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1.
利用荧光标记技术,采用2对引物初步建立检测猪链球菌荧光DNA扩增片段长度多态性方法,结果表明12株猪链球菌扩增的多态性位点数从51~98条不等,该方法能够检测猪链球菌的多态性,区分不同血清型以及同一血清型不同特性的菌株,可用于菌株鉴定及流行病学研究中细菌源的追踪。  相似文献   

2.
In order to identify gene sequences unique to the virulent strains, suppression subtractive hybridization (SSH) was conducted using virulent Streptococcus suis type 2 (SS2) strain HA9801 and avirulent S. suis type 2 strain T15. Thirty genomic regions were absent in T15, and the DNA sequences of these regions in HA9801 were determined. These DNA fragments, containing putative virulence genes, encoded 28 proteins that were homologous to proteins involved in various aspects of cellular surface structure, molecular synthesis, energy metabolism, regulation, transport systems and others of unknown function. According to the published SS2 genomic sequence of the Chinese strain 98HAH33, PCR primers for 14 significant DNA fragments were designed and used for detection of the distribution of these fragments in S. suis strains from different sources, serotypes, regions, groups and times. The results showed that these 14 DNA fragments were widely distributed in 37 detected SS2 strains, yet were absent among the avirulent strain T15. Moreover, these fragments could be detected in other serotypes of S. suis, but each serotype had a different distribution of the fragments.  相似文献   

3.
A total of 142 strains from different serotypes of Streptococcus suis isolated in Spain from diseased pigs (88 strains) and healthy carrier pigs (54 strains) were studied for the presence of a muramidase released protein (MRP) and an extracellular factor (EF). The following five phenotypes: MRP+EF+, MRP+EF-, MRP-EF+, MRP+EF* and MRP*EF- were detected. A high percentage of S. suis serotype 2 strains isolated from diseased pigs (84 per cent) belonged to phenotype MRP+EF+, but this phenotype has also been noticed in other serotypes (serotypes 1, 1/2 and 14). Both proteins were detected in S. suis serotype 2 strains (26%) isolated from healthy carrier pigs and one of both proteins in serotypes 1 and 14 (phenotype MRP+EF*). The isolation of S. suis strains from healthy pigs which have shown both proteins may support the epidemiological significance of these carriers in the maintenance, transmission and distribution of virulent strains within and between swine farms.  相似文献   

4.
猪链球菌PCR检测技术研究进展   总被引:2,自引:2,他引:0  
猪链球菌是猪的一种重要病原菌,并且也会引起人的链球菌病。有35个荚膜血清型(1/21、~34),通常自发病或死亡猪体分离获得1,2,7,9型和14型菌株,其中2型是毒力最强的血清型。根据已知猪链球菌16 SrRNA及溶血素(sly)、谷氨酸脱氢酶(gdh)、荚膜多糖(cps)、胞壁蛋白或溶菌酶释放相关蛋白(mrp)、胞外因子(epf)编码基因序列设计特异性引物,建立猪链球菌群和1(14),2(1/2),7型和9型特异性PCR或多重PCR,建立2型致病性菌株和1型高致病性菌株毒力鉴定PCR或多重PCR,用于检测和鉴别临床病料和细菌分离物中的猪链球菌,具有高敏感性和高特异性,与其他致病菌及其他血清的猪链球菌型无交叉反应,为疫病诊断及流行病学的研究提供了快速、简便和有用的工具。  相似文献   

5.
We developed a new molecular method of typing Streptococcus suis based on polymerase chain reaction (PCR) amplification of a large fragment of rRNA genes, including a part of the 16S and 23S genes and the 16S-23S intergenic spacer region (ISR), followed by restriction fragment length polymorphism (RFLP) analysis with RsaI or MboII endonuclease. The 16S-23S ISRs of 5 S. suis isolates were sequenced and compared. Size and sequence polymorphisms were observed between the S735 reference strain and the 4 wild-type strains. The genetic relationships between 138 independent S. suis strains belonging to various serotypes, isolated from swine or human cases, were determined. The discriminatory power of the method was > 0.95, the threshold value for interpreting typing results with confidence (0.954 with RsaI and 0.984 with RsaI plus MboII). The in vitro reproducibility was 100%. The strains isolated from humans were less genetically diverse than the strains isolated from pigs. For the first time, 2 molecular patterns (R6, M9) were significantly associated with S. suis serotype 2 strains. This genetic tool could be valuable in distinguishing individual isolates of S. suis during epidemiologic investigations.  相似文献   

6.
Streptococcus suis is an important pathogen in pigs and is considered a zoonotic agent. To aid diagnosis of infection caused by S. suis, a species-specific probe targeting 16S ribosomal RNA was designed and used for fluorescent in situ hybridization. Two additional immunohistochemical detection methods, an indirect immunofluorescence assay and a peroxidase-antiperoxidase method, using polyclonal antibodies also were developed. The specificity of the oligonucleotide probe was examined by whole-cell and dot-blot hybridization against reference strains of the 35 serotypes of S. suis and other closely related streptococci and other bacteria commonly isolated from pigs. The probe was specific for S. suis serotypes 1-31. The specificity of the polyclonal antibodies, which has previously been evaluated for use in diagnostic bacteriology for typing of serotype 2, was further evaluated in experimentally infected murine tissue with pure culture of different serotypes of S. suis, related streptococci, and other bacteria commonly found in pigs. The polyclonal antibodies against S. suis serotype 2 cross-reacted with serotypes 1 and 1/2 in these assays. The in situ hybridization and the immunohistochemical methods were used for detection of S. suis in formalin-fixed, paraffin-embedded tissue sections of brain, endocardium, and lung from pigs infected with S. suis. The methods developed were able to detect single cells of S. suis in situ in the respective samples, whereas no signal was observed from control tissue sections that contained organisms other than S. suis. These techniques are suitable for determining the in vivo localization of S. suis for research and diagnostic purposes.  相似文献   

7.
Streptococcus suis serotypes have traditionally been identified by morphology, biochemical profiling and serotyping. Analysis of the sequences of 16S rRNA and cpn60 genes of the 35 characterized serotypes of S. suis led to the observation that two serotypes 32 and 34, are significantly distinct from other S. suis serotypes and may represent a distinct species. Here we present DNA sequence data and biochemical profiles which indicate that S. suis serotypes 32 and 34, isolated from pigs, are clustered with Streptococcus orisratti, a Voges-Proskauer negative, alpha-haemolytic, aesculin-hydrolytic, Lancefield group A streptococcus isolated from the teeth of rats.  相似文献   

8.
A model of experimental Streptococcus suis infection was developed in young mice. Minimum lethal dose (MLD) values were calculated for four virulent serotypes (1/2, 1, 2, 3) of S. suis using this model. Temperature-sensitive (ts) mutants of S. suis serotypes 1/2 and 1-8 were isolated and characterized on the basis of their growth kinetics and reversion rates. Ts mutants of S. suis 1/2, 1, 2, and 3 were tested as vaccines against the virulent homologous and heterologous challenges in mice. The protection provided was evaluated by analyzing the clinical signs, death or survival. Homologous but not heterologous protection was noted in all mice vaccinated with the mutant strains. Ts mutants of S. suis 1/2 provided 100% protection against challenge by virulent strains of S. suis 1/2, 1, and 2.  相似文献   

9.
为了建立猪链球菌(Streptococcus suis,SS)种与9型猪链球菌(SS9)的快速诊断方法,本研究根据GenBank已登录的SS种特异性基因gdh和SS9型特异性基因CPS9H设计引物,以标准SS9株基因组DNA为模板,建立了SS种和SS9的二重PCR检测方法,并进行了特异性、敏感性和重复性试验;利用所建立的方法对检测疑似猪链球菌感染猪临床样品,并与常规细菌分离鉴定方法进行了比对。结果表明成功建立SS种和SS9型猪链球菌二重PCR检测方法,该方法的检测灵敏度可达100个CFU,特异性和重复性好;利用该方法对34份临床分离自疑似猪链球菌感染样品的细菌培养物进行了应用检测试验,其中有11份样品为gdh阳性,11份gdh阳性样品中有3份样品同时为SS9阳性。本研究成功建立了SS种与SS9型猪链球菌二重PCR检测方法,可用于猪链球菌种和SS9型猪链球菌的快速诊断。  相似文献   

10.
猪链球菌1、7、9型多重PCR诊断方法的建立及初步应用   总被引:3,自引:3,他引:0  
为了建立猪链球菌(Streptococcus suis,SS)1、7、9型(SS1、SS7、SS9)的快速鉴别诊断和分型方法,本研究根据GenBank已登录的SS1型特异性的CPS1I基因、7型CPS7H基因、9型CPS9H基因设计引物,以标准SS1、SS7、SS9株基因组DNA为模板,建立了SS1、SS7和SS9的多重PCR检测方法,并进行了特异性、敏感性和重复性试验;利用所建立的多重PCR检测方法对11份猪链球菌的临床分离纯化菌株进行了的应用检测。结果表明,成功建立了SS1、SS7和SS9的多重PCR检测方法,该方法的检测灵敏度可达100 CFU/mL,特异性和重复性好;利用多重PCR检测方法对11份猪链球菌临床分离纯化菌株检测结果表明,11份样品中有3份样品为SS9阳性、2份样品为SS7阳性、1份样品为SS1阳性。本研究为临床上SS1、SS7、SS9的快速鉴别诊断提供了一种新方法。  相似文献   

11.
Streptococcus suis is an important pathogen of swine, causing meningitis, arthritis, polyserositis, septicemia, and sudden death in weaning piglets as well as fattening pigs. Recently, 3 molecular tests have been developed in our laboratory: a multiplex polymerase chain reaction (m-PCR) assay for the detection of S. suis species and serotypes 2 and 1/2, and 2 molecular typing methods, pulsed-field gel electrophoresis and an approach based on PCR amplification of a fragment of rRNA genes, including a part of the 16S and 23S genes and the 16S-23S rDNA intergenic spacer region (ISR), followed by restriction fragment length polymorphism (RFLP) analysis (ISR-RFLP). In the present study, we used these tests to analyze tonsil samples from clinically healthy pigs and to identify individual isolates of S. suis during epidemiologic investigations of 8 related herds with a history of septicemia caused by S. suis serotype 2. Capsular typing showed that 58% of the strains were nontypable. Of the 17 serotypes present, serotype 22 was the most prevalent. In the 7 farms without clinical signs on the day of sampling, we detected S. suis serotype 2 or 1/2, or both, in less than 5% of the pigs by m-PCR or by bacteriologic culture. In the 8th farm, on which 2 pigs had clinical signs of septicemia on the day of sampling, we detected S. suis serotype 2 or 1/2, or both, by m-PCR in the tonsils of 40% of fattening pigs (21 wk old) that lacked symptoms. Molecular typing of the serotype 2 strains showed a common origin of contamination in these herds, given that 1 pattern (C1) was detected in the isolates from 6 of the 8 herds. However, up to 4 patterns were associated with septicemia and sudden death. Several patterns of S. suis serotype 2 can be responsible for disease in the same herd. These molecular tools may be useful for confident studies of the transmission of S. suis, thereby contributing to the control of S. suis infection.  相似文献   

12.
为了探明2018年3月江苏省某规模化猪场发病猪的病原,本研究对发病猪进行采样和细菌分离,并对细菌进行了PCR鉴定、多位点序列分型(MLST)及小鼠致病力分析。结果发现:在该场4份发病猪组织中分离到猪链球菌2型(SS2)、猪链球菌9型(SS9)菌株各2株,MLST分析显示分离的SS2菌株属于ST7,SS9菌株属于ST243,SS2、SS9分离菌株的毒力基因表现型分别为mrp^+epf^+sly^+orf2^+sao^+fbps^+gdh^+和mrp^-epf^-sly^-orf2^+sao^-fbps^+gdh^+。动物试验显示其中3株猪链球菌分离菌株对BALB/c小鼠有较强致病力。研究结果为该养殖场猪链球菌感染防控措施的制定提供了重要参考。  相似文献   

13.
为探究广西部分地区猪链球菌(Streptococcus suis,SS)流行菌株主要血清型及毒力因子分布情况。本试验于2018年1月至2018年6月对从多个猪场采集到的116份疑似链球菌感染的组织病料(脑、肺脏、淋巴结等)进行病原菌检测,采用细菌分离鉴定、形态学观察及PCR扩增等方法对病原菌及其血清型和部分毒力因子进行鉴定。结果显示,116份样品共分离到链球菌32株,阳性率为27.59%(32/116),其血清型主要以SS2和SS9为主,分离率分别为40.63%(13/32)和43.75%(14/32),其他血清型为15.63%(5/32);毒力因子检测结果表明:SLY、MRP、EPF以及SBP2′因子的检出率分别为:81.25%(26/32)、59.38%(19/32)、50.00%(16/32)和71.88%(23/32)。32株链球菌中以SLY^+MRP^+EPF^+SBP2′^+(13株)、SLY^+MRP^-EPF^-SBP2′^-(5株)、SLY^+MRP^+EPF^-SBP2′^+(5株)为主要的毒力基因型,其中SS2均能检测出3个或3个以上的毒力因子。玉林、柳州市主要分布SS9型,南宁、百色市主要分布SS2型;广西不同地区毒力因子的分布情况存在差异且不同血清型或同一血清型的链球菌毒力因子的分布情况也各不相同,其中SS2携带的毒力因子检出率明显高于其他血清型。该研究可为今后猪链球菌疫苗及致病机理研究提供理论依据,为广西地区猪场链球菌血清型疫苗选择提供指导。  相似文献   

14.
Streptococcus suis strains (n=411), isolated from diseased pigs in seven European countries were serotyped using specific antisera against serotype 1 to 28, and were phenotyped on the basis of their muramidase-released-protein (MRP) and extracellular-factor protein (EF) production. Overall, S. suis serotype 2 appeared to be most prevalent (32%), followed by serotype 9 (20%) and serotype 1 (12%). Serotype 2 was most frequently isolated in France, Italy and Spain, whereas serotype 9 was most frequently isolated in Belgium, The Netherlands and Germany. In the United Kingdom serotypes 1 and 14 were most frequently isolated. High percentages of S. suis serotype 1, 2, 1/2 and 14 strains, isolated from tissues associated with S. suis infections such as brain, serosa, joint, heart and organs expressed the EF-protein, indicating that in these serotypes expression of EF is likely to be associated with virulence. In contrast, strains belonging to serotype 7 and 9, isolated from tissues associated with S. suis infections did not produce EF. These results strongly suggest that in the serotypes 7 and 9 EF expression is not related to virulence. More than 80% of the S. suis serotype 9 strains produced an MRP* protein, a high molecular variant of the 136kDa MRP. Expression of MRP* in serotype 9 strains is possibly associated with virulence.  相似文献   

15.
The antimicrobial susceptibility of 151 clinical Streptococcus suis strains isolated from diseased pigs in Spain was determined by a microdilution method. Isolates were mostly susceptible to beta-lactam antimicrobials, aminoglycosides, enrofloxacin, novobiocin and spectinomycin. More than 87% of the S. suis isolates were resistant to tetracyclines, sulphonamides, macrolides and clindamycin. Strains of serotype 9 were significantly more resistant than strains of serotype 2 (P<0.05) to tylosin (94% versus 77%) and clindamycin (94% versus 64%). Eighty-seven percent of the S. suis isolates were resistant to at least four antimicrobials and nine isolates (6%) were resistant to at least six antimicrobials. The most frequently identified multidrug pattern involved resistance against tetracyclines, sulphonamides, macrolides and lincosamides, with 69% of the isolates exhibiting this resistotype. Fifteen out of the 22 strains of serotype 2 (68.2%), and 84 out of the 98 of the strains of serotype 9 (85.7%) exhibited this resistotype, indicating its widespread distribution among the strains of the two most frequently isolated serotypes.  相似文献   

16.
Testing meningeal strains of Streptococcus suis to detect M protein genes.   总被引:2,自引:0,他引:2  
Previous reports have suggested that the surface proteins found in meningeal strains of Streptococcus suis might be similar to the M protein of group A streptococci. Fifty-five strains of S suis, including human and swine meningeal and pneumonic isolates, were tested for M protein genes by DNA probes representing the constant domain of the 3' end of the group A, M protein gene. None of the S suis strains examined was positive, indicating that these organisms either lack M protein genes or harbour different genes, not expressing the constant domains of protein M from group A.  相似文献   

17.
脉冲场凝胶电泳是一种可用于分离20 kb至10 Mb大分子质量DNA的新型凝胶电泳技术。该法应用于猪链球菌的分子分型,通过观察电泳条带的差异,为确定菌株之间的亲缘关系,分析基因型和临床症状之间的关系等方面提供了可靠的技术手段。文章介绍了脉冲场凝胶电泳技术的应用状况及猪链球菌的分型现状,并阐述了该技术在猪链球菌分子分型研究方面的应用及发展前景。  相似文献   

18.
Virulence-associated gene profiling of Streptococcus suis isolates by PCR   总被引:11,自引:0,他引:11  
Definition of virulent Streptococcus suis strains is controversial. One successful approach for identification of virulent European strains is differentiation of capsular serotypes (or the corresponding cps types) and subsequent detection of virulence-associated factors, namely the extracellular factor (EF, epf), the muramidase-released protein (MRP, mrp) and the hemolysin suilysin (SLY, sly). In this work we present a novel multiplex PCR (MP-PCR) and an mrp variant PCR for identification and characterization of virulent S. suis strains. These new methods were used to identify association of disease with particular profiles of virulence-associated genes. The MP-PCR allowed identification of S. suis through detection of the housekeeping gene gdh, differentiation of four cps types (1, 2, 7 and 9), and detection of epf, mrp, sly and arcA (arginine deiminase from S. suis). Furthermore, this study describes the first PCR assay for differentiation of at least six mrp variants. Expression of the corresponding size variants of MRP was shown for four of the six mrp variants, but was undetectable for the two larger mrp variants in the particular strains investigated. The results of this study suggest that cps7 strains are associated with pneumonia and that variation of mrp is very pronounced among these strains. Gene profiles of invasive, pneumonia and carrier S. suis isolates by combination of PCR assays allowed differentiation of 24 different genotypes among cps1, 2, 7 and 9 strains. Forty-five percent of the invasive S. suis diseases investigated in this study were caused by only two of these genotypes, namely cps2/mrp+/epf+/sly+ and cps9/mrp(*)/epf-/sly+. Thus, this study demonstrates for the first time a uniform profile of the particular virulence-associated genes for the vast majority of the investigated invasive cps9 strains.  相似文献   

19.
A double-antibody sandwich enzyme-linked immunosorbent assay (ELISA) was developed for the detection and the identification of Streptococcus suis capsular types 1, 2, 1/2, 3 and 22. The specificity of this test was first evaluated using reference strains of S. suis capsular types 1 to 28 and 1/2 as well as 15 different bacterial species susceptible to be isolated from swine. The ELISA developed was very specific for capsular types 1, 3 and 22 but it could not discriminate between capsular types 2 and 1/2. In a second study, S. suis isolates from 328, 493, 368 and 76 diseased pigs were used to detect capsular types 1, 2 or 1/2, 3 and 22 respectively. The relative specificity and sensitivity varied between 98% and 100%. The ELISA results were in excellent agreement with the standard techniques (biochemical tests, coagglutination and capsular reaction tests) in detecting both positive and negative strains. Kappa values were 0.80, 0.99, 0.97 and 1.00 for detecting S. suis capsular types 1, 2 or 1/2, 3, and 22 respectively. To evaluate the relative-sensitivity of the test, primary cultures from 73 diseased pigs and tissue samples from 67 diseased pigs were used directly for detecting these capsular types. With primary cultures, the relative specificity and sensitivity (95.9% and 91.6% respectively) remained high and the test was very suitable (Kappa = 0.87). The ELISA using tissue samples gave a good specificity (97.6%), a moderate sensitivity (62.5%) and a low agreement with standard tests (Kappa = 0.64).(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

20.
对来自广西边境地区部分发病猪场及屠宰场的370份猪组织进行细菌分离鉴定,共分离到16株链球菌,对这16株链球菌进行了形态学观察、PCR鉴定及小鼠致病性试验。结果表明,其形态、染色、生化特性均符合猪链球菌的特点,通过GDH鉴定与测序,证实这16株菌株均为猪链球菌,分别命名为GX1~GX16。通过特异性引物PCR分型(35个血清型),其中有1株为1型,1株为2型,1株为5型,1株为29型,5株为8型,7株未分出型。用这16株猪链球菌对昆明小鼠和BALB/c小鼠进行动物致病性试验,结果发现,菌株GX10对昆明小鼠和BALB/c小鼠致死率均为100%;菌株GX11对BALB/c小鼠致死率为80%;其他菌株对昆明小鼠和BALB/c小鼠均无致病性。菌株GX10、GX11对BALB/c小鼠的LD50分别为4.5×105和3.6×109 CFU。本试验结果表明,广西边境地区存在致病性猪链球菌8型。BALB/c小鼠对猪链球菌的敏感性高于昆明小鼠,更适合作为猪链球菌致病性研究的动物模型。  相似文献   

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