Degradation kinetics and mechanism of antibiotic ceftiofur in recycled water derived from a beef farm

Ceftiofur is a third-generation cephalosporin antibiotic that has been widely used to treat bacterial infections in concentrated animal feeding operations (CAFOs). Land application of CAFO waste may lead to the loading of ceftiofur residues and its metabolites to the environment. To understand the potential contamination of the antibiotic in the environment, the degradation kinetics and mechanisms of ceftiofur in solutions blended with and without the recycled water derived from a beef farm were investigated. The transformation of ceftiofur in aqueous solutions in the presence of the CAFO recycled water was the combined process of hydrolysis and biodegradation. The total degradation rates of ceftiofur at 15 °C, 25 °C, 35 °C, and 45 °C varied from 0.4-2.8×10(-3), 1.4-4.4×10(-3), 6.3-11×10(-3), and 11-17×10(-3) h(-1), respectively, in aqueous solutions blended with 1 to 5% CAFO recycled water. Hydrolysis of ceftiofur increased with incubation temperature from 15 to 45 °C. The biodegradation rates of ceftiofur were also temperature-dependent and increased with the application amounts of the recycled CAFO water. Cef-aldehyde and desfuroylceftiofur (DFC) were identified as the main biodegradation and hydrolysis products, respectively. This result suggests that the primary biodegradation mechanism of ceftiofur was the cleavage of the β-lactam ring, while hydrolytic cleavage occurred at the thioester bond. Unlike DFC and ceftiofur, cef-aldehyde does not contain a β-lactam ring and has less antimicrobial activity, indicating that the biodegradation of ceftiofur in animal wastewater may mitigate the potentially adverse impact of the antibiotic to the environment.

Therapeutic antibiotic use patterns in dogs: observations from a veterinary teaching hospital

OBJECTIVES

To describe therapeutic antibiotic use patterns in dogs at a small animal teaching hospital.

METHODS

A retrospective case analysis of randomly sampled antibiotic prescriptions in dogs from May 20, 2008 to May 20, 2009, deemed to be for therapeutic use, was performed. Records were reviewed to determine if there was documentation of confirmed, suspected or no evidence of infection. The five most frequently prescribed antibiotics were identified and analysed for their distribution in these categories.

RESULTS

In 17% of therapeutic antibiotic prescriptions there was confirmed infection, in 45% suspected infection, and in 38% there was no documented evidence of infection. Amoxicillin-clavulanate was the most frequently prescribed antibiotic, followed by cefazolin/cephalexin, enrofloxacin, ampicillin/amoxicillin and doxycycline. Doxycycline was the most frequently prescribed with no documented evidence of infection, and amoxicillin-clavulanate was the most frequently prescribed with either confirmed or suspected evidence of infection.

DISCUSSION

Clinicians use a variety of tools when deciding whether or not to prescribe an antibiotic and which antibiotic to use. As in human medicine, there is likely overuse and inappropriate use of antibiotics in veterinary medicine. Veterinarians should engage in discussions regarding clinically applicable guidelines for appropriate antibiotic use.

Corticosteroid hormone receptors and prereceptors as new biomarkers of the illegal use of glucocorticoids in meat production

Despite the European ban on the use of growth promoters in cattle, veterinary surveillance reports indicate that the illicit use of corticosteroids persists both alone and in combination with anabolic hormones and β-agonists. Current control strategies should be informed by research into the effects of corticosteroids on bovine metabolism and improved through the development of specific, sensitive diagnostic methods that utilize potential molecular biomarkers of corticosteroid treatment. The actions of corticosteroids on target tissues are principally regulated by two receptors: the glucocorticoid receptor (GR) and the mineralocorticoid receptor (MR). The effects of these steroids are modulated by prereceptor enzyme-mediated metabolism: the two isoforms of the 11β-hydroxysteroid dehydrogenase (11β-HSDs) enzyme catalyze the interconversion between active glucocorticoids, such as cortisol, into inactive compounds, such as cortisone. This study aimed to determine whether the expression of the prereceptor system and of the corticosteroid receptors could be regulated in different target tissues by the administration of dexamethasone and prednisolone in cattle. It was observed that greater up-regulation of the GR and MR genes followed dexamethasone treatment in the muscle tissues than in the kidney, liver, and salivary glands; up-regulation of GR and MR expression following prednisolone treatment was higher in adipose tissue than in the other tissues. The thymus seemed to respond to dexamethasone treatment but not to prednisolone treatment. Both treatments significantly down-regulated 11β-HSD2 gene expression in the adrenal tissues, but only dexamethasone treatment down-regulated 11β-HSD2 expression in the bulbourethral and prostate glands. Together, these data indicate that the combination of GR, MR, and 11β-HSD2 could provide a useful biomarker system to detect the use of illicit glucocorticoid treatment in cattle.

Levels of antibiotic resistance genes in manure, biosolids, and fertilized soil

Increasing antibiotic resistance genes in the environment may pose a threat to public health. In this study, tetracycline and sulfonamide resistance genes (Tet-W, Tet-O, and Sul-I) were quantified in 24 manure samples from three farms and 18 biosolids samples from seven different wastewater treatment plants using quantitative polymerase chain reaction methods. Concentrations of Tet-W and Tet-O genes were observed to be significantly higher (p < 0.05) in manure than in biosolids samples. The background soil samples showed significantly lower concentration of the above genes compared with manure and biosolids. Lime-stabilized biosolids showed significantly (p < 0.05) lower concentration of antibiotic resistance genes compared with other biosolids treatment methods. Elevated levels of antibiotic resistance genes (Tet-W, Tet-O, and Sul-I) were observed in the amended soil samples after the land application of manure or biosolids (Site A) monitored for a period of about 4 mo. However, at another site (Site B), no significant increase (p > 0.05) in concentration of antibiotic resistance genes was observed after biosolids application on soil. Even though the concentration of antibiotic resistance genes in manure was statistically higher than that in biosolids, when they were applied on land, the contribution to the soil depended on the background soil concentration and the soil characteristics. Further study of multiple soil samples in various locations is needed.

[Update on the Mali Pharmacy Code: legislative section]

Due to colonization (1895-1960) Mali has been submitted, on the legislative and regulation plan to a corpus of numerous and scattered texts relative to pharmacy. It is essentially the Law AN XI of 21 Germinal or the 11 April 1803 Law; the content of Book V of the Public Health Code relative to pharmacy practice, of which some disposals have been extended to Overseas Territories, Togo and Cameroon in 1953; the 1955 Ministerial Order about the dispatching of the Retail Pharmacy in AOF; the 1960 Law creating the Board of Pharmacists in the Federation of Mali etc. After independence, the new Malian State while renewing the pharmacy legislation issued by the old tutor State which was not opposed to the new fundamental Law, has also set up, according to the political orientations of the moment, some new texts. In the framework of this work, we have collected all the legislative and regulation texts that have been allowed in Mali in the pharmacy area and in that of Studies in Pharmacy. We have examined those texts and proceeded to codify the legislative part. The present Code consists of 189 articles divided in 5 titles layed out in chapters and sections.

[Update on the Mali Pharmacy Code: legislative section]

Due to colonization (1895-1960) Mali has been submitted, on the legislative and regulation plan to a corpus of numerous and scattered texts relative to pharmacy. It is essentially the Law AN XI of 21 Germinal or the 11 April 1803 Law; the content of Book V of the Public Health Code relative to pharmacy practice, of which some disposals have been extended to Overseas Territories, Togo and Cameroon in 1953; the 1955 Ministerial Order about the dispatching of the Retail Pharmacy in AOF; the 1960 Law creating the Board of Pharmacists in the Federation of Mali etc. After independence, the new Malian State while renewing the pharmacy legislation issued by the old tutor State which was not opposed to the new fundamental Law, has also set up, according to the political orientations of the moment, some new texts. In the framework of this work, we have collected all the legislative and regulation texts that have been allowed in Mali in the pharmacy area and in that of Studies in Pharmacy. We have examined those texts and proceeded to codify the legislative part. The present Code consists of 189 articles divided in 5 titles layed out in chapters and sections.

Use of Antimicrobial Agents in Veterinary Medicine and Implications for Human Health

This review discusses why veterinary usage of antimicrobial agents is wrongly accused of causing a substantial part of the problem of resistant human pathogens. Without doubt, resistant organisms in animals are selected by veterinary antimicrobials. However, these are not a major human health risk either because the role of veterinary usage in selection or propagation is insignificant, or because resistant populations selected by veterinary usage do not pose a substantial risk to human health. Indeed, resistant bacterial infections in humans causing serious quantitative and qualitative health consequences are rarely food-borne and are not the same as those selected by veterinary usage of antimicrobial agents. The available evidence for veterinary selection of resistance, transmission to humans, and subsequent health consequences are reviewed for food-borne zoonotic pathogens. A risk assessment strategy is proposed to quantify potential hazards in order to decide on the most effective risk management strategy.

Atipamezole

Learn about the pharmacology, applications, and administration of this alpha2-adrenergic antagonist.

The future of veterinary therapeutics: A glimpse towards 2030

The purpose of this article is to make an educated guess as to what veterinary pharmacology will look like in two decades. By examining the past, it is evident that change is incremental unless a transforming discovery occurs. In the last few decades, such events have dramatically changed medicine and pharmacology, however they have not percolated through the system to the effect that novel drugs have replaced our traditional armamentarium. The effect of six transforming technologies (continued advances in computer technology, microfluidics, nanotechnology, high-throughput screening, control and targeted drug delivery, pharmacogenomics) on veterinary therapeutics is examined. These should lead toward more efficacious and safer drugs across most therapeutic classes due to both increases in our knowledge base as well as more efficient drug development. Shorter term improvements in drug delivery should be seen. Although this growth in technology would portend major advances over the next few decades, economic and regulatory constraints must still be overcome for these new drugs or therapeutic approaches to become common practice.

Impact of antimicrobial residues on gut communities: are the new regulations effective?

Veterinary medicines are subject to a rigorous evaluation with regard to safety, efficacy and quality before they are licensed. For drugs used in food producing animals, it is necessary to establish what is referred to as the acceptable daily intake (ADI), this is defined as an estimate of the amount of a substance, expressed on a body weight basis, that can be ingested daily over a lifetime without appreciable risk to human health. It is necessary to determine a toxicological, pharmacological and microbiological ADI. This article describes a recently harmonized guideline that outlines the process for determining the need for a microbiological ADI and discusses the test systems that take into account the complexity of the human intestinal flora. The described process is used to address the effects of antimicrobial drug residues on human intestinal flora for regulatory purposes. The guideline does not recommend any one particular system for use in regulatory decision making but provides recommendations for a harmonized approach to establish a microbiological ADI and offers test options rather than specifying a testing regimen. The process and the challenges of this new guideline are discussed.

Assessment of bacterial contamination of three multidose ophthalmic solutions

OBJECTIVE

To investigate the frequency of bacterial contamination of multidose proparacaine hydrochloride, tropicamide, and eyewash bottles used in veterinary ophthalmology examination rooms during normal operating procedures.

METHODS

Three representative bottles each of proparacaine hydrochloride, tropicamide, and purified water eye wash were opened at the same time, numbered, and placed into small animal examination rooms. Doctors, students and technicians who were using the solutions were blinded to the study. Aerobic cultures were obtained at the time of opening (time 0), at 1 week (time 1), and at 2 weeks after opening (time 2) the bottles. The sites cultured included a drop of each solution, the inside of the bottle cap, the tip of the bottle, and the bottle threads and medication residue found in these threads.

RESULTS

Aerobic cultures of tropicamide and proparacaine had no growth of bacteria from any of the evaluated sites. Staphylococcus epidermidis was cultured from the tip of one bottle of eye wash after 1 week.

CONCLUSIONS

We conclude that proparacaine, tropicamide, and eyewash solutions used in veterinary examination rooms are adequately preserved for use in ophthalmic examination. They have a low level of bacterial contamination 1 or 2 weeks after opening when used and stored according to the recommendations of the product manufacturers and previous studies.

The design of randomized controlled trials of veterinary vaccines

Randomized controlled trials of veterinary vaccines are essential if we are to have a reasonable understanding of how those vaccines can be expected to perform when used in the field. This manuscript reviews a few (but certainly not all) of the key elements that need to be considered in the design of veterinary vaccine trials. The first step in the design of such a trial is to have a clear statement of the objective of the trial that reflects what is expected of the vaccine (e.g. should it minimize clinical disease or does it need to prevent infection?). Because domestic animals are often managed in groups, the ‘unit of concern’ used in a vaccine trial becomes of great importance. Whether the trial should be carried out at the individual or group level will depend on the objectives of the trial and the extent of concern about ‘group effects’ affecting the trial. Sample sizes will also be influenced heavily by the choice of unit of concern and the nature of the primary outcome being assessed. Finally, while there is no easy solution (except to conduct group-level trials, which may be logistically impossible), the potential for group effects to influence the trial outcome must be considered.

Acquainting veterinary students with careers in the pharmaceutical industry

Careers in the pharmaceutical industry were revealed in modules facilitated by senior scientists from companies that sponsor the Cornell Leadership Program for Veterinary Students. One module was structured as a series of interviews for different positions in industry, the other as a competition between hypothetical companies created by students. The interview-based module stimulated wide-ranging discussion of the activities and responsibilities of veterinarians employed in a discovery-intensive pharmaceutical firm and of the characteristics such companies seek in prospective employees, from both professional and personal perspectives. The second module explored the drug discovery and development process from the perspective of animal-health companies that are competitors in the market for animal health care products. The exercise provided insights into the manner in which companies discover new chemical entities, screen candidate drugs, allocate resources, and pursue the development of products through testing, licensing, and distribution.

HPLC determination of chlorhexidine gluconate and p-chloroaniline in topical ointment

A novel fast isocratic reversed-phase HPLC method for simultaneous determination of chlorhexidine and its degradation product p-chloroaniline was developed. Zorbax SB Phenyl column (75 mm x 4.6 mm, 3.5 microm) was used for the separation. Mobile phase composed of acetonitrile and buffer solution of 0.08 M sodium phosphate monobasic containing 5 ml of triethylamine (0.5%) and adjust with 85% phosphoric acid to pH 3.0 in ratio 35:65 (v/v) pumped isocratically at flow rate 0.6 ml min(-1) was used. UV detection was performed at 239 nm, the total analysis time was about 10 min. The method is suitable for practical routine analysis of topical ointment in the quality control laboratory.

Extralabel use of penicillin in food animals

Penicillin is one of the most commonly detected drug residues in tissues and milk, and is the antimicrobial for which information is most often sought through FARAD.

Persistence of antibiotics such as macrolides, tiamulin and salinomycin in soil

The extensive use of veterinary drugs in agriculture leads to contamination of manure. If this manure is used as fertiliser, soil may be exposed to the respective drugs. Additionally soil exposure may stem from contaminated sewage sludge that is used on some agricultural land as fertiliser. This study focuses on the fate of antibiotics in soil. We present a 120-day degradation experiment of six commonly used antibiotics: erythromycin, roxithromycin oleandomycin, tylosin, salinomycin and tiamulin in soil as well as calculating the resulting half-lives. The half-lives were 20 days for erythromycin, 27 days for oleandomycin, 8 days for tylosin, 16 days for tiamulin and 5 days for salinomycin; all according to 1st order kinetics. The concentration of roxithromycin remained nearly unchanged during the whole experiment.

Anticonvulsant Therapy in Dogs and Cats

This article reviews anticonvulsant therapies in current use for dogs and cats and briefly describes new modes of anticonvulsant therapy that are being investigated or pending publication. Most of the information contained within the article is based on published information. Some of the information, however, is based on the author's clinical experience and is identified as such.

Antimicrobial Resistance

Development of antimicrobial resistance is an inevitable consequence of exposure of microorganisms to antimicrobial agents. Although emergence of resistance cannot be prevented, it can be retarded by minimizing use of antimicrobial agents and avoiding selection of relatively resistant pathogenic and nonpathogenic strains caused by exposure to tissue concentrations that confer a competitive advantage. Most attention in veterinary medicine has focused on the emergence of resistance in food-borne pathogens, with relatively little attention being devoted to small companion animals, despite the frequent use of antimicrobial agents in these animals, evidence that resistance is emerging, and potential for transfer of resistance between companion animals and people. To retard further emergence of resistance in small companion animals, it is imperative that surveillance programs be instituted to monitor development of resistance.