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Currently, oxytetracycline and streptomycin are being applied to citrus groves in Florida for the control of citrus greening disease caused by the unculturable bacterium Candidatus Liberibacter asiaticus. Here, the closest cultured relative, L. crescens, was used to estimate the frequency of spontaneous antimicrobial resistance of Liberibacter spp. Results yielded thirteen streptomycin and zero oxytetracycline mutants after exposing 13 billion cells to the antimicrobials. These low rates, alongside the restrictive habitats of the vector and pathogen, suggest resistance may develop very slowly, if at all. Thus, the treatments will likely remain useful long enough before pathogen-resistant or -tolerant genotypes are deployed.

This study investigated the adsorption of Oxytetracycline (OTC) from pharmaceutical wastewater using a kappa carrageenan based hydrogel (KPB). The aim of the present study was to explore the potential of KPB for long-term pharmaceutical wastewater treatment. A sustainable adsorbent was developed to address oxytetracycline (OTC) contamination. The hydrogel's structural and adsorption characteristics were examined using various techniques like Scanning Electron Microscope (SEM), Fourier Transform Infrared (FTIR), X-ray powder diffraction (XRD), and kinetic models. The results revealed considerable changes in the vibrational modes and adsorption bands of the hydrogel, suggesting the effective functionalization of Bentonite nano-clay. Kappa carrageenan based hydrogel achieved the maximum removal (98.5%) of OTC at concerntration of 40 mg/L, pH 8, cotact time of 140 min and adsorbent dose of 0.1 g (KPB-3). Adsorption of OTC increased up to 99% with increasing initial concentrations. The study achieved 95% adsorption capacity for OTC using a KPB film at a concentration of 20 mg/L and a 0.1 g adsorbent dose within 60 min. It also revealed that chemisorptions processes outperform physical adsorption. The Pseudo-Second-Order model, which emphasized the importance of chemical adsorption in the removal process, is better suited to represent the adsorption behavior. Excellent matches were found that R2 = 0.99 for KPB-3, R2 = 0.984 for KPB-2 and R2 = 0.989 for KPB-1 indicated strong chemical bonding interactions. Statisctical analysis (ANOVA) was performed using SPSS (version 25) and it was found that pH and concentration had significant influence on OTC adsorption by the hydrogel, with p-values less than 0.05. The study identified that a Kappa carrageenan-based hydrogel with bentonite nano-clay and polyvinyl alcohol (PVA) can efficiently remove OTC from pharmaceutical effluent, with a p-value of 0.054, but weak positive linear associations with pH, temperature, and contact time. This research contributed to sustainable wastewater treatment and environmental engineering. [ABSTRACT FROM AUTHOR]

The presence of antibiotics in water sources is a significant concern due to their potential environmental impact and the risks to human health. In the present research, hierarchically mesoporous UiO-66 (HP-UiO-66) with a high surface area (1011 m2/g) and large pore volume was synthesized using the reflux method on the liter scale. The successful synthesis was confirmed by FT-IR, XRD, FESEM/EDS, N2-adsorption/desorption, and zeta potential techniques. The HP-UiO-66 was utilized to remove two large structure antibiotics, chlortetracycline hydrochloride (CTC), and oxytetracycline (OTC). Box Behnken design was used to investigate the factors affecting the removal process and the interactions between them. The maximum adsorption capacities for OTC and CTC antibiotics were 252.9 mg/g and 234.2 mg/g at 35 °C, respectively. The sum of the normalized error method was applied to the analysis of various error functions in the nonlinear fitting of equilibrium and kinetic data. The CTC and OTC adsorption kinetic followed a fractal-like pseudo-second-order model. The Langmuir isotherm fitted well to adsorption data. The results demonstrate that HP-UiO-66 can be used as a recyclable and efficient adsorbent for large molecule antibiotics removal. [ABSTRACT FROM AUTHOR]

A ternary composite (KB/BMO-GO) consisting of graphene oxide, Bi 2 MoO 6 and crosslinked benzene polymer was prepared by solvothermal and in-situ deposition methods, which were used to promote the synergistic adsorption-photocatalytic degradation of the refractory pollutant oxytetracycline (OTC). A cycle involving the simultaneous adsorption and photocatalytic enhances the degradation performance of oxytetracycline. The 15% KB/BMO-GO sample exhibited the best synergistic adsorption-photocatalytic degradation performance, which has great potential in practical applications for low concentration refractory pollutants removal of water. [Display omitted] Antibiotics are refractory degradable organic pollutants that present a significant hazard to water environments. In this work, a ternary composite (KB/BMO-GO) comprising of graphene oxide (GO), Bi 2 MoO 6 (BMO), and a cross-linked benzene polymer (KB) was synthesized and applied to promote the synergistic adsorption-photocatalytic degradation of the refractory pollutant, oxytetracycline (OTC). The inclusion of GO and KB in the composite enhanced the OTC adsorption performance of the catalysts, and the construction of Z-scheme heterojunction promoted the photogenerated charge separation efficiency and broadened the range of light absorption, thereby enhancing the photocatalytic performance. Moreover, we compared the performance of catalysts loaded with different mass ratios of KB (x% KB/BMO-GO). Among them, the 15 % KB/BMO-GO catalyst sample had the best OTC degradation performance. Specifically, 15 % KB/BMO-GO could adsorb 69.7 % of OTC in 30 min, reaching an OTC degradation rate of 93.3 % under visible light irradiation. h+ and 1O 2 are the main active substances in the photocatalytic process. In addition, the catalysts are acid-alkali and salt-resistant, as well as good reusability. This study provides a valuable reference for the preparation of highly efficient photocatalysts for synergistic adsorption-photodegradation processes. [ABSTRACT FROM AUTHOR]

Oxytetracycline (OTC) is frequently detected in groundwater and soil, posing substantial risks to the subsurface environment via persistence, phytotoxicity, changing bacterial communities, and antibiotic resistance. In situ chemical oxidation (ISCO) is one of the best alternatives for removing OTC from groundwater. However, its feasibility has rarely been investigated using columns for which optimal conditions can be obtained for practical applications. Thus, a system consisting of oxygen-doped graphitic carbon nitride (OgCN) and peroxymonosulfate (PMS) (OgCN/PMS) was tested for OTC removal using continuous-flow experiments with columns packed with sand and glass beads (GBs). The sand column exhibited better adsorption and degradation of OTC than the GB column in pulse injection experiments, regardless of whether OgCN was packed. Additional experiments were performed using a column saturated with the OTC solution and another filled with deionized water to simulate ISCO, using GB as the medium, to evaluate the net OTC removal by catalytic oxidation, excluding adsorption. Performance improved with increased OgCN packing, PMS dosage, retention time, and pH. Anions slightly affected the performance due to scavenging and propagation of radicals. These findings indicate the high potential of OgCN/PMS for ISCO and the usefulness of column experiments in field applications. [ABSTRACT FROM AUTHOR]

Antibiotics are crucial in the control of bacterial infections on fish farms. However, the influence of licensed antibiotics on DNA damage, histological changes, and protein differentiation in some farmed fish species is unidentified. The current study aimed to investigate the effect of therapeutic (80 mg/kg body weight/day) and high doses (160 mg/kg body weight/day) of oxytetracycline (OTC) on some biological indices, protein differentiation, histological changes, and DNA damage in Oreochromis niloticus (n = 360; 40 ± 3.5 g) and the potential positive effects of dietary ascorbic acid (AA) and whether it is capable of reducing the deleterious impacts of OTC and working synergistically to increase fish disease resistance and decrease morbidity and mortality rates. In the current study, fish were fed diets with or without OTC (80 or 160 mg/kg body weight/day) and AA (100 mg/kg diet/day) for 28 days, followed by a bacterial stress test with two different virulent strains for 14 days. Treatments include CTR (control; without additives), AA, OTC80, OTC160, OTC80 + AA, and OTC160 + AA. The results revealed that the AA group had the best antioxidative (significant increase in SOD, CAT, and GPx) and immunomodulatory effects (an increase in IgM, nitroblue tetrazolium, and total leucocytic count). Furthermore, the hematological parameters, immune indices (NBT), and antioxidant enzymes were significantly reduced by OTC160 (p ≤ 0.05). The results also showed that OTC160 notably augmented the activity of liver (ALT, AST, and LDH) and kidney (creatinine and urea) damage markers (p ≤ 0.05). OTC160 revealed considerable hepatic and renal tissue damage and significantly higher hepatocyte DNA damage. Pathological changes and DNA damage were directly correlated to the dosage of OTC exposure, where they were more severe in OTC160. OTC80 showed insignificant changes in most parameters. Compared to CTR, the inclusion of AA in the O. niloticus diet significantly restored the biological indices, histological changes, and DNA damage in OTC-treated groups. The morbidity and mortality percentages after bacterial challenge were significantly lower in the OTC80 + AA group, followed by the OTC160 + AA group than in the CTR. These results corroborate the use of AA as a potent antioxidant and immune stimulant and a potential co-adjuvant to OTC in the diet of O. niloticus to reach optimal resistance to disease. [ABSTRACT FROM AUTHOR]

An LC–Orbitrap–HRMS method was developed and validated for the simultaneous determination of four tetracyclines—oxytetracycline (OTC), tetracycline (TC), doxycycline (DC), and chlortetracycline (CTC)—in milk. This method involves sample extraction with McIlvaine–EDTA buffer solution (pH 4) and solid-phase extraction (SPE) with Oasis HLB cartridges, followed by the evaporation of the extract and its reconstitution with a 14% methanol aqueous solution before injection into the instrumental system. This method has been validated in terms of linearity, sensitivity, selectivity, precision, and accuracy, in accordance with Commission Decision 2002/657/EC requirements. Compared to existing methods, this approach optimally combines a quantitative procedure for extracting analytes from the milk of different species, including sheep, bovines, and goats, with a very short LC–Orbitrap–HRMS instrumental analysis time (only 8 min), simultaneously ensuring high precision, sensitivity, and applicability as a rapid confirmation method in official food control laboratories. The proposed method was applied to determine the concentration levels of OTC in milk samples derived from healthy Sardinian sheep and those naturally infected with Streptococcus uberis, after the intramuscular administration of an antibiotic, in order to evaluate how much of the drug was "subtracted" during penetration from blood into milk, with a potential effect of reducing its therapeutic efficacy. [ABSTRACT FROM AUTHOR]

Copyright of Asian Journals of Ecotoxicology is the property of Gai Kan Bian Wei Hui and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Oxytetracycline (OTC) and ciprofloxacin (CIP) contamination have caused serious risks to human health, and modified biochar is considered as a potential adsorbent for their removal. The typical agricultural waste of cotton husk was used as the feedstock, then was combined with γ-Fe2O3 and ball milling to innovatively synthesize nano zero-valent iron (nZVI) supporting magnetic cotton hush-derived biochar (Fe2O3@BMBC) by reductive calcination. Fe2O3@BMBC performed excellent adsorption performance with a maximum adsorption capacity for OTC (266.7 mg·g−1) and CIP (83.36 mg·g−1), and its adsorption capacity was 1.6 and 2.3 times that of cotton husk biochar (BC). Characterization analysis showed that Fe2O3@BMBC contained abundant oxygenated functional groups (e.g., -OH, C = O and Fe–O) and its surface was covered by diverse iron oxides. The high magnetization sensitivity of Fe2O3@BMBC guaranteed that it was easily to be separated by a magnet. Oxygenated functional groups (e.g., -OH, C = O and Fe–O) participated in the adsorption process, and solution pH significantly affected the adsorption behaviour, and pseudo-second-order model and Freundlich model better fitting the kinetics and isotherms data. These results confirmed that π-π conjugation, H-bonding, Fe–O complexation and electrostatic interactions contributed to the greater adsorption capacity of Fe2O3@BMBC. Ethanol + ultrasound could efficiently regenerate the used Fe2O3@BMBC and maintain its sustainable adsorption performance for OTC and CIP. Additionally, Fe2O3@BMBC performed a good environmental security in a wide pH range (from 3 to 11) in view of the low leaching risk of Fe. Highlights: • Fe2O3@BMBC was synthesized from cotton hush and γ-Fe2O3 by reductive calcination and ball milling. • Fe2O3@BMBC showed the excellent adsorption performance for OTC and CIP. • Multiple physicochemical forces contributed to OTC and CIP removal by Fe2O3@BMBC. • Ethanol + ultrasound could efficiently regenerate the used Fe2O3@BMBC. [ABSTRACT FROM AUTHOR]

The direct equalizing ray method was employed to design three groups of mixtures of oxytetracycline(OTC) and norfloxacin(NOR) with varying proportions(Group R1 had a higher proportion of OTC, while R2 had similar concentrations of both antibiotics, and R3 had a higher proportion of NOR).The effects of these mixtures on the content and properties of extracellular polymeric substances (EPS) in the biological denitrification process were investigated using an sequencing batch reactor activated sludge reactor (SBR). The results revealed that the removal rates of ammonia nitrogen(NH 3 -N) decreased in all three groups with the addition of antibiotics. As the antibiotic concentration increased, the EPS content decreased by 68.46%, 55.53%, and 65.03% in R1, R2, and R3, respectively. To understand the interaction mechanism of mixed antibiotics on EPS in activated sludge, Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) techniques were employed. The findings demonstrated significant effects of mixed antibiotics on functional groups such as C-O, C O, and C-O-C. Specifically, hydrogen bonding was found to be the primary influencing factor in the R1 ratio, while Π-Π conjugation played a major role in the R3 ratio. [Display omitted] • High-concentration mixture of OTC and NOR inhibitory nitrogen removal performance of SBR. • High-concentration mixture of OTC and NOR reduced the production of extracellular polymeric substances. • High proportion of OTC, the EPS characteristics are mainly affected by hydrogen bonding interactions. • High proportion of NOR, the EPS characteristics are mainly affected by hydrogen bonding interactions and π-π conjugation. [ABSTRACT FROM AUTHOR]

[Display omitted] In the work, Bi 2 WO 6 /C-TiO 2 photocatalyst was successfully synthesized for the first time by loading narrow bandgap semiconductor Bi 2 WO 6 on MOF-derived carboxyl modified TiO 2. The phase structure, morphology, photoelectric properties, surface chemical states and photocatalytic performance of the prepared photocatalysts were systematically investigated using various characterization tools. The degradation efficiency of oxytetracycline by 6BT Z-scheme heterojunction photocatalyst under visible light could reach 93.6 % within 100 min, which was related to the high light harvesting and effective separation and transfer of photo-generated carriers. Furthermore, the effects of various environmental factors in actual wastewater were further investigated, and the results showed that 6BT exhibited good adaptability, durability and resistance to interference. Unlike most works, the degradation system with a different single active species were designed and constructed based on their formation mechanism. In addition, for the first time, a positive study was conducted on the priority attack sites, intermediate products, and degradation pathways for the photocatalytic degradation of oxytetracycline by a single active species through HPLC-MS and Fukui index calculations. The toxicity changes of intermediate products produced in three different single active species oxidation systems were evaluated using toxicity assessment software tools (T.E.S.T.), Escherichia coli growth experiments, and wheat growth experiments. Among them, the intermediate products formed through O 2 – oxidation had the lowest toxicity and the main active sites it attacked were the 20C, 38O, 18C, 41O, and 55O atoms with high f+ values in the oxytetracycline molecular structure. This work provided the insight into the role of each active species in the degradation of antibiotics and offered new ideas for the design and synthesis of efficient and eco-friendly photocatalysts. [ABSTRACT FROM AUTHOR]

Tetracyclines are a class of commonly used four‐ringed antibiotics. A series of DNA aptamers were recently obtained using the capture‐SELEX (systematic evolution of ligands by exponential enrichment) method to bind to oxytetracycline, and one of the aptamers can bind to a few other tetracycline antibiotics as well. Upon binding to the aptamers, the intrinsic fluorescence of tetracycline antibiotics can be enhanced. At least 10 different DNA aptamers were isolated from the previous selection experiment. In this work, a systematic characterization of these ten aptamers was performed. Each of these aptamers shows a different degree of fluorescence enhancement ranging from around 1‐fold to over 20‐fold. Fluorescence enhancement was boosted in the presence of Mg2+. Isothermal titration calorimetry (ITC) studies were done and showed a great variety in dissociation constant (Kd) from 62 nM to 1.6 μM. Steady‐state fluorescence spectroscopy and fluorescence lifetime studies showed a correlation between fluorescence lifetime and degree of fluorescence enhancement. A few aptamers showed slow binding kinetics, although no correlation was found between the kinetics of fluorescence change and degree of fluorescence enhancement. This is the first study of ten different aptamers for the same target, providing fundamental insights into aptamer binding and bioanalytical applications. [ABSTRACT FROM AUTHOR]

Importance: Over the past decade, catfish farming has increased in Southeast Asia. However, there has been no existing for pharmacokinetic data in the hybrid catfish ( Clarias macrocephalus x C. gariepinus). Objective: This study was designed to evaluate the pharmacokinetic characteristics of oxytetracycline (OTC) in the hybrid catfish, following single intravascular (IV) or oral (PO) administration at a single dosage of 50 mg/kg body weight (BW). Methods: In total, 140 catfish (each about 100-120 g BW) were divided into two groups (n = 70). Blood samples (0.6-0.8 mL) were collected from ventral caudal vein at pre-assigned times up to 144 h (sparse samples design). OTC plasma concentrations were analyzed using high-performance liquid chromatography-photodiode array detector. Results: The pharmacokinetic parameter of OTC was evaluated using a non-compartment model. OTC plasma concentrations were detectable for up to 144 and 120 h after IV and PO, respectively. The elimination half-life value of OTC was long with slow clearance after IV administration in hybrid catfish. The average maximum concentration value of OTC was 2.72 µg/mL with a time at the maximum concentration of 8 h. The absolute PO bioavailability was low (2.47%). Conclusions and Relevance: These results showed that PO administration of OTC at a dosage of 50 mg/kg BW was unlikely to be effective for clinical use in catfish. The pharmacodynamic properties and clinical efficacy of OTC after multiple medicated feed are warranted. [ABSTRACT FROM AUTHOR]

Recently, many efforts have been dedicated to construct artificial catalysts with enzyme-like activity. However, it is still a big challenge to endow artificial catalysts with specific substrate selectivity. In this study, we developed a facile strategy to construct a MIL-53(Fe)-based nanocatalyst with designable selectivity in the degradation of oxytetracycline (OTC). Through the Fe–O–P conjunction, oxytetracycline aptamer (OA) can be easily anchored on MIL-53(Fe) to provide the specific site for OTC binding. We verified that the obtained MIL-53(Fe)-Apt nanocatalyst displayed enhanced catalytic ability in the degradation of OTC, whereas obvious suppression toward other substrate analogues. This performance therefore brings about an anticipated selectivity toward OTC. Moreover, we highlighted that the configuration of aptamers on MIL-53(Fe) can be modulated through varying conjunction mode. Structure–function analysis revealed that aptamer configuration affects the local concentration of substrate around catalytic site, which thus decides the catalytic performance toward OTC. This work presented a facile and promising strategy for developing artificial catalysts with designable selectivity. [ABSTRACT FROM AUTHOR]

Water-soluble and highly yellow fluorescent carbon dots were synthesized by using sucrose as a carbon source and phosphoric acid as a dehydrating agent. Instrumental techniques such as fourier transform infrared spectroscopy, ultraviolet absorption and fluorescence spectroscopy, and transmission electron microscopy have been employed to characterize the carbon dots. The results indicated that the synthesized carbon dots have spherical shape with mean diameter of 7 nm. The distribution of carbon dots is uniform which emit yellow fluorescence. Fourier transform infrared spectroscopy study revealed the presence of high amount of –OH groups on carbon dots surface. Oxytetracycline quenched the fluorescence of carbon dots via static quenching mechanism. The reduction in fluorescence intensity of carbon dots permitted to design a fluorometric assay for oxytetracycline. The calibration curve (change in fluorescence intensity vs. concentration of oxytetracycline) was linear in the concentration range of 1.0 μg/mL–10.0 μg/mL with a detection limit of 0.33 μg/mL and correlation coefficient of 0.9981. The method was tested to quantify the oxytetracycline in spiked wastewater, milk, and meat samples and gave satisfactory recoveries. [ABSTRACT FROM AUTHOR]

In the present study, the degradation of oxytetracycline (OTC) under ultraviolet (UV) light in the presence of ZnO catalyst was investigated, and optimum parameters for degradation efficiency were determined. Different pH values, ZnO dosages, reaction times, OTC concentrations, and UV lights were used in this study. The optimum conditions found were as follows: pH 4, ZnO 1 g L−1, reaction time 25 min, and OTC concentration 10 mg L−1. Degradation efficiency was 42.1%, 76%, 70.7%, and 61.7% for ZnO and photocatalytic (for UV‐A, UV‐B, and UV‐C) degradation at optimal conditions, respectively. The resulting products after the photocatalytic oxidation of OTC were determined in the study. To identify the toxicity of degradation products and OTC, the lowest LC 50 (50% lethal concentration) and EC 50 (50% effective concentration) values were found. The resulting ethanamine, 2‐(2,6‐dimethylphenoxy)‐N‐methyl‐ by‐products were observed to be more toxic than OTC. Furthermore, it was seen that isopropoxy carbamic acid, ethyl ester by‐products were formed, whose presence is environmentally risky for aquatic environments due to their low EC50 values. [ABSTRACT FROM AUTHOR]

Abstract This study investigated the adsorption of Oxytetracycline (OTC) from pharmaceutical wastewater using a kappa carrageenan based hydrogel (KPB). The aim of the present study was to explore the potential of KPB for long-term pharmaceutical wastewater treatment. A sustainable adsorbent was developed to address oxytetracycline (OTC) contamination. The hydrogel’s structural and adsorption characteristics were examined using various techniques like Scanning Electron Microscope (SEM), Fourier Transform Infrared (FTIR), X-ray powder diffraction (XRD), and kinetic models. The results revealed considerable changes in the vibrational modes and adsorption bands of the hydrogel, suggesting the effective functionalization of Bentonite nano-clay. Kappa carrageenan based hydrogel achieved the maximum removal (98.5%) of OTC at concerntration of 40 mg/L, pH 8, cotact time of 140 min and adsorbent dose of 0.1 g (KPB-3). Adsorption of OTC increased up to 99% with increasing initial concentrations. The study achieved 95% adsorption capacity for OTC using a KPB film at a concentration of 20 mg/L and a 0.1 g adsorbent dose within 60 min. It also revealed that chemisorptions processes outperform physical adsorption. The Pseudo-Second-Order model, which emphasized the importance of chemical adsorption in the removal process, is better suited to represent the adsorption behavior. Excellent matches were found that R2 = 0.99 for KPB-3, R2 = 0.984 for KPB-2 and R2 = 0.989 for KPB-1 indicated strong chemical bonding interactions. Statisctical analysis (ANOVA) was performed using SPSS (version 25) and it was found that pH and concentration had significant influence on OTC adsorption by the hydrogel, with p-values less than 0.05. The study identified that a Kappa carrageenan-based hydrogel with bentonite nano-clay and polyvinyl alcohol (PVA) can efficiently remove OTC from pharmaceutical effluent, with a p-value of 0.054, but weak positive linear associations with pH, temperature, and contact time. This research contributed to sustainable wastewater treatment and environmental engineering.

Abstract The generic term “Gill disease” refers to a wide range of disorders that affect the gills and severely impact salmonid aquaculture systems worldwide. In rainbow trout freshwater aquaculture, various etiological agents causing gill diseases have been described, particularly Flavobacterium and Amoeba species, but research studies suggest a more complex and multifactorial aetiology. Here, a cohort of rainbow trout affected by gill disease is monitored both through standard laboratory techniques and 16S rRNA Next-Generation Sequencing (NGS) analysis during a natural disease outbreak and subsequent antibiotic treatment with Oxytetracycline. NGS results show a clear clustering of the samples between pre- and post-treatment based on the microbial community of the gills. Interestingly, the three main pathogenic bacteria species in rainbow trout (Yersinia ruckeri, Flavobacterium psychrophilum, and Flavobacterium branchiophilum) appear to be weak descriptors of the diversity between pre-treatment and post-treatment groups. In this study, the dynamics of the gill microbiome during the outbreak and subsequent treatment are far more complex than previously reported in the literature, and environmental factors seem of the utmost importance in determining gill disease. These findings present a potential novel perspective on the diagnosis and management of gill diseases, showing the limitations of conventional laboratory methodologies in elucidating the complexity of this disease in rainbow trout. To the authors’ knowledge, this work is the first to describe the microbiome of rainbow trout gills during a natural outbreak and subsequent antibiotic treatment. The results of this study suggest that NGS can play a critical role in the analysis and comprehension of gill pathology. Using NGS in future research is highly recommended to gain deeper insights into such diseases correlating gill’s microbiome with other possible cofactors and establish strong prevention guidelines.

Taking chicken manure containing antibiotic oxytetracycline (OTC) as the research object, nano-Fe2O3 with a concentration of 300 mg/kg TS and nano-C60 with a concentration of 100 mg/kg TS as carriers were used for a 55-day sequential batch mesophilic anaerobic digestion experiment. The gas production performance, chemical parameters, antibiotic content, enzyme concentration, and resistance gene changes during anaerobic digestion were analyzed to clarify the effect of nanoparticles on anaerobic systems containing antibiotic chicken manure and provide a reliable basis for pollution reduction capacity of livestock and poultry manure. The results showed that (1) adding nano-Fe2O3 and nano-C60 promoted anaerobic gas production in chicken manure with different concentrations of OTC. The cumulative gas production from days 1 to 10 was 2,234(T5) > 2,163(T4) > 1,445(T2) > 1,289(T3) > 1,220(T1) > 1,216(CK) mL. The cumulative gas production of T4 and T5 increased by 77.29 and 83.11%, respectively. The final cumulative gas production for each group was 3,712(CK), 3,993(T1), 4,344(T2), 4,447(T3), 4,671(T4), and 4,849(T5) mL. The final OTC residue concentrations were 15.25, 20.40, 56.56, 17.67, and 16.89 μg/L, with degradation rates of 98.31, 98.80, 98.29, 99.07, and 99.11% respectively; (2) antibiotic OTC increased the activities of dehydrogenase, amylase, protease, and urease, while adding nanoparticles increased the activities of dehydrogenase and amylase, with no significant impact on cellulase, urease, and protease activities; (3) antibiotic resistance gene (ARGs) of various types were found in groups T2, T4, and T5, with the multidrug resistance gene (ARGs)-Multidrug accounting for a high proportion of 33.54, 35.63, and 37.43%, respectively, while the proportions of the other four types MLS, tetracycline, glycopeptide, and peptide ranged from 8.18 to 12.98%.

Nanosorbent NiFe2O4@g-C3N4 was produced via green and ultrasonication methods to remove oxytetracycline (OTC) from aqueous solutions. The prepared material was analyzed using powder x-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, energy-dispersive x-ray spectroscopy (EDX), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The adsorption capacity of the NiFe2O4@g-C3N4 nanosorbent for OTC decontamination was studied using a batch experiment under various parameters. The adsorption capacity was notably increased to 1634 mg g−1 under fixed experimental conditions. The kinetic and isothermal analyses were conducted using several optimal pH and temperature models. The adsorption kinetics graphs aligned with the pseudo-second-order model, suggesting chemical adsorption via electrostatic interactions. The adsorption isotherm curves aligned more closely with the Langmuir model than the Temkin and Freundlich models, suggesting a monolayer adsorption mechanism. The adsorption mechanism was clearly elucidated using FTIR investigations. The results of the study indicate that NiFe2O4@g-C3N4 nanosorbent is a promising candidate for specific elimination of OTC on many different levels for the treatment of wastewater. [ABSTRACT FROM AUTHOR]

Introduction: The administration of antibiotics can expose the digestive microbiota of humans and animals to sub-inhibitory concentrations, potentially favouring the selection of resistant bacteria. The minimal selective concentration (MSC) is a key indicator to understand this process. The MSC is defined as the lowest concentration of an antibiotic that promotes the growth of a resistant strain over a susceptible isogenic strain. It represents the lower limit of the sub-minimal inhibitory concentration (MIC) selective window, where resistant mutants can be selected. Previous studies focused on determining the MSC under standard culture conditions, whereas our research aimed to determine the MSC in a model that approximates in vivo conditions. Methods: We investigated the MSC of oxytetracycline (OTC) in Mueller-Hinton broth (MHB) and sterilised intestinal contents (SIC) from the jejunum, caecum and rectum (faeces) of pigs, using two isogenic strains of Escherichia coli (one susceptible and one resistant to OTC). Additionally, the MIC of OTC against the susceptible strain was determined to assess the upper limit of the sub-MIC selective window. Results: Our study took a novel approach, and the results indicated that MIC and MSC values were lower in MHB than in SIC. In the latter, these values varied depending on the intestinal segment, with distal compartments exhibiting higher MIC and MSC values. Moreover, the sub-MIC selective window of OTC in SIC narrowed from the jejunum to the rectum, with a significantly closer MSC to MIC in faecal SIC. Discussion: The results suggest that OTC binds to digestive contents, reducing the fraction of free OTC. However, binding alone does not fully explain our results, and interactions between bacteria and intestinal contents may play a role. Furthermore, our findings provide initial estimates of low concentrations facilitating resistance selection in the gut. Finally, this research enhances the understanding of antimicrobial resistance selection, emphasising the intricate interplay between antibiotics and intestinal content composition in assessing the risk of resistance development in the gut. [ABSTRACT FROM AUTHOR]

The present study used CeO2-Co3O4 quantum dots@porous carbon/multiwalled carbon nanotube (CeO2-Co3O4 QDs@PC/MWCNT/GE) composites to modify graphite electrodes to fabricate high-sensitivity electrochemical sensors to detect the presence of oxytetracycline (OTC). The quantum dots were made from waste sugarcane bagasse. The electrochemical analysis demonstrated the superior electrochemical performance of CeO2-Co3O4 QDs@PC/MWCNT/GE, with a peak current density of 1.276 mA/cm2. Electrochemical impedance spectroscopy (EIS) revealed lower impedance values for CeO2-Co3O4 QDs@PC/MWCNT/GE compared to other electrodes, indicating enhanced conductivity. The modified electrode exhibited an enlarged electrochemically active area, with values of 0.602 cm2, almost seven times that of the bare graphite electrode (0.079 cm2). The results showed that the CeO2-Co3O4 QDs@PC/MWCNT/GE had excellent performance for OTC detection, and its linear calibration range was 1.007 × 10−8 to 2.04 × 10−7 M (i.e., 0.005–0.1 ppm) and 1.007 × 10−6 to 1.209 × 10−4 M (i.e., 0.5–60 ppm). The limit of detection and limit of quantification were 1.23 nM (0.61 ppb) and 4.09 nM (2.03 ppb) (S/N = 3), respectively. The electrode demonstrated long-term stability for up to 7 weeks. This method provides a new way to prepare electrochemical sensors for OTC detection. [ABSTRACT FROM AUTHOR]

Antibiotic residues have been found to have potentially harmful effects on ecological and human health. Carbon nitride-based photocatalysts have widely focused on antibiotic photocatalytic degradation. Herein, we prepared Fe-modified g-C3N4 nanorod bunches (FCNBs) using chemical vapor co-deposition. Specifically, through the process of calcination, a blend of urea and chlorophyllin sodium iron salt underwent an intriguing transformation, resulting in the integration of Fe into the framework of the g-C3N4 nanorod cluster. The resulting photocatalyst exhibited remarkable stability and superior dispersibility. The prepared FCNBs had a unique structure, which was beneficial for increasing light absorption. Furthermore, the Fe species formed a chemical coordination with the g-C3N4 matrix, thereby altering the electronic structure of the matrix. This modification facilitated charge transfer, prolonged the carrier lifetime, and enhanced light absorption, all of which significantly increased the photocatalytic activity. The oxytetracycline degradation efficiency of FCNBs was 82.5%, and they demonstrated outstanding stability in cycle trials. This work introduces a promising photocatalyst for the degradation of antibiotics. [ABSTRACT FROM AUTHOR]

While emerging pollutants are being detected in water bodies globally, a significant amount of solid waste that could be used for effluent remediation is being discarded. This not only reduces the half-life of landfills but also contributes to environmental pollution. Of these, eggshells (ES) are one of the most discarded food waste items worldwide. This paper presents the development and characterization of ES-based adsorbent for the removal of oxytetracycline (OTC), an emerging pharmaceutical pollutant, from aqueous solutions. The sorption of OTC on ES and ES-derived materials has not been previously studied. The ES was modified by removing the organic layer and both materials were used to grow Fe oxides, which can impart magnetic response to allow indirect manipulation or the addition of new sorption sites. Two methodologies were employed to synthesize Fe oxides: alkaline oxidation in the presence of nitrate and impregnation–pyrolysis (IP), which have not been used previously for developing magnetic ES. The materials developed by IP exhibit the highest total specific surface area and display a magnetic response due to the presence of magnetite and maghemite. Moreover, they exhibit a negative zeta potential over a wide range of pH values. All materials were able to adsorb OTC at pH 3, 7, or 9, indicating that ES (the simplest material) and ESIP (composite with good enough magnetic response) are suitable for removing OTC from aqueous solution. ES is recommended when indirect manipulation is not necessary, whereas ESIP is recommended when it is required. In order to explore the potential for reuse of the composite-pollutant materials, their antibacterial capacity against E. coli and E. faecium was evaluated. The findings of the present work contribute to the development of a circular economy by reducing waste generation, minimizing the consumption of natural resources, and reducing greenhouse gas emissions, while improving environmental protection. [ABSTRACT FROM AUTHOR]

Objective: Age estimation methods have not been validated for many species. Thus, we focused this age estimation study on four species from central Texas: the Guadalupe Bass Micropterus treculii, Channel Catfish Ictalurus punctatus, Gray Redhorse Moxostoma congestum, and Redbreast Sunfish Lepomis auritus. Our objectives for each species were to (1) investigate whether increments form annually in otoliths, fin rays, or spines; (2) determine the seasonal timing of zone deposition in each calcified structure; and (3) compare age estimates between otoliths and fin rays or spines. Methods: Fish were sampled from central Texas waters and injected with oxytetracycline (OTC) quarterly in 2021. In July 2022, otoliths and fin rays or spines were collected to determine whether the increments formed annually and to estimate age. Result: On average, two readers identified the correct number of annuli after the OTC mark in at least 95% of Gray Redhorse, Guadalupe Bass, and Redbreast Sunfish otoliths but in only 69% of Channel Catfish otoliths. However, the more experienced reader identified the correct number of annuli in at least 95% of otoliths from age‐2–4 Channel Catfish. Compared to otoliths, the correct number of annuli after the OTC mark was identified in a smaller percentage of fin rays or spines (47–62%). The probability of identifying the correct number of annuli after the OTC mark differed between the two readers for all spines and fin rays. Age difference plots revealed that age estimates based on fin rays or spines were either overestimated or underestimated compared to otolith‐based ages for all species. Conclusion: We consider annual increment formation in otoliths to be validated for all age‐classes of Gray Redhorse, Guadalupe Bass, and Redbreast Sunfish examined and for ages 2–4 of Channel Catfish. Differences in correctness between readers were most likely due to differences in age estimation experience. Given the level of error observed in our study, caution is advised if using age estimates from unvalidated structures and species. Impact statementWe validated annual increment formation in otoliths from Guadalupe Bass, Gray Redhorse, and Redbreast Sunfish but not in otoliths from Channel Catfish. Annual increment formation was not validated for fin rays or spines from any species examined. [ABSTRACT FROM AUTHOR]

Targeted bactericidal nanosystems hold significant promise to improve the efficacy of existing antimicrobials for treatment of severe bacterial infections by minimizing the side effects and lowering the risk of antibiotic resistance development. In this work, Silver Oxytetracycline Nano-structure (Ag-OTC-Ns) was developed for selective and effective eradication of Klebsiella pneumoniae pulmonary infection. Ag-OTC-Ns were prepared by simple homogenization-ultrasonication method and were characterized by DLS, Zeta potential, TEM and FT-IR. The antimicrobial activity of Ag-OTC-Ns was evaluated in vitro using broth micro-dilution technique and time-kill methods. Our study showed that MICs of AgNO3, OTC, AgNPs and Ag-OTC-Ns were 100, 100, 50 and 6.25 µg/ml, respectively. Ag-OTC-Ns demonstrated higher bactericidal efficacy against the targeted Klebsiella pneumoniae at 12.5 µg/ml compared to the free Oxytetracycline, AgNO3 and AgNPs. In vivo results confirmed that, Ag-OTC-Ns could significantly eradicate K. pneumoniae from mice lung in compare with free Oxytetracycline, AgNO3 and AgNPs. In addition, Ag-OTC-Ns could effectually diminish the inflammatory biomarkers levels of Interferon Gamma and IL-12, and as a result it could effectively lower lung damage in K. pneumoniae infected mice. Ag-OTC-Ns has no significant toxicity on tested mice along the experimental period, there was no sign of behavioral abnormality in the surviving mice indicating that the Ag-OTC-Ns is safe at the used concentration. Furthermore, capability of 5 kGy Gamma ray to sterilize Ag-OTC-Ns solution without affecting it stability was proven. [ABSTRACT FROM AUTHOR]

In droplet microfluidics, UV-Vis absorption spectroscopy along with colorimetric assays have been widely used for chemical and biochemical analysis. However, the sensitivity of the measurement can be limited by the short optical pathlength. Here we report a novel design to enhance the sensitivity by removing oil and converting the droplets into a single-phase aqueous flow, which can be measured within a U-shape channel with long optical pathlength. The flow cells were fabricated via 3D printing. The calibration results have demonstrated complete oil removal and effective optical pathlengths similar to the designed channel lengths (from 5 to 20 mm). The flow cell was further employed in a droplet microfluidic-based phosphate sensing system. The measured phosphate levels displayed excellent consistency with data obtained from traditional UV spectroscopy analysis. This flow cell design overcomes the limitations of short optical pathlengths in droplet microfluidics and has the potential to be used for in situ and continuous monitoring. [ABSTRACT FROM AUTHOR]

The impact of antibiotic residue on sediment ecology at the watershed level is not yet fully understood. In this investigation, varying concentrations of oxytetracycline (OTC) and sulfadiazine (SD) were added to the overlying water of both the upper (0–10 cm) and bottom sediment (20–30 cm) layers at the watershed scale to evaluate the ecological impact on sediment habitats through the analysis of the activities of enzymes, namely urease (UA), alkaline phosphatase (APA), peroxidase (POA), and dehydrogenase (DHA). Results showed that the levels of UA and APA in the bottom sediment layers exceeded those in the top sediment layer upon reintroduction of antibiotics. Conversely, the fluctuations in DHA were notably reduced across various types of antibiotics and exposure concentrations in the bottom sediment layers. Within the top sediment layers, as the concentration of OTC exposure increased, there was a corresponding elevation in POA levels. However, the response of POA initially ascended and subsequently descended with rising SD exposure concentration, although it consistently exceeded the control levels. In contrast, the response of DHA displayed an inverse correlation with OTC exposure concentration but a direct correlation with SD exposure concentration. At the watershed scale, under antibiotic exposure, UA and DHA exhibited significantly higher levels upstream compared to downstream. Conversely, APA and POA appeared relatively stable across the watershed following the reintroduction of antibiotics. Moreover, DHA demonstrated a noticeable decreasing trend with increasing concentrations of OTC exposure. Environmental factors had a predominant influence, exceeding 40%, on enzyme activities during antibiotic reintroduction. Specifically, particle size significantly inhibited enzyme activity, while sediment nutrient conditions, including total carbon, nitrogen, and sulfur content, significantly enhanced enzyme activities. The study suggests that enzyme activities associated with antibiotic reintroduction in watershed sediments are established during stable stages in the bottom sediment layer or downstream sediment environment as part of sedimentary and transport processes. More research is required to explore the maintenance and evolution of antibiotic resistance profiles in the presence of long-term antibiotic residues. [ABSTRACT FROM AUTHOR]

The antibiotic oxytetracycline (OTC) is a fluorochrome marker, and fluorescence microscopy is used to view OTC marks in fishes' calcified structures. However, OTC marks have been observed in calcified structures using standard light microscopy for multiple species. Therefore, we conducted an experiment to investigate potential factors (i.e., season, total length of fish, growth rate, and sex) influencing the observation of OTC in calcified structures (otoliths and fin rays or spines) from channel catfish Ictalurus punctatus, gray redhorse Moxostoma congestum, Guadalupe bass Mircopterus treculii, and redbreast sunfish Lepomis auritus viewed using standard light and fluorescence microscopy. OTC stains were not observed in any otoliths under standard light; however, OTC marks were commonly observed in I. punctatus spines using standard light microscopy (56.2%). Ninety‐nine percent of otoliths and 88.9% of spines and fin rays had a visible fluorescent OTC mark when viewed using fluorescence microscopy. There was a negative relationship between the observed OTC mark and total length of fish for each season, but fish injected in the summer had the most structures with an observed OTC mark under either light condition. Understanding how OTC marking is affected by biological processes and environmental conditions will assist in future studies that rely on chemical marking of calcified structures by increasing efficacy of OTC marking and interpretation of marks. [ABSTRACT FROM AUTHOR]

Pacific Sardine (Sardinops sagax) in the Northeast Pacific Ocean are aged for stock assessments assuming the formation of two otolith growth bands (one opaque and one translucent) a year, but the periodicity of band formation has not been fully validated. To validate our ageing method, we investigated the periodicity of band deposition and somatic and otolith growth rate across a range of temperatures. Live Pacific Sardine (mostly age 0) were collected, marked with oxytetracycline (OTC), and raised in captivity at different temperatures (13 °C, 15 °C, 17 °C, and 21 °C) for up to one year. There was no clear pattern between temperature and somatic growth rate. Otolith growth rate was slower for Pacific Sardine in captivity at 13 °C than at 17 °C. All individuals that were in captivity for one year (n = 21) deposited 2–3 growth bands distal to the OTC mark. Therefore, Pacific Sardine deposited bands in their otoliths at the rate expected for the formation of annuli across ecologically relevant temperatures (13–21 °C) in captivity. Vateritic otoliths were rare but did display an OTC mark at approximately the same distance from the otolith edge as the aragonitic otolith in the pair. The results of this study build upon previous validation research for Pacific Sardine and support the ageing methodology used for this species by all ageing laboratories in the US, Canada, and Mexico. [ABSTRACT FROM AUTHOR]

Simple Summary: Salmonella spp. of both human and animal origin have a high resistance percentage to tetracyclines. Essential oils, including cinnamon, clove, oregano, and red thyme, have demonstrated bactericidal activity against this bacterium. However, in many cases, the minimum inhibitory concentration (MIC) exceeds the cytotoxicity limits. The aim of this study was to evaluate the in vitro effectiveness of combining oxytetracycline with essential oils against multidrug-resistant Salmonella enterica strains. The results indicated a positive interaction (synergy and additivity) between oxytetracycline and the four oils that were tested. This led to a reduction in the MIC of both the oils and the antibiotic. The reduction was between 2 and 4 times the initial value for the oils and between 2 and 1024 times for the antibiotic. The best results were achieved with the combination of oxytetracycline and cinnamon, which decreased the effective concentration of this antibiotic to below the sensitivity threshold. Although differences in response were observed depending on the bacterial strain, there was no antagonistic effect in any case. The study suggests that combining oxytetracycline with cinnamon oil may be an effective alternative for controlling tetracycline-resistant strains of Salmonella, although further studies would be advisable. Tetracyclines have a high resistance percentage in Salmonella spp. of both human and animal origin. Essential oils, such as cinnamon (Cinnamomum zeylanicum), clove (Eugenia caryophyllata), oregano (Origanum vulgare), and red thyme (Thymus zygis), have shown bactericidal activity against this bacterium. However, in many cases, the minimum inhibitory concentration (MIC) exceeds the cytotoxicity limits. The objective of this study was to assess the in vitro efficacy of combining oxytetracycline with essential these oils against field multidrug-resistant (MDR) Salmonella enterica strains. The MIC of each product was determined using the broth microdilution method. The interaction was evaluated using the checkerboard method, by means of the fractional inhibitory concentration index (FICindex) determination. The results showed a positive interaction (synergy and additivity) between oxytetracycline and the four oils tested, resulting in a reduction in both products' MICs by 2 to 4 times their initial value, in the case of oils, and by 2 to 1024 times in the case of the antibiotic. The combination of oxytetracycline and cinnamon achieved the best results (FICindex 0.5), with a decrease in the antibiotic effective concentration to below the sensitivity threshold (MIC of the combined oxytetracycline 0.5 µg/mL). There was no antagonistic effect in any case, although differences in response were observed depending on the bacterial strain. The results of this study suggest that combining oxytetracycline with cinnamon oil could be an effective alternative for controlling tetracycline-resistant strains of Salmonella. However, its individual use should be further evaluated through in vitro susceptibility tests. [ABSTRACT FROM AUTHOR]

Trunk injection of antibiotics has re-emerged as a strategy to mitigate citrus huanglongbing (HLB), a devastating disease associated with the bacterium Candidatus Liberibacter asiaticus (CLas). Despite commercial adoption in Florida, no studies have examined how oxytetracycline (OTC) injection may impact active plant-associated microbial communities. We investigated the impact of OTC trunk injection on tree physiological parameters, HLB control, and the prokaryotic and eukaryotic microbiome of the active inner bark and rhizosphere in a commercial citrus orchard under HLB-endemic conditions. OTC injection significantly increased juice quality and fruit weight. OTC was detected in leaves, bark, and roots but concentrations varied with time and across plant tissues. OTC injection reduced the abundance and diversity of the active prokaryotic microbiome in the bark and rhizosphere during the first three months post-injection. Specific prokaryotic taxa were responsive to OTC injection and their relative abundances related to increased plant performance. This study shows that OTC injection can promote the recovery of tree physiological functions impacted by HLB while also maximizing the benefits from certain prokaryotes of the bark and rhizosphere microbiomes. [ABSTRACT FROM AUTHOR]

Background: Antibiotics are commonly used drugs in farm animals for therapeutic, prophylactic and diagnosis purposes. As a result of the use of antibiotics in livestock, residues of antibiotics may be present in animal‐derived foods, especially in meat. This study aimed at determining the antibiotic residues in cattle slaughtered at Nekemte municipal abattoir and assessing the knowledge, attitude and practice (KAP) level of the community about antibiotic residue in food of cattle origin. Materials and methods: A cross‐sectional study was conducted on randomly selected kidney and muscle samples slaughtered at Nekemte municipal abattoir. The samples were collected aseptically and analysed using liquid chromatography mass spectrometer. In addition the KAP of cattle handlers, butcher men and meat users were collected using structured questionnaire. The data was analysed by SPSS and intercooled Stata version 7.0, 2001. Results: Results are presented as percentages and frequency distributions in tabular and graphical form. From 120 individuals interviewed, only 25.83% knew about withdrawal time and had limited knowledge on effect of antibiotic residue on human health, whereas about 47.5% did not heard about antibiotic residue in meat. Tetracycline was detected in all the sampled meat 60 (100%), whereas oxytetracycline residues were detected in half 15 (50%) of the samples. In the current study doxycycline, sulphadiazine, penicillin G and enrofloxacin were not detected in all samples. Oxytetracycline residue levels ranged from 0.00 to 463.35 µg/kg for the kidney and 0.00 to 354.55 µg/kg for muscle samples. About 10% of kidney and 3.33% muscle samples collected had oxytetracycline residues above maximum residue limits. Conclusion: In general, the study revealed that oxytetracycline residues were prevalent among antimicrobial residues analysed from the study area. The study indicated the presence of high antimicrobial residue and hence exposes for antimicrobial resistance of pathogens warranting coordinated effort to mitigate its health effect on the animal and hence human being. [ABSTRACT FROM AUTHOR]

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Antibiotic contamination has become a global environmental issue of widespread concern, among which oxytetracycline contamination is very severe. In this study, earthworm (Eisenia fetida) was exposed to oxytetracycline to study its impact on the soil environment. The total protein (TP), catalase (CAT), superoxide dismutase (SOD), peroxidase (POD), malondialdehyde (MDA), glutathione S-transferase (GST), and glutathione peroxidase (GPX) oxidative stress indicators in earthworms were measured, and the integrated biomarker response (IBR) approach was used to evaluate the toxic effect of oxytetracycline on earthworms. A Technique for Order Preference by Similarity to an Ideal Solution (TOPSIS) and a path analysis model were used to explore the physiological and metabolic processes of earthworms after stress occurs. The results showed that SOD, GPX, and GST play important roles in resisting oxytetracycline stress. In addition, stress injury showed a good dose–effect relationship, and long-term stress from pollutants resulted in the most serious damage to the head tissue of earthworms. These results provide a theoretical basis for understanding the toxic effect of oxytetracycline on soil animals, monitoring the pollution status of oxytetracycline in soil, and conducting ecological security risk assessment. [ABSTRACT FROM AUTHOR]

Antibiotics are commonly used to prevent and control aquaculture diseases. However, long-term overuse of antibiotics not only leaves residues but also leads to changes in the nitrogen cycle in water, which threatens the survival of aquaculture organisms. The current results showed that sulfamethoxazole had no significant effect on the nitrogen cycle process in the actual aquaculture concentration. The inhibitory effect of 1.05 mg/L norfloxacin on ammonia-oxidizing bacteria was significantly greater than that on ammonia-oxidizing archaea, and the gene abundance of AOB amoA on the 14th day increased by 2.48 times compared with the 7th day. Under the influence of 3.9 mg/L oxytetracycline, the gene abundance of AOB amoA decreased significantly, while the number of AOA amoA genes increased, suggesting that there may be functional redundancy between AOA and AOB. At the genus level in the norfloxacin group, the relative abundance of Sva0485 increased by 14.0% on the 7th day compared with the control group but decreased 12.77% in the addition group. The relative abundance of Firmicutes, another dominant species in the oxytetracycline group, was 25.9%. This study shows that the addition of antibiotics may have a negative effect on the nitrogen-cycling microorganisms in aquaculture water. [ABSTRACT FROM AUTHOR]

A unique luminescent lanthanide metal–organic framework (LnMOF)–based fluorescence detection platform was utilized to achieve sensitive detection of vomitoxin (VT) and oxytetracycline hydrochloride (OTC‐HCL) without the use of antibodies or biomolecular modifications. The sensor had a fluorescence quenching constant of 9.74 × 106 M−1 and a low detection limit of 0.68 nM for vomitoxin. Notably, this is the first example of a Tb‐MOF sensor for fluorescence detection of vomitoxin. We further investigated its response to two mycotoxins, aflatoxin B1 and ochratoxin A, and found that their Stern–Volmer fluorescence quenching constants were lower than those of VT. In addition, the fluorescence sensor realized sensitive detection of OTC‐HCL with a detection limit of 0.039 μM. In conclusion, the method has great potential as a sensitive and simple technique to detect VT and OTC‐HCL in water. [ABSTRACT FROM AUTHOR]

A new analytical method combining magnetic micro‐solid phase extraction (μ‐SPE) in tandem with high‐performance liquid chromatography‐ultraviolet (HPLC‐UV) analysis was developed and used for the simultaneous extraction/preconcentration of tetracycline (TC) and oxytetracycline (OTC) residues in drug manufacturing effluents. The μ‐SPE conducted by the introduction of iron oxide reduced‐graphene oxide (MrGO) doped tin‐lanthanium intercalated with thiosulfate ions to produce magnetic LDH (MrGO/Sn‐La‐S). The adsorbent was synthesized and characterized using x‐ray diffraction, Fourier transform infrared, scanning electron microscopy, energy‐dispersive x‐ray, elemental mapping, transmission electron microscopy, x‐ray photoelectron spectroscopy, and value stream mapping techniques. The effective parameters, including the extraction and desorption steps, were investigated and optimized. Under optimized conditions, the limits of detection (LOD) for TC and OTC were obtained as 5.42 and 3.31 μg.L−1, respectively, while the linearity was in the range of 10.0–500.0 μg.L−1 for both antibiotics with satisfactory determination coefficients (R2) of 0.9811 and 0.9846 for TC and OTC, respectively. The recovery percentages for the analytes in real samples were achieved in the ranges of 89.2%–101.6% and 91.0%–101.3% for TC and OTC antibiotics, respectively. All these features proved the potential of the developed method and adsorbent for real world applications. [ABSTRACT FROM AUTHOR]

Introducing carbon quantum dots (CQDs) into photocatalysts is believed to boost the charge transfer rate and reduce charge complexation. Doping heteroatoms such as N, S, or P enable CQDs to have an uplifting electron transfer capability. However, the application of oxygen-doped CQDs to improve the performance of photocatalysts has rarely been reported. Herein, a type of carbon-oxygen quantum dots (COQDs) was in situ embedded into MIL-53(Fe) to aid peroxydisulfate (PDS)-activated degradation of oxytetracycline (OTC) under visible light irradiation. The successful embedding of COQDs was confirmed by XRD, FT-IR, XPS, SEM, and TEM techniques. Photoelectrochemical testing confirmed its better performance. The prepared COQDs1/MIL-53(Fe) showed 88.2% decomposition efficiency of OTC in 60 min, which was 1.45 times higher than that of pure MIL-53(Fe). In addition, the performance of the material was tested at different pH, OTC concentrations, catalyst dosing, and PDS dosing. It was also subjected to cyclic testing to check stability. Moreover, free radical trapping experiments and electron paramagnetic resonance were conducted to explore the possible OTC deterioration mechanism. Our work provides a new idea for the development of MOFs for water treatment and remediation. [ABSTRACT FROM AUTHOR]

The antibiotic oxytetracycline (OCA) exhibits high insolubility in the natural environment, posing a significant challenge for its removal. This study synthesized a porous structure and a high-surface-area carbon fiber, incorporating zinc oxide (ZnO/CFB) for the effective removal of OCA in wastewater. The material characterization revealed exceptional optical and photochemical properties of ZnO/CFB, featuring a reduced band gap energy of 2.7 eV. ZnO/CFB exhibited robust performance in the photodegradation of OCA in wastewater, achieving an impressive removal efficiency of 86.7%. Remarkably, the reduction of total organic carbon (TOC) reached an outstanding 97.5%. LC-MS analysis confirmed the complete oxidation of OCA and its intermediates, transforming them into inorganic substances within 60 min. This study introduces an efficient strategy for eliminating antibiotic pollutants from wastewater, highlighting the potential of ZnO/CFB as an effective and stable photocatalyst for environmental remediation. [ABSTRACT FROM AUTHOR]

This study is aimed at evaluating the level of enrofloxacin and oxytetracycline residues in chicken meat and giblets and the effect of freezing and heat treatment methods on reduction of these residues. One hundred random samples of chicken breast, thigh, kidney and liver (25 of each) were collected from different chicken slaughter shops located in Sharkia Governorate for evaluation of their enrofloxacin and oxytetracycline residues. The collected samples were examined by using qualitative method by antimicrobial assay and quantitative method by High Performance Liquid Chromatography (HPLC) in addition to the effect of heat treatment (boiling and freezing) on these residues was studied. The obtained results revealed that the incidence of antibiotic residues in chicken breast, thigh, kidney, and liver were 0%, 8%, 20% and 20% respectively by qualitative method and by HPLC the level of enerofloxacine109, 122 and 202 ppb in thigh, liver and kidney respectively; meanwhile oxytetracycline level were 236, 523 and 1153 ppb in thigh, liver and kidney respectively. The results indicated that 75% of the positive samples did not exceed the MRL of enrofloxacin and oxytetracycline residues. Regarding to treatment trials either by freezing for (1month, 3month and 6 months) or by heating (boiling, roasting or frying) The reduction percent of residue levels was calculated and the public health significance and some recommendations to control such antibiotic residue in chicken tissues for human safety were discussed. [ABSTRACT FROM AUTHOR]

European foulbrood caused by the Gram-positive lanceolate coccus, Melissococcus plutonius, is a major bacterial infection of honey bee brood. Oxytetracycline (OTC) has been used to combat this disease in some countries. Although OTC resistance was not previously reported despite its long-term use, the first case was finally detected in an M. plutonius strain isolated in Canada in 2019. In Japan, OTC has not been approved for use in the control of any honey bee diseases. However, after testing 77 M. plutonius strains isolated in Japan between the 1980s and 2010s, we identified four OTC-resistant strains with a minimum inhibitory concentration of OTC on agar medium of 16 µg/ml. The four strains were isolated in 2008 (1 strain), 2013 (1 strain), and 2015 (2 strains); i.e., before the Canadian OTC-resistant isolate. These results provide insights into the mechanisms underlying the development of OTC-resistant M. plutonius. [ABSTRACT FROM AUTHOR]

Purpose: The contamination of soil with antibiotics has become a hot issue for the environment and global public health. However, there are scarcely any studies on the occurrence forms of antibiotics in saline soil. Occurrence forms of antibiotics are related to bioavailability. Therefore, this study facilitates the evaluation of the ecological risk of antibiotics in saline soil. Materials and methods: An experiment with artificial antibiotic contamination of soil and salinization simulations was conducted. The changes in the occurrence forms of oxytetracycline (OTC) and sulfamethoxazole (SMX) in saline soil were analyzed by continuous ultrasonic extraction. The factors for occurrence forms, including aging time and particle size fraction, were considered. Results and discussion: Soil salinization promoted the conversion of OTC and SMX from acid-soluble and bound states to water-soluble and locked states. Oxytetracycline in saline soil was predominantly in the water-soluble and acid-soluble states, accounting for 54.9–83.7% of the total. Sulfamethoxazole as well is accounting for 66.1–82.1%. In addition, the aging process from 7 to 63 days facilitated the conversion of OTC and SMX from the water-soluble, acid-soluble, and bound states to the non-extractable locked states, resulting in reduced bioavailability. Since the content of extractable forms of OTC and SMX in saline clay was high, it favors conversion to a locked state. Conclusions: Oxytetracycline and sulfamethoxazole in saline soil were mainly in bioavailable states. The aging effect reduced the bioavailability of OTC and SMX in saline soil. Clay had the low proportion of OTC and SMX in the bioavailable state, reducing environmental risks. [ABSTRACT FROM AUTHOR]

BackgroundTilapia is a primary aquaculture fish in Thailand, but little is known about the occurrence of antimicrobial resistance (AMR) in Aeromonas hydrophila, Salmonella spp., and Vibrio cholerae colonizing healthy tilapia intended for human consumption and the co-occurrence of these AMR bacteria in the cultivation water.MethodsThis study determined the phenotype and genotype of AMR, extended-spectrum β-lactamase (ESBL) production, and virulence factors of A. hydrophila, Salmonella spp., and V. cholerae isolated from hybrid red tilapia and cultivation water in Thailand. Standard culture methods such as USFDA's BAM or ISO procedures were used for the original isolation, with all isolates confirmed by biochemical tests, serotyping, and species-specific gene detection based on PCR.ResultsA total of 278 isolates consisting of 15 A. hydrophila, 188 Salmonella spp., and 75 V. cholerae isolates were retrieved from a previous study. All isolates of A. hydrophila and Salmonella isolates were resistance to at least one antimicrobial, with 26.7% and 72.3% of the isolates being multidrug resistant (MDR), respectively. All A. hydrophila isolates were resistant to ampicillin (100%), followed by oxytetracycline (26.7%), tetracycline (26.7%), trimethoprim (26.7%), and oxolinic acid (20.0%). The predominant resistance genes in A. hydrophila were mcr-3 (20.0%), followed by 13.3% of isolates having floR, qnrS, sul1, sul2, and dfrA1. Salmonella isolates also exhibited a high prevalence of resistance to ampicillin (79.3%), oxolinic acid (75.5%), oxytetracycline (71.8%), chloramphenicol (62.8%), and florfenicol (55.3%). The most common resistance genes in these Salmonella isolates were qnrS (65.4%), tetA (64.9%), bla TEM (63.8%), and floR (55.9%). All V. cholerae isolates were susceptible to all antimicrobials tested, while the most common resistance gene was sul1 (12.0%). One isolate of A. hydrophila was positive for int1, while all isolates of Salmonella and V. cholerae isolates were negative for integrons and int SXT. None of the bacterial isolates in this study were producing ESBL. The occurrence of mcr-3 (20.0%) in these isolates from tilapia aquaculture may signify a serious occupational and consumer health risk given that colistin is a last resort antimicrobial for treatment of Gram-negative bacteria infections.ConclusionsFindings from this study on AMR bacteria in hybrid red tilapia suggest that aquaculture as practiced in Thailand can select for ubiquitous AMR pathogens, mobile genetic elements, and an emerging reservoir of mcr and colistin-resistant bacteria. Resistant and pathogenic bacteria, such as resistance to ampicillin and tetracycline, or MDR Salmonella circulating in aquaculture, together highlight the public health concerns and foodborne risks of zoonotic pathogens in humans from cultured freshwater fish.

Background: Formaldehyde (FA) and oxytetracycline (OTC) arechemicals commonly used in aquaculture to prevent or to treat fish's diseases due to protozoa, parasites and bacteria. Aim: The goal of the present study is to assess 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 same conditions being applied in intensive aquaculture systems in Tunisia. Methods: 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 vacuolisation, blood congestion, and focal necrosis. Significant elevation in catalyse 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 to FA and OTC when released to the environment. [Open Vet J 2024; 14(2.000): 630-639]

Abstract Background Sheep and goat production in Ethiopia is hindered by numerous substandard production systems and various diseases. Respiratory disease complexes (RDC) pose a significant threat to the productivity of these animals. Pneumonia is a common manifestation of respiratory disease complexes and often necessitates a prolonged course of antibiotic treatment. This study aimed to optimize and propose the ideal duration of therapy for pneumonia in sheep and goats. Methods The study was conducted from February to June 2021 at the Veterinary Teaching Hospital of the College of Veterinary Medicine and Agriculture, Addis Ababa University. The study recruited 54 sheep and goats presented to the hospital for treatment with a confirmed RDC as determined based on clinical signs and bacteriological methods. The animals were randomly allocated to 5 groups each group receiving 10% oxytetracycline (Phenxyl, Phenix, Belgum) intramuscularly for a duration of 3, 4, 5, 6 and 7 consecutive days. The treatment outcomes were assessed by recording vital signs (body temperature, respiratory rate, heart rate, coughing, and nasal discharges), performing lung ultrasonography (L-USG) as well as collection of nasal swabs for bacterial isolation and molecular identification before and after completion of the treatment. An ordered logistic regression model with random effects was employed to determine the optimal therapeutic duration, taking into account the cumulative scores of the outcome variables across the different groups. Results Among the 54 sheep and goats treated with 10% oxytetracycline, a total of 74.07% (95% CI, 60.35–85.04) achieved complete recovery, as confirmed through clinical, ultrasound, and bacteriological methods. In Group 1 (G1), out of 12 sheep and goats, 8 (83.0%) recovered completely; in Group 2 (G2), out of 11 animals, 9 (82.0%) recovered completely; in Group 3 (G3), out of 11 animals, 10 (93.0%) recovered completely; in Group 4 (G4), out of 9 animals, 9 (100.0%) recovered completely; and in Group 5 (G5), out of 11 animals, 10 (91.0%) recovered completely. Bacteriological examination of nasal swabs indicated involvement of M. hemolytica in 27 (50.00%) and P. multocida in 13 (24.07%) of pneumonic animals. Detection of specific marker genes confirmed only five of the presumptive M. hemolytica isolates, whilst no isolates tested positive for P. multocida. Post-treatment samples collected from recovered animals did not yield any M. hemolytica nor P. multocida. Based on results from clinical signs, L-USG, and bacterial infection variables, the group of sheep and goats treated for seven consecutive days (G5) showed the highest recovery score compared to the other groups, and there was a statistically significant difference (coefficient (β) = − 2.296, p = 0.021) in variable score between G5 and G1. These findings suggest that the administration of 10% oxytetracycline for a full course of seven consecutive days resulted in symptomatic and clinical recovery rates from respiratory disease in sheep and goats.