二氢杨梅素和土霉素体外抑菌作用的比较试验

二氢杨梅素(dihydromyricetin，DMY)——3，5，7，3’，4’，5’-六羟基2，3双氢黄酮，为二氢黄酮醇类化合物。熊大胜等(2000)和熊皓平(2002)体外抑菌试验表明，DMY对大肠杆菌、金黄色葡萄球菌、沙门氏菌、绿脓杆菌、青霉菌及黑曲霉菌等16种细菌均有一定抑菌作用。其中对大肠杆菌的MIC为0．125％；对金黄色葡萄球菌、沙门氏菌的MIC均为0．0625％。     

苦参等中草药的体外抑菌作用试验

多年来,应用于兽医临床的抗菌药物都是以各种抗生素为主,由于这些抗生素在临床上的滥用,大多是要么抗菌效果大大降低要么产生了耐药性和耐受性。除此之外,许多临床常常由于抗生素的不合理使用,往往导致在各种畜产品体内产生大量的残留,这就为我国各种畜产品的出口造成了巨大障碍。近年来,随着利用中草药防治畜禽疾病的迅速发展,我国广大的中兽医工作者对中草药药理活性的研究也逐渐加深。中草药对病原菌的体外抑菌试验陆续有研究报道。因此,抗菌中草药在兽医临床上的应用被提上了日程。本试验主要为中草药临床应用提供确切的依据。     

宫康素的体外抑菌作用及安全性试验

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中草药对山羊病原菌体外抑菌作用试验

为了探讨中草药对山羊病原菌的抑菌作用,试验采用试管倍比稀释法,以蒲公英、白花败酱草、马齿苋3种中草药水提物对山羊大肠杆菌、沙门杆菌、葡萄球菌3种致病菌进行体外抑菌试验。结果表明:白花败酱草、马齿苋、蒲公英对山羊大肠杆菌的最小抑菌浓度分别是62.5,125,250 mg/mL;对沙门杆菌的最小抑菌浓度分别是125,250,250 mg/mL;对葡萄球菌的最小抑菌浓度分别是62.5,250,125 mg/mL。白花败酱草对山羊大肠杆菌、葡萄球菌、沙门杆菌抑菌效果较好;马齿苋对山羊大肠杆菌抑菌效果较好;蒲公英对山羊葡萄球菌抑菌效果较好;马齿苋、蒲公英对山羊沙门菌次之。说明这3种中草药对山羊3种病原菌均有不同程度的抑制作用。     

土霉素预混剂的体外抑菌及临床疗效试验

土霉素是四环素类广谱抗生素,对革兰氏阳性菌、革兰氏阴性菌、支原体、衣原体、立克次氏体等引起的感染有疗效,也可用于治疗梨形虫病、附红细胞体病等。由于其抗菌谱广,在畜牧业上得到广泛应用[1]。大量流行病学调查资料显示,由于抗菌药     

纳豆提取物和纳豆菌的体外抑菌作用研究

纳豆固体发酵后,用纳豆激酶、纳豆抑菌物质2种提取液与纳豆菌的培养液对葡萄球菌、大肠杆菌等6种菌进行体外抑菌作用试验,结果显示:纳豆激酶的抑菌作用十分微弱,纳豆芽孢杆菌培养液抑菌效果较纳豆激酶和纳豆抑菌物质强。在6种目标菌中,纳豆芽孢杆菌对葡萄球菌、大肠杆菌等肠道菌的抑菌作用较其它菌强。为纳豆芽孢杆菌作为一种微生态制剂菌种提供了理论依据。     

高百里香酚和香芹酚体外抑菌作用的研究

测定香芹酚和百里香酚单一成分及其联合使用对溶常见病原菌(埃希氏大肠杆菌、金黄色葡萄球菌和猪霍乱沙门氏菌)及常见益生菌(保加利亚乳杆菌和枯草芽孢杆菌)的抑杀浓度.[方法]稀释培养法测定最小抑菌浓度、最小杀菌浓度.[结果]本实验证实在一定的药物浓度下香芹酚和百里香酚能够杀灭常见病原菌,并且对肠道益生菌也有一定的抑杀作用.     

六种中药提取物对金黄色葡萄球菌体外抑菌作用的比较

采集昌黎地区29头外观健康正常的奶牛乳样116份,经CMT(加利福尼亚乳房炎试验)诊断出阳性病例并从阳性乳样中分离鉴定出其中的优势菌;再用连翘、当归、金银花、王不留行、蒲公英、川芎等中药提取物对该菌进行体外抑菌试验。结果表明,引起该地区奶牛隐性乳房炎的主要细菌为金黄色葡萄球菌,经诊断患有该病的奶牛为15例,患病阳性率为51.7%,116个乳样中有30个为阳性,对应乳区阳性率为25.9%;试验中所选中药对金黄色葡萄球菌均有抑制作用,其中以750 mL/L醇提的连翘效果最为明显。     

复方中草药对临床分离猪大肠杆菌的体外抑菌作用试验

为了比较8组复方中草药制剂体外抑菌作用效果,筛选对猪大肠杆菌抑菌作用较好的组方,试验选用21种单味中草药配伍组成8组复方(复方1:石菖蒲、五倍子、黄芩、菊花;复方2:石菖蒲、黄芩、大黄、金银花;复方3:大黄、黄芩、秦皮、艾叶;复方4:白头翁、黄连、黄柏、秦皮;复方5:马齿苋、白头翁、黄柏、五倍子、甘草;复方6:郁金、诃子、黄芩、大黄、黄连、栀子、黄柏、白芍;复方7:地榆、石榴皮、土茯苓;复方8:黄连、白头翁、木香、甘草),采用水煎法制备水提物,分别通过平板打孔法、2倍稀释法和平板接种法对从临床病例中分离的猪大肠杆菌进行药物敏感性及最小抑菌浓度体外测定。结果表明:中草药复方3、复方7对猪大肠杆菌为高度敏感,复方6为中度敏感,复方1为低敏,其他复方不敏感;复方3、复方7对猪大肠杆菌体外抑菌效果较好,最小抑菌浓度为250 mg/m L;复方1、复方6、复方8抑菌效果次之,最小抑菌浓度为500 mg/m L;复方5有抑菌效果,菌落数随药物浓度升高呈降低趋势;复方2、复方4无抑菌作用。     

黄芩体外抑菌作用的初步研究

鸭疫里默氏杆菌病(Riemerrela anatipestifer,RA)又称鸭传染性浆膜炎(infectious serositis induckings),是目前危害养鸭业最重要的传染病之一[1]。目前国际上已经确定的血清型有21型,在美国以Ⅰ、Ⅱ、ⅹ为主,在对我国京、沪、川等地区的鸭疫里默氏杆菌的研究中发现,我国以Ⅰ和Ⅱ型为主[2]。鸭疫里默氏杆菌是主要侵害家鸭、火鸡和鸟类的一种接触性传染病,主要侵害2-7周龄的雏鸭,呈急性或慢性败血症。     

In vitro activity of danofloxacin, tylosin and oxytetracycline against mycoplasmas of veterinary importance

The activities of danofloxacin, a novel fluoroquinolone, and two other antimicrobials were determined in vitro against field isolates of seven Mycoplasma species of veterinary importance isolated from cattle, swine and poultry in five European countries. The minimum inhibitory concentrations (MIC) of danofloxacin, tylosin and oxytetracycline were determined against a total of 68 isolates. Danofloxacin showed excellent activity against isolates of all Mycoplasma species (range 0·008 to 0·5 μg ml⁻¹), but in some isolates there was evidence of reduced sensitivity to tylosin (range 0·008 to 2·0 μg ml⁻¹) and oxytetracycline (range 0·008 to over 16·0 μg ml⁻¹). Danofloxacin was more active than other antimicrobials against, M hyopneumoniae, M dispar and M bovigenitalium, and showed activity similar to that of tylosin against M bovis and M gallisepticum. Tylosin was the most active against M synoviae and M hyosynoviae. Generally, oxytetracycline showed the poorest activity, but was superior to tylosin against M bovigenitalium. A second (final) MIC reading was taken for all isolates 14 or 21 days after the initial reading, and MIC values rose during that time. However, the increase seen in danofloxacin values (typically one to two dilutions) was less than that seen for tylosin and oxytetracycline. It is concluded that danofloxacin is highly active in vitro against all of the Mycoplasma species tested, and thus shows great potential for the treatment of respiratory and other infections caused by Mycoplasma species in cattle, pigs and poultry.     

Factors affecting the accuracy of the live animal swab test for detecting urine oxytetracycline and predicting oxytetracycline residues in calves

The live animal swab test (LAST) was compared with quantitative oxytetracycline (OTC) assay of urine samples and tissue specimens to determine the accuracy of the LAST in detecting OTC in bovine urine and predicting violative residues in tissues. When urine OTC concentration was greater than 4.3 micrograms/ml, the LAST result was 100% accurate. When urine OTC concentration was less than 4.3 micrograms/ml, the LAST result was 60% accurate; 20% of the LAST results were false-positive, and 20% were false-negative. Urine osmolarity was highest (P less than 0.05) in samples with false-positive results and lowest (P less than 0.05) in samples with false-negative results. A similar trend was observed for urine pH, but was not statistically significant. Urine samples with false-positive results apparently had osmolarity and pH conditions that inhibited growth of Bacillus subtilis when OTC was lacking. False-negative results probably were obtained because urine osmolarity and pH conditions were favorable for the growth of bacteria even in the presence of OTC or because OTC concentration was below the limit of detection by the LAST. The LAST was inconsistent in detecting urine OTC in small concentrations and correspondingly failed to accurately predict OTC residues in tissues.     

Chemoprophylactic activity of imidocarb,diminazene and oxytetracycline againts Babesia bovis and B. Bigemina

Splenectomized calves treated with imidocarb, diminazene, and oxytetracycline were exposed to Babesia bigemina and B. bovis stabilites at various time intervals following treatment to evaluate prophylactic efficacy. Diminazene showed no residual activity againts a B. bigemina challenge given 54 days after treatment. Oxytetracycline appeared responsible for an increased incubation time when given 2 days prior to B. bigemina exposure.Imidocarb showed marked prophylactic efficacy against both B. bigemina and B. bovis. Treatment with 1 or 2 mg kg⁻¹ imidocarb, followed by Babesia exposure on the day of treatment, 7 days after treatment, than every 14 days for 91 days, delayed patent B. bigemina infections for 49 days and patent B. bovis infections for 42 days. Imidocarb at 4 or 5 mg kg⁻¹, followed by similar Babesia exposures, delayed patent B. bovis infections for 68 days, and delayed B. bigemina for 81–103 days, and in some instances prevented infections.The delayed onset of injection due to either B. bigemina or B. bovis, following imidocarb treatment was accompanied by a significantly milder clinical response. Calves not responding to the primary challenge were fully susceptible to stabilate challenge 196 days after treatment.Calves experiencing a mild clinical response to B. bovis following imidocarb treatment and exposure failed to show any signs of response to a 196-day challenge exposure. Calves experiencing a mild clinical response to B. bigemina following imidocarb treatment and exposure did, in some instances, show a second mild response when challenge 196 days after initial treatment.     

In vitro susceptibility of avian mycoplasmas to enrofloxacin, sarafloxacin, tylosin, and oxytetracycline.

In vitro susceptibility of avian Mycoplasma gallisepticum (MG) and Mycoplasma synoviae (MS) to enrofloxacin, sarafloxacin, tylosin, and oxytetracycline was determined by a serial broth dilution method. The minimum inhibitory concentration (MIC) was recognized by a conversion of the pH indicator phenol red in culture media to a yellow color. Each isolate or type strain of mycoplasma was tested in two replicates. The MICs of tylosin, enrofloxacin, sarafloxacin, and oxytetracycline against five isolates and two reference strains of MG (approximately 10(5) colony-forming units [CFU]/ml) were 0.05, 0.14, 0.37, and 1.30 microg/ml, respectively. The MICs of the four antimicrobial agents against six isolates and one reference strain of MS (approximate 10(5) CFU/ml) were 0.13, 1.82, 1.76, and 0.91 microg/ml, respectively. There were no differences (P > 0.05) between tylosin, enrofloxacin, and sarafloxacin against MG, but these three antibiotics were different (P < 0.05) from oxytetracycline. The MIC value of tylosin against MS was different (P < 0.05) from those of sarafloxacin and enrofloxacin, but it was not different (P > 0.05) from that of oxytetracycline.     

Randomized field trial comparing the efficacy of florfenicol and oxytetracycline in a natural outbreak of calf pneumonia using lung reaeration as a cure criterion

BackgroundRespiratory infections are the main indication for antimicrobial use in calves. Optimal treatment duration currently is unknown, but shorter duration would likely decrease selection for antimicrobial resistance.Hypothesis/ObjectivesDetermine differences in cure rate and healing time between animals treated with florfenicol and oxytetracycline in a natural outbreak of respiratory disease using reaeration observed on thoracic ultrasound examination as healing criterion.AnimalsCommercial farm housing 130, 3 to 9 month old Belgian blue beef calves.MethodsRandomized clinical trial during an outbreak of respiratory disease. Metaphylactic treatment was initiated, randomly treating animals with either florfenicol or oxytetracycline. Ultrasonographic follow‐up was done the first day and every other day for a 14‐day period. At the individual animal level, treatment was discontinued when reaeration of the lungs occurred. Differences in cure rate and healing time were determined.ResultsOf the 130 animals studied, 67.7% developed a lung consolidation ≥0.5 cm. The mean ultrasonographic healing time was 2.5 days in the florfenicol group compared to 3.1 days in the oxytetracycline group (P = .04). After single treatment, 80.6% and 60.3% had no consolidations in the florfenicol and oxytetracycline groups, respectively (P = .01). A Mycoplasma bovis strain was genetically and phenotypically determined to be susceptible to both antimicrobials.Conclusions and Clinical ImportanceUltrasonographic lung reaeration shows potential as a cure criterion to rationalize antimicrobial use for outbreaks of pneumonia. In our study, florfenicol resulted in a faster cure and higher reduction in antimicrobial usage than did oxytetracycline.     

In vitro susceptibilities of field isolates of Mycoplasma agalactiae to oxytetracycline,tylosin, enrofloxacin,spiramycin and lincomycin-spectinomycin

The minimum inhibitory concentrations (MICs) of tetracycline, enrofloxacin, tylosin, spiramycin and a lincomycin:spectinomycin 1:2 combination, against 24 Sicilian isolates of Mycoplasma agalactiae, the causative organism of contagious agalactia were determined in vitro by a broth dilution method. Enrofloxacin was the most effective antimicrobial in vitro with a range of MIC values from 0.125 to 0.500 microg/ml and an MIC(50) of 0.203 and MIC(90) of 0.365 microg/ml. Using the MIC(50) and MIC(90) values the remaining four antimicrobials are ranked in order of in vitro effectiveness as follows: tylosin (MIC(50)0.292; MIC(90)0.525 microg/ml) was slightly more effective than tetracycline (MIC(50)0.296; MIC(90)0.533 microg/ml), followed by lincomycin:spectinomycin (MIC(50)0.521; MIC(90)0.938 microg/ml) and spiramycin (MIC(50)1.583; MIC(90)2.850 microg/ml). MIC values above 1.000 microg/ml were obtained using tetracycline, tylosin and spiramycin for some M. agalactiae isolates.