[Determination of breakpoints for veterinary medically relevant antibiotics for resistance assessment of veterinary pathogens]. / Zur Festlegung von Grenzwertkonzentrationen (breakpoints) für veterinärmedizinisch relevante Antibiotika zur Resistenzbeurteilung bei tierpathogenen Erregern.

This article describes the meaning of the term clinical breakpoint. This is followed by a discussion of the parameters that need to be considered when setting valid breakpoints for active substances in veterinary medicine; in doing so we closely follow equivalent regulations and guidelines on the establishment of breakpoints in human medicine. Along with pharmacokinetic data and the results of clinical efficacy tests, susceptibility data of relevant organisms play a key role in the establishment of breakpoints. Published breakpoints are currently only available for a few modern drugs in veterinary medicine.

[Guidelines for planning studies to determine the resistance of infectious agents of veterinary relevance]. / Leitfaden zur Planung von Studien zur Erfassung der Resistenzsituation bei veterinärmedizinisch relevanten Infektionserregern.

This paper describes the most important criteria for the planning of statistically sound and representative studies on the prevalence of antimicrobial resistance among pathogenic bacteria from animals. The statistical design of the study is of particular importance and therefore described in some detail. The existing published data about antimicrobial resistance are mostly retrospective summaries of results and do not give a true picture of the resistance situation. The authors propose to conduct a pilot study initially because many basic elements for a sound study design are still not known. The systematic recording and assessment of the target variables including the necessary quality assurance are an important prerequisite. Moreover, potential cause variables can be further narrowed down and conclusively identified. To ensure the representativity of the cross-sectional study and avoid potential bias, it is important to achieve the highest possible response rate. This will form the basis of a scientifically sound resistance monitoring programme which should be the joint responsibility of regulatory authorities, industry and academia.

[Observations on resistance monitoring in animal health]. / Anmerkungen zum Resistenzmonitoring in der Tiergesundheit.

This article describes conventional procedures which are used for susceptibility testing of bacteria isolated from food producing animals against anti-infective substances. Interpretation of results obtained from the different test methods and the conditions necessary to conduct these tests in view of a meaningful resistance monitoring are discussed. Currently, published data about the resistance situation in veterinary medicine are either not representative or have been determined under suboptimal conditions. In view of the public and often non-scientifically based discussion about bacterial resistance it is absolutely necessary to generate a scientifically valid database.

Effects of pyrantel pamoate on adult and preadult Toxocara canis worms: an electron microscope and autoradiography study.

Adult as well as preadult Toxocara canis isolated from the intestine of a beagle were incubated for 2, 4, and 14 h in medium containing either different concentrations of pyrantel pamoate (23.6, 236, and 2360 micrograms/ml medium) or tritiated pyrantel pamoate (2.36 micrograms/ml medium). These incubations were performed to study the effects of pyrantel pamoate on the morphology of the parasitic nematodes and to obtain information concerning the mode of uptake, the distribution, and the total amount of pyrantel pamoate ingested by T. canis. The results of the ultrastructure studies indicate that the intestine, hypodermis, and muscle cells are the organs that are predominantly affected by the drug. Additionally, it turned out that the duration of the treatment, i.e., the incubation time, was more important in determining the efficacy of pyrantel pamoate against T. canis than was the concentration itself. Autoradiography studies revealed that the adult worms ingest the drug orally, whereas preadults absorb pyrantel pamoate mainly through the whole body surface. Finally, measurements of the total amount of pyrantel pamoate taken up by T. canis indicated that adult worms can limit or even reduce the ingestion of pyrantel for more than 4 h, but then ingest large amounts of the drug. Preadult worms, however, absorb the drug more or less continuously during the first 14 h through the cuticula, albeit in lower concentrations than the adults. The different experiments elucidate differences in the uptake of pyrantel pamoate as well as in the total amount of drug ingested or absorbed by adult or preadult worms, leading to the assumption that repeated treatment with lower concentrations will be more effective than high concentrations given only once.