Effect of nonionic surfactant Brij 35 on the fate and transport of oxytetracycline antibiotic in soil

In many parts of the world, river water is used for irrigation. Treated, partially treated, and even untreated water from wastewater treatment plants is discharged directly into rivers, thereby degrading the quality of the water. Consequently, irrigation water may contain surfactants which may affect the fate and transport of chemicals such as pesticides and antibiotics in agricultural soils. A field lysimeter study was undertaken to investigate the effect of the nonionic surfactant, Brij 35, on the fate and transport of an antibiotic, Oxytetracycline, commonly used in cattle farms. Nine PVC lysimeters, 1.0 m long × 0.45 m diameter, were packed with a sandy soil to a bulk density of 1.35 Mg m(-3). Cattle manure, containing Oxytetracycline, was applied at the surface of the lysimeters at the recommended rate of 10 t/ha. Each of three aqueous Brij 35 solutions, 0, 0.5 and 5 g L(-1) (i.e., 'good,' 'poor' and 'very poor' quality irrigation water) were each applied to the lysimeters in triplicate. Over a 90 day period, soil and leachate samples were collected and analyzed. Batch experiment results showed that the presence of the nonionic surfactant Brij 35 significantly reduced the sorption coefficient of OTC from 23.55 mL g(-1) in the aqueous medium to 19.49, 12.49 and 14.53 in the presence of Brij 35 at concentrations of 0.25, 2.5 and 5 g L(-1), respectively. Lysimeter results indicted the significant downward movement of OTC at depths of 60 cm into soil profile and leachate in the presence of surfactant. Thus, the reuse of wastewater containing surfactants might enhance the mobility of contaminants and increase ground water pollution.

Environmental Risk Assessment of antimicrobials applied in veterinary medicine-A field study and laboratory approach

The fate and environmental risk of antimicrobial compounds of different groups of veterinary medicine pharmaceuticals (VMP's) have been compared. The aim was to demonstrate a correlation between the physical and chemical properties of active compounds and their metabolism in target animals, as well as their fate in the environment. In addition, the importance of techniques for manure management and agricultural practice and their influence on the fate of active compounds is discussed. The selected active compounds are shown to be susceptible to at least one environmental factor (sun, water, bacterial or fungal degradation) to which they are exposed during their life cycle, which contributes to its degradation. Degradation under a number of environmental factors has also to be considered as authentic information additional to that observed in the limited conditions in laboratory studies and in Environmental Risk Assessment calculations.

Measurement of oxytetracycline and emamectin benzoate in freshwater sediments downstream of land based aquaculture facilities in the Atlantic Region of Canada

This study investigated the occurrence of oxytetracycline (OTC) and emamectin benzoate (EB) in sediments located near the effluent outfall from four freshwater aquaculture facilities in Atlantic Canada. While two facilities had no detectable concentrations of EB or OTC, two facilities had detectable concentrations of one or both of these chemicals. Concentrations ranged from <0.05-18 mg/kg to <0.01-2.5 mg/kg for OTC and EB respectively. Although these values could not be compared with freshwater toxicant values, some of the concentrations of EB and OTC detected were higher than LC(50) values calculated for marine invertebrates. OTC concentrations measured in this study are also of a magnitude which has been known to produce resistant bacteria.

Salmon aquaculture and antimicrobial resistance in the marine environment

Antimicrobials used in salmon aquaculture pass into the marine environment. This could have negative impacts on marine environmental biodiversity, and on terrestrial animal and human health as a result of selection for bacteria containing antimicrobial resistance genes. We therefore measured the numbers of culturable bacteria and antimicrobial-resistant bacteria in marine sediments in the Calbuco Archipelago, Chile, over 12-month period at a salmon aquaculture site approximately 20 m from a salmon farm and at a control site 8 km distant without observable aquaculture activities. Three antimicrobials extensively used in Chilean salmon aquaculture (oxytetracycline, oxolinic acid, and florfenicol) were studied. Although none of these antimicrobials was detected in sediments from either site, traces of flumequine, a fluoroquinolone antimicrobial also widely used in Chile, were present in sediments from both sites during this period. There were significant increases in bacterial numbers and antimicrobial-resistant fractions to oxytetracycline, oxolinic acid, and florfenicol in sediments from the aquaculture site compared to those from the control site. Interestingly, there were similar numbers of presumably plasmid-mediated resistance genes for oxytetracycline, oxolinic acid and florfenicol in unselected marine bacteria isolated from both aquaculture and control sites. These preliminary findings in one location may suggest that the current use of large amounts of antimicrobials in Chilean aquaculture has the potential to select for antimicrobial-resistant bacteria in marine sediments.

[Pollution characteristics and accumulation of antibiotics in typical protected vegetable soils]

The occurrence and distribution of 14 selected antibiotics in soils from 20 protected vegetable fields in Shandong province were investigated by ultrasonic extraction and UPLC-MS/MS. The results showed that antibiotics were detected in all the soil samples, the dominant antibiotics were tetracycline, oxytetracycline, chlortetracycline and doxycycline with 100% detection rate, the concentration of which in soil ranged from 2.11-139.16, 6.06-332.02, 1.82-391.31, 2.20-248.56 microg x kg(-1), respectively. The total concentration of four compounds sigma (TCs) ranged from 26.79-1010.11 microg x kg(-1), with an average of 274 microg x kg(-1). All the sulfonamides (SAs), quinolones (QNs) and macrolides antibiotics (MACs) were also detected, except for chloramphenicoles. The total concentration of QNs [sigma (QNs)] in soils ranged from 0-1017.06 microg x kg(-1) and the average concentration was 73.05 microg x kg(-1) with detection rate of 85%, and the individual concentrations of SAs and MACs were quite low in soils. The results also showed that the distibution and concentration of antibiotics in soils grown different vegetables were quite different. Notably, the individual concentrations of QNs (NFC, OFC) were 373.73 microg x kg(-1) and 643.34 microg x kg(-1), respectively, which far exceeded the trigger value of the ecological risk (100 microg x kg(-1)). Thus, more attention should be paid to antibiotics pollution in protected vegetable soils.

Characteristics of oxytetracycline sorption and potential bioavailability in soils with various physical-chemical properties

Veterinary antibiotics are widely used for disease treatment, prevention and animal growth promoting. Frequent detection of veterinary antibiotics in environments, caused by land application of untreated or even treated antibiotics-containing animal wastes, has posed the growing concern of their adverse effect on natural ecosystems. Oxytetracycline (OTC) is one of the most widely-used veterinary antibiotics in livestock industry. OTC present as a cation, zwitterions, or net negatively charged ion in soils complicates predicting its sorption characteristics and potential bioavailability and toxicity. This study was to identify soil properties influencing OTC sorption and its subsequent bioavailability in five soils with various physical-chemical properties. A solution used to determine bioavailable analytes in soils and sediments, 1 M MgCl(2) (pH 8.5), was chosen to desorb the potentially bioavailable fraction of OTC sorbed onto soils. Our results demonstrated that soils with higher illite content and permanent cation exchange capacity have higher OTC sorption capacity, but increase the availability of sorbed OTC indicated by higher release of sorbed OTC from soils into aqueous phase in 1 M MgCl(2) (pH 8.5). Reversely, soil organic matter (SOM), clay, kaolinite, variable cation exchange capacity, DCB-Fe and -Al have lower OTC sorption capacity, but decrease the release of sorbed OTC from soils into 1 M MgCl(2). These findings indicate that SOM and clay greatly influence OTC adsorption and potential availability. This study contributes significantly to our understanding of the potential bioavailability of sorbed OTC and the effects of soil properties on OTC sorption behaviors in soils.

[Simultaneous determination of six antibiotics in disinfection products by high performance liquid chromatography tandem mass spectrometry]

OBJECTIVE

To develop a method for determination of the Metronidazole, Chlortetracycline hydrochloride, Oxytetracycline dihydrate, Minocycline hydrochloride, Erythromycin and Tetracycline hydrochloride in disinfection products by high performance liquid chromatography tandem mass spectrometry(LC-MS/MS).

METHODS

Samples were extracted by methanol and filtered through 0.45 microm PTFE membrane filter, then analyzed by LC-MS/MS using Waters Symmetry C18 (2.1 mm x 150 mm, 3.5 microm) column in positive ion scan mode. The mobile phase was 5 mmol/L ammonium acetate, methanol and acetonitrile.

RESULTS

The linear range was 0-2000 ng/ml and the correlation coefficients were more than 0.998, the average recoveries ranged from 74.7% to 114% with the relative standard deviations between 1.6%-20.2%. The method was successfully used to detect the content of antibiotics in 115 disinfection products.

CONCLUSION

The method is simple, sensitive, selective and suitable for the analysis of residual content of antibiotics in cream formulations of disinfection products.

[Dynamics of degradation of oxytetracycline of pig and chicken manures in soil and mechanism investigation]

Simulated indoor incubation experiment was carried out to explore the degradation dynamics of oxytetracycline (OTC) from different manures and the mechanisms were investigated as well. The results suggested that manures accelerated OTC entering soil and degrading period, and resembled the L-type curves. Both degradation rate and degradation percentage were significantly different for different antibiotics with different concentration (P < 0.05). At day 180, the OTC degradation percentage of chicken feces was higher than that of pig feces, and the highest degradation percentage reached to 85.4% and 92.3% respectively. The half-lives of chicken and pig manures were 26.98 d, 31.32 d respectively. Degradation percentage was negatively correlated with the amount of manures used and positively correlated with incubation time (v = A + Blnt, r > 0.96). At day 50, the photo-degradation and micro-degradation accounted for 20.03% and 3.16% of total reduction. 25.05% decreased in photo degradation and 2.50% increased in microbiological degradation. It is indicated that the degradation effects to OTC from pig manures was superior to chicken manures, photo decomposing played an important role in the process of degradation and indigenous soil microorganisms only had a little effect on it. With the extension of incubation time, microbiological decomposing became better, but photo decomposing became weaker.

The operation of two EGSB reactors under the application of different loads of oxytetracycline and florfenicol

This study evaluated the effect of the antibiotics oxytetracycline (OTC) and florfenicol (FLO) on the operation of two EGSB (expanded granular sludge bed) reactors. The experiment was conducted for 210 d in reactor R1 and 245 d in reactor R2. The reactors were inoculated with granular sludge from a upflow anaerobic sludge blanket (UASB) reactor on a local dairy farm. The sludge had an average pellet size of 2.35 mm, good sedimentability and a high percentage of organic material. The antibiotic tolerance and the inhibitory action on the bacterial population were different for each antibiotic studied. The results showed a more severe inhibitory effect on microorganisms that were in contact with increases in loads of FLO than those that were in contact with increasing loads of OTC, a condition reflected in the chemical oxygen demand (COD) removal efficiency.

Effect of temperature, pH and illumination on abiotic degradation of oxytetracycline in sterilized swine manure

Tetracyclines such as oxytetracycline (OTC) are widely used veterinary chemicals. They are often poorly absorbed with a significant fraction being excreted in manure that can subsequently result in environmental contamination. In many countries throughout South East Asia swine manure is not composted, but sun-dried. Using sunlight to heat manure has been suggested as an effective and low-cost strategy to reduce OTC contamination, but this has previously been unexplored. Such conditions have also been shown to reduce bacterial numbers in manure meaning abiotic OTC degradation processes may become more significant. This work investigated for the first time, the role of temperature, illumination and pH in the abiotic degradation of OTC in sterilized swine manure. OTC loss from laboratory-based experiments simulating conditions likely to be experienced in sun-drying were assessed using simple first order and availability-adjusted loss models. ANOVA results suggested that neither model was superior to the other. In addition, pH and light had little influence. Temperature was shown to be the main factor influencing OTC loss. Kinetic results showed reductions in OTC concentrations of 65 % after 100 h at 40°C based on the availability-adjusted loss model, regardless of pH and illumination. Such temperatures are likely to be attained during the process of sun-drying. Therefore this may be a useful and practical means of reducing OTC contamination in manure.

Mobility of veterinary drugs in soil with application of manure compost

Sulfonamides and tetracyclines are pharmaceuticals widely used to treat human and animal diseases. They are of considerable concern in Korea because of the potential risk of residues in aquatic and terrestrial environments. This study investigated the mobility of veterinary drugs in the soil column with the application of manure compost to assess the risk of groundwater contamination by leaching in the Korean agricultural environment. The degree of sulfonamides and tetracyclines mobility, measured by the concentration of leachates from silty loam soil for 9 days, was observed being on the first day of this study, in the order sulfathiazole, sulfamethazine > sulfamethoxazole > chlortetracycline > oxytetracycline, and the sulfonamides concentrations were about ten times higher than the tetracyclines concentrations with continuous leaching. The results indicate that sulfonamides pose a high risk of ground and surface water contamination and tetracyclines have the potential to persist in soils with bioactive epimers.

Distribution and accumulation of endocrine-disrupting chemicals and pharmaceuticals in wastewater irrigated soils in Hebei, China

This study investigated the occurrence of 43 emerging contaminants including 9 endocrine-disrupting chemicals and 34 pharmaceuticals in three sites in Hebei Province, north China. Each site has a wastewater irrigated plot and a separate groundwater irrigated plot for comparison purpose. The results showed that the concentrations of the target compounds in the wastewater irrigated soils were in most cases higher than those in the groundwater irrigated soils. Among the 43 target compounds, nine compounds bisphenol-A, triclocarban, triclosan, 4-nonylphenol, salicylic acid, oxytetracycline, tetracycline, trimethoprim and primidone were detected at least once in the soils. Preliminary environmental risk assessment showed that triclocarban might pose high risks to terrestrial organisms while the other detected compounds posed minimal risks. Irrigation with wastewater could lead to presence or accumulation of some emerging contaminants to some extent in irrigated soils.

Ozonation performance of WWTP secondary effluent of antibiotic manufacturing wastewater

The ozonation performance of wastewater treatment plant secondary effluent of oxytetracycline (OTC) manufacturing wastewater was investigated in terms of ozone dosage and initial pH levels when OTC contributed to a negligible fraction in the chemical oxygen demand (COD) ingredients of the medium-organic-strength wastewater with low biodegradability. A particular emphasis was placed on ammonia, OTC, and residual antibacterial activity (RAA) (evaluated using the objective pathogenic bacterium Staphylococcus aureus). It appears that an ozone dosage of 657 mg L⁻¹ (120 min of reaction) was enough to achieve an OTC abatement of 96%, and COD and biochemical oxygen demand removals of 29% and 33%, respectively, at initial levels of 10.4, 1360, and 300 mg L⁻¹ , respectively. There is a clear correlation between complete OTC depletion and complete RAA disappearance with an increase of ozone dosage. The presence of plentiful non-antibiotic refractory substances influenced the determination of the optimum ozone dosage for biodegradability enhancement and OTC/RAA reduction as well as the ozonation transformation of NH(3). The initial pH adjustment from the original level (pH 9) to pH 11 significantly reduced COD removal while RAA and NH(3) levels were not significantly influenced.

Development of an efficient extraction method for oxytetracycline in animal manure for high performance liquid chromatography analysis

Oxytetracycline (2-(amino-hydroxy-methylidene)-4-dimethylamino-5,6,10,11,12a-pentahydroxy-6-methyl-4,4a,5,5a-tetrahydrotetracene-1,3,12-trione) is a major member of the tetracycline antibiotics family of which are widely administered to animals in concentrated animal feeding operations for purposes of therapeutical treatment and health protection. With the disposal of animal manure as fertilizer into agricultural land, tetracyclines enter the environment. However, tetracyclines chelate with multivalent cations and proteins, resulting in low extraction efficiencies from animal manure for tetracycline residue analysis. In this study an efficient extraction method for oxytetracycline from steer manure using methanol/water solution amended with chelating organic acid was developed for the analysis of high performance liquid chromatography. The effect of species and amount of amendment acids, shaking time, methanol/water ratio, manure weight, and repeated times of extraction was investigated. It was optimized to amend 2.5 g citric acid and 1.1 g oxalic acid with 10.0 g manure sample in a 50-ml centrifuge tube and extract with 15 ml methanol/water (9:1 in volume) by vigorously shaking for 30 min in a reciprocating shaker. After centrifugation at 11,000 rpm, supernatant is collected. Sample was extracted for a total of 3 times. The developed extraction method was further applied to extract oxytetracycline from fresh and aged cow manure, swine and poultry manure, and soil. Satisfactory recoveries ranging from (84.1 +/- 2.4) % to (102.0 +/- 3.1) % were obtained, demonstrating that the optimized extraction method is robust for oxytetracycline from different manure sample matrixes.

A novel colorimetric aptasensor using gold nanoparticle for a highly sensitive and specific detection of oxytetracycline

We have successfully developed a novel colorimetric aptasensor using gold nanoparticles for highly sensitive and specific detection of oxytetracycline (OTC), one of the most common antibacterial agents. A highly specific ssDNA aptamer that bind to OTC with high affinity was employed to discriminate other tetracyclines (TCs), such as doxycycline (DOX) and tetracycline (TET). Aggregation of AuNPs was specifically induced by desorption of the OTC binding aptamers (OBAs) from the surface of gold nanoparticles as a result of the aptamer-target interaction, leading to the color change from red to purple. The detection limit of OTC was enhanced up to 25 nM, which is 20-fold lower than the limit USA-EPA regulated, with two orders of magnitudes in its linear dynamic range by successful optimization on the amount of the aptamers, AuNPs, and salts. This colorimetric aptasensor is advantageous over the other conventional methods in terms of its simple signal generation and detection with the naked eye, which can be realized in on-site detection of antibacterial agents.

Acute effects of the antibiotic oxytetracycline on the bacterial community of the grass shrimp, Palaemonetes pugio

The toxicity of oxytetracycline (OTC) was evaluated in adult grass shrimp, Palaemonetes pugio. Initially, static acute (96 h) toxicity tests were conducted with shrimp exposed from 0 to 1,000 mg/L OTC. A calculated lethal concentration 50% value of 683.30 mg/L OTC (95% confidence interval 610.85-764.40 mg/L) was determined from these tests, along with a lowest-observable-effect concentration of 750 mg/L and no-observable-effect concentration of 500 mg/L. Moreover, chronic sublethal effects of OTC exposure on grass shrimp intestinal bacterial population were assessed using doses from 0 to 32 mg/L OTC. The total viable counts in digestive tract content had levels between 5.2 and 1x10(4) colony-forming units per gram of tissue at times 0 and 96 h, respectively. Aeromonas hydrophila were the most resistant isolates (27.78%) to OTC exposure. Vibrio alginolyticus showed significant positive growth following exposure to OTC, whereas other bacterial species abundance declined over time. A total of 268 bacterial isolates were screened using antibiotic resistance analysis from a library containing 459 isolates. Among the tested isolates from the OTC treatments, 15.4% were resistant to OTC and 84.6% were OTC sensitive. Oxytetracycline was generally not consistently quantifiable with liquid chromatography-mass spectroscopy technique in shrimp homogenates. The only peak detected was at the 32 mg/L dose of OTC at 96 h. Nevertheless, OTC had a significant biological effect on the bacterial population. Antibiotic resistance to five other antibiotics (penicillin G, sulfathiazole, trimethoprim, trimethoprim and sulfamethoxazole, and tetracycline) was strongly associated with OTC exposures. The present study indicates that OTC toxicity effects in P. pugio and changes in the shrimp microbial community would only be expected under special circumstances.

[Enhanced sorption of OTC on clays via complexation with Zn2+]

Oxytetracycline (OTC) and Zn2+ are both widely used as growth promoters in concentrated animal feeding operations, which are discharged into soil system by manure application. There is special environment significance to study the sorption and interaction of OTC with accompanied metal cations on clays to elucidate their environmental behaviors and to assess ecological risks. Much stronger sorption of OTC was observed on montmorillonite than that on kaolinite, which might be resulted from the larger cation exchange capacity of the former. Different pH-dependent Kd patterns were illustrated on montmorillonite and kaolinite, which might be contributed by the different properties of surface charge. During 4 < pH < 5, OTC sorption was decreased by cation competition of Zn2+, while OTC sorption was promoted by OTC-Zn-clay bridge while 5 < pH < 9, and the most significant effect was shown at pH = 6.5. The sorption of Zn2+ on two clays was decreased by OTC in the pH range studied, which can be explained by cation competition of OTC at lower pH, or by prohibition in the sorption or precipitation resulted from complexation between OTC and Zn2+ at higher pH. CD and UV-Vis spectrometry analysis showed that there was no complexation observed between OTC and Zn2+ at pH = 4. But with increasing of pH value, complexation might happen at the sites of O11, O12 or O12, O1.

Comparison of the ozonation and Fenton process performances for the treatment of antibiotic containing manure

An integrated treatment method based on magnesium salt extraction followed by chemical oxidation was used for the treatment of a veterinary antibiotic, oxytetracycline (OTC) contaminated cow manure since animal manure can be an important source for antibiotic pollution in the environment. Pretreatment with magnesium salt enhanced the efficiencies of subsequent oxidation processes by extracting 63.9% of OTC from the manure thereby making it more favorable for oxidation with the hydroxyl radicals produced by the Fenton and ozone oxidation processes. Both the 24 h Fenton oxidation process with 434 mM H(2)O(2) and 43.4 mM Fe(2+) doses and the 1-h ozonation process with an applied ozone dose of 2.5 mg min(-1) provided more than 90% OTC removal from the manure slurry. However, the second-order OTC removal rate constant of Fenton process (119 M(-1)s(-1)) was remarkably lower than that obtained with the ozonation process (548 M(-1)s(-1)). The oxidant dose was a significant factor for the efficiency of the Fenton treatment but not for the ozone treatment. The efficiencies of both the Fenton and ozone oxidation processes were not affected by the pH adjustment of the manure slurry.

Effects of agricultural conditions on the leaching behaviour of veterinary antibiotics in soils

Antibiotics may be released to soils during the application of manure as fertiliser to land. The compounds may subsequently be transported to and contaminate groundwater and surface waters. This paper describes a series of lysimeter-based studies to explore the leaching behaviour of three veterinary antibiotics (sulfachloropyridazine, oxytetracycline and tylosin) under different conditions that could occur in the agricultural environment. The specific objectives were to: (1) explore the influence of slurry amendment and incorporation on leaching; (2) assess the effects of climate on leaching behaviour; and (3) evaluate the predictive capability of a leaching model used in the regulatory assessment of veterinary medicines. Sulfachloropyridazine was detected sporadically in leachate at concentrations up to 0.66 microg L(-1) under typical irrigation conditions and more frequently at concentrations up to 8.5 microg L(-1) under extreme irrigation conditions. Incorporation and timing of rainfall had no effect on leaching behaviour. Oxytetracycline and tylosin were not detected in any leachate samples. These differences in behaviour were explained by the sorption and persistence characteristics of the compounds. Comparison of the experimental measurements with simulations from the leaching model indicated that the model greatly underestimates the transport of antibiotics to groundwater which raises questions over the application of these models in the regulatory risk assessment process.

Determination of oxytetracycline/oxytetracycline hydrochloride in animal feed, fish feed, and veterinary medicinal products by liquid chromatography with fluorescence detection: collaborative study

A method for determining oxytetracycline (OTC) in animal feed, fish feed, and veterinary medicinal products at medicated use and contamination levels was collaboratively studied. The method is applicable to the analysis of animal feeds and mineral premixes containing levels > or =2 mg/kg, and fish feed containing levels > or =10 mg/kg. Oxytetracycline hydrochloride (OTC.HCI) is extracted from ground feed material in acid-methanol solution using mechanical agitation. After centrifugation for 5 min at 1230 x g, an aliquot of the extract is diluted with water andlor acid-methanol so that the concentration of OTC.HCI is approximately the same as that in the working standard, and the solutions contain at least 50% water. Injectable veterinary medicinal materials (also called animal remedy materials) are diluted with water andlor extractant to reach the target concentration. The extracts are filtered and analyzed by reversed-phase liquid chromatography with fluorescence detection with excitation at 390 nm and emission at 512 nm. Twenty-eight test samples of medicated feeds, supplements, and drug premixes, including 4 test samples for trace-level analysis, were sent to 17 collaborators in Canada, The Netherlands, and the United States. Results were received from 11 laboratories. The RSDr values (within-laboratory repeatability) ranged from 1.26 to 9.21%; RSDR values (among-laboratory reproducibility) ranged from 2.14 to 12.9%, and HorRat values ranged from 0.54 to 3.02. It is recommended that this method be adopted AOAC Official First Action.

Laboratory study of oxytetracycline degradation kinetics in animal manure and soil

Oxytetracycline (OTC) is a major member of tetracyclines, which are widely administered to animals in confined feeding operations. To diminish the contamination of OTC in the environment, which results from the application of OTC-containing manure as fertilizer in agricultural lands, OTC degradation kinetics in manure and soil under laboratory aerobic conditions was investigated. OTC degradation kinetics was found to be described well by the previously developed availability-adjusted first-order model at all moistures and low temperatures (<or=25 degrees C). OTC degradation increased with increasing moisture from 60 to 100%. However, OTC became very persistent in water-saturated manure. Increasing temperature greatly accelerated OTC degradation, and thermal degradation became noticeable at high temperatures (>or=35 degrees C) in manure. At 25 degrees C, OTC half-life was determined to be 8.1 days in manure with moisture at 80%, 33 days in manure-amended soil (amendment ratio at 5%), and 56 days in non-amended soil with both moistures at 20%, demonstrating that OTC may become persistent in the environment once it is released from manure into soil. No pronounced effect of coexistent antibiotics on OTC degradation in manure was observed.

Determination and fate of oxytetracycline and related compounds in oxytetracycline production wastewater and the receiving river

This study investigated the occurrence and fate of oxytetracycline (OTC) and its related substances, 4-epi-oxytetracycline (EOTC), alpha-apo-oxytetracycline (alpha-apo-OTC), and beta-apo-oxytetracycline (beta-apo-OTC), in a wastewater treatment plant (WWTP) treating OTC production wastewater and a river receiving the effluent from the WWTP using liquid chromatography electrospray ionization mass spectrometry (LC-ESI-MS). The percent removal of OTC in the WWTP was 38.0 +/- 10.5%, and the concentration of OTC was still up to 19.5 +/- 2.9 mg/L in the treated outflow. The concentration slightly decreased along the river, from 641 +/- 118 microg/L at site R2 (discharging point) to 377 +/- 142 microg/L at site R4 ( approximately 20 km from site R2), which was still higher than the minimal inhibition concentration of OTC reported ( approximately 250 microg/L). On the other hand, the total amount of its related substances in the treated effluent was less than 5% of OTC. Concentrations of alpha-apo-OTC and beta-apo-OTC increased along the river, from 5.76 +/- 0.63 and 2.08 +/- 0.30 microg/L at site R2 to 11.9 +/- 4.9 and 12.0 +/- 4.6 microg/L at R4, respectively, although EOTC decreased from 31.5 +/- 3.8 to 12.9 +/- 1.1 microg/L, respectively. The mean concentration of beta-apo-OTC in river sediments was 20.8 +/- 7.8 mg/kg, and its ratio to OTC was approximately 0.11, nearly twice the ratio of alpha-apo-OTC and EOTC to OTC (0.058 +/- 0.014 and 0.061 +/- 0.015, respectively).

Studies on the residues of terramycin and furazolidone in broiler meat--a public health concern

The concentration of Terramycin and Furazolidone residues in broiler meat following their subtherapeutic use in the ration of the birds were detected as 296 ng/g, 174 ng/g, 40 ng/g, 60 ng/g and 124 ng/ml in kidney, liver, thigh muscle, breast muscle and serum for Terramycin and 270 ng/g 160 ng/g and 88 ng/ml in kidney, liver and serum for Furazolidone. One week of withdrawal period from the antibiotic in feed/water was sufficient to render the meat free from residues.

Simultaneous determination of selected veterinary antibiotics in gilthead seabream (Sparus Aurata) by liquid chromatography–mass spectrometry

A method was optimised and validated for simultaneous monitoring of several drugs of different classes of antibiotics such as quinolones (oxilinic acid and flumequine), tetracyclines (oxytetracycline), sulfonamides (sulfadiazine) and trimethoprim in fish muscle and skin. The method is based on solid-liquid extraction without further sample clean up followed by liquid chromatography-mass spectrometry (LC-MS) determination with electrospray ion source (ESI) in positive mode. The limits of quantification (LOQs) were lower than 20 microg/kg for all compounds and repeatability, expressed as relative standard deviations (RSD), were lower than 15%. Therefore, the LC-MS method was successfully applied for the quantitative determination of antibiotics in gilthead sea bream muscle and skin and oxytetracycline in medicated fishes.