细菌对四环素类抗生素的耐药机制研究进展

四环素类药物为广谱抗生素,广泛用于临床治疗,并常被用做动物促生长剂,但耐药性的出现限制了该类药物的使用.四环素类药物产生耐药性的机制主要有核糖体保护作用、外输泵作用及产生钝化酶等.本文详细综述了其耐药机制的研究进展及耐药基因的发生率.     

四环素类抗生素残留检测方法研究进展

总结了四环素类抗生素药物残留的几种常用检测方法,并对这些方法的优缺点进行了归纳。     

免疫分析技术在四环素类抗生素残留检测中的应用

四环素类抗生素一类广谱性抗生素,主要用于治疗各种感染性疾病,但长期的违规滥用,导致其在动物源性食品以及环境中大量残留,严重威胁人类健康。因此,急需建立简单、灵敏的快速检测方法。免疫分析技术因其特异性强、灵敏度高等优势已成为快速检测方法研究的热点。本文主要综述了已在四环素类抗生素残留检测中应用的放射性免疫、酶联免疫、胶体金免疫层析以及电化学免疫传感器免疫分析方法,并对其发展方向进行展望。     

四环素类抗生素在环境中的风险评估研究进展

四环素类抗生素因成本低、价格低、抗菌谱广及抗菌活性好等特点被广泛用于养殖业,由于其在动物体内吸收较少,大部分以原形或代谢物的形式排出体外,随动物的粪便、尿液进入环境。多项研究表明,四环素类抗生素在环境中的暴露量大,吸附能力强、迁移能力弱,微生物、光照及温度都会影响其在环境中的稳定性,其在环境中的暴露对植物生长、水生生物及微生物群落结构数量和抗性基因均会产生负面影响。作者综述了四环素类抗生素在环境中的暴露现状、吸附及降解行为特性、效应研究及其在环境中的风险评估现状,旨在引起人们对环境中四环素类抗生素污染的重视,为环境中四环素类抗生素及抗性基因的去除提供参考,并对今后四环素类抗生素的环境风险评估提出展望。     

四环素类抗生素的环境行为研究进展

四环素类抗生素被广泛用于动物疾病的治疗,并长期以亚治疗剂量添加于动物饲料中用于动物疾病的预防和促进动物生长.由于四环素类抗生素大量使用使其在环境中普遍存在,并导致了细菌耐药性.研究表明某些四环素类抗生素在环境中具有一定的持久性,因此其在环境中行为引起了众多学者的关注.论文回顾了四环素类抗生素在环境中残留、迁移转化等方面...     

四环类抗生素生产状况与市场发展前景

介绍了四环素类抗生素的八个主要代表产品的产品形式、生产工艺、质量标准、生产厂家,梳理了四环素类抗生素当前的生产状况。通过梳理这些品种在医药、兽药、饲料添加剂上的应用和新用途的发现,预见了各品种发展方向和市场前景,得到如下结论：围绕替加环素的开发,去甲金霉素、米诺环素的生产有较大的发展空间和良好的市场前景,四环素类抗生素一代产品在兽药和饲料添加剂上,仍然有一定市场需要,通过老药新用发现,特别是替加环素的特殊贡献,说明四环素类抗生素还有较大市场空间。     

牛奶中四环素类抗生素残留及其检测分析

随着奶牛业的不断发展和抗生素的不断运用,牛奶中抗生素的残留越来越受到人们的关注,本文详细介绍了牛奶中四环素类抗生素残留的检测分析方法。     

四环素类抗生素的用途、注意事项及使佣方法

四环素类抗生素是碱性广谱抗生素,包括从链霉菌属培养物提取的四环素、土霉素、金霉素以及多种半合成四环素,如多西环素。本类药物对革兰氏阳性菌的作用优于革兰氏阴性菌,而对变形杆菌、绿脓杆菌无作用。半合成四环素类对许多厌氧菌有良好作用,70％以上的厌氧菌对多西环素敏感。     

猪链球菌对四环素类抗生素耐药机制的研究进展

四环素类抗生索为广谱抗生素,曾在兽医临床广泛使用.但随着该抗生素在我国的广泛使用,猪链球菌的耐药现象日益严重.猪链球菌的四环素类耐药机制主要由核糖体保护蛋白及外排泵蛋白介导.     

四环素类抗生素在养猪生产中的正确应用

四环素类是从链霉菌培养液中提取或经半合成制得的抗菌特性和抗菌谱相似的一类碱性广谱抗生索,因分子结构中有4个环而得名,也称四环素族。除对大多数革兰氏阳性（G＋）菌和阴性（G-）菌有抑制作用（高浓度时有杀菌作用）外,还对立克次体、衣原体、支原体、附红细胞体、螺旋体、放线菌及某些原虫等均有抑制作用,故称广谱抗生素。但对绿脓杆菌、变形杆菌、棒状杆菌、克雷伯氏菌通常耐药,对真菌、病毒无效。     

The entry of bound residues of tetracyclines into the food chain--a contribution to hazard identification

Actually, some 67% of therapeutical used antibiotics in livestock in the European Union are tetracyclines. Their use can result in unwanted residues in food of animal origin. Apart the risk of the possible development of resistances in enterobacteriaceae we have to keep in mind secondary circuits. This paper focuses on tetracycline residues in bones. Bones have been widely used as raw material for meat and bone meal and gelatine, and are also a frequent contamination of mechanical recovered meat. Bones contain tetracycline residues in concentrations up to 50 mg/kg. These bound tetracycline residues have ever been thought to be of no significance to health. Nevertheless, recent studies have shown that these tetracyclines could be released in vivo and re-obtain their bioavailability. Further, several toxic degradation products of tetracyclines could be formed during heating. Additionally, in acid solutions from the production of gelatine high tetracycline concentrations have been found. These solutions are processed to dicalciumphosphate, which is used as a feed supplement in animal husbandry and as fertilizer in agriculture.     

Critical review on the withdrawal period calculation for injection site residues

This review concerns a statistical method for calculating withdrawal period for injection site residues. A recently adopted Committee for Medicinal Products for Veterinary Use/European Agency for the Evaluation of Medicinal Product (CVMP/EMEA) guideline recommends to apply the same method for the calculation of withdrawal period for injection site residues as for other edible tissues. For reasons in this study developed below, this approach is deemed to be inappropriate for the injection site residues. The injection site residues often violate regression assumptions with regard to homoscedasticity (same variance in residue concentrations for different slaughter times) and linearity (of the mean depletion curve in log(e)-scale). The currently recommended method cannot adequately handle these aspects. An alternative pragmatic method taking into account the last slaughter time with all data below the reference threshold, combined with a safety span, is proposed for injection site residues. A nonparametric approach for calculating the withdrawal period is also presumed to be a sound alternative. The references commonly used are the Maximum Residue Limit (MRL) and the Acceptable Daily Intake (ADI). Unfortunately these references are not relevant to the acute risk exposure associated with injection site consumption. The use of alternative references, such as the Acceptable Single Dose Intake (ASDI) or the Acute Reference Dose (ARD) are thought to be more appropriate.     

今年一季度水产市场述评

一季度国内水产品市场供应充足,尽管由于长江春季禁渔制度的实施和海区专属经济区政策的执行导致淡水、海水捕捞产量的下降,但是由于淡水和海水养殖业的健康发展,市场上水产品的价格基本维持在一个比较稳定的状态;由于国家相关政策的实施,许多传统渔民无法继续从事生产,这使得许多渔民面临着专业转产的难题,积极处理渔民转产转业中出现的问题,对渔     

高效液相色谱法测定水产品中孔雀石绿和隐性孔雀石绿的残留量

采用高效液相色谱法测定鱼体组织中孔雀石绿及其代谢物隐性孔雀石绿的残留量,共检测不同水产品市场的样品559份(包括太阳鱼、桂花鲈、鲮鱼、边鱼、鳗鱼、多宝鱼).未检测到孔雀石绿阳性样品;而隐性孔雀石绿阳性率分别为:桂花鲈8.22%、边鱼5.79%、鳗鱼0%、太阳鱼7.88%、鲮鱼4.17%、多宝鱼为0,样品中隐性孔雀石绿的总检出率为5.01%.本试验的MG回收率范围在91.78%～99.87%,LMG的回收率范围在78.02%～94.97%.MG的相对标准偏差为0.89%～2.09%,LMG的相对标准偏差为1.27%～3.41%.检出限为2μg/kg.     

The effect of citric acid on the availability of tetracyclines in calves

The effect of citric acid on the availability of tetracyclines was studied in calves. Citric acid did not significantly increase the serum levels of tetracyclines when calves were fed low doses (6-8 mg/kg) of oxytetracycline and chlortetracycline. When the dose of chlortetracycline was increased to 50 mg/kg, addition of citric acid caused higher serum levels the first two hours after feeding. The ratio citric acid: tetracyclines was 5:1 and 25:1. The palatability of the milk replacer was reduced when large amounts of citric acid was added.     

The availability of tetracyclines in calves

The bioavailability of oxytetracycline (OTC) and chlortetracycline (CTC) was studied in non-fasting calves. The availability of OTC was found to be 5% and of CTC 37% after oral administration of 10 mg/kg. The availability was reduced when the drugs were given in a milk replacer or in cow's milk. The area under curve (AUC) was reduced 68% when OTC was given in milk replacer, the reduction of CTC availability was 40%. In milk the reduction was 72% for OTC and 47% for CTC. Calcium and iron caused a dramatic reduction of the serum levels. OTC was stored mixed in milk powder at room temperature for 6 months without loss in availability. OTC did not chelate calcium ions in serum. The conclusion drawn from the results was that CTC is more suitable than OTC for oral therapy in calves.     

Impact of oxidative stress on male fertility - a review

Oxidative stress is a state related to increased cellular damage caused by oxygen and oxygen-derived free radicals known as reactive oxygen species (ROS). It is a serious condition, as ROS and their metabolites attack DNA, lipids and proteins, alter enzymatic systems and cell signalling pathways, producing irreparable alterations, cell death and necrosis. While small amounts of ROS have been shown to be required for several functions of spermatozoa, their excessive levels can negatively impact the quality of spermatozoa and impair their overall fertilising capacity. These questions have recently attracted the attention of the scientific community; however, research aimed at exploring the role of oxidative stress and antioxidants associated with male fertility is still at its initial stages. This review summarises the current facts available in this field and intends to stimulate interest in basic and clinical research, especially in the development of effective methods for the diagnosis and therapy of semen damage caused by oxidative stress.     

Human health hazards associated with the administration of antimicrobials to slaughter animals. Part I. An assessment of the risks of residues of tetracyclines in pork

This article describes the assessment of consumer risks of residues of tetracyclines in slaughter pigs in the Netherlands. The assessed risks were toxic and allergic reactions, and the disturbance of the consumers' intestinal flora. Toxic and allergic reactions in humans and animals have only been observed at therapeutic doses, affecting between an estimated 1 in 5,000 and one 1 in 140,000 individuals exposed. Residues of tetracyclines in pigs are closely associated with treatment with injectable formulations. Established Maximum Residue Levels (MRLs) do not reflect actual consumer risks in case a limit is violated incidentally. For example, when the established MRLs for tetracyclines in meat are exceeded with a factor 400, 40,000, and 200,000, respectively, the actual risk of an adverse drug reaction for the consumer following a single consumption of this meat is maximally 1 in 3 million, 1 in 300,000, and 1 in 8,000, respectively. At the current estimated low levels of incidental exposure via pork, the annual risk of negative health effects for a random consumer is estimated at maximally 1 in 33 million. The annual risk that a temporary disturbance of the intestinal flora may also result in a facilitated infection with certain enteropathogens, such as Salmonella spp., is estimated at 1 in 45 million. It is concluded that the current microbiological risks of pork are greater than the risks of residues of tetracyclines as such, and that the control of the microbiological risks of pork should therefore be given first priority.