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Bent Halling-Sørensen

Publications and source records attributed to Bent Halling-Sørensen.

9 recordsLinked to original sources
PubMed2003

Susceptibility of Escherichia coli and Enterococcus faecium isolated from pigs and broiler chickens to tetracycline degradation products and distribution of tetracycline resistance determinants in E. coli from food animals.

One hundred Escherichia coli isolates from diseased and healthy pigs, cattle and broiler chickens were screened for the presence of tetracycline resistance genes tet(A), (B), (C), (D) or (E). The tet(A) gene was the most abundant (71% of the 100 isolates) followed by tet(B) (25%). The predominance of tet(A) and tet(B) applied to all three animal species, and there was no difference between the distribution of tet(A) and tet(B) genes among non-pathogenic and pathogenic E. coli in any of the animal species. The susceptibility of 20 of these isolates together with 10 tetracycline sensitive E. coli and 18 tetracycline resistant and 10 sensitive Enterococcus faecium to tetracyclines and tetracycline degradation products was determined. The resistant isolates showed reduced resistance to anhydrotetracycline, 4-epi-anhydrotetracycline, anhydrochlortetracycline and 4-epi-anhydrochlortetracycline. In general both the tetracycline resistant and susceptible E. faecium were more susceptible to the compounds tested than E. coli.

Animals↗
PubMed2003

Analysis of alcohol ethoxylates and alkylamine ethoxylates in agricultural soils using pressurised liquid extraction and liquid chromatography-mass spectrometry.

Nonionic surfactants e.g. alcohol ethoxylates (AEOs) and alkylamine ethoxylates (ANEOs) are commonly utilised as adjuvants in pesticide formulations to enhance their effectiveness. In this study, analytical methods for AEO and ANEO determination in soil samples using pressurised liquid extraction (PLE) were developed and used in connection with LC-MS. The recovery of the method, which was highly dependent on the soil properties, varied in the range 47-106% for AEO and 27-109% for ANEO. Detection limits (LOD) were 7-13 microg kg(-1) for AEO and 24-43 microg kg(-1) for ANEO. The developed method has been applied to determine AEOs and ANEOs in surface soil samples from fields sprayed with glyphosate herbicides. Tallowalkylamine ethoxylates (an ANEO) were detected in the soil before and after pesticide application, with increasing concentrations after treatment. The highest concentration in the soil samples was observed for the ANEO homologues with the longest ethoxy chains; in the clay soil the concentration decreased with the length of the ethoxy chain. ANEOs added to pesticide formulations as a technical mixture will, as demonstrated in this study, behave as individual homologues, which is reflected in their behaviour in the environment.

Journal Article↗
PubMed2003

Determination of oxytetracycline and its degradation products by high-performance liquid chromatography-tandem mass spectrometry in manure-containing anaerobic test systems.

This paper describes the development of a HPLC-MS-MS (ESI) method with baseline separation of oxytetracycline, 4-epi-oxytetracycline, alpha-apo-oxytetracycline and beta-apo-oxytetracycline using an XTerra column and an MeOH-MilliQ-water (containing 8 mM formic acid) mobile phase. Limits of quantification for aqueous standards were in the range of 0.004 to 0.008 microM. The linear range tested was 0.003 to 0.5 microM and in one case up to 17 microM. An experiment simulating the degradation of oxytetracycline in manure was set up and free concentrations of the four antibiotics were determined during 6 months. Oxytetracycline (>0.02 microM) was observed up till 6 months after spiking. No important increase in free concentrations of the degradation products was observed.

Anaerobiosis↗
PubMed2003

Characterisation of the abiotic degradation pathways of oxytetracyclines in soil interstitial water using LC-MS-MS.

The fate of oxytetracyclines (OTCs) in soil interstitial water was investigated and the structure of a number of degradation products elucidated in a time-related experiment. A previously developed separation method for LC-MS-MS able to base separate and quantify OTC and three of its epimers and degradation products was applied. Compounds detected were 4-epi-oxytetracycline (EOTC) (t(R)=3.0 min), OTC (t(R)=4.4 min), alpha-apo-oxytetracycline (alpha-apo-OTC) (t(R)=11.4 min) and beta-apo-oxytetracycline (beta-apo-OTC) (t(R)=18.4 min). Furthermore, we tentatively identified 4-epi-N-desmethyl-oxytetracycline (E-N-DM-OTC) (t(R)=3.0 min), N-desmethyl-oxytetracycline (N-DM-OTC) (t(R)=3.5), N-didesmethyl-oxytetracycline (N-DDM-OTC), 4-epi-N-didesmethyl-oxytetracycline (E-N-DDM-OTC) (t(R)=3.7 and 4.7 min) and 2-acetyl-2-decarboxamido-oxytetracycline (t(R)=8.7) in all samples. Most compounds were only present in trace concentrations (less than 2%) relative to the parent OTC. EOTC was on the other hand formed up to a ratio of 0.6 relative to parent OTC concentration. Only EOTC, E-N-DM-OTC, N-DM-OTC, N-DDM-OTC and E-N-DDM-OTC were formed during the time-related experiment. All other compounds were probably only present as impurities in the spiked OTC formulation as they declined in concentration from the start of the experiment. Half-lives (T(1/2), days) of the OTCs in soil interstitial water were in the order of 2 days (EOTC) to 270 days (beta-apo-OTC).

Chromatography, High Pressure Liquid↗
PubMed2003

Use of oxytetracycline and tylosin in intensive calf farming: evaluation of transfer to manure and soil.

Antibiotics may enter soils with manure from treated animals. Because of their biological effects, antibiotics are regarded as potential micropollutants. The levels of oxytetracycline and tylosin over time were followed in faeces, bedding and manure, and then in the soil of a manured field and surrounding drainage courses, after oral treatment of calves. Fifty Simmental calves were treated for 5 days with 60 mg/kg/day of oxytetracycline. After 15 days the animals were treated for 5 days with 20 mg/kg/day of tylosin. Tylosin degraded rapidly, and was no longer detected in manure 45 days after cessation of treatment and no trace of the compound was detected in soil or surrounding water (detection limits 10 microg/l). The half-life of oxytetracycline in manure was 30 days and the compound was still detectable in this matrix (820 microg/kg) after 5 months maturation. In the manured soil oxytetracycline was detected at concentrations at least 10 times lower than the European Agency for the Evaluation of Medicinal Products threshold (100 microg/kg) requiring phase II environmental risk assessment. Oxytetracycline was not detected in the water courses (detection limit 1 microg/l). These results demonstrate that the processes occurring between faeces production and application of manure to the soil are very effective in reducing the load of TYL and OTC in the environment. For both drugs a toxicity test was performed using the alga Selenastrum capricornutum. The EC50 was 4.18 mg/l for oxytetracycline and 0.95 mg/l for tylosin. A worst-case hazard assessment for the aquatic environment was performed comparing the ratio between the measured concentrations (LOD) and effect data from previous work (OTC) or from this work (TYL). This showed ratio between toxicity levels (bacteria) (EC50=0.14 mg/l) and measured concentrations (LOD=1 microg/l) for OTC to be 140. The corresponding value for TYL (LOD=10 microg/l) was 95.

Animal Husbandry↗
PubMed2003

Bacterial antibiotic resistance levels in Danish farmland as a result of treatment with pig manure slurry.

Resistance to tetracycline, macrolides and streptomycin was measured for a period of 8 months in soil bacteria obtained from farmland treated with pig manure slurry. This was done by spread plating bacteria on selective media (Luria Bertani (LB) medium supplemented with antibiotics). To account for seasonal variations in numbers of soil bacteria, ratios of resistant bacteria divided by total count on nonselective plates were calculated. Soil samples were collected from four different farms and from a control soil on a fifth farm. The control soil was not amended with animal manure. The occurrence of tetracycline-resistant bacteria was elevated after spread of pig manure slurry but declined throughout the sampling period to a level corresponding to the control soil. Higher load of pig manure slurry yielded higher occurrence of tetracycline resistance after spreading; however, the tetracycline resistance declined to normal occurrence defined by the tetracycline resistance occurrence in the control soil. Concentrations of tetracycline in soil and in pig manure slurry were measured using HPLC. No tetracycline exceeding the detection limit was found in soil samples. Manure slurry concentrations of tetracycline for three of the farms were 42, 81 and 698 microg/l, respectively. For streptomycin and macrolides, only minor variations in resistance levels were detected. Results obtained in this study thus indicate that tetracycline resistance levels in soil are temporarily influenced by the addition of pig manure slurry. The results indicate also that increased amount of pig manure slurry amendment may result in increased levels of tetracycline resistance in the soil.

Agriculture↗
PubMed2002

Liquid chromatography-mass spectrometry method to determine alcohol ethoxylates and alkylamine ethoxylates in soil interstitial water, ground water and surface water samples.

Alcohol ethoxylates (AEs) and alkylamine ethoxylates (AMEs) are used as adjuvants in pesticide formulations. Analytical procedures for these compounds in environmental aqueous samples using LC-MS are presented. Sample preparation uses solid-phase extraction with Porapak Rdx cartridges. Detection limits and recoveries in ground water and surface water are, respectively, AEs: 16-60 ng/l, 35-93% and AMEs: 0.3-6 microg/l, 28-96%. The lower recoveries are obtained for the apolar surfactants. The procedure was employed on samples of ground water and soil interstitial water collected from farming areas. The individual AEs were detected at concentration levels ranging from 33 to 189 ng/l water.

Alcohols↗
PubMed2002

Determination of the distribution coefficient (log Kd) of oxytetracycline, tylosin A, olaquindox and metronidazole in manure.

Olaquindox (log Kow = -2.3) and metronidazole (log Kow = -0.1) both have low tendencies to sorp to particles in manure. This corresponds with the negative log Kow values of these antibiotics. Tylosin (log Kow = 1.63) and oxytetracycline (log Kow = -1.12) sorp relatively strongly to the manure particles and have log Kd values between 1.5 and 2.0. The tendency to bind to manure was ranked after increasing binding as follows: metronidazole < olaquindox << tylosin A and oxytetracycline. This order of ranking is consistent with results of sorption in soil. Our experiments illustrate that for some antibacterial agents estimation of the partitioning coefficients, Kd, cannot be made from Kow and f(oc) alone. Sorption of oxytetracycline to manure is much higher than expected from the negative log Kow value of the compound. It is believed that sorption of oxytetracycline to manure is influenced by ionic binding to divalent metal ions as such Mg2+ and Ca2+ as well as other charged compounds in the matrix. Binding of oxytetracycline to soil is stronger than the binding to manure. This is most likely due to the strong mineral related metal complexes formed between soil, metal ion and oxytetracycline. These complexes are not known to exist in manure. The relatively strong sorption of tylosin A to manure corresponds with data found for soil sorption of tylosin. Tylosin has a log Kow value of 2.5, thus it is not surprising that this drug binds strongly to manure.

Adsorption↗