Development of an HPLC-PDA Method for the Simultaneous Estimation of Three Antibiotics in Pharmaceutical Formulations and Bovine Milk and Health Risk Assessment.

A simple new, rapid, sensitive, and cost-effective HPLC-PDA method was developed and validated for the determination of tetracycline (TC), oxytetracycline (OTC), and ciprofloxacin (CIP) simultaneously. Chromatographic separations were carried out using a reversed-phase Shim-pack GIS C18 column (4.60 × 250.00 mm; 5.00 µm) at 30°C. Oxalic acid (0.05 M), acetonitrile, and methanol were used as mobile phase under gradient elution conditions at the flow rate of 1.50 mL min-1. Detection wavelength was set at 330 nm. An aliquot of 20.00 µL solution was injected, and three drugs were eluted within 7.39 ± 0.05 min. As per ICH guidelines linearity, recovery, accuracy, precision, selectivity, specificity, sensitivity, stability, column efficiency, system suitability, and robustness were determined for the validation of the proposed method. Calibration curves were linear over a studied concentration range of 8.00 µg mL-1 with a correlation coefficient (r) of 0.999 for all drugs. Relative standard deviation (RSD) for intra- and interday precision was found less than 2.87% and 3.22%, respectively, indicating the method to be reproducible. The proposed method has been suitably applied for the estimation of TC, OTC, and CIP in pharmaceutical formulation and milk samples collected from local market in Bangladesh. Among 15 milk samples analyzed, most of the cases (more than 50%) TC, OTC, and CIP were detected above maximum residue levels (MRLs) though no significant toxicological effect on the health of consumers in the study area was identified.

Assessment of antibiotic residues in chicken meat.

Background: Nowadays veterinarians and poultry producers use antibiotics to increase growth rates, bird health, and feed efficiency, egg production, for preventative and therapeutic purposes, and to lessen the prevalence of poultry diseases. Most poultry producers have used a variety of antibiotics, either with or without veterinarian instruction. Although antibiotics are beneficial for the majority of their uses, their unauthorized use has resulted in residues accumulated in poultry products intended for human consumption which represents a serious risk to the general public that could be toxicological, microbiological, or immunological. Aim: This study aimed to the estimation of the residues of three major antimicrobials used in the intensive chicken-rearing systems in Egypt, namely Oxytetracycline (OTC), Gentamicin, and Ciprofloxacin. Moreover, the effect of cooking on such residues was investigated. Methods: A total of 100 chicken meat samples (breast, thigh, gizzard, liver, 25 each) were examined for detection of the aforementioned antimicrobials using the microbial inhibition assay and high-performance liquid chromatography (HPLC). Besides, samples containing the highest antimicrobial residues were examined for the effect of boiling for 30 minutes on such residues. Results: The obtained results revealed that 23%, 21%, and 17% of the examined samples were positive for OTC, gentamicin, and ciprofloxacin residues , respectively . Cooking (boiling) for 30 minutes showed a reduction of the antibiotic residue by 88.2%, 95.2%, and 31.3%, respectively. Conclusion: Antimicrobial residues were detected in the chicken meat parts retailed in Egypt. Cooking can reduce the antimicrobial residues at least in part.

Liver histopathological and oxidative stress assessment by a combination of formaldehyde and oxytetracycline in sea bass (Dicentrarchuslabrax L).

Background: Formaldehyde (FA) and oxytetracycline (OTC) are the chemicals commonly used in aquaculture to prevent or treat fish diseases due to protozoa, parasites, and bacteria. Aim: The goal of the present study is to assess the liver injury and oxidative stress induced by exposure of sea bass (Dicentrarchuslabrax L) to therapeutic doses of FA (200 ml.m-3) and OTC (40 g.m-3) under the same conditions being applied in intensive aquaculture systems in Tunisia. Methods: The liver histopathological survey was achieved after 5 and 10 days of exposure to FA, OTC separately or mixed. In parallel, liver catalase activity and malondialdehyde (MDA) were measured to assess oxidative stress. Results: Results showed that treatment with FA and OTC used alone or in combinations induced liver damage as measured by sinusoid dilatation, intensive vacuolization, blood congestion, and focal necrosis. Significant elevation in catalyze activity and MDA levels were also observed in liver homogenates by the treatment (p ≤ 005). Conclusion: Combined treatment induced higher effects suggesting the critical hazards associated with FA and OTC when released to the environment.

Physiological cost of Ulva lactuca under combined pressure of nutrient-oxytetracycline: One potential formation and maintenance mechanism of Ulva sp. green tide.

Environmental pollution is considered to lead to Ulva sp. green tides. Nevertheless, nutrients with high concentrations inhibit algae which may be damaged by antibiotics, such as OTC (oxytetracycline). Thus, Ulva sp. algae might pay a physiological cost under nutrient-OTC combined pressures. If this hypothesis is confirmed, Ulva sp. algae cannot easily form green tides, or green tides are difficult to maintain. To test this hypothesis, an uniform design experiment during which OTC, ammonia (NH4-N) and phosphate (PO4-P) were factors was set to simulate nutrient-OTC combined pressures, and Ulva lactuca was exposed to the pressures for 96 h. The TN (total nitrogen, CTN) or TP (total phosphorus, CTP) content in U. lactuca increased with increasing nutrient concentrations, as CTN = 21.206±1.000+ 1.227±0.418NH4-N × PO4-P (R2 = 0.282, p < 0.05) and CTP = 1.886±0.266+ 0.877±0.126PO4-P (R2 = 0.689, p < 0.05), respectively. The increase in dry weight of U. lactuca (Wdry) had a relationship with combined pressures, Wdry = 0.011±0.029 - 0.036±0.014PO4-P (R2 = 0.243, p < 0.05), i.e., the algal growth was inhibited by increasing PO4-P concentration. The SOD (Superoxide dismutase) activity (ASOD) was stimulated by OTC, as ASOD = 127.868±8.741+9.587±4.179 OTC (R2 = 0.193, p < 0.05). The contents of Chl a and b (Ca and Cb) were negatively affected by OTC or PO4-P with high concentration, as Ca = 0.566±0.042 - 0.024±0.022 OTC × PO4-P (R2 = 0.179, p < 0.05) and Cb = 0.512±0.043-0.044±0.020PO4-P (R2 = 0.180, p < 0.05). Thus, too high concentrations of PO4-P or OTC may hinder the formation and maintenance of Ulva sp. green tides.

In vitro assessment of the bacterial stress response and resistance evolution during multidrug-resistant bacterial invasion of the Xenopus tropicalis intestinal tract under typical stresses.

The intestinal microbiome might be both a sink and source of resistance genes (RGs). To investigate the impact of environmental stress on the disturbance of exogenous multidrug-resistant bacteria (mARB) within the indigenous microbiome and proliferation of RGs, an intestinal conjugative system was established to simulate the invasion of mARB into the intestinal microbiota in vitro. Oxytetracycline (OTC) and heavy metals (Zn, Cu, Pb), commonly encountered in aquaculture, were selected as typical stresses for investigation. Adenosine 5'-triphosphate (ATP), hydroxyl radical (OH·-) and extracellular polymeric substance (EPS) were measured to investigate their influence on the acceptance of RGs by intestinal bacteria. The results showed that the transfer and diffusion of RGs under typical combined stressors were greater than those under a single stressor. Combined effect of OTC and heavy metals (Zn, Cu) significantly increased the activity and extracellular EPS content of bacteria in the intestinal conjugative system, increasing intI3 and RG abundance. OTC induced a notable inhibitory response in Citrobacter and exerted the proportion of Citrobacter and Carnobacterium in microbiota. The introduction of stressors stimulates the proliferation and dissemination of RGs within the intestinal environment. These results enhance our comprehension of the typical stresses effect on the RGs dispersal in the intestine.

[Distribution Characteristics and Risk Assessment of Tetracycline Antibiotics (TCs) in Soil-Vegetable System with Soil Fertilized with Animal Manure].

The effects of antibiotic contamination on vegetable safety and the ecological risks of soil after returning livestock and poultry manure to the land require sufficient future attention. Tetracycline antibiotics (TCs) are often detected at high concentrations in livestock manure and vegetable production soils. Recently, pot experiments and field investigation methods have often been used to understand the effects of TCs contamination on the vegetable safety and ecological risks of soil, whereas field experiments are employed less frequently. This study investigated the distribution characteristics of TCs in the soil-vegetable system following manure application using a combination of pot and field experiments. The human health risks of the edible parts of Chinese flowing cabbage were assessed using the health risk quotient method based on the acceptable daily intake (ADI-HQ), and the ecological risks of TCs-contaminated soils were evaluated using the risk quotient method associated with the species sensitivity distribution model (SSD-RQ). The results showed that oxytetracycline (OTC) was the major type of TCs in Chinese flowering cabbage based on both the pot and field experiments. The maximum contents (dry weight) of OTC in the aboveground parts of the Chinese flowering cabbage for the pot and field experiments were 29.25 µg·kg-1 and 45.03 µg·kg-1, respectively, whereas those of their underground parts were 87.32 µg·kg-1 and 135.44 µg·kg-1, respectively. Meanwhile, higher contents of TCs were detected in Chinese flowering cabbage collected from the field experiment than those from the pot experiment. OTC was also the major type of TCs in soil from both the pot and field experiments, with their contents up to 604.30 µg·kg-1 and 1013.68 µg·kg-1, respectively. Higher residual contents of three TCs were detected in soils collected from the field experiment than those from the pot experiment. Under the experimental conditions, with the except that OTC in Chinese flowering cabbage from the field experiment would pose medium health risks (HQ>0.1) to children, the contents of three TCs in other treated Chinese flowering cabbage would pose low health risks (HQ ≤ 0.1) to adults and children. In the pot experiments, three TCs present in Chinese flowering cabbage would pose low health risks (HQ ≤ 0.1) to adults and children. Additionally, the TCs in soils with manure application from the pot and field experiments may have posed both moderate or high levels of ecological risks (HQ>0.1 or HQ>1). Therefore, the effects of antibiotic contamination on vegetable safety and their potential ecological risks on soil following manure fertilization need to be given special attention.

In Vitro and In Vivo Bone Regeneration Assessment of Titanium-Doped Waste Eggshell-Derived Hydroxyapatite in the Animal Model.

In this work, a titanium-doped hydroxyapatite (HAp) scaffold was produced from two different sources (natural eggshell and laboratory-grade reagents) to compare the efficacy of natural and synthetic resources of HAp materials on new bone regeneration. This comparative study also reports the effect of Ti doping on the physical, mechanical, and in vitro as well as in vivo biological properties of the HAp scaffold. Pellets were prepared in the conventional powder metallurgy route, compacted, and sintered at 900 °C, showing sufficient porosity for bony ingrowth. The physical-mechanical characterizations were performed by density, porosity evaluation, XRD, FTIR, SEM analysis, and hardness measurement. In vitro interactions were evaluated by bactericidal assay, hemolysis, MTT assay, and interaction with simulated body fluid. All categories of pellets showed absolute nonhemolytic and nontoxic character. Furthermore, significant apatite formation was observed on the Ti-doped HAp samples in the simulated body fluid immersion study. The developed porous pellets were implanted to assess the bone defect healing in the femoral condyle of healthy rabbits. A 2 month study after implantation showed no marked inflammatory reaction for any samples. Radiological analysis, histological analysis, SEM analysis, and oxytetracycline labeling studies depicted better invasion of mature osseous tissue in the pores of doped eggshell-derived HAp scaffolds as compared to the undoped HAp, and laboratory-made samples. Quantification using oxytetracycline labeling depicted 59.31 ± 1.89% new bone formation for Ti-doped eggshell HAp as compared to Ti-doped pure HAp (54.41 ± 1.93) and other undoped samples. Histological studies showed the presence of abundant osteoblastic and osteoclastic cells in Ti-doped eggshell HAp in contrast to other samples. Radiological and SEM data also showed similar results. The results indicated that Ti-doped biosourced HAp samples have good biocompatibility, new bone-forming ability, and could be used as a bone grafting material in orthopedic surgery.

Inhomogeneous antibiotic distribution in sediment profiles in anthropogenically impacted lakes: Source apportionment, fate drivers, and risk assessment.

Antibiotic residues in lake ecosystems have been widely reported; however, the vertical distribution of antibiotics in lake sediment profiles have rarely been examined. This study systematically revealed the vertical distribution pattern, sources, and risks of antibiotics in sediments of four typical agricultural lakes in central China. Nine of 33 target antibiotics were detected with a total concentration range of 39.3-18,250.6 ng/g (dry weight), and the order of average concentration was erythromycin (1447.4 ng/g) > sulfamethoxazole (443.7 ng/g) > oxytetracycline (62.6 ng/g) > enrofloxacin (40.7 ng/g) > others (0.1-2.1 ng/g). The middle-layer sediments (9-27 cm) had significantly higher antibiotic detected number and concentration than those in the top layer (0-9 cm) and bottom layer (27-45 cm) (p < 0.05). Correlation analysis showed that significant relationships existed between antibiotic concentrations and the octanol-water partition coefficients (Kow) of antibiotics (p < 0.05). Redundancy analysis indicated that Pb, Co, Ni, water content, and organic matter (p < 0.05) jointly affected the distribution of antibiotics in sediment profiles. Risk assessment showed that the highest potential ecological and resistance selection risks of antibiotics occurred in the middle-layer sediments, and oxytetracycline, tetracycline, and enrofloxacin had the most extensive potential risks in the sediment profiles. Additionally, the positive matrix factorization model revealed that human medical wastewater (54.5%) contributed more antibiotic pollution than animal excreta (45.5%) in sediment. This work highlights the inhomogeneous distribution of antibiotics in sediment profiles and provides valuable information for the prevention and control of antibiotic contamination in lakes.

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.

Occurrence and risk assessment of antibiotics in feces of elderly individuals in Shenzhen.

The occurrence of antibiotics in the feces of elderly individuals in Shenzhen, China, was investigated by monitoring 78 compounds to understand the adverse effects and its association with antibiotic residues in animal products collected from local markets. In total, 18 compounds belonging to 5 classes of antibiotics were identified in 74 of 140 fecal samples. Furthermore, 17.9% of the fecal samples contained at least two antibiotics, and 14.3% of the samples showed antibiotic concentrations higher than 100 µg/kg. Cephalothin exhibited the highest detection frequency (22.1%), followed by azithromycin (15.7%) and tilmicosin (12.9%). Oxytetracycline, norfloxacin, and azithromycin showed extremely high concentrations (> 1000 µg/kg). Eight antibiotics were detected in the animal products, with detection frequencies ranging from 4.8 to 40.0%. Five antibiotics exhibited similar detection frequencies and strong correlations between the human fecal and animal product samples. Health risk assessment based on hazard quotients showed that ciprofloxacin in animal products and human feces posed a medium and high risk, respectively. The hazard quotients of oxytetracycline, norfloxacin, and azithromycin in the feces were greater than 1, indicating a high health risk. These findings suggest that the elderly individuals were frequently exposed to antibiotics via the food chain and faced health risks posed by these antibiotics.

Degradation of oxytetracycline and doxycycline by ozonation: Degradation pathways and toxicity assessment.

Tetracyclines are one of the antibiotics widely employed worldwide and frequently detected in surface waters because of incomplete removal from wastewater treatment. Various advanced oxidation processes have been investigated for tetracyclines degradation and their transformation products (TPs) have recently gained more attention. Studies on ozonation are however seldom for the degradation of oxytetracycline (OTC) and doxycycline (DTC). In the present study, a lower O3 inlet gas concentration (4.67 ± 0.13 mg/L), supplied at a flow rate of 0.27 L/min, was shown to be more effective at removing OTC than the same dose of ozone applied at higher inlet gas concentration (up to 6.29 mg/L) over a shorter time at the same flow rate. The use of pCBA and t-BuOH indicated that ozone plays a more important role in the degradation of OTC than HO•. The DTC degradation was less efficient than for OTC, with 99 % removal requiring twice the amount of ozone. OTC had almost no inhibition of Vibrio fischeri, however, the inhibition ratio was increased to 37 % (5-min) and 46 % (15-min) within 1 min of ozonation. Contrastly, DTC had toxic effects on V. fischeri (inhibition rate5min of 84 %) and sustained toxicity in samples treated for up to 40-min. The observed toxicities after treatment could be explained by the identified TPs (26 TPs for OTC and 23 for DTC, some identified for the first time) and their quantitative structure-activity relationship analysis data. Several TPs showed toxic or extremely toxic predicted effects on fish, daphnid, and green algae, corresponding with the V. fischeri inhibition results. Among the possible degradation pathways, aromatic ring hydroxylation and ring-opening pathways could lead to the formation of TPs less harmful to the environment.

An exhaustive investigation on antibiotics contamination from livestock farms within sensitive reservoir water area: Spatial density, source apportionment and risk assessment.

Although the studies on antibiotic contamination are common at present, large-scale sampling studies drawing highly representative conclusions are still scarce. This study conducted a comprehensive investigation on a total of 1183 samples from 70 livestock farms within a sensitive area around reservoir waters. 45 types of antibiotics belonging to 5 different classes were monitored. This is the first analysis to comprehensively investigate the density distribution, source apportionment, ecological and health risk of antibiotics in an entire area of sensitive waters. The results showed that the layer manure samples had highest detection rate of antibiotics (0.0 %-96.1 %, average value = 30.7 %) followed by pig manure samples. Oxytetracycline had the highest concentration of 712.16 mg/kg in a pig manure sample. Different from using antibiotic concentration as a proxy for pollution level, the spatial density was calculated by averaging antibiotic concentration to area and converting different livestock to pig equivalent. The spatial density of pig equivalent can more realistically reflect the pollution caused by different breeds of livestocks. It was shown that the pig farms contributed higher to total antibiotic density than the layer and cattle farms did. After assessed, a few antibiotics (oxytetracycline, chlorotetracycline and tetracycline) have posed high ecological risks to soil around the farms. However, none of them caused hazard quotient (HQ) risk and carcinogenic risk (CR) to human health in the water of reservoir. Children were more likely to be at hazard risk than adults. Antibiotic mass fluctuation rules were analyzed along the chain (feed → livestock waste → soil → surface water). Feed, livestock waste and soil had similar diversity, but the antibiotic concentrations continued to decline, implying the possible sources of antibiotic residues were similar. Thus, it is important to reduce unnecessary antibiotic use to prevent the potential long-term risk of antibiotics.

Divergent Analyses of Genetic Relatedness and Evidence-Based Assessment of Therapeutics of Staphylococcus aureus from Semi-intensive Dairy Systems.

Use of antibiotics without following standard guidelines is routine practice in developing countries which is giving rise to genetic divergence and increased drug resistance. The current study analyzed genetic divergence and drug resistance by S. aureus and therapeutic efficacy of novel antibiotic combinations. The study revealed that 42.30% (minimum 20%-maximum 70%) of milk samples are positive for S. aureus. Study also revealed seven SNPs in the S. aureus nuc gene (c.53A>G, c.61A>G, c.73T>C, c.93C>A, c.217C>T, c.280T>C, and c.331T>A). Local isolates Staph-2 and Staph-3 were closely related to Bos taurus nuc gene (bovine S. aureus), while Staph-1 was closely related to Homo sapiens (human S. aureus) indicating shifting of host. Change of two amino acids and staphylococcal nuclease conserved domain was observed in all local isolates of S. aureus. The isoelectric points predicted by protParam of Staph-1, Staph-2, and Staph-3 proteins were 9.30, 9.20, and 9.20, respectively. The antibiotic susceptibility profile of S. aureus presented highest resistance against penicillin (46.67%) and glycopeptide (43.33%). When a single antibiotic regimen was adopted in a field trial, the highest efficacy was reported in the case of oxytetracycline (80%) while lowest was presented by azithromycin. Among antibiotics' combined regimen, the highest efficacy (80%) was presented by gentamicin with oxytetracycline: cefotaxime with vancomycin; and ciprofloxacin with vancomycin. The current study concluded rising percentages of S. aureus from dairy milk, proofs of genetic host shifts, and altered responses of in on field therapeutics.

Low-cost Posidonia oceanica bio-adsorbent for efficient removal of antibiotic oxytetracycline from water.

The presence of antibiotics as micro-contaminants in the water and aqueous environments is a health concern to humans and the ecosystem. Therefore, their elimination by adsorption to available and cheap materials in water treatment plants is a research topic of high relevance. The present paper reports on the adsorption behavior of oxytetracycline on a bio-adsorbent prepared from Posidonia oceanica; an abundant Mediterranean biomass. Characterization of the pretreated Posidonia biomaterial was achieved using several analyses such as Boehm acid-base titration method, pHPZC determination, and analysis techniques (FTIR, 13C CP-MAS NMR, optical microscopy, and TGA). The pHPZC occurred around pH 2.11. Posidonia biomaterial showed a fast and high uptake rate throughout the adsorption process, which is a definite advantage for analytical applications such as water decontamination. The experimental kinetic data fitted very rightly the pseudo-second-order kinetic model and the equilibrium uptake can adopt the bi-Langmuir isotherm model for all studied pH values which assumes adsorptions at the two localized sites. Maximum adsorption capacities of 11.8 mg∙g-1 and 4.4 mg∙g-1 for the two adsorption sites are reached at pH 6. The oxytetracycline adsorption process onto Posidonia bio-adsorbent is spontaneous (ΔadsG0 < 0), exothermic (ΔadsH0 < 0), and entropically favorable (ΔadsS0 > 0). The effect of pH on adsorption behavior and the thermodynamic parameters of adsorption are consistent with a possible origin of adsorption of oxytetracycline by means of hydrogen bonding interactions between surface hydroxyl and phenolic groups of the biomaterial and oxytetracycline. The proposed green and environmentally friendly biomaterial offers potential benefits as a bio-adsorbent in the remediation of aquatic environments contaminated by various organic materials.

Simulation and risk assessment of typical antibiotics in the multi-media environment of the Yangtze River Estuary under tidal effect.

Frequent human activities in estuary areas lead to the release of a large number of antibiotics, which poses a great threat to human health. However, there are very limited studies about the influence of the special natural phenomena on the occurrence and migration of antibiotics in the environment. In this study, we simulated the migration and transformation of six typical antibiotics, including oxytetracycline (OTC), tetracycline (TC), norfloxacin (NOR), ofloxacin (OFX), erythromycin (ETM), and amoxicillin (AMOX), in the environmental media from 2011 to 2019 in the Yangtze River Estuary, by using the level III multi-media fugacity model combined with the factor of tides. The simulation results showed that the most antibiotics mainly existed in soil and sediment while erythromycin were found mainly in water. The concentrations of antibiotics in air, freshwater, seawater, groundwater, sediment, and soil were 10-23-10-25, 0.1-12 ng/L, 0.02-7 ng/L, 0.02-16 ng/L, 0.1-13 ng/g, and 0.1-15 ng/g respectively. Sensitivity analysis showed that the degradation rate (Km) and the soil-to-water runoff coefficient (Kl) were important model parameters, indicating that hydrodynamic conditions had a significant impact on the migration of antibiotics in various environmental phases in estuarine areas. Tide can enhance the exchange between water bodies and cause the transformation of the antibiotics from freshwater to seawater and groundwater, which improved the accuracy of the model, especially the seawater and soil phase. Risk assessments showed that amoxicillin, erythromycin, ofloxacin, and norfloxacin posed a threat to the estuarine environment, but the current source of drinking water did not affect human health. Our findings suggested that, when one would like to exam the occurrence and migration of antibiotics in environment, more consideration should be given to the natural phenomena, in addition to human activities and the nature of antibiotics.

Field study on loss of tetracycline antibiotics from manure-applied soil and their risk assessment in regional water environment of Guangzhou, China.

Tetracycline antibiotics (TCs) introduced into agricultural fields via manure application tend to accumulate in soils and further reach water environments via surface runoff and leachate, posing potential risks to regional water environment. This study investigated the loss of tetracycline (TC), oxytetracycline (OTC), and chlortetracycline (CTC) in surface runoff and leachate samples collected from a vegetable farmland with manure application in Guangzhou, South China. A risk assessment method was constructed for evaluating the ecological and health risks of manure-associated antibiotics released from soil into water environment. The results showed that the concentrations of three TCs in surface runoff, 30-cm leachate, and 60-cm leachate after the first rainfall event were 2.79-35.97, 1.71-18.44, and 0.4-2.66 µg/L, respectively, which all decreased with sampling depth and the time after rainfall events. Up to 0.13% of TCs were transported into the surface water through surface runoff, while less than 0.01% of TCs were transported into the groundwater through leachate at 60 cm. OTC had a higher total mass percentage (0.13%) into surface water via runoff than CTC (0.11%) and TC (0.07%) likely due to its smallest Kd value and largest input mass. Based on loss percentages, their predicted environmental concentrations (PEC) ranged from 4.87 (TC) to 16.91 (OTC) ng/L in regional surface water and 1.42 (TC) to 5.20 (CTC) ng/L in regional groundwater. The risk assessment based on PEC results suggested non-negligible health risk (HQ > 1.0 × 10-6) and low ecological risk (RQ < 0.1) in both regional surface water and groundwater, drawing concerns on the potential hazards of TCs released from manure-amended soil into water environments.

Sulfonamide and tetracycline in landfill leachates from seven municipal solid waste (MSW) landfills: Seasonal variation and risk assessment.

Antibiotics have received increased attention as emerging contaminants due to their toxicity and potential risk. Landfills serve as one of the important reservoirs of antibiotics. The antibiotics in landfills leaching to nearby environment by leachate may threat ecosystem health. The present study aimed to evaluate the levels of tetracyclines (TCs) and sulfonamides (SAs) in seven Chinese Municipal Solid Waste (MSW) landfill leachates over two years (2017-2018). Seven target antibiotics, TC, oxytetracycline (OTC), doxycycline (DXC), sulfonamide sulfadiazine (SD), sulfamerazine (SM), sulfamethazine (SMX), and sulfamethoxazole (SMT), were detected in 56 landfill leachate samples. Among these, SMT had the highest mean concentration at 654 ng/L (n = 45), followed by OTC (219.58 ng/L, n = 47), and SD (209.98 ng/L, n = 49). The temporal trend showed that antibiotic concentrations were higher in 2017 than in 2018. Furthermore, physicochemical properties were significantly correlated with SAs (p < 0.05), whereas no significant correlation was found for TCs. Seasonal variation analysis revealed that antibiotic levels were higher in spring and winter compared to summer and fall seasons, which might be attributed to the higher waterfall levels in these seasons. Risk assessment revealed that SAs (SM, SMX, SMT) are associated with high risk, and the RQs follow the order of: SMX > SMT > SM. In contrast, TCs had insignificant risk. The findings of this two-year comprehensive monitoring project have produced positive results regarding antibiotic pollution at landfill sites, which can be applied to antibiotics management in landfill and further ensure public health.

Health risk assessment of antimicrobial residues in sheep carcasses marketed in Kuwait.

A total of 450 samples comprising 150 each of muscles, livers and kidneys were collected from 150 sheep carcasses in Kuwait and tested by both Rapid Premi®Test kits for rapid detection of antimicrobial-positive samples, and the High-performance liquid chromatography (HPLC) for residual determination of amoxicillin, tetracycline, oxytetracycline, and tylosin. Premi test revealed that 82%, 64% and 100% of the muscle, liver and kidney samples examined, respectively were positive for antimicrobials. HPLC analysis revealed mean concentrations (µg/kg) of 45.26, 148.17, 103.18, and 71.80 for amoxicillin, oxytetracycline, tetracycline, and tylosin respectively in muscles; 64.43, 263.15, 177.04, and 112.94, respectively in livers; and 53.12, 368.21, 196.40, and 138.63, respectively in kidneys. Although many samples exceeded the maximum residue limit (MRL) of Codex Alimentarius, the assessment of dietary exposure to the antimicrobials tested through consumption of sheep meat and organs did not constitute any health hazards in the different age groups of Kuwaiti population.

[Pollution Characteristics and Risk Assessment of Tetracycline Antibiotics in Farmland Soil in Yinchuan].

A total of 43 surface soil samples were collected from Yinchuan farmland and high performance liquid chromatography(HPLC) was used to measure the concentrations of oxytetracycline(OTC), tetracycline(TC), chlortetracycline(CTC), and doxycycline(DOC). The pollution characteristics and spatial distribution of TC were further analyzed using spatial Kriging interpolation, and the ecological risks of OTC, TC, CTC, and DOC in farmland soils were also assessed. Tetracycline antibiotics were detected in all the soil samples at concentrations ranging from 40.68 to 1074.42 µg·kg-1 and an average of 462.24 µg·kg-1. The average proportions were ranked ΣTCs: CTC(69.26%) > OTC(16.34%) > TC(12.86%) > DOC(1.54%), and CTC pollution was the most serious among. The space tended to be high in the middle and low in the periphery, but the concentrations of TC were highest in the northwest. The average contents of ΣTCs in different soils was ranked as follows:vegetable field(596.01 µg·kg-1) > pasture(487.04 µg·kg-1) > cultivated land(437.52µg·kg-1) > garden plot(404.99 µg·kg-1). The average risk values of OTC, TC, CTC, and DOC in farmland soils were 0.14, 0.69, 0.14, and 1.02, respectively. TC and DOC represented a high level of risk in 23.26% and 6.98% of the samples, respectively, which requires particular attention.

Photodegradation of Antibiotics by Noncovalent Porphyrin-Functionalized TiO2 in Water for the Bacterial Antibiotic Resistance Risk Management.

Antibiotics represent essential drugs to contrast the insurgence of bacterial infections in humans and animals. Their extensive use in livestock farming, including aquaculture, has improved production performances and food safety. However, their overuse can implicate a risk of water pollution and related antimicrobial resistance. Consequently, innovative strategies for successfully removing antibiotic contaminants have to be advanced to protect human health. Among them, photodegradation TiO2-driven under solar irradiation appears not only as a promising method, but also a sustainable pathway. Hence, we evaluated several composite TiO2 powders with H2TCPP, CuTCPP, ZnTCPP, and SnT4 porphyrin for this scope in order to explore the effect of porphyrins sensitization on titanium dioxide. The synthesis was realized through a fully non-covalent functionalization in water at room conditions. The efficacy of obtained composite materials was also tested in photodegrading oxolinic acid and oxytetracycline in aqueous solution at micromolar concentrations. Under simulated solar irradiation, TiO2 functionalized with CuTCPP has shown encouraging results in the removal of oxytetracycline from water, by opening the way as new approaches to struggle against antibiotic's pollution and, finally, to represent a new valuable tool of public health.