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根据我们最近的试验,由安农试验牧场鸡场分离得的柔嫩艾美球虫虫株已对氯甲吡啶酚产生耐药性(已有报道),该药在推荐药物浓度下已不能抑制耐药虫株。本试验系采用该虫株进行研究,以确定是否对喹诺酮类药物——苄氧喹甲酯亦产生了交叉耐药性。一、材料和方法 1、寄生虫:本试验采用2株柔嫩艾美球虫,其一是安农试验牧场鸡场分离株(RL株),该虫株经测定已对氯甲吡啶酚产生了耐药性,现由安农牧医系药理实验 相似文献
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中兽药在抗寄生虫方面的应用 总被引：1，自引：0，他引：1
寄生虫病可发生于动物养殖过程的各个环节,不同品种、不同年龄、不同性别的动物均可感染寄生虫病。随着抗寄生虫药的广泛应用及不合理应用,导致世界各地均有耐药虫株出现。耐药虫株不但使原有的药物治疗无效,而且还对结构相似或作用机理相同的药物产生了交叉耐药性, 相似文献
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大环内酯类抗寄生虫药耐药性研究进展 总被引：1，自引：0，他引：1
近年来,世界各国陆续报道了寄生虫对大环内酯类抗寄生虫药物的耐药性。影响这类药物耐药性产生和发展的因素很多,包括药物的结构、性质、药物选择压力、耐药基因的遗传特性、用药频率、用药时机、治疗效果以及用药剂量等。谷氨酸门控氯离子通道亚基构象的突变,是引起寄生虫对依赖其作用的药物产生耐药的主要原因。但是,这类药物的耐药机制比较复杂,还存在着γ-氨基丁酸门控氯离子通道受体结构改变引起的耐药以及P-糖蛋白基因结构改变引起的耐药。 相似文献
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为明确地克珠利耐药虫株与敏感虫株在基因水平的差异,进而解析地克珠利耐药性产生的分子机制,本研究以实验室保存的2株柔嫩艾美耳球虫地克珠利耐药虫株和2株柔嫩艾美耳球虫地克珠利敏感虫株为研究对象,将4个虫株进行全基因组重测序(NGS),通过单核苷酸多态性(SNP)密度分布解析耐药株与敏感株之间的差异。结果显示,与敏感株相比,耐药株在第13号染色体0.1～1 Mb区间内的SNP比较富集。本研究结果为解析鸡球虫14条染色体上抗原变异位点和耐药性位点等的研究提供了科学依据。 相似文献
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耐药性是指在现场情况下，某一寄生虫虫株在使同种寄生虫毁灭和抑制其繁殖的药物浓度下仍能繁殖和生存的能力。现时情况下，还必须依赖抗球虫药物来控制球虫病的发生，所有肉鸡配合饲料几乎都添加抗球虫药，因此肉鸡从１日龄到上市前一周为止，球虫的整个发育阶段都处在受抑制，甚至被杀灭的药物压力之下，这种选择压力就会使虫株不可避免地产生耐药性。一、影响球虫耐药性产生的因素１．供试动物的数量研究表明，在接种卵囊数量一定、药物浓度的选择压力一定、供试动物的数量越大获得耐药虫株的机率也就越大，可见在现场情况下鸡群数量越大… 相似文献
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为评估盐酸氟乙基硫胺素产生抗药性的倾向,采用药物浓度递增法,在实验条件下进行柔嫩艾美耳球虫耐药性的诱导研究。每组动物用10只快大黄肉鸡,每只鸡接种1×105个孢子化卵囊,以50 mg/kg盐酸氨丙啉和盐酸氟乙基硫胺素为起始诱导浓度连续传代,以病变记分、存活率和卵囊数三项指标综合判定耐药性。经过10次传代,盐酸氨丙啉对敏感虫株的ACI为192.6,而对耐药虫株的ACI为109.1;经过12次传代,盐酸氟乙基硫胺素对敏感虫株的ACI为197.5,而对耐药虫株的ACI为110.6,对盐酸氨丙啉耐药虫株的ACI为163.2;结果表明成功地诱导出对盐酸氨丙啉、盐酸氟乙基硫胺素完全耐药的虫株。盐酸氟乙基硫胺素产生耐药速度慢于盐酸氨丙啉,与盐酸氨丙啉有部分交叉耐药性。 相似文献
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寄生虫病是较严重的人畜共患病之一,而阿维菌素类药物是目前畜牧业上防治寄生虫病的主要药物。阿维菌素类药物属于大环内酯类抗生素,抗虫药效强大,但也具有神经毒性和发育毒性,脂溶性强,在动物体内分布广泛且代谢周期长,极易造成动物源食品中药物残留的问题,通过食物链危害人类健康。因此,对动物源样品中的阿维菌素类药物残留量进行检测意义重大。目前,应用于动物源样品中阿维菌素类药物残留分析的方法主要有液相色谱-紫外检测法、液相色谱-荧光检测法、酶联免疫吸附法、液相色谱-串联质谱法等。作者对近年来阿维菌素类药物各种检测方法进行了综述,旨在探究各种方法的优劣,为更精准有效地检测动物源食品中阿维菌素类药物的残留提供参考依据。 相似文献
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Prichard RK 《Veterinary parasitology》2005,133(2-3):243-253
Heartworm prophylaxis is currently largely dependent on the ability of avermectins and milbemycins to arrest the development of third and fourth stages of Dirofilaria immitis for prolonged periods, without producing adulticidal effects. Major control programs, dependent on the activity of ivermectin, are being implemented for human onchocerciasis and lymphatic filariasis. The avermectins and milbemycins act on glutamate-gated and gamma-aminobutyrate-gated chloride channel subunit proteins in nematodes. Ivermectin resistance has been widely described in trichostrongylid nematodes of ruminants. There is evidence that when ivermectin resistance occurs in nematodes, there may be selection on some, but not all of the genes that code for ligand-gated chloride channel subunit proteins as well as on some ABC-transporter genes, whose products may be involved in regulating macrocyclic lactone drug concentrations at receptors, and on some structural protein genes of amphidial neurones. Although ivermectin resistance has not been reported in filarial nematodes, there have recently been reports of suboptimal responses to ivermectin in Onchocerca volvulus. Evidence has been found of ivermectin selection on at least ABC-transporter genes and some neuronal structural protein genes in O. volvulus. To date, there is no evidence of avermectin/milbemycin resistance in D. immitis, also a filarial nematode. Chemotherapy against trichostrongylids of animals, human filariae, and D. immitis, relies on avermectins or milbemycins. However, control involves targeting different stages or processes in the nematode life cycles, different control strategies, different proportions of the nematode population in refugia, and different drug dosage rates. Consideration of the proportion of the D. immitis population normally in refugia, the life cycle stage targeted, and the anthelmintic dosages used suggest that it is unlikely that significant avermectin/milbemycin resistance will be selected in D. immitis with current treatment strategies. 相似文献
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Fernando A. Borges Gabriel D. Almeida Rafael P. Heckler Raul T. Lemes Marcel K. V. Onizuka Dyego G. L. Borges 《Tropical animal health and production》2013,45(3):723-727
The performance of grazing cattle in tropical areas is deeply influenced by parasitism, and the increasing reports of resistance are a threat to effective nematode control. The present study aimed to evaluate the effect of avermectins on the performance of weaned calves naturally infected by ivermectin-resistant gastrointestinal nematodes. The effect of four commercial endectocides (ivermectin 2.25 % + abamectin 1.25 %, ivermectin 3.15 %, doramectin 3.15 %, and doramectin 1 %) on parasitism and performance of a hundred weaned Nellore calves were evaluated during 112 days. The most effective anthelmintic showed efficacy of 84 % and resulted in an increase (P?<?0.05) of live weight gain of 11.85 kg, compared to untreated group, 9.05 and 9.41 kg compared to those treated with more ineffective avermectins which showed efficacy of 0 and 48.2 %, respectively. A significant (P?<?0.05) and weak negative correlation (r?=??0.22) between the eggs per gram (EPG) and body weight was observed, indicating that even the low mean EPG (175?±?150) observed at day 0 in the control group, with predominance of Haemonchus sp., was responsible for production losses. These results indicate that control of nematode parasites in beef cattle in the weaning phase may not result in increased productivity when carried out without technical criteria. 相似文献
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Anthelmintic resistance detection methods. 总被引：4，自引：0，他引：4
The development of species and populations of parasitic helminths with resistance to one or more anthelmintics is an increasing problem world-wide. The majority of currently available anthelmintics used to control parasitic nematodes of cattle and sheep belong to only three main groups, the benzimidazoles, imidazothiazoles and the avermectins/milbemycins. The successful implementation of helminth control programmes designed to limit the development of resistance in nematode populations depends to some degree on the availability of effective and sensitive methods for its detection and monitoring. A variety of in vivo and in vitro tests have been developed for the detection of nematode populations resistant to the main anthelmintic groups, but each suffers to some degree from reliability, reproducibility, sensitivity and ease of interpretation. This review covers those tests that have been reported and described and highlights some of their strengths and weaknesses. 相似文献
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Anthelmintic resistance in parasitic nematodes of livestock is a chronic problem in many parts of the world. Benzimidazoles are effective, broad-spectrum anthelmintics that bind to and selectively depolymerise microtubules. Resistance to the benzimidazoles, however, developed quickly and is caused by genetic changes in genes encoding beta-tubulins, subunits of microtubules. In Haemonchus contortus, resistance to avermectins has been correlated with genetic changes at a gene encoding a P-glycoprotein, a cell membrane transport protein that has a very high affinity for ivermectin. The substrate specificity of P-glycoprotein is very broad, and resistance to benzimidazoles can be modulated by lectins specific for P-glycoprotein. We investigated the possibility that genetic changes in P-glycoprotein might be correlated with benzimidazole resistance in nematodes. An analysis of restriction fragment length polymorphisms of a P-glycoprotein gene from a sensitive and a cambendazole-selected strain of H. contortus, derived from the sensitive strain, showed a significant difference in allele frequencies between strains. The frequency of one allele in particular increased substantially. The same allele was also found at a high frequency in an independently derived thiabendazole-selected field isolate. We present genetic evidence of selection at a P-glycoprotein locus during selection for benzimidzole resistance in H. contortus. 相似文献
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Swarnkar CP Sanyal PK Singh D Khan FA Bhagwan PS 《Tropical animal health and production》2001,33(4):305-312
Monitoring anthelmintic resistance in strongyle nematodes by the faecal egg count reduction test and a commercial larval development assay on an organized sheep farm in the semi-arid area of Rajasthan revealed the emergence of resistance to benzimidazoles and rafoxanide and a potential risk of the development of levamisole/tetramisole resistance. A benzimidazole/levamisole combination, avermectins and closantel were each found to be efficacious. 相似文献
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Plasma pharmacokinetics and faecal excretion of ivermectin, doramectin and moxidectin following oral administration in horses 总被引：6，自引：0，他引：6
The present study was carried out to investigate whether the pharmacokinetics of avermectins or a milbemycin could explain their known or predicted efficacy in the horse. The avermectins, ivermectin (IVM) and doramectin (DRM), and the milbemycin, moxidectin (MXD), were each administered orally to horses at 200 microg/kg bwt. Blood and faecal samples were collected at predetermined times over 80 days (197 days for MXD) and 30 days, respectively, and plasma pharmacokinetics and faecal excretion determined. Maximum plasma concentrations (Cmax) (IVM: 21.4 ng/ml; DRM: 21.3 ng/ml; MXD: 30.1 ng/ml) were obtained at (tmax) 7.9 h (IVM), 8 h (DRM) and 7.9 h (MXD). The area under the concentration time curve (AUC) of MXD (92.8 ng x day/ml) was significantly larger than that of IVM (46.1 ng x day/ml) but not of DRM (53.3 ng x day/ml) and mean residence time of MXD (17.5 days) was significantly longer than that of either avermectin, while that of DRM (3 days) was significantly longer than that of IVM (2:3 days). The highest (dry weight) faecal concentrations (IVM: 19.5 microg/g; DRM: 20.5 microg/g; MXD: 16.6 microg/g) were detected at 24 h for all molecules and each compound was detected (> or = 0.05 microg/g) in faeces between 8 h and 8 days following administration. The avermectins and milbemycin with longer residence times may have extended prophylactic activity in horses and may be more effective against emerging and maturing cyathostomes during therapy. This will be dependent upon the relative potency of the drugs and should be confirmed in efficacy studies. 相似文献
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NI Teng-teng PENG Da-peng XIE Shu-yu CHEN Dong-mei WANG Yu-lian PAN Yuan-hu TAO Yan-fei YUAN Zong-hui 《中国畜牧兽医》2016,43(9):2344-2351
Currently,avermectins are the most widespread anti-parasite drugs,and it is urgent to develop the simple,faste,high sensitive high-throughput and low cost methods for residues rapid detection because of its residual in animal body for a long time.In order to provide certain reference for the choice and application of current multi-residues detection method,the rapid detection technology of avermectins in feeds and animal products were reviewed in this paper,such as biochip,fluorescent immunoassay,immune affinity chromatography and enzyme linked immunosorbent assay.At the same time,this paper described the prospects of the development in residues detection methods. 相似文献