硫酸黏菌素毒性及其残留检测研究进展

对兽用硫酸黏菌素的毒副作用及其残留检测方法进行了综述,为其在畜牧兽医领域的进一步研究及应用提供参考。     

微生物浊度法测定硫酸黏菌素E含量的研究

以大肠杆菌为试验菌,抗生素检定培养基Ⅲ号为试验用培养基,研究比浊法测定硫酸黏菌素及其制剂的含量。硫酸黏菌素的浓度在44.9 u/ml～93.2u/ml之间时,检测菌液接种浓度为0.3%,培养时间为2～3h,其浓度的对数值与相对应的吸光度具有良好的线性关系,相关系数：r＝0.9978。所建立的浊度法重现性较好,具有简便、精确、快速的特点,可用于硫酸黏菌素及其制剂含量的测定。     

硫酸黏菌素对原代背根神经元细胞的毒性作用

建立了新生小鼠原代背根节(Dorsal root ganglion,DRG)神经元细胞原代培养的方法,作为评价硫酸黏菌素毒性的体外研究模型.在此模型基础上,使用不同浓度的硫酸黏菌素作用细胞24h后,应用MTT方法观察细胞毒性效应并测定细胞半数抑制浓度(IC50).结果表明,不同浓度硫酸黏菌素处理细胞后,高剂量组DRG神经元细胞出现明显病变,硫酸黏菌素浓度低于10μg/mL时,对DRG神经元细胞存活率无明显影响,硫酸黏菌素浓度达到10μg/mL以上时,细胞存活率降低,出现细胞毒性,且毒性作用强度随药物浓度增加而增强;试验测得硫酸黏菌素对DRG神经元的半数抑制浓度(IC50)为222.7μg/mL.     

微生物浊度法测定硫酸黏菌素及其制剂含量的研究

以大肠杆菌为试验菌,抗生素检定培养基Ⅲ号为试验用培养基,研究微生物比浊法测定硫酸黏菌素及其制剂的含量.硫酸黏菌素的浓度在44.9 u/mL～93.2 u/mL之间时,检测菌液接种浓度为0.3%,培养时间为2～3 h,其浓度的对数值与相对应的吸光度具有良好的线性关系,相关系数:r＝0.997 8.所建立的微生物浊度法重现性较好,具有简便、精确、快速的特点,可用于硫酸黏菌素及其制剂含量的测定.     

硫酸多黏菌素B的脱色工艺研究

主要进行了硫酸多黏菌素B的膜脱色和活性炭脱色2种工艺的比较.结果表明,膜脱色在泵出口压力为25 kgf/cm2、料液pH值为2.5、进料温度为50℃时,其脱色率为86％;而A类活性炭的脱色条件为:料液脱色时间为50 min、进料温度为55℃、活性炭添加量为料液的2.5％时,其脱色率为75％.     

恩诺沙星残留对土壤细菌耐药性的影响

兽药吸收进入动物机体后,少部分药物将残留于动物组织细胞内,而大部分药物将排泄出体外,最终进入生态环境中,且可能造成环境污染.为了了解恩诺沙星在环境中残留对土壤细菌耐药性的影响,本试验采用琼脂稀释法对土壤细菌进行了抗菌药物敏感性试验.结果表明,恩诺沙星对用药前分离的土壤优势细菌的MIC值都比较低,为0.008～2 μg/mL,对其中大多数细菌的MIC值为0.032～0.125 μg/mL;用药后分离的土壤细菌对恩诺沙星的敏感性降低,细菌对恩诺沙星的耐药率和耐药水平随土壤中药物浓度加大和时间的延长而明显增高.     

氟苯尼考胁迫对土壤细菌耐药性的影响

为了了解土壤中残留氟苯尼考对土壤中细菌耐药性的影响,在土壤中添加不同浓度的氟苯尼考,于添加药物后第14天、28天、56天采集土壤样品分离细菌,采用微量肉汤二倍稀释法进行细菌对氟苯尼考的敏感性试验,并采用药敏纸片扩散法对用药前后分离的氟苯尼考敏感菌和耐药菌进行抗菌药物的敏感性试验。结果表明氟苯尼考残留的浓度越大,耐药菌的数量也就越多;在供试的18种抗菌药中,氟苯尼考敏感菌对其中的9种药物的敏感性均显著高于氟苯尼考耐药菌(P<0.01)。     

诺氟沙星对土壤细菌数量及耐药性影响

为了解诺氟沙星在环境中残留对土壤细菌的影响,在诺氟沙星作用于土壤后第35天对纯培养法分离的土壤细菌进行计数,并对土壤细菌进行抗菌药物敏感性试验。结果表明,添加药物组的细菌总数均低于对照组,且药物浓度越高,细菌数量越少;在供试的20种抗菌药中,诺氟沙星敏感菌对其中18种药物的敏感性与诺氟沙星耐药菌差异不显著(P>0.05)。     

恩诺沙星对土壤细菌数量及耐药性的影响

兽药吸收进入动物机体后,少部分药物将残留于动物组织细胞内,而大部分药物将排泄到体外,最终进入生态环境中,且可能造成环境污染。为了解恩诺沙星在环境中残留对土壤细菌的影响,在恩诺沙星作用于土壤后第35天,对纯培养法分离的土壤细菌进行了计数,并对土壤细菌进行了抗菌药物敏感性试验。结果表明,添加药物组的细菌总数均低于空白对照组,且药物浓度越高,细菌数量越少;在供试的19种抗菌药中,恩诺沙星敏感菌对其中的16种药物的敏感性均显著高于恩诺沙星耐药菌（P〈0.01）。     

环丙沙星残留对土壤细菌数量及耐药性的影响

为了解环丙沙星在环境中残留对土壤细菌的影响,在环丙沙星作用于土壤后第35天,对纯培养法分离的土壤细菌进行了计数,并对土壤细菌进行了抗菌药物敏感性试验。结果表明,添加药物组的细菌总数均低于对照组,且药物浓度越高,细菌数量越少;在供试的20种抗菌药中,环丙沙星敏感菌对其中的12种药物的敏感性与环丙沙星耐药菌差异不显著(P>0.05)。     

复方紫花地丁对鸭大肠杆菌MIC逆转效果的影响

以恩诺沙星人工诱导鸭大肠杆菌耐药菌株,原始菌株和诱导株经不同浓度的复方紫花地丁溶液处理,检测其MIC及菌体药物蓄积浓度.结果表明,经复方紫花地丁溶液处理的菌株,MIC显著降低,且与紫花地丁溶液呈浓度依赖关系.研究结果提示,一定浓度的紫花地丁溶液可以逆转鸭大肠杆菌的耐药性.     

高寒草地土壤优势细菌在草地物质循环中的作用初探

选择从高寒草地土壤中分离获得的具有代表性的8株优势细菌和特有细菌菌株NX2（Acinetobacter sp．）、NX4（Arthrobacter sp．）、NX6（Chryseobacterium sp．）、NXIO（Pseudomonas sp．）、NXll（Flavobacterium sp．）、HX1（Lysobacter sp．）、WX15（Brevundimonas sp．）和HX5（Pseudoxanthomonas sp．）,测定了其运动特性、生长温度和对多种碳源、氮源及对大分子物质的分解能力。结果表明：NX2、NX4、NX10和WX15具有较强的运动性;HX1和NX2在5℃下生长良好,NX4、NX6、NXIO、NX11、WX15和HX5在0℃低温下生长良好,表现出对低温很强的适应性;8种细菌对硝酸盐等无机氮、蛋白质等有机氮以及各种碳源的利用能力和利用程度均存在差异,表明细菌对草地土壤中动、植物残体的分解和利用具有一定的选择性,同时反应出这些优势细菌在物质循环和分解利用中互相分工和合作。     

乌鲁木齐市宠物猫源大肠杆菌耐药性及耐药基因检测

为了解宠物猫源大肠杆菌对临床常用抗菌药物的耐药性及其耐药基因携带情况,在乌鲁木齐市多家宠物医院采集宠物猫肛拭子样品59份进行大肠杆菌的分离鉴定,通过琼脂稀释法测定10种抗菌药物的最小抑菌浓度,利用PCR方法检测13种耐药基因。结果:分离鉴定出大肠杆菌47株,分离率79.7%(47/59)。分离菌对四环素(TET)(83.0%)、阿莫西林-克拉维酸(A/C)(66.0%)和磺胺异噁唑(FIS)(66.0%)耐药情况严重;对头孢他啶(TAZ)、头孢曲松(CRO)、恩诺沙星(EN)、庆大霉素(GEN)耐药率在38.3%～48.9%;对环丙沙星(CIP)、阿米卡星(AMK)敏感性较好,未检出亚胺培南耐药菌株。菌株多药耐药分布在5～8耐,占比59.6%,耐药表型以1耐TET和6耐A/C+GEN+CRO+TAZ+TET+FIS为主。共检出ant(3″)-Ia、aac(6′)-Ib、bla_TEM、bla_CTX-M、qnrS、tetA、tetB、tetM、sulⅠ、sulⅡ10种耐药基因,检出率分布在8.5%～57.4%,未检出耐药基因oqxB、bla     

Incidence of drug resistance and transmissible R factors in strains of E. coli isolated from faeces of healthy pigs

Two hundred and twenty-six strains of E. coli were isolated from faeces of 107 pigs at different ages and without clinical signs of infectious diseases. The resistance of the strains to sulphonamide, tetracycline, streptomycin, chloramphenicol, ampicillin, and nalidixic acid was determined. In 74 % of the animals the predominant E. coli flora was found to be resistant to one or more of the drugs mentioned. Fifty-three % of the strains were resistant. Multiple resistance was predominant among resistant strains (67 %). R factors transmissible to a sensitive strain of E. coli K12 W3132 were demonstrated in 28 %. The proportion of resistant strains was largest in young animals (0–14 weeks) accounting for 65 % of the strains isolated, as compared to 43 % of strains from pigs and sows (6 months or more). The incidence of resistance to sulphonamide, tetracycline, and streptomycin was high, whereas most of the strains were sensitive to ampicillin and chloramphenicol. All strains were sensitive to nalidixic acid.The incidence of resistance to antibiotics in a population of pigs to whom these drugs are not fed but applied as therapeutic agents solely seems rather high. When based on clinical findings only, the value is therefore questionable of sulphonamide, tetracycline and streptomycin treatment of infectious diseases caused by E. coli.     

不同保护性耕作措施对三种土壤微生物氮素类群数量及其分布的影响

通过设置在陇中黄土高原丘陵沟壑区的长期定位试验,研究了不同保护性耕作措施下旱作春小麦-豌豆轮作系统中土壤氨化细菌、硝化细菌和自身固氮菌数量及其分布的差异。结果表明,无论是小麦地还是豌豆地,土壤氨化细菌、硝化细菌、自身固氮菌数量在0～5,5～10和10～30 cm土层中均呈现免耕秸秆覆盖＞秸秆还田＞免耕不覆盖＞传统耕作的趋势,且随着土层的加深,在小麦地中,免耕秸秆覆盖处理的氨化细菌数量比免耕不覆盖处理分别增加了76.21%,146.92%和67.82%, 且差异均达到5%的显著水平,在豌豆地中,各处理自身固氮菌数量逐渐减少,而硝化细菌数量呈先增加后减少的趋势,免耕秸秆覆盖、秸秆还田处理土壤氨化细菌数量逐渐下降,而免耕不覆盖、传统耕作处理的土壤氨化细菌数量先增加后减少。     

Drug resistance in strains of Escherichia coli isolated from the intestinal tract of pigs in Norway.

Faecal samples from 95 healthy pigs and samples of jejunal content from 85 piglets suffering from colienterotoxaemia were tested for the presence of drug resistant E. coli strains. Practically all pigs in both groups harboured E. coli strains resistant to one or more of the 6 antibiotics/chemotherapeutic agents tested (Oxytetracycline, streptomycin, sulphaisodimidin, neomycin, ampicillin, chloramphenicol). Almost 100% of healthy and approx. 90% of diseased pigs harboured strains resistant to Oxytetracycline, streptomycin and sulphaisodimidin. Pigs with strains resistant to neomycin, ampicillin and chloramphenicol were less frequently found. The predominant coliform flora consisted of E. coli strains” resistant to Oxytetracycline, streptomycin and sulphaisodimidin in 71% to 81% of diseased pigs and in 47% to 69% of the healthy pigs. In diseased pigs ¾ of the animals had a coliform flora dominated by neomycinresistant E. coli strains.Of the 721 resistant E. coli strains isolated from healthy pigs, 11% were single resistant while the corresponding figure for the 518 resistant strains isolated from diseased pigs was 6%. Thus 89% and 94% of strains showed simultaneous resistance to 2 or more antibiotics. E. coli strains resistant to 3 or more drugs were found in approx. 60% and 70% of the isolates from healthy and diseased animals, respectively. Oxytetracycline/streptomycin/sulphaisodimidin resistance was most commonly found, approx. 22% and 38% of the strains from healthy and diseased pigs, respectively, showing this resistance pattern.Transmission of drug resistance which was examined in E. coli strains originating from the diseased pigs was demonstrated in approx. 76% of the isolates. The incidence of drug resistance transfer in single, double, triple and quadruple resistant strains was 11%, 68%, 97% and 98%, respectively.