Antibiotic residues in the cirata reservoir, Indonesia and their effect on ecology and the selection for antibiotic-resistant bacteria.

Antibiotic residues, their mixture toxicity, and the potential selection for antibiotic-resistant bacteria could pose a problem for water use and the ecosystem of reservoirs. This study aims to provide a comprehensive understanding of the occurrence, concentration, distribution, and ecological risks associated with various antibiotics in the Cirata reservoir, Indonesia. In our water and sediment samples, we detected 24 out of the 65 antibiotic residues analyzed, revealing a diverse range of antibiotic classes present. Notably, sulphonamides, diaminopyrimidine, and lincosamides were frequently found in the water, while the sediment predominantly contained tetracyclines and fluoroquinolones. Most antibiotic classes reached their highest concentrations in the water during the dry season. However, fluoroquinolones and tetracyclines showed their highest concentrations in the water during the wet season. Ecotoxicological risk assessments indicated that the impact of most antibiotic residues on aquatic organisms was negligible, except for fluoroquinolones. Looking at the impact on cyanobacteria, however, varying risks were indicated, ranging from medium to critical, with antibiotics like sulfamethoxazole, ciprofloxacin, norfloxacin, and lincomycin posing substantial threats. Among these, ciprofloxacin emerged as the antibiotic with the strongest risk. Furthermore, fluoroquinolones may have the potential to contribute to the selection of antibiotic-resistant bacteria. The presence of mixtures of antibiotic residues during the wet season significantly impacted species loss, with Potentially Affected Fraction of Species (msPAF) values exceeding 0.75 in almost 90% of locations. However, the impact of mixtures of antibiotic residues in sediment remained consistently low across all locations and seasons. Based on their occurrences and associated risks, 12 priority antibiotic residues were identified for monitoring in the reservoir and its tributaries. Moreover, the study suggests that river inflow serves as the most significant source of antibiotic residues in the reservoir. Further investigations into the relative share attribution of antibiotic sources in the reservoir is recommended to help identify effective interventions.

Impact of graded doses of enrofloxacin on the safety and biological responses of Nile tilapia Oreochromis niloticus.

The cultivation of tilapias, the third most farmed fish group globally, has been rapidly growing, especially in Southeast Asia. This surge in tilapia farming intensification has led to increased use of antibiotics to control bacterial diseases. This study investigated the safety implications of administering graded doses of enrofloxacin (ENF) at 0 (control), 10, 30, 50 and 100 mg/kg biomass/day orally to Oreochromis niloticus. The 43-day study comprised 7 days of pre-dosing, 15 days of ENF-dosing, and a 21-day recovery period with a periodical assessment of the biological responses of fish. The results revealed that the overdosed groups experienced up to 21% reduction in feed consumption, 11% mortalities, and adverse impacts on hematology, including a decrease in erythrocytes, and monocytes and an increase in leukocytes, thrombocytes, lymphocytes, and neutrophils. Haematological indices like mean corpuscular volume and mean corpuscular hemoglobin decreased, while mean corpuscular hemoglobin concentration increased. The plasma biochemical parameters including glucose and liver and kidney enzymes unveiled a significant dose- and time-dependent increase, while calcium and chloride levels decreased. Erythrocytes displayed several erythrocyte cellular and nuclear abnormalities. The frequency of micronucleus increased with dose and time, suggesting potential genotoxicity of ENF. Additionally, a dose-dependent increase in residues in the tissues with the highest accumulation in muscle was documented. Nevertheless, the recovery of the measured parameters upon dose termination indicated that the ENF-induced alterations are reversible. The study affirmed the safety of ENF at the recommended dose (10 mg) in O. niloticus and their adoptive responses to higher doses.

Detection of Multiple Antibiotic Residues in Turkish Pine and Blossom Honeys Using LC-MS/MS Method.

Due to the high demand for honey, beekeepers often feed the bees with antibiotics to protect honeybees against illnesses; the determination of veterinary drugs and their residues in bee products especially in honey is gaining importance. In this study, commercially available 15 different brands, a total of 22 honey (14 blossoms and 8 pines) samples obtained from 5 chain supermarkets in the city of Bingöl and Diyarbakir, Turkey were analysed for 29 antibiotic residues. These antibiotics belong to 10 different categories, including tetracyclines, aminoglycosides, macrolides, sulfonamides, fluoroquinolones, benzimidazoles, anthelmintic, amphenicols, quinolines, and oxazolidines. For the qualitative and quantitative determination of the antibiotics, a triple quadrupole liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used. A total of 10 out of 22 honey (8 blossom, 57.14 % and 2 pine, 25 %) samples were found to be positive for antibiotics. Among the tested antibiotics, tetracycline, dihydrostreptomycin, streptomycin, erythromycin, and sulfadimidine were detected in the honey samples. Dihydrostreptomycin and sulfadimidine were detected in 6 samples, erythromycin was determined in 4 samples, streptomycin was found in 2 samples, and lastly, tetracycline was detected only in one sample. The highest and the lowest concentrations of antibiotics detected in the samples were dihydrostreptomycin and erythromycin found at the amount of 992.58 µg/kg and 0.77 µg/kg respectively. The proposed method was validated with a limit of quantification (LOQ) and limit of detection (LOD) ranging between 0.42 and 3.22 µg /kg and 0.13-0.97 µg /kg respectively. Good linearities were also achieved ranging between R2 =0.987 and 0.999.

Silver Nanoparticle-Embedded Hydrogels for Electrochemical Sensing of Sulfamethoxazole Residues in Meat.

A disposable electrochemical sensor based on silver nanoparticle-embedded cellulose hydrogel composites was developed for sensitive detection of sulfamethoxazole residues in meat samples. Scanning electron microscopy confirmed the porous structure of the cellulose matrix anchored with 20-50 nm silver nanoparticles (AgNPs). Fourier transform infrared spectroscopy and X-ray diffraction verified that the metallic AgNPs coordinated with the amorphous cellulose chains. At an optimum 0.5% loading, the nanocomposite sensor showed a peak-to-peak separation of 150 mV, diffusion-controlled charge transfer kinetics, and an electron transfer coefficient of 0.6 using a ferro/ferricyanide redox probe. Square-wave voltammetry was applied for sensing sulfamethoxazole based on its two-electron oxidation peak at 0.72 V vs. Ag/AgCl in Britton-Robinson buffer of pH 7.0. A linear detection range of 0.1-100 µM sulfamethoxazole was obtained with a sensitivity of 0.752 µA/µM and limit of detection of 0.04 µM. Successful recovery between 86 and 92% and less than 6% RSD was achieved from spiked meat samples. The key benefits of the proposed disposable sensor include facile fabrication, an antifouling surface, and a reliable quantification ability, meeting regulatory limits. This research demonstrates the potential of novel cellulose-silver nanocomposite materials towards developing rapid, low-cost electroanalytical devices for decentralized on-site screening of veterinary drug residues to ensure food safety.

Computational prediction of retention times of veterinary antibiotics obtained by liquid chromatography-mass spectrometry.

BACKGROUND: Veterinary antibiotics are chemical compounds used to kill or inhibit the growth of pathogenic bacteria associated with animal diseases. These molecules can be defined by their retention times (tR) in liquid chromatography-mass spectrometry (LC-MS). One strategy to predict the tR of new veterinary antibiotics is the development of predictive quantitative structure-property relationships (QSPRs), which were used in this study. RESULTS: A database of 122 antibiotics was selected in which the tR was measured using a Hypersil GOLD column. An optimal three-feature model was developed by integrating the unsupervised variable reduction, replacement method variable subset selection, and multiple linear regression. The negligible differences among the coefficient of determination and the root-mean-square error for the training set (R2 = 0.902 and RMSEC = 0.871) and test set (Q2 = 0.854 and RMSEP = 1.064) indicate a stable and predictive model. In a further step, a more in-depth explanation of the mechanism of action of each descriptor in predicting the tR is provided, with the construction of the theoretical chemical space for accurate predictions of new antibiotics. CONCLUSION: The in silico model developed in this work identified three molecular descriptors associated with aqueous solubility, octanol-water partition coefficient, and the presence of negative and lipophilic atom pairs. The QSPR developed here could be implemented by agricultural and food chemists to identify and monitor existing and new antibiotics within the framework of LC-MS. The computational model was developed in accordance with five principles outlined by the Organization for Economic Co-operation and Development. © 2024 Society of Chemical Industry.

Similarities of Geobacillus bacteria based on their profiles of antimicrobial susceptibility in milk samples.

The genus Geobacillus is composed of thermophilic bacteria that exhibit diverse biotechnological potentialities. Specifically, Geobacillus stearothermophilus is included as a test bacterium in commercial microbiological inhibition methods, although it exhibits limited sensitivity to aminoglycosides, macrolides, and quinolones. Therefore, this article evaluates the antibiotic susceptibility profiles of five test bacteria (G. stearothermophilus subsp. calidolactis C953, Geobacillus thermocatenulatus LMG 19007, Geobacillus thermoleovorans LMG 9823, Geobacillus kaustophilus DSM 7263 and Geobacillus vulcani 13174). For that purpose, the minimum inhibitory concentrations (MICs) of 21 antibiotics were determined in milk samples for five test bacteria using the radial diffusion microbiological inhibition method. Subsequently, the similarities between bacteria and antibiotics were analyzed using cluster analysis. The dendrogram of this multivariate analysis shows an association between a group formed by G. thermocatenulatus and G. stearothermophilus and another by G. thermoleovorans, G. kaustophilus and G. vulcani. Finally, future microbiological methods could be developed in microtiter plates using G. thermocatenulatus as test bacterium, as it exhibits similar sensitivities to G. stearothermophilus. Conversely, G. vulcani, G. thermoleovorans and G. kaustophilus show higher MICs than G. thermocatenulatus.

Development and validation of a sensitive ultra-high-performance liquid chromatography-tandem mass spectrometry method for quantitative analysis of bambermycin in livestock and aquatic products: Implications for food safety control and regulatory enforcement.

A sensitive and accurate analytical method was developed and validated to detect bambermycin, a commonly used antibiotic in animal feed and livestock. The presence of bambermycin residues in food products can pose health risks to consumers, emphasizing the need for a sensitive and accurate analytical method. A reversed-phase analytical column was utilized with a mobile phase comprising 0.005 mol/L ammonium acetate in 5% acetonitrile (A) and 0.005 mol/L ammonium acetate in 95% acetonitrile (B) to achieve effective chromatographic separation. Quantitative determination of bambermycin in various samples, including beef, pork, chicken, milk, eggs, flatfish, eel, and shrimp, was performed using ultra-high-performance liquid chromatography-tandem mass spectrometry. Sample extraction involved a mixture of methanol and a 25% ammonium hydroxide solution, followed by low-temperature purification and phospholipid removal utilizing a Phree cartridge. The method exhibited a satisfactory recovery rate ranging from 69% to 100%. Validation results demonstrated the reliability, robustness, and accuracy of the method, exhibiting good linearity, precision, and recovery. This validated method can be applied for routine analysis of bambermycin residues, assisting in the development of effective monitoring and control measures to ensure the safety of livestock and aquatic products.

Oxytetracycline changes the behavior of zebrafish larvae by inhibiting NMDA receptors.

Oxytetracycline (OTC), a tetracycline antimicrobial, is one of the antimicrobial drugs frequently used in the aquaculture and livestock industries. Due to its extensive usage and emissions, OTC has been identified as a significant new emerging pollutant (EP) in a number of environments. OTC frequently causes toxic effects on the central nervous system, but it can be challenging to monitor, and it is still unclear how these toxicities are caused. We used bioinformatic analysis techniques to screen for OTC targets and discovered that NMDA receptors are potential targets of OTC neurotoxicity. To confirm this finding, we exposed zebrafish embryos to 5 mg/L OTC-containing rearing water from 2-hour post fertilization (hpf) to 8-day post fertilization (dpf), performed spontaneous movement and light-dark stimulation assays at 6 and 8 dfp, and discovered that OTC inhibited locomotor activity and attenuated anxiety-like responses in zebrafish larvae. Meanwhile, the qPCR and immunofluorescence staining results suggested that OTC inhibited the expression of multiple subtypes of NMDA receptors (grin1a, grin1b, grin2bb, grin2ca) and induced apoptosis in the brains of zebrafish embryos. Simultaneous administration of NMDA, an NMDA receptor agonist, completely antagonized the inhibitory neurobehavioral changes in zebrafish larvae, as well as the downregulation of N-methyl-D-aspartate (NMDA) receptor expression and apoptosis in the embryonic brains caused by OTC exposure. In conclusion, OTC exhibited significant inhibitory neurobehavioral toxicity in zebrafish larvae during early development, which may be dependent on its suppression of NMDA receptor activity and expression. Furthermore, OTC-induced neurodevelopmental toxicity may be associated with NMDA receptor-regulated neuronal apoptosis.

Towards One Health surveillance of antibiotic resistance: characterisation and mapping of existing programmes in humans, animals, food and the environment in France, 2021.

BackgroundInternational organisations are calling for One Health approaches to tackle antimicrobial resistance. In France, getting an overview of the current surveillance system and its level of integration is difficult due to the diversity of surveillance programmes.AimThis study aimed to map and describe all French surveillance programmes for antibiotic resistance (ABR), antibiotic use (ABU) and antibiotic residues, in humans, animals, food and the environment, in 2021. Another objective was to identify integration points, gaps and overlaps in the system.MethodsWe reviewed the literature for surveillance programmes and their descriptions. To further characterise programmes found, semi-directed interviews were conducted with their coordinators.ResultsIn total 48 programmes in the human (n = 35), animal (n = 12), food (n = 3) and/or the environment (n = 1) sectors were identified; 35 programmes focused on ABR, 14 on ABU and two on antibiotic residues. Two programmes were cross-sectoral. Among the 35 ABR programmes, 23 collected bacterial isolates. Bacteria most targeted were Escherichia coli (n = 17 programmes), Klebsiella pneumoniae (n = 13), and Staphylococcus aureus (n = 12). Extended-spectrum beta-lactamase-producing E. coli was monitored by most ABR programmes (15 of 35) in humans, animals and food, and is a good candidate for integrated analyses. ABU indicators were highly variable. Areas poorly covered were the environmental sector, overseas territories, antibiotic-resistant-bacterial colonisation in humans and ABU in companion animals.ConclusionThe French surveillance system appears extensive but has gaps and is highly fragmented. We believe our mapping will interest policymakers and surveillance stakeholders. Our methodology may inspire other countries considering One Health surveillance of ABR.

Synthetic organic antibiotics residues as emerging contaminants waste-to-resources processing for a circular economy in China: Challenges and perspective.

Synthetic antibiotics have been known for years to combat bacterial antibiotics. But their overuse and resistance have become a concern recently. The antibiotics reach the environment, including soil from the manufacturing process and undigested excretion by cattle and humans. It leads to overburden and contamination of the environment. These organic antibiotics remain in the environment for a very long period. During this period, antibiotics come in contact with various flora and fauna. The ill manufacturing practices and inadequate wastewater treatment cause a severe problem to the water bodies. After pretreatment from pharmaceutical industries, the effluents are released to the water bodies such as rivers. Even after pretreatment, effluents contain a significant number of antibiotic residues, which affect the living organisms living in the water bodies. Ultimately, river contaminated water reaches the ocean, spreading the contamination to a vast environment. This review paper discusses the impact of synthetic organic contamination on the environment and its hazardous effect on health. In addition, it analyzes and suggests the biotechnological strategies to tackle organic antibiotic residue proliferation. Moreover, the degradation of organic antibiotic residues by biocatalyst and biochar is analyzed. The circular economy approach for waste-to-resource technology for organic antibiotic residue in China is analyzed for a sustainable solution. Overall, the significant challenges related to synthetic antibiotic residues and future aspects are analyzed in this review paper.

Occurrence and ecological risk assessment of antibiotic residues in urban wastewater discharged into the coastal environment of the Persian Gulf (the case of Bandar Abbas).

This is the first attempt to detect antibiotic residues released into the Persian Gulf marine environment. In particular, this study quantifies and assesses the ecological risks of amoxicillin (AMX) and azithromycin (AZM) residues in wastewater outfalls from Bandar Abbas, one of the major coastal cities in southern Iran. The wastewater effluent samples were collected from two main wastewater discharging stations, Gursuzan and Suru, between December 2020 and February 2021. High-performance liquid chromatography (HPLC) analysis revealed the average concentration (± 95% CL) of AMX were 460 ± 230.0 µg L-1 and 280 ± 100.6 µg L-1 in Gursuzan and Suru stations. Mean AZM concentrations were also 264 ± 10.59 µg L-1 and 295 ± 89.75 µg L-1 in these stations, respectively. Pooled data indicated that there are 335.17 ± 105.11 and 288.17 ± 37.94 µg of AMX and AZM residues in the wastewater per liter. The values of potential ecological risk, hazard quotient (HQ), were extensively above 10 (AMX: 90,586.5 and AZM: 5541.7) which suggest that these substances have a high health risk for the ecosystem and public. Given that Bandar Abbas wastewater treatment plant (WWTP) outlets are discharged at about 500 to 700 L s-1, the daily maximum potential AMX and AZM released were estimated to be 19.05 (± 0.283) × 103 and 14.74 (± 0.113) × 103 g day-1, respectively (α = 0.05). Our findings show that there is a concerning volume of antibiotic residues released into the northern Persian Gulf, and hence urgent policies and actions are necessary to reduce this pollution.

Determination of antibiotic residues in bovine milk by HPLC-DAD and assessment of human health risks in Northwestern Himalayan region, India.

Antibiotic residues in milk affects economics of dairy industry and poses health risks to consumers. This study aimed to assess health risks associated with presence of antibiotics in 173 raw and pasteurized milk sampled from northwestern Himalayan state of India. The oxytetracycline and amoxicillin were quantitatively analyzed using validated HPLC-DAD. Methods were selective and linear (R2 > 0.99) with decision limit and detection capability of 1.4 and 0.9 µg/kg and 2.5 and 1.5 µg/kg for oxytetracycline and amoxicillin, respectively. Recoveries ranged from 88-98% with relative standard deviation < 10%. Oxytetracycline and amoxicillin were detected in 8.1% and 1.2% samples, with 1.7% and 1.2% samples exceeding the tolerance limits, respectively. Health risk assessment revealed that estimated daily intakes of antibiotics through milk were lower than acceptable daily intakes (ADI). However, children might receive 9-21% of determined ADI through milk consumption only. Therefore, continuous, sub-therapeutic and long term exposures of antibiotics can pose health risk to consumers. Hence, current findings elucidate the need for vigilant monitoring of antibiotics accompanied by educational programs to farmers for adopting good husbandry practices and adherence to withdrawal periods to meet the expectations of food safety and safeguarding human health. SUPPLEMENTARY INFORMATION: The online version of this article contains supplementary material available at (10.1007/s13197-021-04988-8).

Multi-residue method for the detection of 40 ß-lactam-antibiotics in vaccines by LC-MS/MS.

Antibiotics are widely used to treat bacterial infections during the process of vaccine production and storage resulting in antibiotic residues that can cause serious harm. A simple and sensitive method for residue analysis of 40 ß-lactam antibiotics was developed and validated for vaccines including inactivated enterovirus 71 vaccine (Vero cells), recombinant hepatitis B vaccine (Saccharomyces cerevisiae), and live attenuated varicella vaccine using liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI- MS/MS). Samples were prepared with acetonitrile as the protein precipitant. LC separation was performed on a C18 column. These analytes were determined by LC-MS/MS operating multiple-reaction monitoring (MRM) scans in positive mode. The ranges for limits of detection (LOD) and quantification (LOQ) were as follows: 0.02-4 ng/dose (S/N ≥ 3) and 0.04-10 ng/dose in inactivated enterovirus 71 vaccine (Vero cells) and recombinant hepatitis B vaccine (Saccharomyces cerevisiae), 0.04-16 ng/dose and 0.2-20 ng/dose in live attenuated varicella vaccine. The ranges of recoveries of all antibiotics were 84.5%-108.2% in inactivated enterovirus 71 vaccine (Vero cells), 73%-108% in recombinant hepatitis B vaccine (Saccharomyces cerevisiae), and mostly 68.2%-107.8% in live attenuated varicella vaccine. This method simultaneously offers qualitative and quantitative analysis of multi-antibiotics in vaccines, which improves vaccine safety.

Distribution, abundance, and risk assessment of selected antibiotics in a shallow freshwater body used for drinking water, China.

With rapid improvements in industrialization and urbanization, antibiotics are now extensively used to prevent and treat human and animal diseases and husbandry and aquaculture. Some research has been conducted to assess the environmental distribution and risk level of antibiotics, but their distribution remains largely uncharacterized. Thus, this study investigated the distribution and abundance of 39 antibiotics belonging to five groups, and their associated risks in surface water around Luoma Lake in the north of Jiangsu province, China. Nineteen antibiotics were detected, at a detection frequency (DF) ranging from 2.27% to 100%. The total antibiotics (ΣABs) concentrations ranged from 34.91 to 825.93 ng/L, with a median concentration of 195.45 ng/L. Among these antibiotics, chlortetracycline (DF: 100%; median: 172.02 ng/L) was the dominant antibiotic, accounting for a median percentage of 91.0% of ΣABs concentrations. Spearman rank correlation method found a significant correlation between clindamycin (DF: 72.7%; median: 2.01 ng/L) and lincomycin (DF: 79.5%; median: 4.58 ng/L). The ecological risk quotient (RQ) values for two out of 44 sampling sites were higher than 1, indicating a high risk; 11.4% of the RQ values fell between 0.1 and 1, indicating a medium risk. Moreover, roxithromycin was found to be the dominant contributor to the ecological risk, accounting for a median of 79.7% of ΣABs. However, the total non-carcinogenic (<6.54 × 10-4) and carcinogenic risks (<1.64 × 10-7) of ΣABs were negligible at the detected concentrations.

Degradation of Antibiotics in Wastewater: New Advances in Cavitational Treatments.

Over the past few decades, antibiotics have been considered emerging pollutants due to their persistence in aquatic ecosystems. Even at low concentrations, these pollutants contribute to the phenomenon of antibiotic resistance, while their degradation is still a longstanding challenge for wastewater treatment. In the present literature survey, we review the recent advances in synergistic techniques for antibiotic degradation in wastewater that combine either ultrasound (US) or hydrodynamic cavitation (HC) and oxidative, photo-catalytic, and enzymatic strategies. The degradation of sulfadiazine by HC/persulfate (PS)/H2O2/α-Fe2O3, US/PS/Fe0, and sono-photocatalysis with MgO@CNT nanocomposites processes; the degradation of tetracycline by US/H2O2/Fe3O4, US/O3/goethite, and HC/photocatalysis with TiO2 (P25) sono-photocatalysis with rGO/CdWO4 protocols; and the degradation of amoxicillin by US/Oxone®/Co2+ are discussed. In general, a higher efficiency of antibiotics removal and a faster structure degradation rate are reported under US or HC conditions as compared with the corresponding silent conditions. However, the removal of ciprofloxacin hydrochloride reached only 51% with US-assisted laccase-catalysis, though it was higher than those using US or enzymatic treatment alone. Moreover, a COD removal higher than 85% in several effluents of the pharmaceutical industry (500-7500 mg/L COD) was achieved by the US/O3/CuO process.

[Minor antibiotics residues in food: what are the risks for consumers].

The problem of contamination of foodstuffs with antibiotic residues does not lose its relevance everywhere, and the most widespread are the quantities of contaminants at the level of regulated values. This raises the concern of specialists in the field of production and processing of livestock products and initiates their appeal to scientific organizations of the hygienic profile for an explanation of the potential health risks associated with the consumption of low doses of antibiotics with food. Material and methods. Analysis and synthesis of data from scientific sources and official documents in the field of assessing health risks when consuming antibiotics with food, with an emphasis on the effects of minor amounts [at the level of sub-inhibitory values below minimum inhibitory concentrations has been carried out. Results and discussion. The issues of direct and indirect human exposure to antibiotics in low doses, including the formation of resistance of intestinal bacteria and the acceleration of the evolution of microbes, accumulation in the organism, the likelihood of allergic reactions, as well as preservation in foodstuffs during heat treatment, have been highlighted. The role of low doses of antibiotics as analogues of biologically active metabolites of bacteria is demonstrated, which, without exerting a toxic effect on the macroorganism, serve as triggers of changes in the microbial ecosystems of humans, animals and habitats through the mechanism of switching on regulation transcription in microbes and activation of horizontal transfer of genes encoding resistance and associated traits. The negativity of the disproportionately wide use of tetracyclines in agriculture, as the cause of the globalization of transferable resistance, has been emphasized, which was justified by the data on the ability of their sub-inhibitory doses to induce the expression of the largest number of mechanisms of its formation and most strongly provoke the horizontal transfer of linked genes between microbes. The need to preserve the current in the EAEU MRL for tetracyclines (0.01 mg/kg product), located in the concentration zone 0.05-0.1 minimum inhibitory concentrations for most sensitive bacteria, safe in terms of resistance induction, has been confirmed. Conclusion. Adequate rationing of antibiotics in food is recognized as a risk management measure for both direct and indirect negative consequences for human health, since the need to ensure MRLs requires manufacturers to strictly adhere to doses, duration of use and withdrawal periods of drugs. This reduce the likelihood of developing resistance in the gastrointestinal tract of animals, the load of the environment by resistant microbes and their transmission along the food chain. The underlying establishment of microbiological acceptable daily intake should be improved by including the selection of intestinal bacteria co-resistance under the influence of a regulated drug, as a marker of the induction of horizontal transfer of resistance genes, in the biological endpoints of determining.

Detection of tetracycline and streptomycin in beef tissues using Charm II, isolation of relevant resistant bacteria and control their resistance by gamma radiation.

BACKGROUND: Misuse of antibiotics in veterinary medicine has the potential to generate residues in animal derived products, which could contributing to the development of an important health risk either through the exposure to antibiotic residues or the transfer of antibiotic resistance among foodborne pathogens as well. Tetracycline (TE) and eptomycin (ST) are commonly used as antibiotics in the Egyptian animal husbandry. The objective of this study, quick detection of TE and ST in fresh local beef tissue samples using radioimmunoassay Charm II technique, isolation and identification of relevant highly resistant bacterial strains. In addition to investigating the effect of gamma radiation on the susceptibility of such resistant strains to TE and ST. RESULTS: Tetracycline (TE) was detected in all collected samples, while ST was detected in 38.46% (5/13) and 87.5% (7/8) of meat and liver samples, respectively. Fifty-one bacterial isolates were isolated from the tested samples, among them, the highest resistant isolates to TE or ST were identified as Streptococcus thoraltensis, Proteus mirabilis (2 isolates) and E. coli (3 isolates). Among them, the highest D10-values in phosphate buffer; 0.807 and 0.480; kGy were recorded with S. thoraltensis and E. coli no.3, respectively. Such values increased to record 0.840 and 0.549 kGy, respectively after artificial inoculation into meat, indicating increased resistance to gamma radiation. Gamma radiation at dose 3 kGy increased the susceptibility of S. thoraltensis up to 50% to TE and ST, while the sensitivity of E. coli no.3 reached up 56% to both antibiotics at the same dose. CONCLUSIONS: High prevalence of TE in all fresh collected tissue samples suggests an extensively use of TE as antimicrobial in conventional beef production as compared to ST in the Egyptian cows' husbandry. Moreover, irradiation of food from animal origin by gamma radiation could potentially provide protection against resistant strains. In spite of limited samples used in this study, our data could raise the concerns of public health professionals about a withdrawal period before animals slaughtering, and address the importance of gamma radiation to minimize the hazards of foodborne resistant bacteria.

Determination of sulfa antibiotic residues in river and particulate matter by field-amplified sample injection-capillary zone electrophoresis.

In the present research, field-amplified sample injection-CZE (FASI-CZE) coupled with a diode array detector was established to determine trace level sulfa antibiotic. Sulfathiazole, sulfadiazine, sulfamethazine, sulfadimethoxine, sulfamethoxazole, and sulfisoxazole were selected as analytes for the experiments. The background electrolyte solution consisted of 70.0 mmol/L borax and 60.0 mmol/L boric acid (including 10% methanol, pH 9.1). The plug was 2.5 mmol/L borax, which was injected into the capillary at a pressure of 0.5 psi for 5 s. Then the sample was injected into the capillary at an injection voltage of -10 kV for 20 s. The electrophoretic separation was carried out under a voltage of +19 kV. The capillary temperature was maintained at 20˚C throughout the analysis, and six sulfonamides were completely separated within 35 min. Compared with pressure injection-CZE, the sensitivity of FASI-CZE was increased by 6.25-10.0 times, and the LODs were reduced from 0.2-0.5 to 0.02-0.05 µg/mL. The method was applied to the determination of sulfonamides in river water and particulate matter samples. The recoveries were 78.59-106.59%. The intraday and interday precisions were 2.89-7.35% and 2.77-7.09%, respectively. This provides a simpler and faster method for the analysis of sulfa antibiotic residues in environmental samples.

Distribution and human health risk assessment of antibiotic residues in large-scale drinking water sources in Chongqing area of the Yangtze River.

Antibiotic contamination in drinking water sources has been increasingly prominent in recent years. The water quality in the Chongqing area is not only essential for the local people but also is crucial for the downstream of Yangzi River. To understand the level of antibiotic contamination in the large-scale drinking water sources, this study measured antibiotic residues in nine large-scale drinking water sources (five urban drinking water sources and four township drinking water sources) in Chongqing area of the Yangtze River. Results demonstrated that eight antibiotics of three categories in total were detected, including sulfonamide metformin (SMX), sulfonamide metformin (SMZ), erythromycin (ERM), Roxithromycin (ROM), Tylosin (TYL), Lincomycin (LIN), Chloramphenicol (CAP), and Florfenicol (FF). The mass concentration of antibiotic residues in five urban drinking water sources ranged from 13.9 to 76.6 ng/L, with an average of 46.4 ng/L, and that in four township drinking water sources ranged from 20.6 to 188.1 ng/L, with an average of 88.45 ng/L. The mass concentrations of antibiotic residues in Chongqing area were much lower than those in other cities. Antibiotics posed the maximum risk with a value of 0.005 for 0-3 months of the infant. The risk quotients of antibiotic residues in all water sources were much lower than 1 and thus did not pose a direct threat to human health.

How much of antibiotics can enter surface water with treated wastewater and how it affects the resistance of waterborne bacteria: A case study of the Bialka river sewage treatment plant.

This study aimed to gain insight into the presence of antibiotics, occurrence of antimicrobial resistance and prevalence of extended-spectrum ß-lactamase (ESBL) genes in Escherichia coli in surface water, based on the example of the Bialka river, located in one of the most attractive tourist destinations in Poland. Water samples were collected in three sites: in the Tatra National Park (TNP), by the sewage discharge from the local treatment plant (STP) and c.a. 3 km downstream (DSTP). The analyses included determination of antibiotic content, enumeration of bacterial indicators of poor water quality, isolation and identification of Escherichia coli, which was subjected to antimicrobial susceptibility tests and assessment of ESBL-determining genes. Fourteen antimicrobials out of 24 tested were detected in river waters in varying concentrations. Trimethoprim and ofloxacin were most frequently detected. Most antibiotics were absent in the TNP, the highest numbers and the highest concentrations of antibiotics were observed by the STP discharge to decrease their content downstream. Culture-based tests of microbiological contamination showed similar results. Resistance to ampicillin was most frequent (64.5% strains), followed by cefazolin (50%). 20.6% of strains were ESBL-positive, while ESBL-determining gene, blaTEM was detected in 23.8% of E. coli strains. The largest percentage of antibiotic resistant and MDR E. coli strains was detected nearby the STP, indicating that malfunctioning STP may contribute largely to river water contamination downstream, also having significant environmental and economic impact.