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1.
为研究A型产气荚膜梭菌(CpA)的β_2毒素对仔猪坏死性肠炎(NEC)的影响,本试验采用改良FTG培养基从江西地区健康与腹泻哺乳仔猪新鲜粪便中初分离Cp,再对所分离Cp菌株进行生化和16S r DNA分子鉴定,统计江西省7个地区健康和腹泻仔猪肠道Cp分离率;通过多重PCR技术对CpA菌株及CpA β_2~+毒素基因携带率进行测定;将CpA(β_2~+/β_2~-)分离株进行小鼠毒性试验。结果显示:255份哺乳仔猪粪便样品中,腹泻样品Cp分离率为89.6%(138/154),健康样品Cp分离率为90.1%(91/101),其中CpA占分离菌株的89.5%(205/229);CpA菌株的β_2毒素携带率为99.5%(204/205),表明江西地区仔猪肠道CpA携带率及CpA(β_2~+)比例均较高;所分离的CpA菌株通常携带2个以上质粒,且β_2毒素基因位于CpA菌其中的质粒中;来源于腹泻仔猪的CpA(β_2~+)、CpA(β_2~-)和健康仔猪的CpA(β_2~+)培养上清分别以腹腔接种小鼠,均可引起小鼠不同程度死亡。从小鼠毒性试验结果表明CpA与菌株来源健康或腹泻仔猪、是否携带β_2毒素没有直接关系,其毒性作用可能主要与宿主肠道环境有关。本实验为研究CpA(β_2~+)在NEC中的影响提供初步实验依据。 相似文献
2.
《中国兽医学报》2019,(1):57-62
为探究产气荚膜梭菌(Cp)及其产生的β2毒素对7日龄内仔猪腹泻的影响,本试验利用PCR技术对江西不同地区96份仔猪粪样DNA进行分析。首先检测产气荚膜梭菌α、β、β2、ε、ι、CPE毒素基因来推断Cp存在和基因型,然后对不同地区的β2毒素基因全长进行测序比对、MEGA7构建进化树,最后采用荧光定量PCR对携带CpA(β2+)的健康、腹泻样品中的Cp菌数进行测定。结果显示:α毒素基因在健康、腹泻仔猪的检测率分别为85.4%(41/48),81.3%(39/48),β2毒素基因则分别为79.2%(38/48),77.1%(37/48);β、ε、CPE及ι毒素基因未能检测到,综合各分型毒素检测结果,阳性粪样存在的Cp均为A型。β2基因全长除九江地区得到的β2基因在第706～733bp缺失28个碱基,其他地区β2全长序列不多于3个碱基的差异,与GenBank登录号AJ537530.1对应序列同源性最高。携带CpA(β2+)的健康、腹泻粪样同浓度DNA中Cp菌数为104～105 CFU,经SPSS17分析,差异不显著(P0.05)。结果表明,江西地区的猪源β2毒素基因保守性较高,但仔猪腹泻与β2毒素基因存在与否和Cp菌数没有明显的相关关系,是否与毒素表达有关有待进一步的研究,本试验结果为研究Cp致病机制提供了依据。 相似文献
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4.
为分析江苏地区仔猪腹泻性大肠杆菌的致病性、血清型、耐药性及生物被膜(BF)形成能力等生物特性,本研究从2017年～2019年采集江苏地区患腹泻的仔猪粪便、肛拭子等216份病料样品,从中分离培养后经16S rRNA PCR鉴定获得156株大肠杆菌,进一步通过小鼠感染性实验得到118株致病性大肠杆菌.对分离的致病性大肠杆菌... 相似文献
5.
《中国预防兽医学报》2016,(12)
为从腹泻仔猪肠道内分离鉴定猪流行性腹泻病毒(PEDV)并明确其致病性,本文研究应用Vero-81细胞从腹泻仔猪小肠及其内容物中分离鉴定了一株PEDV(HBMC2012株),分析了其遗传变异特征,并将该病毒分离株经口腔感染5头3 d健康初生仔猪,观察其临床表现和病理变化,检测病毒在组织中的分布,分析病毒血症和经粪便排毒的动态。结果显示,分离的PEDV HBMC2012株可以引起明显的细胞病变,与目前国内及美国流行的PEDV株同源性高,与2010年之前的国内流行PEDV株、欧洲株CV777和韩国株DR13同源性低。该病毒株可以导致仔猪出现PED典型的临床症状与病理变化,病毒主要分布于空肠后端、回肠和十二指肠黏膜上皮细胞内,病毒血症和粪便排毒至少持续14 d。该研究结果为PEDV的致病机制和弱毒疫苗研究奠定了基础。 相似文献
6.
<正>关键点:(1)新生仔猪腹泻往往是由多种因素共同作用的结果。(2)因此,有效的控制措施需要从多个方面着手。相对于仔猪腹泻得到有效控制的猪场而言,仔猪出生后不久就发生腹泻的猪场会有较高的断奶死亡率和治疗成本,并且断奶体重通常较轻。幼龄猪对肠道微生物感染高度敏感,而且很多肠道微生物在猪场内广泛存在。轮状病毒(Rotavirus,RV)、A型产气荚膜梭菌(Clostridiumperfringens type A,CpA)和大肠杆菌(Escherichia Coli, 相似文献
7.
为了调查引起仔猪腹泻的致病性大肠杆菌的耐药性,笔者于2011—2012年对黑龙江省双城市6个规模化猪场进行了调查,共采集到106份腹泻仔猪粪便,通过分离培养、生化试验获得90株大肠杆菌,其中致病性大肠杆菌34株。采用K—B法对34株致病性大肠杆菌分离菌株进行了22种抗菌药物的耐药性检测,从而为仔猪腹泻的临床治疗、合理用药提供了依据。 相似文献
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为研究仔猪腹泻中猪圆环病毒2型(PCV2)的生物信息,参考Gen Bank发表的猪圆环病毒2型(PCV2)全基因组序列,设计并合成一对特异性引物,从四川地区猪场送检的腹泻仔猪病料中扩增PCV2全长基因序列,回收PCR产物。将其插入PMD19-T载体,构建了重组质粒,转化后筛选、提取阳性重组质粒进行测序。将测序结果及推导的氨基酸序列与国内外的不同分离株进行生物信息学分析。结果表明,分离株基因组全长为1 767 bp,分离的三株基因组与Gen Bank上已发表的PCV2分离株之间的核苷酸同源性分别为1#94.7%~89.6%、2#94.7%~89.3%、3#96.4%~86.8%,氨基酸序列同源性为1#97.9%~95.7%、2#97.1%~95.5%、3#98.4%~94.8%,说明四川地区腹泻仔猪病料中PCV2的变异相对保守。 相似文献
9.
《中国预防兽医学报》2015,(9)
为研究小肠结肠炎耶尔森氏菌(Y.enterocolitica)在断奶仔猪腹泻发生中可能的致病作用,本研究采集黑龙江地区58份断奶仔猪腹泻粪便样品,经细菌分离鉴定,共分离到18株Y.enterocolitica,命名为Y1~Y18;对其6种毒力基因(ail、yst A、yst B、vir F、yad A和rfb C)进行检测,结果显示,其中10株携带yst B基因,3株携带ail基因,其余5株分离株未检测到任何毒力基因。致病性试验结果显示,这些分离株的致病性存在很大差异,含有ail基因的致病性分离株Y7对小鼠和猪均具有致病性,而Y17分离株则无致病性;含有yst B基因的Y11分离株对小鼠具有致病性对猪无致病性,Y18分离株则对小鼠也无致病性;不含毒力基因的分离株Y9和Y16则可以引起小鼠和猪不同程度发病。各分离株除引起腹泻的程度、持续时间和粪便带菌天数不同以外,在肺、后肢关节液、肠系膜淋巴结和小肠内容物中的分离情况也存在差异。本研究结果表明菌株携带毒力基因的情况与其致病性并不具有明确的相关性,并且初步证明Y.enterocolitica在断奶仔猪腹泻发生过程中起到了一定的作用。 相似文献
10.
《养殖与饲料．饲料世界》2019,(12)
奇异变形杆菌是一种能引起腹泻的条件性致病菌,长期以来没有引起兽医工作者的重视。在此项研究中,从重庆地区的养猪场收集了122份腹泻仔猪的粪便样本,通过分离纯化、分子生物学鉴定和小鼠的攻毒试验,共分离到22株奇异变形杆菌,分离率为18.03%(22/122)。其中15株分离菌有很强的致病性,能在24 h内致死小鼠,并引起肠道黏膜严重出血。这些结果表明奇异变形杆菌在仔猪腹泻中可能扮演着重要的角色,需要引起兽医工作者的重视。 相似文献
11.
This study was aimed at determining the genetic diversity of Campylobacter jejuni from healthy ruminants and poultry, and study by multilocus sequence typing (MLST) their links to human isolates in Spain. MLST analysis of 160 animal isolates generated 45 sequence types (STs, nine of them new to this study), that clustered into 18 clonal complexes (CC) and nine singletons. The 71 isolates from humans generated 28 STs (13 CC plus four singletons). Only 11 STs and nine CCs were shared by humans and animals (particularly from dairy cattle and sheep), mainly corresponding to sporadic cases rather than outbreaks, probably as an adaptation of the general human population to the types commonly circulating in livestock. PCR analysis of the distribution of four virulence-associated genes detected the cdtABC gene cluster in all 160 isolates but with a 700-bp deletion in four of them, and amplified the virB11, cgtB and wlaN genes in 4.7%, 21.3% and 21.9% respectively. A subset of 87 C. jejuni animal isolates analysed using flaA PCR-RFLP, MLST and pulsed-field gel electrophoresis generated 31, 38 and 55 types respectively. The combined typing approach used provided reliable inter-strain relationships, confirming the co-existence of several strains in some farms, but also identifying identical genotypes sampled over a wide temporal span in different environments and hosts. Typing results confirmed a high genetic diversity of C. jejuni in our region and suggested that ruminants are also important sources for human infection. MLST data provided will help to obtain a more comprehensive image of the population structure of C. jejuni and establish reliable source attribution schemes. 相似文献
12.
Musangu Ngeleka Jane Pritchard Greg Appleyard Dorothy M Middleton John M Fairbrother 《Journal of veterinary diagnostic investigation》2003,15(3):242-252
To identify emerging Escherichia coli that have the potential to cause diarrhea in pigs, the prevalence of E. coli pathotypes was determined among 170 and 120 isolates from diarrheic and nondiarrheic piglets, respectively. The isolates were tested for F4, F5, F6, F18, and F41 fimbriae, for E. coli attaching and effacing (EAE), porcine attaching and effacing-associated (Paa), and adhesin involved in diffuse adherence (AIDA-I) factors, for LT, STa, STb, and enteroaggregative heat-stable (EAST1) enterotoxins, and for Shiga toxins (Stxl, Stx2, and Stx2e), using DNA hybridization and polymerase chain reaction. All isolates were O-serotyped and tested for antibiotic resistance against 10 drugs. Seventeen different pathotypes, accounting for 40.0% of the isolates, were recovered from diarrheic piglets. The main pathotypes included EAST1 (13.5%), F4/LT/STb/EAST1 (6.5%), AIDA-I/STb/EAST1 (4.1%), F5/STa (2.9%), EAE/EAST1 (2.9%), and AIDA-I/F18 (2.3%). Only 3 pathotypes, EAE (11.7%), EAST1 (10.8%), and EAE/EAST1 (3.3%), were recovered from nondiarrheic piglets. Paa factor was detected in 8.8% and 7.5% of isolates from diarrheic and nondiarrheic piglets, respectively, and always was associated with other virulence determinants. Overall, 22.9% of isolates from diarrheic piglets appeared to be enteropathogens: enterotoxigenic E. coli (11.7%), enteropathogenic E. coli (3.5%), and E. coli isolates (3.0%) for which none of the above adherence factors was detected. Pathotypes AIDA-I/STb/EAST1 and AIDA-I/STb were isolated only from diarrheic piglets and accounted for 4.7% of isolates. Strains of these pathotypes induced diarrhea when inoculated into newborn colostrum-deprived pigs, in contrast to an isolate positive only for EAST1, which did not induce diarrhea. Antibiotic sensitivity test showed that isolates of the AIDA-I/STb/EAST1 and AIDA-I/STb pathotypes were the only strains sensitive to enrofloxacin, gentamicin, neomycin, and trimethoprim-sulfamethoxazole. This study showed that at least 20.5% of isolates from diarrheic piglets appeared to be associated with AIDA-I/STb pathotype and that EAST1 pathotype is probably not an important marker for diarrhea in piglets. 相似文献
13.
De L Garcia S Orden JA Ruiz-Santa-quiteria JA Diez R Cid D 《American journal of veterinary research》2002,63(2):262-266
OBJECTIVE: To determine the prevalence and characteristics of attaching and effacing Escherichia coli (AEEC) in diarrheic and healthy small ruminants. ANIMALS: 502 lambs and kids with diarrhea and 511 healthy sheep and goats. PROCEDURE: Fecal samples from diarrheic and healthy sheep and goats were screened for the eae gene. In addition, E coli isolates with positive results for the eae gene (E coli eae+) were analyzed for the espB gene, production of verotoxins (VT), and serogroup. RESULTS: A significantly higher prevalence of healthy lambs and kids were infected with AEEC, compared with diarrheic lambs and kids and healthy adult sheep and goats. Some differences in the characteristics of E coli eae strains isolated from diarrheic and healthy animals were detected. Thus, the espB gene was detected more frequently among E coli eae+ strains isolated from healthy animals than in those isolated from diarrheic animals, and VT production was only detected in E coli eae+ strains isolated from healthy lambs and kids. The E coli eae+ isolates belonged to several O serogroups. However, 17 of 40 (42.5%) isolates from diarrheic lambs and only 4 of 168 (2.4%) isolates from healthy sheep belonged to serogroup 026. CONCLUSIONS AND CLINICAL RELEVANCE: Our results suggest that E coli eae+ 026 strains may play a role in diarrheal disease in lambs, whereas E coli eae+ strains that also had VT production and eae+ strains that had positive results for the espB gene did not appear to be associated with diarrhea in small ruminants. 相似文献
14.
Parsons BN Porter CJ Stavisky JH Williams NJ Birtles RJ Miller WG Hart CA Gaskell RM Dawson S 《Veterinary microbiology》2012,157(3-4):391-397
Risk of Campylobacter infection in humans has been associated with many sources, including dogs. C. upsaliensis is the most common species found in canines, and has been occasionally isolated from symptomatic humans. This study aimed to investigate the genetic diversity of 41 C. upsaliensis isolates carried by dogs and from nine isolates carried by humans using Multilocus sequence typing (MLST). We identified considerable genetic diversity amongst the C. upsaliensis isolates from both dogs and humans, identifying 45 different sequence types (STs). All STs were new, apart from that of the reference strain. Only three STs were found in more than one isolate: ST-72 (2 isolates), ST-98 (2 isolates) and ST-104 (3 isolates). ST-104 was the only ST to be encountered in both dogs and humans. Thirty-one of the 45 STs were assigned to one of 13 clonal complexes (CCs). Four of these CCs contained STs originating from both humans and dogs. None of the CCs contained exclusively human isolates, and two isolates from dogs within the same kennel belonged to the same CC. The large amount of diversity found in both dog and human isolates of C. upsaliensis, combined with the relatively small database, made it difficult to assign strains to sources of infection. This emphasizes the need to increase the size of the database. Dog and human isolates occasionally grouped together, however there were insufficient human-derived isolates to determine whether or not dogs are a common source of infection. Although C. upsaliensis infection is rare in humans, dogs still remain a potential source, and are therefore a possible zoonotic risk. Further work is needed to investigate the epidemiology of C. upsaliensis infection in humans. 相似文献
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Chantal Amar Sonja Kittl David Spreng Andreas Thomann Bożena M. Korczak André P. Burnens Peter Kuhnert 《Veterinary microbiology》2014
Campylobacter jejuni is the most important cause of bacterial gastroenteritis in humans. It is a commensal in many wild and domestic animals, including dogs. Whereas genotypes of human and chicken C. jejuni isolates have been described in some detail, only little information on canine C. jejuni genotypes is available. To gain more information on genotypes of canine C. jejuni and their zoonotic potential, isolates from routine diagnostics of diarrheic dogs as well as isolates of a prevalence study in non-diarrheic dogs were analyzed. Prevalence of thermophilic Campylobacter among non-diarrheic dogs was 6.3% for C. jejuni, 5.9% for Campylobacter upsaliensis and 0.7% for Campylobacter coli. The C. jejuni isolates were genotyped by multi locus sequence typing (MLST) and flaB typing. Resistance to macrolides and quinolones was genetically determined in parallel. Within the 134 genotyped C. jejuni isolates 57 different sequence types (ST) were found. Five STs were previously unrecognized. The most common STs were ST-48 (11.2%), ST-45 (10.5%) and ST-21 (6.0%). Whereas no macrolide resistance was found, 28 isolates (20.9%) were resistant to quinolones. ST-45 was significantly more prevalent in diarrheic than in non-diarrheic dogs. Within the common time frame of isolation 94% of the canine isolates had a ST that was also found in human clinical isolates. In conclusion, prevalence of C. jejuni in Swiss dogs is low but there is a large genetic overlap between dog and human isolates. Given the close contact between human and dogs, the latter should not be ignored as a potential source of human campylobacteriosis. 相似文献
16.
In this study, 98 Escherichia coli isolates from 42 diarrheic neonatal piglets were screened for the presence of cytolethal distending toxin coding gene by polymerase chain reaction (PCR). PCR yielded a single product which was specifically generated for E. coli cdt(+) control strain and not for other control strains. Twenty two (22.4%) of the isolates tested were cdtB positive, and 50% of the cdtB(+) isolates were also estII positive. The most prevalent pathotype was O32 cdtB(+) estII(+), which accounted for 59% of the cdtB positive strains. These results indicate an association between the presence of the cdtB gene and diarrhea, and support the need for further studies to determine the role of this toxin in diarrhea. 相似文献
17.
Tom La Nyree D. Phillips Belinda L. Harland Phatthanaphong Wanchanthuek Matthew I. Bellgard David J. Hampson 《Veterinary microbiology》2009,138(3-4):330-338
The purpose of this study was to develop and apply a multilocus sequence typing (MLST) scheme to study the molecular epidemiology of Brachyspira hyodysenteriae, the aetiological agent of swine dysentery. Sequences of seven conserved genomic loci were examined in 111 B. hyodysenteriae strains. Fifty-eight of these previously had been analysed by multilocus enzyme electrophoresis (MLEE), and for some the results of pulsed field gel electrophoresis (PFGE), restriction endonuclease analysis (REA) and/or serotyping also were available. The discriminatory power of these methods was compared. The strains were divided into 67 sequence types (STs) and 46 amino acid types (AATs) by MLST. The Index of Association value was significantly different from zero, indication that the population was clonal. Eleven clonal complexes (Cc) comprising between 2 and 10 STs were recognised. A population snapshot based on AATs placed 77.5% of the isolates from 30 of the AATs into one major cluster. The founder type AAT9 included 13 strains from nine STs that were isolated in Australia, Sweden, Germany and Belgium, including one from a mallard. The MLST results were generally comparable to those produced by MLEE. The MLST system had a similar discriminatory power to PFGE, but was more discriminatory than REA, MLEE or serotyping. MLST data provided evidence for likely transmission of strains between farms, but also for the occurrence of temporal “micro-evolution” of strains on individual farms. Overall, the MLST system proved to be a useful new tool for investigating the molecular epidemiology and diversity of B. hyodysenteriae. 相似文献
18.
Avian pathogenic Escherichia coli (APEC) causes economically significant infections in poultry. The genetic diversity of APEC and phylogenetic relationships within and between APEC and other pathogenic E. coli are not yet well understood. We used multilocus sequence typing (MLST), PCR-based phylogrouping and virulence genotyping to analyse 75 avian E. coli strains, including 55 isolated from outbreaks of colisepticaemia and 20 from healthy chickens. Isolates were collected from 42 commercial layer and broiler chicken farms in Sri Lanka. MLST identified 61 sequence types (ST) with 44 being novel. The most frequent ST, ST48, was represented by only six isolates followed by ST117 with four isolates. Phylogenetic clusters based on MLST sequences were mostly comparable to phylogrouping by PCR and MLST further differentiated phylogroups B1 and D into two subgroups. Genotyping of 16 APEC associated virulence genes found that 27 of the clinical isolates and one isolate from a healthy chicken belonged to highly virulent genotype according to previously established classification schemes. We found that a combination of four genes, ompT, hlyF, iroN and papC, gave a comparable prediction to that of using five and nine genes by other studies. Four STs (ST10, ST48, ST117 and ST2016) contained APEC isolates from this study and human UPEC isolates reported by others, suggesting that these STs are potentially zoonotic. Our results enhanced the understanding of APEC population structure and virulence association. 相似文献
19.
六十二株水貂源大肠杆菌分离株耐药表型与耐药基因及克隆菌群分析 总被引：2，自引：2，他引：0
为了调查诸城地区某水貂养殖场粪便源大肠杆菌的表观及其分子特征,采集某个水貂养殖场的水貂粪便进行大肠杆菌分离鉴定,对分离鉴定的大肠杆菌进行血清型鉴定和对14种常见抗菌药物的耐药表型鉴定;使用PCR检测耐药基因以及Ⅰ整合子基因盒的携带情况,利用多位点序列分型（MLST）来分析菌株的克隆关系并构建系统发育树来分析相同克隆群菌株的遗传相似性。结果显示,自82份水貂粪便样品分离到62株大肠杆菌,分离率75.61%;大肠杆菌分离株对AMP和TET的耐药率超过90%,多重耐药菌株（MDR）占比为85.48%。PCR检测到5类耐药基因的存在,qnrS检出率最高,为61.29%（38/62）;aaC2、aaC4、sul1和aac（6'）-Ib-cr耐药基因与菌株产生相应的耐药抗性存在一致性（P<0.01）。分离菌株中Ⅰ类整合子可变区域的优势结构为dfrA27-aadA2-qnrA。鉴定出致病性血清型的存在,且对应菌株都具有多重耐药性,优势血清型为O104：H4。分离株中存在33个STs,ST46为优势STs（16.13%）,具有3个主要克隆群,依次为CC10、CC46和CC176;与致病性相关菌株的STs和人源大肠杆菌具有共同的遗传背景。本研究表明,养殖场的水貂受到致病性和多重耐药性大肠杆菌的污染,相同克隆群菌株的耐药基因分布具有多态性,表观特征差异明显。 相似文献
20.
《Veterinary microbiology》2015,175(1):92-98
Mycoplasma bovis is a primary agent of mastitis, pneumonia and arthritis in cattle and the bacterium most frequently isolated from the polymicrobial syndrome known as bovine respiratory disease complex. Recently, M. bovis has emerged as a significant health problem in bison, causing necrotic pharyngitis, pneumonia, dystocia and abortion. Whether isolates from cattle and bison comprise genetically distinct populations is unknown. This study describes the development of a highly discriminatory multilocus sequencing typing (MLST) method for M. bovis and its use to investigate the population structure of the bacterium. Genome sequences from six M. bovis isolates were used for selection of gene targets. Seven of 44 housekeeping genes initially evaluated were selected as targets on the basis of sequence variability and distribution within the genome. For each gene target sequence, four to seven alleles could be distinguished that collectively define 32 sequence types (STs) from a collection of 94 cattle isolates and 42 bison isolates. A phylogeny based on concatenated target gene sequences of each isolate revealed that bison isolates are genetically distinct from strains that infect cattle, suggesting recent disease outbreaks in bison may be due to the emergence of unique genetic variants. No correlation was found between ST and disease presentation or geographic origin. MLST data reported here were used to populate a newly created and publicly available, curated database to which researchers can contribute. The MLST scheme and database provide novel tools for exploring the population structure of M. bovis and tracking the evolution and spread of strains. 相似文献