. Moreover, these bio-hybrid mineral microparticles were found to be stable, even after the repeated usages, maintaining the initial capturing efficiency.

CONCLUSION

Using the newly synthesized bio-hybrid inorganic microparticles, we could successfully capture OTC by facile magnet-based separation. With advantages of theses bio-hybrid inorganic microparticles such as easy fabrication, low-price, and environmental friendliness, this novel material could be utilized in the drinking water treatment, in vitro medicinal diagnostics, or in vitro removal of antibiotics lining out from the blood (blood purification).

Occurrence and distribution of antibiotics in mariculture farms, estuaries and the coast of the Beibu Gulf, China: Bioconcentration and diet safety of seafood

The occurrence, distribution, bioconcentration and diet safety via seafood consumption of 19 antibiotics were investigated in eight closed mariculture ponds, four estuaries, two nearshore areas and one offshore area from the Beibu Gulf. Seventeen, 16, 15 and 7 antibiotics were detected at total concentrations of 43.2 - 885 ng L^-1, 22.4 - 118 ng L^-1, 22.7 - 24.5 ng L^-1, and 1.81-3.23 ng L^-1 in the water of the above different areas, respectively. This indicates that the mariculture ponds are important sources of antibiotic pollution on the coast of the Beibu Gulf. Ten antibiotics were detected in feed samples with concentrations ranging from 0.03 to 95.4 ng g^-1, demonstrating the presence of antibiotics in the feed and/or residual antibiotics in the raw material of the feed. The field bioconcentration factors (BCFs) of the antibiotics calculated in different culture organisms ranged from 0.55 to 10,774 L kg^-1. The estimated daily intakes (EDIs) of sulphonamides, fluoroquinolones, macrolides and chloramphenicols via aquatic products were 19.8-105, 33.7-178, 34.9-186 and 6.9-37.1 ng d^-1, respectively. According to the acceptable daily intakes (ADIs) and maximum residue limits (MRLs) proposed by different organisations, these aquatic products (shrimp, crab and oyster) reached the standard of safe consumption and could not pose a health risk to humans. However, a potential elevated risk to humans may remain because of the occurrence of multiple antibiotics in the cultured organisms, particularly for sensitive populations, such as pregnant women, the elderly and children.

Personal care products in wild fish in two main Chinese rivers: Bioaccumulation potential and human health risks

Personal care products (PCPs) are widely applied in our daily life, however, little is known about their occurrence in wild fish. We investigated the bioaccumulation and potential risks of 24 PCPs in muscle and liver tissues of wild fish collected from two large rivers of Pearl and Yangtze Rivers in China. The results showed the detection of a total of 13 PCPs including 9 biocides, 2 synthetic musks and 2 benzotriazoles in at least one type of fish tissue from 12 fish species. The compounds with high detection frequencies (>50%) in fish muscle or liver tissues were N,N-diethyl-3-methylbenzamide, carbendazim, climbazole, miconazole (MCZ), methylparaben, propylparaben, triclosan (TCS), tonalide, galaxolide (HHCB) and 5-methyl-1H-benzotriazole (5-TT). Among biocides, synthetic musks and benzotriazoles, TCS, HHCB and benzotriazole showed the maximum concentrations of 79.5ng/g wet weight (ww), 299ng/g ww and 3.14ng/g ww, respectively, in muscle tissue, while MCZ, HHCB and 5-TT showed the maximum concentrations of 432ng/g ww, 2619ng/g ww and 54.5ng/g ww, respectively, in liver tissue. The median values of logarithm of bioaccumulation factors (BAF) for the detected 13 PCPs were ranged 0.8-3.35 in muscle and 0.85-4.58 in liver. The log BAF values of the PCPs displayed good linear relationships with log K_ow and log D_ow (pH-dependent K_ow). The health hazard assessment of 10 detected PCPs in the muscle indicated no appreciable risk to human via consumption of the wild fish.

Occurrence and risk assessment of fluoroquinolones and tetracyclines in cultured fish from a coastal region of northern China

Occurrence and levels of 11 fluoroquinolones (FQs) and four tetracyclines (TC) in 14 cultured fish species from a coastal city in the northern China were investigated. Five FQs (ofloxacin, enoxacin, ciprofloxacin, enrofloxacin, and sarafloxacin) and oxytetracycline were detected. Lower detection frequencies of antibiotics were observed in the marine fish. The concentrations of ΣFQs ranged from not detectable (nd) to 130 ng/g wet weight (ww) (median, 7.2 ng/g ww), and the concentration range of ΣTCs was nd to 200 ng/g ww (median, nd ng/g ww). The Chinese snakehead contained the highest concentrations of ΣFQs (130 ng/g ww) and the small yellow croaker accumulated the highest concentrations of ΣTCs (200 ng/g ww), respectively. Although the calculated estimated daily intakes (EDI) suggested that the consumption of these cultured fish from this region was not associated with significant human health risks, this study provides useful information that will be helpful in the appropriate antibiotic use in aquaculture. To our knowledge, this can be the first report on the occurrence and levels of antibiotics in cage-cultured marine fish from the Bohai Rim region, China.

Tissue distribution, bioaccumulation characteristics and health risk of antibiotics in cultured fish from a typical aquaculture area

The negative impacts of residual antibiotics in the environment on ecosystem and human health are big concerns. However, little information is available on the antibiotic bioaccumulation in aquaculture farms. In this study, the bioaccumulative potentials of 21 antibiotics in the plasma, bile, liver and muscle of cultured fish from a typical aquaculture area were systematically investigated.

RESULTS

indicated that antibiotic distribution in the cultured fish was mainly influenced by species and specific substances. The mean values of log bioaccumulation factors (Log BAFs) for the detected antibiotics were in the range of 0.43-3.70, 0.36-4.75, -0.31-4.48, and 0.23-4.33 in the fish plasma, bile, liver and muscle tissues, respectively. For grass carp, both ciprofloxacin and enrofloxacin showed high transportability from the plasma to the muscle and liver. The correlations of various antibiotic concentrations between the plasma and the other three tissues indicated that the concentrations of ciprofloxacin and enrofloxacin in the fish tissues could be predicted by their concentrations in the plasma. Based on the calculated hazard quotients, human health risk evaluation of antibiotic exposure by fish consumption indicated that the consumption of these cultured fish posed low risks to human health.

Sediment and salinity effects on the bioaccumulation of sulfamethoxazole in zebrafish (Danio rerio)

The dynamic distribution of a widely used antibiotic sulfamethoxazole between water, sediment and aquatic organisms (zebrafish) was studied in microcosms. Sulfamethoxazole concentrations in water were gradually reduced, while in sediment and zebrafish gradually increased, suggesting active adsorption and bioaccumulation processes occurring. The presence of sediment particles and their interactions with water reduced the bioaccumulation of sulfamethoxazole in zebrafish by 13-28%. The sediment of smaller particle size with more organic carbon content and higher surface area, adsorbed sulfamethoxazole more extensively and decreased its bioaccumulation most significantly. The effect became more severe with increasing salinity in water due to the salting out of sulfamethoxazole, resulting in 24-33% reduction in bioaccumulation. At equilibrium, the distribution of sulfamethoxazole in different phases was quantified, with most sulfamethoxazole being associated with water (97.3%), followed by sedimentary phase (2.7%) and finally zebrafish (0.05%). The findings provided important data for further research into antibiotics fate and bio-uptake in aquatic organisms, and subsequent ecotoxicity.

Wild small mammals as sentinels for the environmental transmission of antimicrobial resistance

Antimicrobial resistance (AMR) represents a serious threat to human health worldwide. We have tested the use of free-living small mammals (mice, voles and shrews) as sentinels of variation in the distribution of AMR in the environment and the potential for transmission from the natural environment to animal hosts. Escherichia coli isolated from the faeces of small mammals trapped at paired coastal and inland sites were tested for resistance to four antibiotics: trimethoprim, ampicillin, ciprofloxacin and cefotaxime. Coastal individuals were over twice as likely to carry AMR E. coli than inland individuals (79% and 35% respectively), and both between-site and between-species variation was observed. Animals from coastal populations also excreted increased numbers of AMR E. coli and a greater diversity of E. coli phylotypes, including human-associated pathogenic strains. Small mammals appear to be useful bioindicators of fine-scale spatial variation in the distribution of AMR and, potentially, of the risks of AMR transmission to mammalian hosts, including humans.

Antibiotic Pollution in Marine Food Webs in Laizhou Bay, North China: Trophodynamics and Human Exposure Implication

Little information is available about the bioaccumulation and biomagnification of antibiotics in marine food webs. Here, we investigate the levels and trophic transfer of 9 sulfonamide (SA), 5 fluoroquinolone (FQ), and 4 macrolide (ML) antibiotics, as well as trimethoprim in nine invertebrate and ten fish species collected from a marine food web in Laizhou Bay, North China in 2014 and 2015. All the antibiotics were detected in the marine organisms, with SAs and FQs being the most abundant antibiotics. Benthic fish accumulated more SAs than invertebrates and pelagic fish, while invertebrates exhibited higher FQ levels than fish. Generally, SAs and trimethoprim biomagnified in the food web, while the FQs and MLs were biodiluted. Trophic magnification factors (TMF) were 1.2-3.9 for SAs and trimethoprim, 0.3-1.0 for FQs and MLs. Limited biotransformation and relatively high assimilation efficiencies are the likely reasons for the biomagnification of SAs. The pH dependent distribution coefficients (log D) but not the lipophilicity (log K_OW) of SAs and FQs had a significant correlation (r = 0.73; p < 0.05) with their TMFs. Although the calculated estimated daily intakes (EDI) for antibiotics suggest that consumption of seafood from Laizhou Bay is not associated with significant human health risks, this study provides important insights into the guidance of risk management of antibiotics.

Biomimetic synthesis of Ag3PO4-NPs/Cu-NWs with visible-light-enhanced photocatalytic activity for degradation of the antibiotic ciprofloxacin

Cu-NWs/Ag₃PO₄-NPs can be used as photocatalysts under visible light irradiation and have high photocatalytic performance for degradation of CPFX.

Stress-related phenomena and detoxification mechanisms induced by common pharmaceuticals in alfalfa (Medicago sativa L.) plants

Pharmaceutically active compounds (PhACs) have been recently shown to exert phytotoxic effects. The present study explores the uptake, systemic translocation, and abiotic stress responses and detoxification mechanisms induced by the exposure of alfalfa plants grown in sand under greenhouse conditions to four common, individually applied PhACs (10μgL(-1)) (diclofenac, sulfamethoxazole, trimethoprim, 17a-ethinylestradiol) and their mixture. Stress physiology markers (lipid peroxidation, proline, H2O2 and NO content, antioxidant activity assays) and gene expression levels of key plant detoxification components (including glutathione S-transferases, GST7, GST17; superoxide dismutases, CuZnSOD, FeSOD; proton pump, H(+)-ATP, and cytochrome c oxidase, CytcOx), were evaluated. PhACs were detected in significantly higher concentrations in roots compared with leaves. Stress related effects, manifested via membrane lipid peroxidation and oxidative burst, were local (roots) rather than systemic (leaves), and exacerbated when the tested PhACs were applied in mixture. Systemic accumulation of H2O2 in leaves suggests its involvement in signal transduction and detoxification responses. Increased antioxidant enzymatic activities, as well as upregulated transcript levels of GST7, GST17, H(+)-ATPase and CytcOx, propose their role in the detoxification of the selected PhACs in plants. The current findings provide novel biochemical and molecular evidence highlighting the studied PhACs as an emerging abiotic stress factor, and point the need for further research on wastewater flows under natural agricultural environments.

Mesostructured silica and aluminosilicate carriers for oxytetracycline delivery systems

Oxytetracycline delivery systems containing various MCM-type silica and aluminosilicate with different antibiotic content were developed in order to establish the influence of the support structural and textural properties and aluminum content on the drug release profile. The antibiotic molecules were loaded into the support mesochannels by incipient wetness impregnation method using a drug concentrated aqueous solution. The carriers and drug-loaded materials were investigated by small- and wide-angle XRD, FTIR spectroscopy, TEM and N2 adsorption-desorption isotherms. Faster release kinetics of oxytetracycline from uncalcined silica and aluminosilicate supports was observed, whereas higher drug content led to lower delivery rate. The presence of aluminum into the silica network also slowed down the release rate. The antimicrobial assays performed on Staphylococcus aureus clinical isolates showed that the oxytetracycline-loaded materials containing MCM-41-type mesoporous silica or aluminosilicate carriers inhibited the bacterial development.

Biological fate and effects of propranolol in an experimental aquatic food chain

The aim of this study was to evaluate the trophic transfer of the β-blocker propranolol (PRP) in an experimental aquatic food chain involving the green algae Scenedesmus obliquus, the water flea Daphnia magna and the crucian carp Carassius auratus, as well as the metabolism and effects of PRP in the liver of crucian carp. After a 48 h PRP aqueous exposure for algae, with a subsequent 48 h dietary exposure for daphnia and an 8d dietary exposure for crucian carp, PRP was observed in each trophic level, despite significant bioaccumulation did not occur in daphnia and crucian carp. A portion of the absorbed PRP was metabolized by the crucian carp to N-desisopropylated propranolol, propranolol glucuronic acid, monohydroxylated propranolol, hydroxypropranolol glucuronide and dihydroxypropranolol glucuronide, which were similar to those in mammals. In addition, multiple biomarkers in the liver of crucian carp (7-ethoxyresorufin O-deethylase, EROD; 7-benzyloxyresorufin O-dealkylation, BROD; superoxide dismutase, SOD and malondialdehyde, MDA) were measured. BROD and MDA were not significantly affected by PRP, while EROD and SOD did change significantly during the 8d dietary exposure. This work indicated that the trophic transfer of PRP, resulting in biochemical perturbations of fish biological systems, should be a concern for the assessment of the environmental risks to aquatic food chains.

Effect of microalgal treatments on pesticides in water

The effect of the microalgae Chlorella vulgaris on a wide range of different pesticides in water was studied. Treatments included short-term exposure (1 h) to living and dead microalgal biomass and long-term exposure (4 days) to actively growing microalgae. The initial pesticide concentration was 63.5 ± 3.9 µg L(-1). There was no significant overall reduction of pesticides after short-term exposure. A significant reduction of the total amount of pesticides was achieved after the long-term exposure to growing microalgae (final concentration 29.7 ± 1.0 µg L(-1)) compared with the long-term control (37.0 ± 1.2 µg L(-1)). The concentrations of 10 pesticides out of 38 tested were significantly lowered in the long-term algal treatment. A high impact of abiotic factors such as sunlight and aeration for pesticide reduction was observed when the initial control (63.5 ± 3.9 µg L(-1)) and the long-term control (37.0 ± 1.2 µg L(-1)) were compared. The results suggest that water treatment using microalgae, natural inhabitants of polluted surface waters, could be further explored not only for removal of inorganic nutrients but also for removal of organic pollutants in water.