Oxytetracycline In Sediments Research Articles

Presence, concentrations and risk assessment of selected antibiotic residues in sediments and near-bottom waters collected from the Polish coastal zone in the southern Baltic Sea — Summary of 3 years of studies

Concentrations of selected antibiotic compounds from different groups were measured in sediment samples (14 analytes) and in near-bottom water samples (12 analytes) collected in 2011–2013 from the southern Baltic Sea (Polish coastal zone). Antibiotics were determined at concentration levels of a few to hundreds of ng g−1 d.w. in sediments and ng L−1 in near-bottom waters. The most frequently detected compounds were sulfamethoxazole, trimethoprim, oxytetracycline in sediments and sulfamethoxazole and trimethoprim in near-bottom waters. The occurrence of the identified antibiotics was characterized by spatial and temporal variability. A statistically important correlation was observed between sediment organic matter content and the concentrations of sulfachloropyridazine and oxytetracycline. Risk assessment analyses revealed a potential high risk of sulfamethoxazole contamination in near-bottom waters and of contamination by sulfamethoxazole, trimethoprim and tetracyclines in sediments. Both chemical and risk assessment analyses show that the coastal area of the southern Baltic Sea is highly exposed to antibiotic residues.

Influence of Humic Acid Colloid on Adsorption of Oxytetracycline in Sediment

Influence of Humic Acid Colloid on Adsorption of Oxytetracycline in Sediment

Oxytetracycline Assay in Pond Sediment

The fate of drug residues and their metabolites in the environment is relatively rarely investigated in the conditions of the Czech Republic, resulting in limited availability of scientific information. To demonstrate one example, we prepared a model study with medicated feedstuff containing oxytetracycline hydrochloride (OTC HCl), which was used in fish under normal conditions of use. The oxytetracycline (OTC) contents were determined in the sediments of the pond where the fish were treated. The ELISA method was used for OTC detection and the HPLC method was used for final quantification of OTC. The increasing contents of OTC in sediment depended on the repeated treatment and excretion of OTC by the fish. The concentration on day 59 after the last administration was 1516 μg kg-1 OTC in the sediment, which indicates a long-term persistence of the substance in the environment.

Preliminary investigation on the environmental occurrence and effects of antibiotics used in aquaculture in Italy

A preliminary investigation has been carried out on the occurrence and effects of antibiotics used in Italian aquaculture with the objective of identifying priorities for monitoring programmes. According to the information available on the most pertinent and diffuse fish diseases and their related therapies, the presence of flumequine and oxytetracycline in sediments sampled from two trout farms and three sea-bass farms and in their surrounding environments was selected for an analytical investigation. The concentrations of oxytetracycline and flumequine varied up to a maximum of 246.3 and 578.8 μg/kg d.w., respectively. Flumequine was seen to have the highest toxicity in a bioluminescence assay with EC 50 values varying within the range of 12–15 mg/l, while the EC 50 values for oxytetracycline were within the range of 121–139 mg/l. The results of the present study indicate flumequine and oxytetracycline as priority chemicals to be monitored for possible environmental side effects of aquaculture in Italy. Apart from peak concentrations the chronic presence of flumequine and oxytetracycline in sediments both inside and outside farms should also be considered. In spite of the potential risks related to the use of antibiotics, the concentrations found in the sediments of the studied fish farms are significantly lower than those found in other areas.

Preliminary assays to elucidate the structure of oxytetracycline’s degradation products in sediments: Determination of natural tetracyclines by high-performance liquid chromatography–fast atom bombardment mass spectrometry

A very specific high-performance liquid chromatography–mass spectrometric method for the determination of natural tetracyclines was developed in order to characterise the degradation products of oxytetracycline in sediments. First, extraction used a clean up step with a Bond Elut Certify ® LRC cartridge. A 3 μm Spherisorb ® ODS1 column was then used with a methanol, acetonitrile and oxalic acid mobile phase gradient. Chromatographic resolution in these conditions was 3.31 between oxytetracycline and tetracycline. Two liquid chromatography–mass spectrometry methodologies based on a particle beam and a frit fast atom bombardment interface were developed. In the first approach, ionisation was performed in the negative chemical mode using methane as reacting gas. In the other case, glycerol–thioglycerol mixture was used as matrix to ensure good sensitivity. MS–MS experiment was performed to determinate oxytetracycline fragmentation pattern in the perspective of degradation product study.

Antibacterial residues in marine sediments and invertebrates following chemotherapy in aquaculture

Salmon net-cage culturists in the USA use oxytetracycline, and to a lesser extent Romet ® 30 and amoxycillin, to prevent or treat bacterial disease. This study examined the environmental fate of oxytetracycline and Romet ® 30 at three farm sites and in flow-through, sediment microcosms dosed with antibacterials at rates intended to mimic farm conditions. The frequency of detection of oxytetracycline in sediments beneath the farms paralleled drug usage, with residues rarely detected beneath a farm that used very little oxytetracycline (8.5 kg active ingredient), and concentrations commonly between 0.5 and 4 μg g −1 at a farm that used 186 kg in a single prophylactic treatment period. The presence of oxytetracycline residues in surficial and subsurface sediments even before that treatment indicated persistence since at least the prior summer (10 months previous) or possibly longer. The area of sediments containing measurable oxytetracycline residues was very localized, however, with residues detectable only under the cages and to a distance of 30 m, but absent from a 100 m site. In laboratory microcosms, one-fourth to one-half of the oxytetracycline remained in microcosm sediments after 60 days, and the one treatment in which loss of the drug approximated an exponential curve indicated a 36-day half-life. Sulfadimethoxine and ormetoprim, the active ingredients in Romet ® 30, appeared to be very short-lived in marine sediments, based on preliminary data. Residues of both drugs at concentrations slightly above the analytical level of detection were found in one microcosm 2 days after the cessation of treatment, but no residues were found in microcosms 22–34 days after treatment or 21–62 days after treatment at two farm sites. We also collected crabs and oysters from the area surrounding the one farm that relied upon antibacterials most heavily. No more than trace oxytetracycline residues (about 0.1 μg g −1) were found in oysters ( Crassostrea gigas) or Dungeness crab ( Cancer magister) collected under the farm, but about half the red rock crab ( Cancer productus) collected under the cages during and within 12 days of oxytetracycline treatment contained oxytetracycline in meat at concentrations of 0.8 to at least 3.8 μg g −1, well in excess of the US Food and Drug Administration limit for commercially sold seafood of 0.1 μg g −1.

Concentration and persistence of oxytetracycline in sediments under a marine salmon farm

The concentration of oxytetracycline in the sediment under two adjacent cage blocks in a marine salmon farm was determined following the therapeutic use of the drug. The sediment cores were grey, indicating some build-up of organic material. Infaunal polychaetes were present as were mobile fauna including crabs, starfish and flat fish. There were no significant accumulations of undigested feed pellets under the cages. At one block where 186 kg oxytetracycline was used over 10 days the oxytetracycline concentrations were determined under a single cage that received 8.65 kg oxytetracycline during the treatment. Peak concentrations in the top 2 cm of the sediment were 9.9±2.9 μg·g −1. This declined at an exponential rate ( r 2=0.99) with a half-life of 16 days. At the second block the oxytetracycline concentration was measured with a sampling programme designed to determine the horizontal and vertical distribution of oxytetracycline under the whole cage block during and after a treatment where 175 kg of oxytetracycline were used over 12 days. Peak concentrations, in the top 2 cm of the sediments under the cage block, were 10.9±6.5 μg·g −1 and this declined at an exponential rate ( r 2=0.99) with a half-life of 13 days. Nineteen days after the end of the therapy oxytetracycline was detected at depths of up to 8 cm in the sediment, but the concentration of the antibacterial agent had decreased at all levels in the sediment 14 days later. At the end of the treatment oxytetracycline was detected in an area of the sediment less than twice the area of the cages themselves. Data on current flow and sedimentation rate were used to generate a predictive model of the area of sediment that would be subject to the deposition of both pelleted fish feed and fish faeces. Oxytetracycline was confined to the area of sediment predicted to be subject to feed deposition that was directly under and slightly to the west of the cage block. Oxytetracycline was not detected in the area predicted to be subject to faecal deposition only.

Resistance to oxytetracycline, oxolinic acid and furazolidone in bacteria from marine sediments

Sediments experimentally treated with oxytetracycline (OTC) or oxolinic acid (OXA) were placed on the seabottom for a period of 1 year. At the end of the test period the fraction of bacteria resistant to OTC in sediments to which OTC had been added (SOT) was more than three times higher (16%) than the background level (5%). The same tendency was found for the sediments to which OXA was added (SOX). Cross-resistance towards OTC and OXA was found both in SOT and SOX. A high level of cross-resistance (34%) towards furazolidone was found for SOX, but was not observed for SOT.

Long-range changes in oxytetracycline concentration and bacterial resistance towards oxytetracycline in a fish farm sediment after medication

Following 10 days medication with oxytetracycline, marine sediment was sampled beneath three selected cages (cages 1, 2 and 3) at a fish farm over a period of 18 mnd., in order to detect any change in the sediment oxytetracycline concentration, bacterial number and bacterial resistance towards the drug. The bulk of oxytetracycline disappeared during the first weeks, but it persisted in the sediment at lower concentrations for quite some time after the medication. Half-life ( f 1 2 ) of oxytetracycline in the sediment was measured as: 125, 144 and 87 days under cages 1, 2 and 3, respectively. At the end of the medication, all three sediments had > 100% oxytetracycline-resistant bacteria. This value dropped to 20% after 72 days and stabilised at levels of between 10 and 50%. The change in bacterial numbers, described as total and plate counts, was due to seasonal variations rather than to the medication.

Degradation of oxytetracycline in seawater at two different temperatures and light intensities, and the persistence of oxytetracycline in the sediment from a fish farm

A rapid procedure for the quantitative determination of the antibiotic oxytetracycline in sediments and in seawater using high performance liquid chromatography is presented. The mean recoveries from the sediment and from seawater were 98.4% and 99.5%, respectively. The limit of detection was 0.1 ppm for sediment and 0.01 ppm for seawater when injecting 150 μgl of sample. The persistence of oxytetracycline in the sediment was highly dependent on the rate of sedimentation. Based on measurements during the first 12 weeks and with a very small sedimentation rate, the half-life ( t 1 2 ) of the antibiotic was 32 days. When the oxytetracycline layer was immediately covered with an additional 4 cm of sediment, the degradation was much slower ( t 1 2 =64 days ). The degradation of oxytetracycline in seawater was rapid. The half-lives were 128 and 168 h at 5 and 15°C, respectively, under illumination for 24 h a day with a 40-W fluorescent tube, and 390 and 234 h, respectively, in aquaria maintained in darkness.

Persistence of oxytetracycline in sediments from fish farms

The persistence of oxytetracycline, an antibacterial agent, in bottom deposits from fish farms was investigated. The drug was found in concentrations capable of causing antimicrobial effects up to 12 weeks after administration. A half-life of approximately 10 weeks was estimated through a pilot study. Possible effects on sulphide ion activity are suggested.