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1.
The 16S rRNA gene of 39 S. equi subsp. zooepidemicus strains and two S. equi subsp. equi strains was amplified by polymerase chain reaction and subsequently digested with the restriction enzyme Hinc II. A restriction profile with two fragments with sizes of 1250 bp and 200 bp could be observed for both S. equi subsp. equi strains and for 30 of the 39 S. equi subsp. zooepidemicus strains indicating a sequence variation within the V2 region of the 16S rRNA gene of the remaining nine S. equi subsp. zooepidemicus isolates. A segment of the 16S rRNA gene including the hypervariable V2 region of 11 S. equi subsp. zooepidemicus and two S. equi subsp. equi could be amplified by PCR and sequenced. The sequence of the V2 region of eight S. equi subsp. zooepidemicus strains appeared to be identical or almost identical to the sequence of the two S. equi subsp. equi strains. The sequence of the remaining three S equi subsp. zooepidemicus strains differed significantly from the sequence of S. equi subsp. equi. These differences allowed a division of S. equi subsp. zooepidemicus strains into two 16S rRNA types and might possibly have consequences for the taxonomic position of these phenotypically indistinguishable strains of one subspecies. A molecular typing could additionally be performed by amplification of the gene encoding the 16S-23S rRNA spacer region. A single amplicon of the spacer gene of 1100 bp could be observed for one S. equi subsp. zooepidemicus, an amplicon of 950 bp for two S. equi subsp. equi strains and 10 S. equi subsp. zooepidemicus strains, a amplicon of 780 bp for 27 S. equi subsp. zooepidemicus strains and a single amplicon of 600 bp for one S. equi subsp. zooepidemicus strain. The variations of the V2 region of the 16S rRNA gene and the size variations of the 16S-23S rRNA spacer gene were not related to each other. Both variations could be used for molecular typing of this species, possibly useful in epidemiological aspects.  相似文献   

2.
The 16S-23S rRNA intergenic spacer regions (ISRs) of five strains of "Fusobacterium pseudonecrophorum" which had been proposed as a new species, were compared with those of F. varium ATCC 8501T. All the strains of "F. pseudonecrophorum" exhibited of sequence similarities of 97.7% to 100% to the strain of F. varium in their 16S-23S rRNA ISR sequences. This indicates that the strains of "F. pseudonecrophorum" and the type strain of F. varium are identical at the species level.  相似文献   

3.
The primer set for 16S rDNA amplified an amplicon of about 1500 bp in length for three strains of Taylorella equigenitalis (NCTC11184T, Kentucky188 and EQ59). Sequence differences of the 16S rDNA among the six sequences, including three reference sequences, occurred at only a few nucleotide positions and thus, an extremely high sequence similarity of the 16S rDNA was first demonstrated among the six sequences. In addition, the primer set for 16S-23S rDNA internal spacer region (ISR) amplified two amplicons about 1300 bp and 1200 bp in length for the three strains. The ISRs were estimated to be about 920 bp in length for large ISR-A and about 830 bp for small ISR-B. Sequence alignment of the ISR-A and ISR-B demonstrated about 10 base differences between NCTC11184T and EQ59 and between Kentucky188 and EQ59. However, only minor sequence differences were demonstrated between the ISR-A and ISR-B from NCTC11184T and Kentucky188, respectively. A typical order of the intercistronic tRNAs with the 29 nucleotide spacer of 5'-16S rDNA-tRNAIle-tRNAAla-23S rDNA-3' was demonstrated in the all ISRs. The ISRs may be useful for the discrimination amongst isolates of T. equigenitalis if sequencing is employed.  相似文献   

4.
In cattle, sheep, and other ruminants, clostridial myonecrosis (gas gangrene) is mostly caused by Clostridium chauvoei, C septicum, C novyi and C sordellii. A polymerase chain reaction (PCR) system using common primers designed from multiple alignment of the 16S rRNA and 23S rRNA genes of Clostridium species was developed to identify pathogenic clostridia. The PCR was performed with total DNA from 26 strains which included seven different Clostridia species. These bacteria were differentiated at species level by the different PCR product patterns. To characterise the 16S-23S rDNA spacer regions of these clostridia further, most PCR products of these bacteria were sequenced. The smallest PCR products of each bacterium represented the fundamental 16S-23S rDNA spacer region; larger PCR products of each bacterium were caused by insertion sequences, i.e. tRNA gene sequences. The authors' observations indicate that the PCR patterns of the 16S-23S rDNA spacer regions have the potential to be used as an identification marker of pathogenic clostridia in gas gangrene.  相似文献   

5.
The nucleotide sequences of the DNA gyrase B subunit gene (gyrB) of Fusobacterium necrophorum subsp. necrophorum, F. necrophorum subsp. funduliforme and F. varium were determined and analyzed together with those of F. nucleatum subsp. nucleatum and F. nucleatum subsp. vincentii. On the phylogenetic tree constructed, the strains of each fusobacterial species formed distinct clusters with deep sublines. The degree of sequence similarity within each cluster was 93.2% or more, whereas similarities between clusters ranged from 70.1 to 72.7%. These clusters were recovered with 100% bootstrap probabilities and are in very good agreement with the species of Fusobacterium. These data suggest that gyrB is an accurate genealogical marker for the classification of the fusobacterial taxa considered in this study.  相似文献   

6.
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7.
A 37-day-old male Japanese black calf showing marked salivation and leucocytosis died and was examined the tissues histologically. Histological lesions were characterized by severe focal necrotic glossitis on the ventral side of the root of the tongue. Immunohistochemically, Fusobacterium necrophorum subsp. necrophorum antigen was detected in the necrotic tissues and its distribution corresponded to that of the gram-negative, nonsporeforming, long filamentous organisms. Ultrastructural similarities between the organism and F. necrophorum subsp. necrophorum, but not subsp. funduliforme were observed. These findings clearly demonstrated that the fatal necrotic glossitis was caused by F. necrophorum subsp. necrophorum. This is the first report of bovine fatal necrotizing glossitis with leucocytosis caused by F. necrophorum subsp. necrophorum infection, and this organism may be an important fatal pathogen in calves with glossal lesions.  相似文献   

8.
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   

9.
为考察恩诺沙星与乙酰甲喹的联合抗菌活性,采用肉汤稀释棋盘法测定了恩诺沙星与乙酰甲喹单用及联用对大肠杆菌、沙门氏菌临床菌株的体外抗菌活性。结果显示:恩诺沙星与乙酰甲喹单独使用对大肠杆菌的最小抑菌浓度为8μg/m L和32μg/m L,对沙门氏菌的最小抑菌浓度为16μg/m L和256μg/m L。两药联用对大肠杆菌和沙门氏菌的FIC指数为0.5和0.75,分别表现为协同作用和相加作用。试验表明,恩诺沙星与乙酰甲喹联用可以增强对大肠杆菌和沙门氏菌感染的治疗效果。  相似文献   

10.
家蚕线粒体基因组1.8kb片段的克隆及序列分析   总被引：2，自引：0，他引：2  
克隆并测定了家蚕 (Bombyxmori)线粒体基因组 1781bp的EcoRⅠ和HindⅢ双酶切片段序列 ,根据序列同源性比较 ,推测该DNA片段包括 :ND1基因、16SrRNA基因 3′端、tRNALeu(UAG)基因和一个尚待确定的tRNA基因。家蚕与果蝇ND1基因序列同源性约为 81 85 % ,16SrRNA基因 3′端序列同源性约为 74 5 %。在家蚕、果蝇、蜜蜂、蝗虫、卤虫和人 6个物种中 ,线粒体ND1编码的疏水性氨基酸比例较稳定 ,显示了ND1基因的保守性。对上述 6个物种ND1基因序列和 16SrRNA基因 3′端序列进行系统进化分析 ,构建了系统进化树。  相似文献   

11.
The aims of the study were to characterize isolates of Bartonella henselae and to determine the prevalence of bacteremic domestic cats in urban and suburban parts of Prague, Czech Republic. Five (18%) gram-negative fastidious bacterial single-cat isolates were recovered from 27 hemocultures incubated without previous freezing. Four of these isolates originated from flea infested stray cats (n=6) and one from a shelter cat without any ectoparasites (n=21). None of the 34 previously frozen specimens from flea free pet cats yielded any bacteria. All five isolates were catalase and oxidase negative. Their enzymatic activity, RFLP profile of citrate synthetase gene (gltA) and DNA-DNA hybridization results were typical of B. henselae. According to their PvuII and BglI ribotypes the isolates could be allocated to two homogeneous groups. Ribotype HindIII and RFLP of 16S-23S rRNA spacer region analysis gave unique profiles different from those of Bartonella quintana, Bartonella elizabethae and Bartonella clarridgeiae. The 16S rRNA type-specific amplification revealed an identical profile typical of B. henselae genotype II for all the cat isolates studied. Pulsed-field gel electrophoresis (PFGE) assigned a different profile to each of the isolates studied. Determination of the enzymatic activity, RFLP of gltA gene, RFLP of 16S-23S rRNA spacer region, and HindIII ribotype could be efficient tools for identification of B. henselae isolates. Ribotyping (PvuII, BglI), 16S rRNA typing and PFGE may be useful methods to prospect ecology and epidemiology of the agent.  相似文献   

12.
Fusobacterium necrophorum, a gram-negative, non-spore-forming anaerobe, is a normal inhabitant of the alimentary tract of animals and humans. Two types of F. necrophorum, subspecies necrophorum (biotype A) and funduliforme (biotype B), have been recognized, which differ morphologically, biochemically and biologically. The organism is an opportunistic pathogen that causes numerous necrotic conditions (necrobacillosis) such as bovine hepatic abscesses and ruminant foot abscesses. Subspecies necrophorum strains are considered to be more virulent for cattle and have been shown to produce greater amounts of leukotoxin than subspecies funduliforme strains. The leukotoxin operon of F. necrophorum consists of three genes (lktBAC) of which the leukotoxin structural gene (lktA) is the second gene in the operon. In this study, the promoter regions of the leukotoxin operons from the two subspecies were identified and their nucleotide sequence compared. The promoter regions were found to differ in sequence, in length of the sequence between the upstream determinant (oppF) and the first gene of the leukotoxin operon (lktB), and in promoter strength as assayed in Escherichia coli host cells.  相似文献   

13.
肠膜明串珠菌种共有4个亚种,其中肠膜明串珠菌肠膜亚种被我国卫生部与美国食品药品监督管理局列为可食用菌种之一.而16S rRNA基因,无法确定肠膜明串珠菌菌株的亚种地位.实验利用16S～23S核糖体间隔序列与3种种特异性基因,并根据肠膜明串珠菌已有的引物进行分析,确定肠膜明串珠菌BD1710归属肠膜明串珠菌肠膜亚种.  相似文献   

14.
根据GenBank中乳酸杆菌16 S～23 S rRNA基因间沉默区序列设计引物,进一步鏊定猪源乳酸杆菌分离株HZ521;并通过体外试验,以嗜酸乳酸杆菌ATCC 4356为参考菌株,探讨HZ521株的益生素作用.部分16 S～23 S rRNA基因序列同源性分析结果表明,该分离株属于瑞士乳酸杆菌.HZ521株具有较强的产酸能力,能耐受强酸,对Hela细胞的黏附率为87.2%,显著高于ATCC 4356株(P<0.01).表明瑞士乳酸杆菌HZ521株具有益生素特性,可作为肠道益生素的候选菌株.  相似文献   

15.
Streptococcus equi subsp. zooepidemicus (SEZ) is an opportunistic and zoonotic pathogen of horses. In this study, genetic intraspecies variability of SEZ obtained mainly from respiratory and genital samples of horses was investigated by analysis of the 16S–23S rRNA intergenic spacer region (ISR) and of the 16S rRNA gene. 16S–23S ISR rRNA type A1 was predominant, although a high rate of multiple products (30.5%) was obtained. Phylogenetic analysis of the 16S rRNA gene detected three genogroups (I, II and III). 16S rRNA variable regions V1 and V2 are the most important regions for evaluating SEZ intraspecies variability, but at least V1-V5 regions should be considered to avoid mistakes. Analysis of all 16S rRNA sequences available in databases assigned human SEZ to groups I and III but not to group II. These results show a high genetic variability in SEZ collected from different specimens of horses from various regions of Italy.  相似文献   

16.
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17.
The phylogenic relationships of two subspecies of Fusobacterium necrophorum were investigated by randomly amplified polymorphism DNA-polymerase chain reaction (RAPD-PCR). With each of the 12 random primers, the DNA fingerprints generated were subjected to cluster analysis for dendrograms. The analysis indicated that twelve strains were organized into two major clusters, and that all strains of each subspecies were confined to one cluster. Furthermore, two of the random primers examined each generated a unique band in F. n. necrophorum strains. We cloned these specific bands and determined the nucleotide sequences. A search for amino acid sequence homologies revealed that the two specific fragments had significant homology to the rpoB gene of Lactococcus lactis subsp. lactis and the hemagglutinin-related protein gene of Ralstonia solanacearum, respectively. New specific primers designed for the rpoB gene were able to amplify 900bp fragments from both subspecies. However, the specific primers designed for the hemagglutinin-related protein gene amplified only a 250bp fragment of the genome of the F. n. necrophorum strains, suggesting that this gene is unique to F. n. necrophorum. These results were further confirmed by dot blot hybridization. Finally, a one-step duplex PCR technique in a single tube for the rapid detection and differentiation of the F. necrophorum subspecies was developed.  相似文献   

18.
Bacterial superantigens are one of the major virulence factors produced by Streptococcus pyogenes and Staphylococcus aureus. The two novel superantigen encoding genes seeM and seeL were described for S. equi subsp. equi which is known as the causative agent of strangles in equids. In the present study previously characterized S. equi subsp. equi strains and strains of various other animal pathogenic streptococcal species and subspecies were investigated for the presence of the superantigen encoding genes seeM and seeL by polymerase chain reaction. According to these studies seeL and seeM appeared to be a constant characteristic of all investigated S. equi subsp. equi strains. Surprisingly, one S. equi subsp. zooepidemicus strain (S.z. 122) was also positive for both genes. The species identity of this S. equi subsp. zooepidemicus strain could additionally be confirmed by sequencing the 16S rRNA gene and the 16S-23S rDNA intergenic spacer region. The superantigen encoding genes could not be found among additionally investigated S. equi subsp. zooepidemicus strains or among strains of seven other streptococcal species. The seeL and seeM genes of the S. equi subsp. equi strain S.e. CF32 and the genes szeL and szeM of the S. equi subsp. zooepidemicus strain S.z. 122 were cloned and sequenced. A sequence comparison revealed a high degree of sequence homology between seeL, szeL, speL and seeM, szeM and speM, respectively. The superantigenic toxins L and M seemed to be widely distributed virulence factors of S. equi subsp. equi, rare among S. equi subsp. zooepidemicus but did not occur among a number of other animal pathogenic streptococcal species.  相似文献   

19.
Polymerase chain reaction (PCR) was used to amplify the spacer regions between the 16S and 23S genes of rRNA genetic loci of Salmonella serovars for their rapid identification. These genetic loci revealed a significant level of polymorphism in length across the species/serovar lines. When the 16S-23S spacer region amplification products were subjected to agarose electrophoresis, the patterns observed could be used to distinguish all the serovars of Salmonella tested. Unique elements obtained in amplification products were mostly clustered at serovar level, although certain genus-specific patterns were also observed. On the basis of the results obtained, the amplification of 16S-23S ribosomal spacer region could suitably be used in a PCR-based identification method for Salmonella serovars.  相似文献   

20.
Seventeen Streptococcus equi subsp. zooepidemicus strains isolated from camels and camel milk in Kenya and Somalia were identified by their cultural characteristics, by biochemical and serological reactions with the help of commercial identification systems and by molecular studies using a multiplex PCR. The isolates were further characterized by a PCR-mediated detection of size polymorphisms in the 16S-23S rDNA intergenic spacer region and the virulence gene szp and by amplification of the virulence gene cne. These molecular analysis are potentially useful in identifying and characterizing S. equi subsp. zooepidemicus strains of this origin and could possibly be valuable in epidemiological investigations.  相似文献   

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