不同地区福氏2a志贺菌质粒DNA多态性分析

目的 对福氏2a志贺菌质粒DNA进行基因分型，提高福氏2a志贺菌痢疾暴发流行时同源克隆的鉴定分析水平。方法 对93株分离自不同地区、不同时间的福氏2a志贺菌用质粒图谱和限制性内切酶图谱法进行基因分型和同源克隆鉴定。结果 质粒DNA分析表明，不同地区、不同时间分离的93株福氏2a志贺菌具有13种不同的质粒DNA图谱特征(PLTl～PLTl3型)和15种限制性内切酶图谱特征(ReTl～ReTl5型)。结论 93株来自不同地区、分离自不同时间的福氏2a志贺菌分属于15个克隆群，PLT型和ReT型分布呈现多态性特征，PLTl／ReTl型是海南、江门、蚌埠、合肥、安庆地区福氏2a志贺菌的优势克隆群组。表型相同的福氏2a志贺菌实际上是遗传结构多态性群体的集合，表型分析结果作为判断传染来源或传播途径的依据具有很大的局限性。     

一起菌痢爆发的分子流行病学分析

目的 探讨江门一起菌痢爆发的特异传染源。方法 对8株福氏2a志贺菌进行质粒图谱及质粒限制性酶切图谱分析。结果 此次菌痢爆发期间分离的8株福氏2a志贺菌具有两种不同的质粒图谱特征(PPⅠ、PPⅡ型)，其中2株病例密切接触分离株J98101(PPⅡ型)和J9826(PPⅠ型)分属不同克隆。除上述两种质粒图谱特征外，同属PPⅠ型质粒图谱特征的J9871具有独特的质粒限制性酶切图谱特征ReTⅡ型。结论 本次爆发偶合有部分散发病例。相对于传统表型分型方法(生化反应、血清型)而言，质粒DNA分析具有更高的分辨率，它提供的遗传学信息更为丰富、直接、精细。     

福氏2a志贺菌菌痢爆发的质粒DNA多态性分析

目的对福氏2a志贺菌质粒DNA进行基因分型,提高福氏2a志贺菌菌痢爆发流行时同源克隆的鉴定水平。方法对8株福氏2a志贺菌进行质粒图谱及质粒限制性酶切图谱分析。结果此次菌痢爆发期间分离的8株福氏2a志贺菌具有两种不同的质粒图谱特征(PPⅠ、PPⅡ型),其中2株病例密切接触者分离株J98101(PPⅡ型)和J9826(PPⅠ型)分属不同克隆。除上述两种质粒图谱特征外,同属PPⅠ型质粒图谱特征的J9871具有独特的质粒限制性酶切图谱特征ReⅢ型。结论本次爆发偶合有部分散发病例。相对于传统表型分型方法(生化反应、血清型)而言,质粒DNA分析具有更高的分辨率,它提供的遗传学信息更为丰富、直接、精细。     

内蒙一起F2a志贺菌痢爆发的质粒分析

目的　探讨内蒙一起菌痢爆发的特异传染源。方法　对４３ 株Ｆ２ａ志贺菌进行质粒图谱和质粒ＤＮＡ 酶切图谱分析。结果　①质粒图谱和质粒ＤＮＡ酶切图谱特征相同的菌株为引起本次菌痢爆发的优势克隆;②本次爆发偶合有部分散发病例;③经污染的食物传播是本次爆发的主要传播途径。结论　质粒分析能较为特异、敏感地揭示不同来源志贺菌间的遗传联系和差别,从而准确说明爆发或流行事件的真相     

福氏2a志贺菌肠毒素ShET1/ShET2基因分型在菌痢暴发研究中的应用

目的 对福氏2a志贺菌肠毒素ShET1(Shigella enterotoxinl)和肠毒素ShET2(Shigella enterotoxin2)进行基因分型，提高菌痢暴发流行时同源克隆的鉴定分析水平。方法 对在菌痢暴发期间分离的8株福氏2a志贺菌用PCR法检测志贺菌肠毒素ShET1/ShET2基因，进行基因分型和同源克隆鉴定。结果 8株福氏2a志贺菌可分为3种基因型，即2株ShET1(-)/ShET2( ),1株ShET1( )/ShET2(-)，5株ShET1( )/ShET2( )。结论 本次菌痢暴发部分患可能并非真正的暴发病例，之所以被归入暴发事件之中，可能是一种与暴发事件在空间、时间上偶合的散发病例。     

志贺菌痢暴发菌株的分子流行病学分析

目的 探讨4种基因分型方法在一起F2a志贺菌痢暴发的流行病学研究中的意义。方法 对43株从患粪便和食物中分离菌株进行质粒图谱分析、质粒DNA酶切图谱分析、随机PCR分析、setl／set2毒力基因PCR分析。结果 随机PCR将43株F2a志贺菌分为2个不同的谱型，质粒图谱、setl／set2毒力基因PCR分为3个不同的谱型。而质粒：DNA酶切图谱分为4个不同的谱型。其中基因型完全相同的菌株35株，为引起本次菌痢暴发的流行株。7株基因型不同的菌株是本次暴发期间同时存在的散发病例。从食物中分离的菌株基因型与流行株相同，证明此次暴发是通过污染的食物而引起传播的。食堂炊事员粪便中虽然分离出了F2a志贺菌，但基因型与流行株不同，不是本次暴发的传染源。结论 DNA水平上的分型方法能更为准确、深入地揭示菌痢暴发过程中各分离株之间的流行病学联系。     

福氏2a志贺氏菌肠毒素基因分型

目的：对福氏２ａ志贺氏菌（Ｓｈｉｇｅｌｌａ ｆｌｅｘｎｅｒｉ２ａ,Ｆ２ａ）的志贺氏肠毒素１（Ｓｈｉｇｅｌｌａ ｅｎｔｅｒｏｔｏｘｉｎ１,ＳＥＴ１）和志架氏肠毒素２（Ｓｈｉｇｅｌｌａ ｅｎｔｅｒｏｔｏｘｉｎ２,ＳＥＴ２）进行基因分型,提高菌痢暴发流行时同源性分析的水平。方法：对一起暴发Ｆ２ａ菌痢在现场流行病学调查的基础上,用聚合酶链反应（ＰＣＲ）方法,检测４３株Ｆ２ａ菌的志贺氏肠毒素１基因（ｓｅｔ１     

江门市福氏2a菌痢暴发的RAPD分析

首次采用随机PCR（RAPD）技术分析了1994年广东省江门市一起菌痢暴发期间分离的福氏2a暴发株和密切接触者分离株。结果表明：此次菌痢暴发期间分离的12株福氏2a暴发株具有三种不同的RAPD特征（RSⅠ、RSⅣ、RSⅤ）,其中J9406（RSⅠ）和J9420（RSⅣ）分属不同克隆。提示：此次菌痢暴发中少数患者可能并非真正的暴发病例,之所以被归入暴发事件之中,可能是一种空间与时间上的偶合。同期分离的14株密切接触者分离株包含五种不同的RAPD特征（RSⅠ、RSⅡ、RSⅢ、RSⅣ、RSⅤ）,进一步证实部分密切接触者感染的福氏2a并非来自所接触的病例。相对于质粒分析而言,RAPD分析具有更高的分辨率,它提供的遗传学信息更为丰富、直接、精细。     

福氏志贺菌4c型暴发和散发菌株的脉冲场凝胶电泳分型

目的了解杭州地区福氏志贺菌4c型暴发菌株和散发菌株的分子分型特征。方法对2003和2005年杭州地区的2次食物中毒暴发分离的福氏志贺菌菌株（暴发1和暴发2,菌株数分别为13株和12株）和2005年1例散发腹泻患者分离的福氏志贺菌4c型离株（1株）进行生化鉴定和血清分型,PCR检测侵袭性抗原基因ipaH,改良Kirby-Bauer纸片法检测菌株的耐药谱及脉冲场凝胶电泳（pulse field gel electrophoresis,PFGE）进行分子分型。结果暴发1中分离的13株菌株均为福氏4c型,但检测的6株菌株间的PFGE图谱存在着相当的差异,Dice系数为0．78至0．92。暴发2中分离的菌株有10株福氏4c型和2株福氏x型,所有菌株的PFGE图谱几乎完全一致。暴发2分离株和暴发1的部分分离株可能存在着一定相关性（Dice系数大于0．8）,而散发菌株与2起暴发的绝大部分菌株间的距离较远（Dice系数小于0．8）。暴发1、暴发2的分离株和1株散发菌株对14种抗生素的耐药谱略呈差异,暴发2中分离的福氏4c型和x型菌株的耐药谱一致。结论PFGE能够很好地辨别福氏志贺菌4c型的两起暴发菌株和1株散发菌株。福氏志贺菌4c型菌株具有易变性,可在暴发流行过程中产生PFGE图谱的差异、血清亚型的转换、耐药谱的变化等。     

多位点酶电泳法在菌痢暴发中的应用

从广州、江门两地分离到７９株Ｆ２ａ，采用多位点酶电泳（ＭＥＥ）技术对该菌的６种代谢酶进行了检测。结果表明，７９株Ｆ２ａ共分为１０个电泳型（ＥＴ），存在一个优势型（ＥＴ１）和一个次优势型（ＥＴ２），以及８个非优势型。该现象说明，ＥＴ１型是引起菌痢暴发和流行的优势克隆。用ＭＥＥ方法检测表型一致的Ｆ２ａ，可发现二者之间具有差异。     

Molecular epidemiology for local outbreaks of methicillin resistantStaphylococcus aureus (MRSA)

Subtyping isolates may be useful for epidemiological studies of methicillin-resistant-Staphylococcus aureus (MRSA) outbreaks. Among subtyping methods, DNA-based techniques have been applied very effectively for this purpose. An outbreak of MRSA infections took place in one hospital in Barcelona early during 1991. From the beginning of the outbreak to December 92, 70 MRSA isolates from different patients and sources were collected. All strains were evaluated by restriction endonuclease analysis of plasmid DNA (REAP) and macrorestriction endonuclease analysis of genomic DNA usingSma I and pulsed-field-gel-electrophoresis (PFGE). Plasmid screening and REAP usingHind III demonstrated two plasmid subtypes: subtype A showing a large plasmid, and subtype B showing the same large plasmid plus a smaller one. Subtypes A and B corresponded to the more recent and older isolates, respectively, suggesting the loss of the small plasmid during the epidemic. PFGE usingSma I displayed two closely related profiles (PFGE subtype A and A'; CS=0.90). These subtypes were different from those subtypes exhibited from 4 methicillin-susceptible-Staphylococcusaureus (MSSA) isolates from the same hospital and from 2 epidemiologically unrelated MRSA isolates. Almost all isolates showing PFGE subtype A preceded those isolates showing PFGE subtype A'. This fact and the similarity between both subtypes suggested minor chromosomal DNA rearrangement during the outbreak from a unique strain. While PFGE usingSma I is a useful tool in evaluation of clonal dissemination, our data suggest epidemic or local outbreaks may need several methods to best delineate the source and spread of MRSA strains. The reproducibility and discriminatory power of REAP makes it a useful adjunct in this context.     

福氏志贺菌4c亚型的分子生物学特征分析

目的 了解杭州地区2003-2007年从爆发和散发细菌性痢疾患者中分离之福氏志贺菌4c亚型(F4c)菌株的分子生物学特征.方法 对24株F4c菌株以生化反应和血清分型进行鉴定,利用PCR法检测侵袭性质粒抗原H基因(ipaH)及脉冲场凝胶电泳(PFGE)进行分型分析.结果 24株菌株全部为F4c,均具有ipaH毒力基因.用PFGE分型方法将24株菌株分成17种不同的带型,Dice系数为0.71～1.00.2005年、2006年、2003年三次爆发(分别简称为爆发1、2、3)中各自分离到的菌株基因型紧密相关.三次爆发中的部分菌株可能存在一定的相关性(Dice系数>0.8).散发菌株和爆发1、3菌株间的距离较远(Dice系数<0.8),和爆发2菌株间可能存在一定的相关性(Dice系数>0.8).结论 F4c菌株具有ipaH毒力基因,PFGE提示杭州地区近年F4c三起爆发菌株可能属共同的克隆群.     

某地3起沙门菌肠炎暴发疫情溯源分析

目的某地区1月内连续地发生3起由肠炎沙门菌引起的食源性疾病,应用脉冲场凝胶电泳分型技术对疫情分离菌株进行分析,为查找传染源和传播途径,控制疫情发展提供依据。方法运用限制性内切酶XbaⅠ,对3起疫情中分离的7株肠炎沙门菌进行脉冲场凝胶电泳(PFGE)分子分型,BioNumerics V4.0软件UPGMA方法进行聚类分析。结果 3起疫情中分离的7株肠炎沙门菌交叉分为3个基因型,其中分别从疫情1、2、3中的4株菌同属基因型1,分别从疫情1、2中分离的2株菌同属基因型2,从疫情1中分离的1株菌属基因型3。结论此地区1月内暴发的3起疫情分离菌株的PFGE型别具有相同的型别,提示该地1月内暴发的3起疫情有共同的传染来源。     

Molecular epidemiology ofSalmonella enteritidis

Sixteen strains ofSalmonella enteritidis isolated in 1991 from 13 unrelated poultry-associated sources, 7 strains from 2 community outbreaks, and 18 human sporadic isolates were investigated by phage typing, analysis of rRNA gene restriction patterns (ribotyping) and plasmid profiles. Four different phage types and 10SphI patterns were found, whereas plasmids were identical in all but 4 isolates. Only one ribotype (RT A) occurred among both human and avian strains. This particular ribotype was also responsible for the two outbreaks investigated, suggesting that such strains may be of special significance for the increase ofS. enteritidis infections.     

质粒谱分析用于痢疾流行病学调查的初步探讨

本文报道了1985年从北京市的海淀区和密云县以及浙江省湖州地区分离到的134株痢疾杆菌进行质粒谱分析的结果,发现在每一菌群的痢疾杆菌内均有许多不同的质粒谱,推测在当地痢疾的流行可能是由许多在遗传学上不同的痢疾杆菌引起的;而且质粒谱的数量一般超过耐药谱数,说明前者能比后者鉴别更多的菌株。同时又发现,在同一地区内在爆发流行的短时期(一个月)内分离到的痢疾杆菌中,尽管耐药谱不同,部分菌株可呈现为相同的质粒谱。所以,质粒谱分析有可能做为痢疾流行病学调查工具之一,用于鉴别菌株、鉴定传染源、追踪耐药性质粒或评价防治效果。     

Molecular epidemiology of Shigella infection in Central Australia

Shigellosis is endemic in Central Australia and the infections are predominantly due to Shigella flexneri 6, Shigella flexneri 2a and Shigella sonnei. Plasmid profiles of isolates collected from 1985-9, suggested that infections caused by Shigella flexneri 6 were predominantly due to a single clone, whereas those caused by Shigella flexneri 2a and Shigella sonnei were due to several genetically diverse strains, although strains with identical plasmid profiles were found in widely separated geographical areas and in different years.     

Phenotypic variation amongst genotypically homogeneous Legionella pneumophila serogroup 1 isolates: implications for the investigation of outbreaks of Legionnaires' disease.

One hundred and seventy-nine isolates of Legionella pneumophila serogroup 1, obtained from a site associated with an outbreak of Legionnaires'' disease, were examined by monoclonal antibody subgrouping, restriction fragment length polymorphism typing, restriction endonuclease analysis and plasmid content. Nine distinct phenotypes were detected but at the genotypic level all strains were closely related. The data presented indicate that phenotypic variation of a single parent strain can occur within an environmental site. The implications of these findings are discussed in relation to the investigation of outbreaks of Legionnaires'' disease.     

Escherichia coli 0142.H6; a drug-resistant enteropathogenic clone?

For many years strains of Escherichia coli belonging to particular serotypes (EPEC) were a common cause of outbreaks of infantile enteritis in Europe and North America. E. coli 0142.H6 was first isolated from infants with diarrhoea in Indonesia in 1960 and a further outbreak occurred in Mexico in 1965. Between 1967 and 1972 outbreaks of infantile enteritis caused by E. coli 0142 were reported in hospitals in Scotland, England, Northern Ireland and Eire. Sporadic cases occurred in Canada in 1972 and a further outbreak occurred in Arizona, U.S.A. in 1975. Strains from all these incidents were examined by biochemical and serological methods. Their resistance to antimicrobial drugs was determined and their resistance plasmids characterized; their plasmid profiles were visualized by agarose gel electrophoresis. The cumulative evidence suggests that strains isolated in the British Isles all belonged to a single clone and were related to those isolated in Indonesia, the U.S.A. and Canada. However, the strains from Mexico appeared to be unrelated. This study demonstrates that single clones of enteropathogenic E. coli may spread throughout the world, causing outbreaks of diarrhoeal disease and acquiring resistance to antimicrobial drugs.