Prescription patterns of antimicrobials in veterinary practices in Switzerland

OBJECTIVES The objective of this study was to analyse antimicrobial prescriptions by veterinarians and to evaluate the appropriateness of use compared with prudent use guidelines. PRACTICES AND METHODS: Computerized records of prescriptions and treatments from eight mixed veterinary practices were analysed over a period of 2 years. A total of 61 212 antimicrobial treatments were recorded. Treatments were classified according to animal species treated, indication for treatment, route of administration and antimicrobial class used. For each treatment and antimicrobial substance, the prescribed dose was calculated. Dosage, antimicrobial classes and combinations of different classes used for different indications were compared with published recommendations. RESULTS From the total amount of 1590 kg of active antimicrobial substance, sulphonamides (594 kg), tetracyclines (335 kg), and penicillins and cephalosporins (290 kg) were the classes of which the largest quantity was prescribed. Penicillins and cephalosporins were most frequently prescribed (37% of treatments), followed by aminoglycosides (18%), tetracyclines (14%) and sulphonamides (11%). Sixty-one per cent of the amount of antimicrobials prescribed was used for the treatment of groups of animals via feed or water. Antimicrobial classes classified as highest priority for human medicine by an international group of experts were used in 9% of the prescriptions. The dosage corresponded to the manufacturer's recommendation in 45% of the analysed prescriptions. CONCLUSIONS Most prescriptions corresponded well to guidelines on prudent use of antimicrobials. Nevertheless, the large variation of prescriptions among different veterinarians indicates that the usage of critical antimicrobial substances and the amount of antimicrobials used for group medication without a specific indication could be further reduced.

The effects of thoracic epidurally administered drugs on urethral sphincter function in women: a pooled analysis

OBJECTIVES Thoracic epidural analgesia (TEA) has been shown to inhibit detrusor activity in patients undergoing open renal surgery, resulting in clinically relevant post-void residuals. However, the impact of different epidural drug mixtures on urethral sphincter function is not completely elucidated. DESIGN Pooled analysis of an open observational study and a double-blind randomized trial. SETTING Single tertiary centre. SUBJECTS Twenty-eight women without lower urinary tract symptoms and post-void residual <100 mL, who underwent open renal surgery with TEA. METHODS Pooling results in three groups with different epidural regimens (7 with bupivacaine 0.125%, 8 with bupivacaine 0.125% and fentanyl 2 μg/mL, and 13 with bupivacaine 0.1% plus fentanyl 2 μg/mL and epinephrine 2 μg/mL). All women underwent urethral pressure measurements before TEA and during TEA 2-3 days postoperatively. All patients received a TEA placed at the insertion site interspace T 8-9. RESULTS Maximum urethral closure pressure at rest decreased significantly during TEA with bupivacaine alone (median 70 cm H2 O [interquartile range 66-76] to 43 [43-65], P = 0.031) and with bupivacaine/fentanyl/epinephrine (75 cm H2 O [68-78] to 56 [52-75], P = 0.028), whereas with bupivacaine/fentanyl, no significant change could be detected (74 [51-88] vs 67 [46-70], P = 0.156). In all groups, functional profile length at rest was not influenced during TEA. CONCLUSION TEA with bupivacaine and the addition of fentanyl and epinephrine appears to decrease maximum urethral closure pressure at rest in women. The addition of fentanyl alone to bupivacaine may reduce this effect. Thus, the TEA effect on urethral sphincter function seems to depend on the drug mixture administered.

Equine cytochrome P450 2B6--genomic identification, expression and functional characterization with ketamine

Ketamine is an anesthetic and analgesic regularly used in veterinary patients. As ketamine is almost always administered in combination with other drugs, interactions between ketamine and other drugs bear the risk of either adverse effects or diminished efficacy. Since cytochrome P450 enzymes (CYPs) play a pivotal role in the phase I metabolism of the majority of all marketed drugs, drug-drug interactions often occur at the active site of these enzymes. CYPs have been thoroughly examined in humans and laboratory animals, but little is known about equine CYPs. The characterization of equine CYPs is essential for a better understanding of drug metabolism in horses. We report annotation, cloning and heterologous expression of the equine CYP2B6 in V79 Chinese hamster fibroblasts. After computational annotation of all CYP2B genes, the coding sequence (CDS) of equine CYP2B6 was amplified by RT-PCR from horse liver total RNA and revealed an amino acid sequence identity of 77% and a similarity of 93.7% to its human ortholog. A non-synonymous variant c.226G>A in exon 2 of the equine CYP2B6 was detected in 97 horses. The mutant A-allele showed an allele frequency of 82%. Two further variants in exon 3 were detected in one and two horses of this group, respectively. Transfected V79 cells were incubated with racemic ketamine and norketamine as probe substrates to determine metabolic activity. The recombinant equine CYP2B6 N-demethylated ketamine to norketamine and produced metabolites of norketamine, such as hydroxylated norketamines and 5,6-dehydronorketamine. V(max) for S-/and R-norketamine formation was 0.49 and 0.45nmol/h/mg cellular protein and K(m) was 3.41 and 2.66μM, respectively. The N-demethylation of S-/R-ketamine was inhibited concentration-dependently with clopidogrel showing an IC(50) of 5.63 and 6.26μM, respectively. The functional importance of the recorded genetic variants remains to be explored. Equine CYP2B6 was determined to be a CYP enzyme involved in ketamine and norketamine metabolism, thus confirming results from inhibition studies with horse liver microsomes. Clopidogrel seems to be a feasible inhibitor for equine CYP2B6. The specificity still needs to be established with other single equine CYPs. Heterologous expression of single equine CYP enzymes opens new possibilities to substantially improve the understanding of drug metabolism and drug interactions in horses.

Metabolism of nitro drugs metronidazole and nitazoxanide in Giardia lamblia: characterization of a novel nitroreductase (GlNR2).

OBJECTIVES The protozoan parasite Giardia lamblia causes giardiasis, a persistent diarrhoea. Nitro drugs such as the nitroimidazole metronidazole and the nitrothiazolide nitazoxanide are used for the treatment of giardiasis. Nitroreductases may play a role in activating these drugs. G. lamblia contains two nitroreductases, GlNR1 and GlNR2. The aim of this work was to elucidate the role of GlNR2. METHODS Expression of GlNR2 was analysed by reverse transcription PCR. Recombinant GlNR2 was overexpressed in G. lamblia and drug susceptibility was analysed. Recombinant GlNR2 was subjected to functional assays. Escherichia coli expressing full-length or truncated GlNR1 and GlNR2 were grown in the presence of nitro compounds. Using E. coli reporter strains for nitric oxide and DNA damage responses, we analysed whether GlNR1 and GlNR2 elicited the respective responses in the presence, or absence, of the drugs. RESULTS G. lamblia trophozoites overexpressing GlNR2 were less susceptible to both nitro drugs as compared with control trophozoites. GlNR2 was a functional nitroreductase when expressed in E. coli. E. coli expressing GlNR1 was more susceptible to metronidazole under aerobic and semi-aerobic and to nitazoxanide under semi-aerobic growth conditions. E. coli expressing GlNR2 was not susceptible to either drug. In reporter strains, GlNR1, but not GlNR2, elicited nitric oxide and DNA repair responses, even in the absence of nitro drugs. CONCLUSIONS These findings suggest that GlNR2 is an active nitroreductase with a mode of action different from that of GlNR1. Thus, susceptibility to nitro drugs may depend not only on activation, but also on inactivation of the drugs by specific nitroreductases.

Thiazolides, a Novel Class of Anti-Infective Drugs, Effective Against Viruses, Bacteria, Intracellular and Extracellular Protozoan Parasites and Proliferating Mammalian Cells

The thiazolide nitazoxanide (2-acetolyloxy-N-(5-nitro 2-thiazolyl) benzamide; NTZ) is composed of a nitrothiazole- ring and a salicylic acid moiety, which are linked together through an amide bond. NTZ exhibits a broad spectrum of activities against a wide range of helminths, protozoa, enteric bacteria, and viruses infecting animals and humans. Since the first synthesis of the drug, a number of derivatives of NTZ have been produced, which are collectively named thiazolides. These are modified versions of NTZ, which include the replacement of the nitro group with bromo-, chloro-, or other functional groups, and the differential positioning of methyl- and methoxy-groups on the salicylate ring. The presence of a nitro group seems to be the prerequisite for activities against anaerobic or microaerophilic parasites and bacteria. Intracellular parasites and viruses, however, are susceptible to non-nitro-thiazolides with equal or higher effectiveness. Moreover, nitro- and bromo-thiazolides are effective against proliferating mammalian cells. Biochemical and genetic approaches have allowed the identification of respective targets and the molecular basis of resistance formation. Collectively, these studies strongly suggest that NTZ and other thiazolides exhibit multiple mechanisms of action. In microaerophilic bacteria and parasites, the reduction of the nitro group into a toxic intermediate turns out to be the key factor. In proliferating mammalian cells, however, bromo- and nitro-thiazolides trigger apoptosis, which may also explain their activities against intracellular pathogens. The mode of action against helminths may be similar to mammalian cells but has still not been elucidated.

Equine pastern vasculitis: a clinical and histopathological study.

Equine pastern vasculitis is clinically challenging and the underlying aetiopathogenesis is unclear. The aims of this retrospective study were to establish histopathological criteria for pastern vasculitis, to look for an underlying cause, to investigate whether the histopathological lesions are associated with a distinct clinical picture, to assess if and how the clinical picture varies, and to determine the treatment response. Skin biopsies and clinical data from 20 horses with a diagnosis of vasculitis of the distal extremities were investigated and histology was compared to biopsies from healthy horses. It was concluded that intramural inflammatory cells, leukocytoclasia with nuclear dust, thickening and oedema of the vessel walls, and microhaemorrhages are highly specific histological findings in equine pastern vasculitis. Based on the feedback from the clinicians, the lesions were mostly seen on the lateral and medial aspects of un-pigmented legs. Lesions in white skin were characterised by exudation and crusts, whereas those in pigmented skin were alopecic and characterised by scaling. The response to treatment was poor and the prognosis guarded. No association was found between any of the histopathological findings and a distinct clinical picture. An underlying cause of equine pastern vasculitis could not be identified. Considering the large number of confounding factors, the causative agents are difficult to identify, but may involve drugs or a hypersensitivity reactions to yet unknown antigens.

European veterinary public health specialization: post-graduate training and expectations of potential employers

Residents of the European College of Veterinary Public Health (ECVPH) carried out a survey to explore the expectations and needs of potential employers of ECVPH diplomates and to assess the extent to which the ECVPH post-graduate training program meets those requirements. An online questionnaire was sent to 707 individuals working for universities, government organizations, and private companies active in the field of public health in 16 countries. Details on the structure and activities of the participants' organizations, their current knowledge of the ECVPH, and potential interest in employing veterinary public health (VPH) experts or hosting internships were collected. Participants were requested to rate 22 relevant competencies according to their importance for VPH professionals exiting the ECVPH training. A total of 138 completed questionnaires were included in the analysis. While generic skills such as "problem solving" and "broad horizon and inter-/multidisciplinary thinking" were consistently given high grades by all participants, the importance ascribed to more specialized skills was less homogeneous. The current ECVPH training more closely complies with the profile sought in academia, which may partly explain the lower employment rate of residents and diplomates within government and industry sectors. The study revealed a lack of awareness of the ECVPH among public health institutions and demonstrated the need for greater promotion of this veterinary specialization within Europe, both in terms of its training capacity and the professional skill-set of its diplomates. This study provides input for a critical revision of the ECVPH curriculum and the design of post-graduate training programs in VPH.

Equine parasite control under prescription-only conditions in Denmark - Awareness, knowledge, perception, and strategies applied.

Due to widespread development of anthelmintic resistance in equine parasites, recommendations for their control are currently undergoing marked changes with a shift of emphasis toward more coprological surveillance and reduced treatment intensity. Denmark was the first nation to introduce prescription-only restrictions of anthelmintic drugs in 1999, but other European countries have implemented similar legislations over recent years. A questionnaire survey was performed in 2008 among Danish horse owners to provide a current status of practices and perceptions with relation to parasite control. Questions aimed at describing the current use of coprological surveillance and resulting anthelmintic treatment intensities, evaluating knowledge and perceptions about the importance of various attributes of parasite control, and assessing respondents' willingness to pay for advice and parasite surveillance services from their veterinarians. A total of 1060 respondents completed the questionnaire. A large majority of respondents (71.9%) were familiar with the concept of selective therapy. Results illustrated that the respondents' self-evaluation of their knowledge about parasites and their control associated significantly with their level of interest in the topic and their type of education (P<0.0001). The large majority of respondents either dewormed their horses twice a year and/or performed two fecal egg counts per horse per year. This approach was almost equally pronounced in foals, horses aged 1-3 years old, and adult horses. The respondents rated prevention of parasitic disease and prevention of drug resistance as the most important attributes, while cost and frequent fecal testing were rated least important. Respondents' actual spending on parasite control per horse in the previous year correlated significantly with the amount they declared themselves willing to spend (P<0.0001). However, 44.4% declared themselves willing to pay more than what they were spending. Altogether, results indicate that respondents were generally familiar with equine parasites and the concept of selective therapy, although there was some confusion over the terms small and large strongyles. They used a large degree of fecal surveillance in all age groups, with a majority of respondents sampling and/or treating around twice a year. Finally, respondents appeared willing to spend money on parasite control for their horses. It is of concern that the survey suggested that foals and young horses are treated in a manner very similar to adult horses, which is against current recommendations. Thus, the survey illustrates the importance of clear communication of guidelines for equine parasite control.

Inventory of veterinary syndromic surveillance initiatives in Europe (Triple-S project): current situation and perspectives.

Within the current context that favours the emergence of new diseases, syndromic surveillance (SyS) appears increasingly more relevant tool for the early detection of unexpected health events. The Triple-S project (Syndromic Surveillance Systems in Europe), co-financed by the European Commission, was launched in September 2010 for a three year period to promote both human and animal health SyS in European countries. Objectives of the project included performing an inventory of current and planned European animal health SyS systems and promoting knowledge transfer between SyS experts. This study presents and discusses the results of the Triple-S inventory of European veterinary SyS initiatives. European SyS systems were identified through an active process based on a questionnaire sent to animal health experts involved in SyS in Europe. Results were analyzed through a descriptive analysis and a multiple factor analysis (MFA) in order to establish a typology of the European SyS initiatives. Twenty seven European SyS systems were identified from twelve countries, at different levels of development, from project phase to active systems. Results of this inventory showed a real interest of European countries for SyS but also highlighted the novelty of this field. This survey highlighted the diversity of SyS systems in Europe in terms of objectives, population targeted, data providers, indicators monitored. For most SyS initiatives, statistical analysis of surveillance results was identified as a limitation in using the data. MFA results distinguished two types of systems. The first one belonged to the private sector, focused on companion animals and had reached a higher degree of achievement. The second one was based on mandatory collected data, targeted livestock species and is still in an early project phase. The exchange of knowledge between human and animal health sectors was considered useful to enhance SyS. In the same way that SyS is complementary to traditional surveillance, synergies between human and animal health SyS could be an added value, most notably to enhance timeliness, sensitivity and help interpreting non-specific signals.

Higher frequency of genetic variants conferring increased risk for ADRs for commonly used drugs treating cancer, AIDS and tuberculosis in persons of African descent

There is established clinical evidence for differences in drug response, cure rates and survival outcomes between different ethnic populations, but the causes are poorly understood. Differences in frequencies of functional genetic variants in key drug response and metabolism genes may significantly influence drug response differences in different populations. To assess this, we genotyped 1330 individuals of African (n=372) and European (n=958) descent for 4535 single-nucleotide polymorphisms in 350 key drug absorption, distribution, metabolism, elimination and toxicity genes. Important and remarkable differences in the distribution of genetic variants were observed between Africans and Europeans and among the African populations. These could translate into significant differences in drug efficacy and safety profiles, and also in the required dose to achieve the desired therapeutic effect in different populations. Our data points to the need for population-specific genetic variation in personalizing medicine and care.

The polarized distribution of poly(A+)-mRNA-induced functional ion channels in the Xenopus oocyte plasma membrane is prevented by anticytoskeletal drugs

Foreign mRNA was expressed in Xenopus laevis oocytes. Newly expressed ion currents localized in defined plasma membrane areas were measured using the two-electrode voltage clamp technique in combination with a specially designed chamber, that exposed only part of the surface on the oocytes to channel agonists or inhibitors. Newly expressed currents were found to be unequally distributed in the surface membrane of the oocyte. This asymmetry was most pronounced during the early phase of expression, when channels could almost exclusively be detected in the animal hemisphere of the oocyte. 4 d after injection of the mRNA, or later, channels could be found at a threefold higher density at the animal than at the vegetal pole area. The pattern of distribution was observed to be similar with various ion channels expressed from crude tissue mRNA and from cRNAs coding for rat GABAA receptor channel subunits. Electron microscopical analysis revealed very similar microvilli patterns at both oocyte pole areas. Thus, the asymmetric current distribution is not due to asymmetric surface structure. Upon incubation during the expression period in either colchicine or cytochalasin D, the current density was found to be equal in both pole areas. The inactive control substance beta-lumicolchicine had no effect on the asymmetry of distribution. Colchicine was without effect on the amplitude of the expressed whole cell current. Our measurements reveal a pathway for plasma membrane protein expression endogenous to the Xenopus oocyte, that may contribute to the formation and maintenance of polarity of this highly organized cell.

Cancer drugs and the heart: importance and management.

Progress in the detection and treatment of cancer has led to an impressive reduction in both mortality and morbidity. Due to their mechanism of action, however, conventional chemotherapeutics and some of the newer anti-cancer signaling inhibitors carry a substantial risk of cardiovascular side effects that include cardiac dysfunction and heart failure, arterial hypertension, vasospastic and thromboembolic ischaemia, dysrhythmia, and QT prolongation. While some of these side effects are irreversible and cause progressive cardiovascular disease, others induce only temporary dysfunction with no apparent long-term sequelae for the patient. The challenge for the cardiovascular specialist is to balance the need for life-saving cancer treatment with the assessment of risk from cancer drug-associated cardiovascular side effects to prevent long-term damage. This review discusses concepts for timely diagnosis, intervention, and surveillance of cancer patients undergoing treatment, and provides approaches to clinical uncertainties.

Recommendations for the Management of Hepatitis C Virus Infection Among People Who Inject Drugs

In the developed world, the majority of new and existing hepatitis C virus (HCV) infections occur among people who inject drugs (PWID). The burden of HCV-related liver disease in this group is increasing, but treatment uptake among PWID remains low. Among PWID, there are a number of barriers to care that should be considered and systematically addressed, but these barriers should not exclude PWID from HCV treatment. Furthermore, it has been clearly demonstrated that HCV treatment is safe and effective across a broad range of multidisciplinary healthcare settings. Given the burden of HCV-related disease among PWID, strategies to enhance HCV assessment and treatment in this group are urgently needed. These recommendations demonstrate that treatment among PWID is feasible and provides a framework for HCV assessment, management, and treatment. Further research is needed to evaluate strategies to enhance assessment, adherence, and SVR among PWID, particularly as new treatments for HCV infection become available.

Voluntary ingestion of antiparasitic drugs emulsified in honey represents an alternative to gavage in mice

The oral route is the most frequently used method of drug intake in humans. Oral administration of drugs to laboratory animals such as mice typically is achieved through gavage, in which a feeding needle is introduced into the esophagus and the drug is delivered directly into the stomach. This method requires technical skill, is stressful for animals, and introduces risk of injury, pain and morbidity. Here we investigated another method of drug administration. The benzimidazole derivative albendazole was emulsified in commercially available honey and administered to mice by voluntary feeding or gavage. Mice that received albendazole by either gavage or honey ingestion had virtually identical levels of serum albendazole sulfoxide, indicating that uptake and metabolism of albendazole was similar for both administration techniques. In addition, dosing mice with the albendazole-honey mixture for 8 wk had antiparasitic activity comparable to earlier studies using gavage for drug administration. Compared with gavage, voluntary ingestion of a drug in honey is more rapid, less stressful to the animal, and less technically demanding for the administrator. Because of its low cost and ready availability, honey presents a viable vehicle for drug delivery.