共查询到20条相似文献，搜索用时 296 毫秒
1.
肠球菌毒力因子研究进展 总被引：1，自引：0，他引：1
肠球菌(Enterococcus)是人和动物肠道的正常菌群,通常不引起发病,为一种重要的机会致病菌.最近几年,由于免疫制剂的广泛使用,侵入性治疗机会的增加和抗生素的过渡使用,尤其是第3代头孢菌素的广泛应用,使得肠球菌的感染不断上升,成为医院内感染的主要致病菌.肠球菌致病机制与其致病岛编码的毒力因子表面蛋白、溶血素、蛋白明胶酶等有关,肠球菌致病机理不是由单一毒力因子所决定,而是多种毒力因子共同作用的结果.文章综述了肠球菌的各种潜在毒力因子的生物特性及其与致病性的关系,为预防和控制肠球菌感染提供参考. 相似文献
2.
对致羔羊脑炎肠球菌和羔羊正常菌群肠球菌进行培养特性、生化特性、溶血特性、药物敏感性以及拥有毒力因子基因种类与分布进行比较,结果表明2种不同来源羔羊肠球菌的培养特性和生化特性基本一致.致病菌均对链霉素、庆大霉素、红霉素等抗生素耐药,1株正常菌对四环素、红霉素及链霉素耐药.11株致病性肠球菌中有5株菌同时检测到esp、cyIA、asa1、ace、efa、EF0591和EF3314等7种毒力因子基因,2株菌没有检测到其中任何毒力因子基因.30株正常菌有3株菌存在gelE和EF3314,l株菌同时存在gelE、EF3314和asa1 3种毒力因子基因.正常菌群株3种毒力因子基因片段序列与GenBank中登录的相应序列同源性在95%以上,与致病株相应序列同源性在96%以上.致病菌能导致小鼠死亡,而正常菌群肠球菌则不能引起小鼠的死亡. 相似文献
3.
为探究明胶液化的表型与其5种毒力基因在不同来源和不同种属猪肠球菌中的分布差异,本研究采用PCR方法以及明胶液化试验对湖南分离的375株肠球菌携带的明胶酶基因(gelE)、调控gelE表达的毒力基因反应调节子基因(fsrA)、前肽加工蛋白基因(fsrB)、组氨酸激酶基因(fsrC)、丝氨酸蛋白酶基因(sprE)共5种毒力基因的分布情况以及液化明胶现象进行检测。结果显示,共263株肠球菌检测到了毒力基因,检出率分别为41.3%(gelE)、45.9%(fsrA)、50.9%(fsrB)、48.8%(fsrC)、48.8%(sprE)。能够同时检测到5种毒力基因的菌株共有110株,其中粪肠球菌106株,且该5种毒力基因在106株粪肠球菌中的检出率均为最高,另外4株为其它肠球菌。在明胶液化试验中,共有155株肠球菌检测到gelE基因,但只有106株能够发生明胶液化现象,且这些菌株正是能够同时检测到5种毒力基因的106株粪肠球菌,而另外4株能够同时检测到5种毒力基因的其它肠球菌却不能发生明胶液化现象。结果表明,粪肠球菌是肠球菌中主要携带毒力基因的菌属,与屎肠球菌以及其它肠球菌相比,更容易出现液化明胶的表型,这可能与粪肠球菌中某些明胶液化的机制有关,且除gelE外,参与gelE表达的几种毒力基因对该表型的出现也具有一定的影响。 相似文献
4.
旨在调查和分析广东省养禽场肠球菌的亚型屎肠球菌和粪肠球菌耐药性及其毒力因子流行分布特征,为控制禽源肠球菌耐药性传播、保障公共卫生安全提供理论依据。作者于2018年从广东省4个养禽场采集肠道样品493份,进行屎肠球菌和粪肠球菌的分离鉴定;采用琼脂二倍稀释法测定肠球菌的最小抑菌浓度（MIC）;PCR方法检测肠球菌的耐药基因和毒力基因。结果显示：1）共分离到125株肠球菌,其中粪肠球菌84株（鸡源66株,鸭源18株）;屎肠球菌41株,均来自鸡肠道样本。2）菌株对四环素、多西环素、红霉素几乎全部耐药,对氟苯尼考和氯霉素的耐药率高达89.60%和74.40%。屎肠球菌耐药率普遍高于粪肠球菌,而粪肠球菌对环丙沙星和利奈唑胺的耐药率高于屎肠球菌;鸭源粪肠球菌对利奈唑胺的耐药率（94%）显著高于鸡源粪肠球菌（39.4%）,屎肠球菌对利奈唑胺均敏感。从鸡分离的1株粪肠球菌对万古霉素耐药。3）耐药基因在屎肠球菌中的检出率高于粪肠球菌,鸭源分离株检出率高于鸡源。耐药基因tetL、fexA、ermB最为流行,检出率均高于90%。其次是optrA基因,检出率为73.60%,poxtA和fexB的检出率均低于20%。在3株鸭源粪肠球菌中检测出cfr基因。4）已检测的毒力基因中efaA的携带率最高,为63.04%（58/92）,其他依次为gelE（54.35%,50/92）、ace（47.83%,44/92）、asa1（44.57%,41/92）。对环丙沙星及高浓度氨基糖苷类耐药的菌株及携带cfr基因的菌株,大多携带agg、asal、gelE或ace。本研究显示养殖场禽源肠球菌耐药严重,鸭源肠球菌对利奈唑胺耐药率高,耐药基因和毒力基因流行且多样,且检测出人医临床重要抗生素耐药基因,应加强对养禽场肠球菌耐药性监测。 相似文献
5.
6.
《中国兽医学报》2015,(12):1965-1970
通过了解粪肠球菌在BHI和SRFE培养基中生长不同时期时其15种因子的表达情况,为粪肠球菌致病机制的研究奠定基础。将粪肠球菌N10株在BHI和SRFE培养基中培养,分别提取其在2种培养基生长至对数中期、对数后期和稳定期时的总RNA,并进行SYBR Green I实时荧光定量PCR,从而测定15种因子的表达情况。结果显示,15种因子中的13种因子在SRFE培养基中表达量较高,与菌毛生成相关因子ebp ABC和rnj B以及与生物膜形成相关因子srt A、atn和psr在SRFE培养基中的表达量都高于其在BHI培养基中的表达量(P0.01),这说明SRFE培养基可能不仅有利于菌毛和生物膜的形成,而且也有利于其他毒力相关因子的形成,从而增加了粪肠球菌的致病性。 相似文献
7.
《中国兽医学报》2016,(10):1722-1726
本研究旨在构建粪肠球菌胶原蛋白黏附素基因(ace)缺失突变株,为进一步探讨该基因编码的毒力因子Ace的功能奠定基础。利用pK18mobSacB质粒作为基因敲除载体,构建粪肠球菌ace基因重组自杀质粒pK001,通过体内同源重组筛选成功敲除ace基因的突变株,然后对突变株细菌黏附体外培养猪肠上皮细胞IPEC-J2及其细菌生物被膜形成的情况进行了检测。结果显示,同源重组后,经过卡那霉素抗性筛选、PCR及Southern blot鉴定,成功获得了ace基因缺失突变株肠球菌△ace。细菌生长曲线测定试验表明,ace基因敲除对细菌的生长繁殖并无明显影响,但体外生物被膜测定试验显示基因缺失突变株肠球菌△ace的生物被膜形成能力有所降低。本研究证实了毒力因子Ace对猪源粪肠球菌与宿主黏附的重要作用,该基因缺失突变株的构建为进一步的理论研究和疫苗研发奠定基础。 相似文献
8.
为了探讨粪肠球菌明胶酶E(gelE)基因对粪肠球菌生物膜形成能力的影响,试验取鸡源粪肠球菌50株,设计特异性引物,通过PCR扩增粪肠球菌毒力基因gelE;利用96微孔板结晶紫染色法在595 nm波长下测定其OD值,对gelE基因和生物膜进行相关性分析。结果表明:有78%(39/50)的粪肠球菌呈生物膜阳性,22%(11/50)的粪肠球菌呈生物膜阴性;82%(41/50)的粪肠球菌呈gelE基因阳性,18%(9/50)的粪肠球菌呈gelE基因阴性,粪肠球菌毒力基因gelE和生物膜具有一致性。说明粪肠球菌gelE基因能够调控生物膜的形成。 相似文献
9.
《中国预防兽医学报》2017,(3)
为研究猪流行性腹泻(PED)病猪群中肠球菌及其携带毒力基因的变化情况,本研究采用PCR方法对115株猪源肠球菌检测其11种毒力基因的分布情况及进行了其溶血试验和明胶液化试验。结果,共检测到9种毒力基因:EF3314、efaA、gelE、ace、asal、cylA、esp、Hyl和EF0591,其中asa373和AS未检测到。72株健康猪源分离菌中毒力基因检出率分别为12.5%、9.7%、5.6%、2.8%、13.9%、4.2%、8.3%、15.3%和1.4%。43株PED病猪分离菌毒力基因阳性率分别为20.9%、25.6%、2.3%、18.6%、51.2%、11.6%、20.9%、0和7.0%。溶血试验结果显示115株肠球菌中溶血的占88.7%,其中α-溶血占40%,β-溶血占48.7%,共有8株检测到溶血素A基因(clyA),检出率为6.9%。11株粪肠球菌全部表现溶血,其中健康猪源分离株为α-溶血,PEDV感染猪分离株为β-溶血。明胶液化试验表明115株肠球菌中只有两株能液化明胶,均为粪肠球菌,一株为健康猪源分离株,一株为PEDV感染猪分离株,而且从这两株菌中均检测到了明胶酶E(gelE)基因。表明PED猪源肠球菌毒力基因检出率明显高于健康猪源肠球菌(p0.05)。明胶液化试验和溶血试验结果表明,粪肠球菌的这两种表型与基因型为肠球菌种中表达一致性是最高的,其携带毒力基因为肠球菌中所占比例最高。通过两种不同来源肠球菌毒力基因的比较,为PED的分析治疗与防控提供依据。 相似文献
10.
11.
乳房炎是奶牛养殖业中最常见的一种疾病，会造成奶牛乳腺发炎肿胀，使产奶量大幅下降。作为一种多因素性疾病，奶牛乳房炎发病原因复杂，饲料污染、病原菌感染以及环境因素均可以导致乳房炎的发生。无乳链球菌（Streptococcus agalactiae）作为奶牛乳房炎的主要致病菌，常会造成乳腺组织的局部炎症，随着无乳链球菌分离率的增加以及抗菌药物的滥用，其对抗菌药物的耐药性逐步攀升，给临床治疗带来了一定的困难。此外，无乳链球菌能够定植于宿主体内，破坏宿主的免疫系统，而其自身毒力因子会引起宿主机体疾病的产生。随着相关研究的深入，发现毒力与耐药性本身互为关联，耐药性的增强以不同的方式影响毒力，表明了耐药性与毒力因子之间存在着一定的相关性。笔者主要回顾了国内外链球菌以及其他细菌毒力基因与耐药性之间相关性的研究进展，从无乳链球菌毒力因子及耐药性等多种角度入手，分析了无乳链球菌的毒力机制以及毒力基因，并对近5年国内不同地区无乳链球菌耐药性进行统计，从细菌种类、环境和相关机制对链球菌的毒力和耐药性之间的关系展开综述，以期为无乳链球菌所引起的临床症状筛选出合理的抗菌药物并对毒力基因与耐药性的相关性研究提供理论参考。 相似文献
12.
HUANG Cheng-cheng SUN Lei ZHANG Ze-hui ZHANG Peng ZHANG De-xian LIU Ming-chun 《中国畜牧兽医》2016,43(12):3363-3367
Antimicrobial agents play a crucial role in the prevention and treatment of bacterial diseases. However, the widely clinical use of antibiotics makes the bacteria antibiotic-resistance problem much more severe, which could increase the difficulty of clinical treatment. Recently, the method of using traditional Chinese herbs to control bacterial infection by suppressing the bacterial virulence factors has got researchers'attention around the world. Hemolysin is one of the crucial virulence factors in many kinds of bacteria, therefore hemolysin is an ideal target to combat the infection caused by bacteria. The suppressing effect of Chinese herbs to the hemolysin is synthesized and reviewed here to lay theoretical foundation for the clinical treatment of bacterial diseases. 相似文献
13.
14.
猪链球菌2型(SS2)是一种重要的人兽共患病病原菌,其主要毒力因子包括荚膜多糖、溶菌酶释放蛋白、溶血素、纤连蛋白结合蛋白、谷氨酸脱氢酶等,但是这些经典的毒力因子不足以解释猪链球菌病发病的临床症状,而且毒力表型往往与实际毒力及临床症状不符。近年来随着研究的深入,鉴定出一系列毒力相关元件,主要有Sao蛋白、存在于89K毒力岛的双信号转导系统(salk-salR)、dltA基因、pgdA基因、srtA基因、Ⅳ型二肽基肽酶(dipeptidyl peptidaseⅣ,DPPⅣ)、毒力调控子R(control of virulence R,CovR)、烯醇酶(enolase)、谷氨酰胺合成酶(glutamine synthetase,GlnA)等。论文对以上毒力因子研究进展进行综述,以期为SS2毒力因子及致病机制研究提供参考。 相似文献
15.
Silva E Gaivão M Leitão S Jost BH Carneiro C Vilela CL Lopes da Costa L Mateus L 《Veterinary microbiology》2008,132(1-2):111-118
Arcanobacterium pyogenes is considered to be the most relevant bacterium involved in the establishment of puerperal uterine infection in cattle due to its persistence in utero, resistance to treatment and synergic action with Gram negative anaerobes. Once the infection is established, A. pyogenes is responsible for the persistence of the infection. The objective of this study was to characterize A. pyogenes field isolates recovered from the uterus of cows with either normal puerperium or clinical metritis, in an attempt to identify factors that might be associated with the establishment and persistence of the disease. This characterization was based on BOX-PCR typing and on screening of eight virulence factor genes (plo, nanP, nanH, cbpA, fimA, fimC, fimE, fimG) by conventional PCR. Finally, a relationship between clonal types, virulence factors and presence of disease was investigated. A. pyogenes clonal types identified from isolates recovered from the uterus of postpartum dairy cows differed among herds. Although some clonal types were strictly associated with the development of clinical metritis, others were identified from isolates recovered from normal puerperium and clinical metritis cows. Moreover, the presence of the eight virulence factor genes was not related with the ability to induce clinical metritis, suggesting that the type of A. pyogenes may not be a determinant factor in the development of the disease. We suggest that host intrinsic factors, the synergism between A. pyogenes and other bacteria and the differential gene expression of virulence factor genes may play a more relevant role in the establishment of puerperal uterine infections. 相似文献
16.
Update on the diagnosis of Haemophilus parasuis infection in pigs and novel genotyping methods 总被引：1，自引：0，他引：1
Haemophilus parasuis causes Gl?sser's disease as well as a number of other diseases in pigs. The diagnosis of H. parasuis-associated disease is usually established by clinical signs, pathological findings and bacterial isolation but diagnosis is complicated by the existence of non-virulent strains and the early colonisation of the upper respiratory tract of healthy piglets. Moreover, several strains can be found on a farm and even within a single animal so it is important to determine the specific strain that is causing the clinical outbreak. Recently, genotyping methods have been developed with the goal of correlating genotype with the degree of virulence of H. parasuis strains. The association between genotype and virulence in H. parasuis is challenging due to the lack of knowledge of the complete genomic sequence and virulence factors of this bacterium. 相似文献
17.
Ramos S Igrejas G Rodrigues J Capelo-Martinez JL Poeta P 《Veterinary journal (London, England : 1997)》2012,193(1):301-303
The prevalence of vancomycin resistant-enterococci (VRE) in faecal samples from cattle, sheep and pigs slaughtered for human consumption was evaluated. Enterococci containing the vanA gene were detected in 25.3% and 2.7% of the porcine and ovine samples, respectively, and were identified as Enterococcus faecium. No vanA-containing enterococcal strains were detected in bovine samples. Enterococcal strains with intrinsic vancomycin resistance were detected in seven (9.9%) faecal samples from pigs and in two samples from both cattle and sheep (3.7% and 2.7%, respectively). All vanA-positive isolates from pigs were resistant to tetracycline and erythromycin, and the mobile element Tn916/Tn1545-like transposon was detected in 90.5% of the tetracycline-resistant isolates that contained the tet(M) gene. Although gelatinase and haemolytic activity were not detected, the hyl and cylB virulence genes were found within the VRE strains isolated. 相似文献
18.
Occurrence and diagnostic relevance of virulence-associated factors in Streptococcus suis 总被引：7，自引：0，他引：7
Baums CG Da Silva LM Goethe R Valentin-Weigand P 《DTW. Deutsche tier?rztliche Wochenschrift》2003,110(9):378-381
Streptococcus suis (Sc. suis) can cause very different clinical entities. In contrast to Sc. suis-associated pneumonia, the induction of meningitis, septicemia, and polyarthritis by certain Sc. suis strains requires the expression of virulence factors that contribute to the invasiveness of the pathogen. In the presented study, we examined the occurrence of known virulence-associated factors in Sc. suis isolates from samples sent to the Institute of Microbiology, School of Veterinary Medicine Hannover, in order to evaluate their significance as potential virulence factors in different disease complexes in Northern Germany. The results show that (i) MRP + EF + serotype 2 and MRP* EF-serotype 9 strains are statistically significant associated with the disease complex meningitis/septicemia/arthritis and, thus, have to be considered invasive strains, (ii) serotyping alone is not sufficient for identification of virulent strains, (iii) there is a remarkable heterogeneity among pneumonia-associated Sc. suis strains and (iv) activity of haemolysin or suilysin appears to be not appropriate as virulence marker. Finally, it has to be noted that at present only half of the Sc. suis isolates from pigs with meningitis/septicemia/poyarthritis can be characterised by the detection of virulence-associated factors. Thus, the identification and characterisation of additional, serotype independent virulence factors of Sc. suis is a very important issue in future studies. 相似文献
19.
仔猪早期断奶腹泻是困扰养猪业的严重问题,随着饲用抗生素作为饲料添加剂的禁止使用,寻求能够替代抗生素的新的生长促进剂成为研究的热点。益生肠球菌主要应用于医疗保健行业,研究主要集中在粪肠球菌(Enterococcus faecalis)和屎肠球菌(Enterococcus faecium),有关益生肠球菌作为饲料添加剂在动物饲料中的应用也逐渐引起了人们的关注,对其作用机制及有效包被技术的研究已取得了一些进展。通过介绍益生肠球菌在动物饲养,尤其是断奶仔猪中的应用现状和存在问题,以亟为该领域的研究提供参考。 相似文献
20.
E. coli bacteria isolated from localized and systemic disease processes in poultry are designated as Avian Pathogenic E. coli (APEC). The disease-inducing potential of these isolates has been explained by the occurrence of specific virulence factors. Despite the extensive literature on virulence factors for E. coli, unambiguous markers of virulence have not been identified yet. The relationship between serotyping and virulence is not straightforward either and raises the question whether E. coli infections in poultry should mainly be considered as opportunistic. Investigations into the occurrence of certain (combinations of) virulence factors in APEC isolates as virulence markers should fulfil the molecular version of Koch's postulates if the former question is to be answered. 相似文献