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1.
为设计研发新型天蚕素类抗菌肽(Cecropin-like antibacterial peptide,CLP),本研究参照抗菌肽Cecropin P1的作用机理和氨基酸组成,通过人工方法设计合成CLP,并分别测定其体外和体内抗菌活性。体外抑菌试验结果显示,新型CLP对金黄色葡萄球菌(ATCC29213)、禽多杀性巴氏杆菌(CVCC474)、鸡白痢沙门氏菌(ATCC10398)、鸡致病性大肠杆菌O1均具有良好的抑菌活性,对这4种细菌的最小抑菌浓度(MIC)分别为6.25μg/mL、1.56μg/mL、3.12μg/mL和6.25μg/mL。酸稳定性试验显示,新型CLP在pH值为6~8时活性最高,热稳定性试验显示新型CLP于100℃加热2 h后仍具有抑菌活性。在对鸡白痢沙门氏菌感染雏鸡的体内疗效试验中,新型CLP显示了良好的治疗效果。本研究为临床上设计有效的天蚕素类抗菌肽提供了参考数据。  相似文献   

2.
抗菌肽LL-37的抑菌作用及其稳定性研究   总被引：1，自引：0，他引：1  
采用微量2倍稀释法测定抗菌肽LL-37对大肠杆菌、沙门菌和金黄色葡萄球菌的最小抑菌浓度(MIC),并进一步研究温度、pH和保存时间对LL-37稳定性的影响。结果显示:LL-37对大肠杆菌、沙门菌和金黄色葡萄球菌的最小抑菌浓度分别为3.12、1.56和0.78μg/mL。热稳定性试验显示:重组抗菌肽121℃加热21 min、100℃加热3 h仍有较好的活性。酸碱稳定性试验结果显示:LL-37在pH 2.0～12.0时均具有一定的活性,pH 5.0～6.0时活性最好。此外,-20℃为此抗菌肽长期保存的最佳条件。  相似文献   

3.
为探讨鲎素对仔猪腹泻致病性大肠杆菌的杀伤作用,采用琼脂糖弥散试验和试管二倍稀释法检测了鲎素对大肠杆菌K_(88)、K_(99)和F_(41)的杀伤活性、最小抑菌浓度(minimal inhibitory concentration,MIC)和最小杀菌浓度(minimal bactericidal concentration,MBC);将鲎素(32μg/mL)与K_(99)37℃共孵育2h,扫描电镜和透射电镜观察细菌形态的变化。结果表明,鲎素对上述细菌均具有较强的抑杀活性,其MIC为1～2μg/mL,MBC为2～8μg/mL;经鲎素处理后的K_(99)细胞壁膜和菌体内部遭到不同程度的破坏。结果提示鲎素具有抑杀断奶仔猪腹泻致病性大肠杆菌的生物功能。  相似文献   

4.
试验旨在研究抗菌肽BSN-37的抑菌活性和稳定性。采用微量倍比稀释法测定抗菌肽BSN-37的最小抑菌浓度(MIC),菌落计数法分析抗菌肽BSN-37对大肠杆菌CVCC1568的杀菌动力学特征,扩散法测定抗菌肽BSN-37的盐离子稳定性、酸碱稳定性、血清稳定性、胰酶稳定性、热稳定性、反复冻融稳定性、室温保持稳定性、药效保持时间稳定性。结果显示,抗菌肽BSN-37对革兰氏阴性菌(大肠杆菌和沙门氏菌)的MIC为1.5625～25μg/mL,对革兰氏阳性菌(枯草芽孢杆菌和短小芽孢杆菌)的MIC为1.5625～12.5μg/mL,对真菌(白色念珠菌)没有活性;抗菌肽BSN-37可在90min内完全杀灭大肠杆菌CVCC1568;除了Fe2+和胰酶会影响抗菌肽BSN-37的抑菌活性外,在75～100℃的高温、150～250mmol/L高浓度盐离子(Na+、K+、Ca2+和Mg2+)、20%～25%饱和浓度的Cu2+、pH 4～10、20%～25%的血清、10～12次的反复冻融、10～12d室温保存等条件下仍能保持较好的抑菌活性,药效保持时间可达7.5d。本试验结果表明,抗菌肽BSN-37具有替代抗生素成为新抗菌药物的潜力,为抗菌肽BSN-37的临床应用提供了理论依据。  相似文献   

5.
为设计研发新型猪源抗菌肽PMAP-23,本研究参照PMAP-23的作用机理和氨基酸组成,人工设计并合成新型抗菌肽PMAP-23LR,通过药敏试验检测其体外抗菌活性,同时以感染鼠伤寒沙门菌的小鼠作为实验动物感染模型,研究抗菌肽PMAP-23LR对致病菌的体内抗菌活性。体外抑菌试验结果显示,PMAP-23LR相较于PMAP-23对猪霍乱沙门菌C78-1的最小抑菌浓度未发生变化,对金黄色葡萄球菌25923、鼠伤寒沙门菌1344、禽巴氏杆菌C48-3、产肠毒素性大肠杆菌7915的抑菌活性增强;酸碱稳定性试验结果显示,PMAP-23LR在pH2～pH12时具有100%的抗菌活性;热稳定性试验显示,PMAP-23LR在沸水中2 h后仍具有抑菌活性,溶血试验结果显示PMAP-23和PMAP-23LR在2μg/mL～1 mg/mL的浓度下均不能使鸡红细胞发生溶血。在对鼠伤寒沙门菌感染小鼠的体内治疗试验中,PMAP-23LR能够减少小鼠肝脏和肺脏的病理损伤,增加了小鼠的存活率。本研究为抗菌肽PMAP-23的改造及应用提供了参考依据。  相似文献   

6.
试验旨在研究抗菌肽BSN-37的抑菌活性和稳定性。采用微量倍比稀释法测定抗菌肽BSN-37的最小抑菌浓度(MIC),菌落计数法分析抗菌肽BSN-37对大肠杆菌CVCC1568的杀菌动力学特征,扩散法测定抗菌肽BSN-37的盐离子稳定性、酸碱稳定性、血清稳定性、胰酶稳定性、热稳定性、反复冻融稳定性、室温保持稳定性、药效保持时间稳定性。结果显示,抗菌肽BSN-37对革兰氏阴性菌(大肠杆菌和沙门氏菌)的MIC为1.5625～25μg/mL,对革兰氏阳性菌(枯草芽孢杆菌和短小芽孢杆菌)的MIC为1.5625～12.5μg/mL,对真菌(白色念珠菌)没有活性;抗菌肽BSN-37可在90min内完全杀灭大肠杆菌CVCC1568;除了Fe2+和胰酶会影响抗菌肽BSN-37的抑菌活性外,在75～100℃的高温、150～250mmol/L高浓度盐离子(Na+、K+、Ca2+和Mg2+)、20%～25%饱和浓度的Cu2+、pH 4～10、20%～25%的血清、10～12次的反复冻融、10～12d室温保存等条件下仍能保持较好的抑菌活性,药效保持时间可达7.5d。本试验结果表明,抗菌肽BSN-37具有替代抗生素成为新抗菌药物的潜力,为抗菌肽BSN-37的临床应用提供了理论依据。  相似文献   

7.
本实验采用琼脂扩散和稀释法,对发酵得到的基因工程抗菌肽Pa-AMP05的抗菌活性进行研究,结果表明,抗菌肽Pa-AMP05具有较强的抑制大肠杆菌与金黄色葡萄球菌的活性,对金黄色葡萄球菌的最低抑菌浓度(MIC)为15.625μg/mL,对大肠杆菌的最低抑菌浓度(MIC)为31.25μg/mL;且其浓度与抗菌活性呈线性正相关。  相似文献   

8.
牛乳酪蛋白来源新型抗菌肽抗菌活性的初步研究   总被引：5，自引：2，他引：5  
通过胃蛋白酶水解牛乳酪蛋白得到了一种新的具有抗菌活性的多肽,并进行了初步的抗菌试验。研究采用胃蛋白酶在不同时间条件下水解酪蛋白,测定水解液及其分离物质对不同细菌的抗菌活性。结果表明:2、3、4h胃蛋白酶的酪蛋白水解产生的抗菌肽对多种细菌均具有抗菌活性,尤其是对金黄色葡萄球菌和沙门氏菌具有很强的抗菌作用,其最小杀菌浓度(MBC)分别是3.69μg/mL和0.157μg/mL,最小抑菌浓度(MIC)与MBC相同。该抗菌肽具有良好的热稳定性。酪蛋白和胃蛋白酶本身无此活性,说明酪蛋白经胃蛋白酶水解可以产生抗菌活性肽。  相似文献   

9.
对大肠杆菌和金黄色葡萄球菌进行正己酸的抗性试验,以研究正己酸对病原菌的抑制作用。试验采用等浓度梯度稀释、光密度值测定、平板涂布方法、牛津杯法,分别测定大肠杆菌及金黄色葡萄球菌的的最小抑菌浓度(minimum inhibitory concentration,MIC)以及最小杀菌浓度(minimum bactericidal concentration,MBC),绘制1/2MIC以及MIC处理过的大肠杆菌以及金黄色葡萄球菌的生长曲线,抑菌圈直径,结合扫描电镜图片分析最小杀菌浓度处理后的细胞形态结构的变化。结果表明:正己酸对大肠杆菌的最小抑菌浓度为700μg/mL、对金黄色葡萄球菌的最小抑菌浓度为1 000μg/mL;对大肠杆菌的最小杀菌浓度为1 000μg/mL、对金黄色葡萄球菌的最小杀菌浓度为1 300μg/mL;当正己酸浓度为1 600μg/mL时,电镜下,大肠杆菌数量较少,金黄色葡萄球菌数量少且呈现出细胞破裂萎缩现象。综上,正己酸对大肠杆菌和金黄葡萄球菌有抑制作用,破坏了金黄葡萄球菌的细胞膜结构。  相似文献   

10.
为了研究氟苯尼考与乳酸诺氟沙星在治疗鸡大肠杆菌病时的相互作用,本试验采用肉汤稀释棋盘法,用氟苯尼考与乳酸诺氟沙星对鸡致病性大肠杆菌进行了体外联合药敏试验。氟苯尼考与乳酸诺氟沙星单独用药时的最小抑菌浓度(MIC)分别为16μg/mL、0.8μg/mL,联合用药的MIC分别为16μg/mL、3.2μg/mL,经计算FIC指数为5。结果表明,氟苯尼考与乳酸诺氟沙星联合用药对鸡大肠杆菌呈现拮抗作用。  相似文献   

11.
新型抗菌肽Hadrurin基因的克隆与表达   总被引：1，自引：1，他引：0  
Hadrurin是一种分离自毒蝎的高活性抗菌肽,对多种细菌有较强抑制活性.本试验构建Hadrurin全基因并在其两端加入了可切除的保护性多肽基因;再酶切Hadrurin基因产生黏性末端并连入pET-32a(+)原核表达载体;IPTG诱导表达抗菌肽蛋白,亲和层析纯化抗菌肽蛋白.结果表明,构建的Hadrurin全基因片段序列完全正确,连接进入pET-32a(+)表达载体的基因由0.1 mmol/L终浓度的IPTG诱导5 h可达到表达的高峰,重组蛋白经亲和层析可到达纯化的目的.  相似文献   

12.
OBJECTIVE: To determine the antibacterial activity of bovine lactoferrin hydrolysate (bLf-lysate) alone or in combination with other antimicrobials against antimicrobial-resistant Escherichia coli strains isolated from baby pigs. SAMPLE POPULATION: 3 clinical strains of E coli were isolated from baby pigs with severe diarrhea and designated as strains 9061, 9062, and 9065. PROCEDURE: The broth microdilution checkerboard and fractional inhibitory (or bactericidal) concentration index were used to evaluate the antibacterial effect elicited by bLf-lysate in combination with kanamycin, gentamicin, cephalothin, cefamandole, penicillin G, ampicillin, tetracycline, erythromycin, or rifampicin against the 3 strains of E coli. RESULTS: The 3 strains of E coli were susceptible to gentamicin and rifampicin but highly resistant to most of the other antimicrobials tested, except for strain 9061 that was also susceptible to cephalothin but intermediately inhibited by kanamycin and cefamandole. Synergistic growth-inhibitory activity was observed between bLf-lysate and gentamicin against 1 strain of E coli (strain 9062); synergistic bactericidal activity was found between bLf-lysate and rifampicin against all 3 strains of E coli. Moreover, partial synergy was observed between bLf-lysate and kanamycin, gentamicin, cephalothin, or cefamandole against the strains of E coli, but this partial synergistic activity was mostly seen against only 1 of the strains. Little interaction between bLf-lysate and tetracycline, ampicillin, penicillin G, or erythromycin was observed against the clinical strains of E coli. CONCLUSIONS AND CLINICAL RELEVANCE: A combination of bLf-lysate and certain antimicrobials may prove clinically effective against antimicrobial-resistant strains of E coli.  相似文献   

13.
Fourteen enteropathogenic and five nonenterotoxigenic Escherichia coli strains isolated from pigs were used for producing antisera in rabbits and pigs. These antisera were used in an vitro test system for antibacterial activity against homologous and heterologous porcine E. coli strains. Antibacterial titres were determined against the homologous strains and the percent reduction in CFU/ml caused by a 1/200 dilution of the sera against heterologous strains was determined. The results indicated that following immunization the antibacterial activity of serum against homologous and heterologous strains was significantly increased. This activity did not appear to be influenced by O and K antigen relationships among the organisms or by enterotoxigenicity of the vaccine strains. When antiserum produced against a combination of three enteropathogenic E. coli was tested against 20 strains a wider spectrum of heterologous antibacterial activity was obtained than with antiserum produced against any individual strain. The results indicate the existence in E. coli strains of porcine origin of common antigenic determinants not related to the serological formula and that a selected combination of strains can be expected to induce antibacterial acitivity against a wide variety of serological types of porcine enteropathogenic E. coli.  相似文献   

14.
Minimum inhibition concentrations (MICs) were determined for ampicillin, ceftiofur, cephalothin, chloramphenicol, enrofloxacin, gentamicin, lincomycin, lincospectin (lincomycin/spectinomycin), neomycin, premafloxacin, spectinomycin, sulfamethoxazole/trimethoprim, and tetracycline against a total of 180 isolates of Actinobacillus pleuropneumoniae, Escherichia coli, and Salmonella choleraesuis (60 each) clinically isolated from pigs on farms in Taiwan from 1994 to 1996. No more than 3 isolates per farm were used. Ceftiofur had the highest activity in vitro against isolates of A. pleuropneumoniae, E. coli, and S. choleraesuis, with MIC90 values of 0.03, 2, and 1 microg/ml, respectively. Premafloxacin was highly active against isolates of A. pleuropneumoniae, E. coli, and S. choleraesuis, with MIC90 values of 2, 8, and 0.5 microg/ml, respectively, which were lower than those with enrofloxacin (MIC90 8, 32, and 2 microg/ml, respectively). Neomycin was moderately active against A. pleuropneumoniae and E. coli, with MIC90 values of 8 and 64 microg/ml, respectively, but was inactive with S. choleraesuis. Gentamicin showed high activity against A. pleuropneumoniae (MIC90 of 2 microg/ml) but was only moderately active with E. coli and S. choleraesuis (MIC90 of 64 and 32 microg/ml). Cephalothin was highly active against isolates of A. pleuropneumoniae (MIC90 of 1 microg/ml) but was inactive with E. coli (MIC90 of 128 microg/ml). Lincomycin had moderate activity (MIC90 of 32 microg/ml) against A. pleuropneumoniae. Chloramphenicol, lincomycin, and tetracycline were inactive with E. coli and S. choleraesuis (MIC90 > 128 microg/ml). In conclusion, ceftiofur and premafloxacin were highly active against isolates of A. pleuropneumoniae, E. coli, and S. choleraesuis, enrofloxacin and gentamicin were highly to moderately active; cephalothin was highly active against A. pleuropneumoniae and moderately active against S. cholearesuis; chloramphenicol, lincomycin, and tetracycline were active only with A. pleuropneumoniae; neomycin was moderately active against A. pleuropneumoniae and E. coli. The other antimicrobials tested were inactive.  相似文献   

15.
为研究蒙药对3种血清型牛源致病性大肠杆菌（Escherichia coli，E. coli）的体外抑菌效果，采用牛津杯法测定16味蒙药对受试菌株的抑菌圈直径，利用微量稀释法结合平板法测定最小抑菌浓度（MIC）和最低杀菌浓度（MBC），采用棋盘法测定敏感蒙药的协同指数（FICI）。结果表明，乌里史古—达兰—哈力苏、协日—洪连、乌拉勒吉嘎纳对3种血清型大肠杆菌的抑菌圈直径为16.10-29.64 mm，MIC为7.81-31.25 mg/mL，MBC为15.63-125 mg/mL。联合抑菌试验结果表明，乌拉勒吉嘎纳与协日—洪连，舒布格日—希木勒德格与呼仍—图如对E. coli O26的FICI为0.50，乌拉勒吉嘎纳与乌里史古—达兰—哈力苏对E. coli O83的FICI为0.50。结果提示，乌里史古—达兰—哈力苏、协日—洪连、呼仍—图如、乌拉勒吉嘎纳、阿纳尔对3种血清型大肠杆菌的综合抑菌效果较好；舒布格日—希木勒德格与呼仍—图如在抑制E. coli O26时表现为协同作用，组方时可优先考虑；乌拉勒吉嘎纳与乌里史古—达兰—哈力苏在抑制E. coli O83时表现为协同作用，组方中可优先考虑。  相似文献   

16.
Nineteen antisera produced in pigs against 14 enteropathogenic and five nonenterotoxigenic porcine strains of Escherichia coli were tested for their ability to inhibit gut loop fluid accumulation induced by homologous and heterologous organisms. In addition, four antisera produced in pigs by an intensive series of intravenous inoculations and three by a less intensive series of intramuscular injections of a polyvalent E. coli vaccine were evaluated. Antisera were also produced in rabbits against eight strains of porcine enteropathogens and tested in pig gut loops. Fluid inhibiting activity was detected in prevaccinal sera of pigs but not of rabbits. This activity was significantly increased following immunization. When single strains of E. coli were used for immunization the activity of the antisera against heterologous organisms varied considerably from one test strain to another and was usually much less than that against the homologous organism. The activity against heterologous organisms could not be associated with relatedness of the O, K and H antigens of the vaccine and the test strains. Antisera produced against a vaccine made by combining three strains were shown to exert inhibitory effects on heterologous organisms similar to those against homologous organisms. Considerably less activity against homologous and heterologous organisms was present in antisera produced by the series of intramuscular compared with the series of intravenous injections.  相似文献   

17.
The objective of the study was to determine the in vitro interaction between enrofloxacin and ciprofloxacin against Escherichia coli and staphylococcal isolates from dogs. The microdilution checkerboard assay was used to determine the interaction of the drugs against 50 E. coli and 50 beta-haemolytic staphylococcal clinical isolates. The checkerboard assay revealed that the activity of enrofloxacin and ciprofloxacin was additive against E. coli and staphylococcal clinical isolates. It was concluded that for bacterial species against which ciprofloxacin is more potent than enrofloxacin, the in vivo transformation of enrofloxacin to ciprofloxacin may enhance the efficacy of enrofloxacin, if additivity of the drugs is confirmed in vivo.  相似文献   

18.
The aim of this study was to compare the in vitro antimicrobial activity of the veterinary fluoroquinolones against a panel of recently isolated porcine and bovine bacterial pathogens. The study used enrofloxacin as a benchmark against which other agents were compared, being the most common fluoroquinolone used in treatment of bovine and porcine infections. The activity of ciprofloxacin was also assessed as it is the main metabolite of enrofloxacin in cattle. Enrofloxacin and ciprofloxacin generally showed higher antibacterial activity, in terms of MIC(50) values, for most pathogen species when compared with marbofloxacin, difloxacin, danofloxacin and norfloxacin. Ciprofloxacin showed significantly greater in vitro antibacterial activity than enrofloxacin against M. haemolytica, P. multocida and E. coli, whereas enrofloxacin showed greater activity than ciprofloxacin against S. aureus. Marbofloxacin was significantly more active than enrofloxacin against M. haemolytica, E. coli and B. bronchiseptica but less active against P. multocida, S. aureus, coagulase negative Staphylococci, S. dysgalactiae, S. uberis, A. pleuropneumoniae and S. suis. Danofloxacin was significantly less active than enrofloxacin against P. multocida, E. coli, S. uberis, A. pleuropneumoniae and S. suis. Enrofloxacin and its metabolite ciprofloxacin showed the highest in vitro activities against most bovine pathogens tested and the porcine pathogens also showed a high degree of sensitivity to enrofloxacin. These data facilitate further pharmacokinetic/pharmacodynamic comparison of fluoroquinolones currently used in veterinary medicine.  相似文献   

19.
采用肉汤稀释法和牛津杯法观察了蛇莓水提物对金黄色葡萄球菌、大肠杆菌、沙门菌标准菌和临床菌株体外抗菌活性;影印培养法观察亚抑菌浓度作用下,水提物对以上3种临床菌株质粒的消除作用;用微量滴定板法检测不同浓度水提物对金黄色葡萄球菌和大肠杆菌临床菌株生物膜形成的影响。结果显示,蛇莓水提物对大肠杆菌等不同临床菌株均有抑菌作用,当质量浓度≥125g／l。时对菌株累计抑菌率达100％;蛇莓亚抑菌浓度作用大肠杆菌、沙门菌和金黄色葡萄球菌24h后,质粒消除率分别为1．4％,5．1％,2．2％;不同浓度蛇莓水提物对大肠杆菌和金黄色葡萄球菌菌膜形成量均有影响,且存在浓度依赖关系。由此可见,蛇莓水提物对大肠杆菌等兽医临床常见病原菌有抗菌作用,对质粒有消除作用,能抑制细菌生物膜形成。  相似文献   

20.
Milk from sows whose progeny developed post weaning E. coli diarrhoea (PWD milk) and from sows which were immunized by intramuscular vaccination using a homologous strain of E. coli (immune milk) were tested in ligated segments of pig intestine. The results showed that PWD milk neutralized the enterotoxigenic, fluid accumulating capacity of the lysate of the disease-causing E. coli pathogen. A similar effect was seen by using immune milk (Table I). Neither PWD milk nor immune milk contained sufficient antibacterial activity to neutralize the fluid accumulating capacity of live cultures of E. coli O149:K91, while such activity was contained in immune serum. It is concluded that milk from sows whose progeny developed PWD contains antibodies capable of neutralizing the enterotoxigenic effects of the homologous E. coli organisms. It is suggested that the presence in milk from these sows of antibody-mediated activity against enteropathogenic E. coli organisms may be instrumental in preventing the disease in the progeny during the suckling period and consequently, when this protective milk supply stops at weaning, the disease may develop in susceptible animals, mainly because their own production of specific E. coli antibodies is insufficient to prevent PWD.  相似文献   

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