贵州省伤寒沙门菌分离株16s核糖体基因型的多态性及其流行病学意义

目的：探讨贵州省不同时间、不同地区伤寒流行菌株的遗传多态性及内在联系。方法：利用southern杂交技术，对贵州省9个地区26个县、市1959－1999年伤寒沙门菌分离株进行染色体DNA基因限制性酶切16s rDNA探针杂交图谱分析及药物敏感性试验。结果：分析发现选择的209株分属26个RT型，以RT1和RT2为优势型；在局部发生伤寒流行时，均由独特的RT型引起。耐药菌株以RT7和RT1型为主。结论：贵州省不同地区、不同时间的分离菌株在核糖体杂交图谱上有明显的多态性，分析认为具有多重耐药性以及存在众多克隆群菌株是引起贵州伤寒发病率居高不下的主要原因。     

贵州省莱姆病螺旋体的核糖体基因分型研究

目的 对从贵州省农耕区的鼠类动物分离到的21株莱姆病螺旋体菌株进行分子流行病学研究。方法 应用聚合酶链反应(PCR)从21株莱姆病螺旋体分离株的全基因组DNA扩出5S～23S rRNA基因间隔区，扩增产物用限制性片段长度多态性分析(RFLP)和核酸序列分析。结果 贵州省21株莱姆病螺旋体菌株可分为两个基因型：Borrelia valaisiana(B．valaisiana)20株，Borrelia sp1株。结论 贵州省农耕区以B．zalaisiana基因型为主，目前B．valaisiana对人的致病性已经得到证实。     

中国莱姆病螺旋体的核糖体基因分型研究

目的 莱姆病螺旋体的基因型和临床表现、疫苗菌株和抗原菌株的选择存在密切的关系，所以对中国菌株进行分子流行病学研究，可为莱姆病的防治提供科学依据。方法 5S－23S rRNA基因间隔区RFLP分析和16＋23S rRNA基因RFLP分析。结果 中国菌株至少被分为3个基因型（B.burgdorferi sensu stricto、B.garinii和B.afzelii),B.garinii和B.afzelii占优势，B.burgdorferi sensu stricto少见。少数菌株用上述方法尚不能明确其分类地位，需进一步研究，中国很可4能存在世界上独特的新基因型。结论 中国菌株的基因型明显不同于北美菌株，而同欧洲菌株比较接近，5S－23S rRNA基因间隔区RFLP分析方法简便、快速、准确，是理想的基因型分类方法，可作为国内菌株基因型鉴定的常规方法。     

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.     

金黄色葡萄球菌的API-STAPH生化鉴定及核糖体分型分析

食源性致病金黄色葡萄球菌的筛查和检测备受关注,传统的生化鉴定方法存在耗时长和灵敏度低等缺陷,本文以原核生物核糖体小亚基为主要研究对象,利用16S核糖体RNA测序和核糖体基因分型技术对46株金黄色葡萄球菌进行了鉴定和分型,结果表明:API-STAPH生化方法鉴定的准确率为93％,而分子生物学鉴定的准确率≥99％;全自动微生物核糖体基因分型系统将46株金黄色葡萄球菌分为22个Ribogroup.上述研究将食源性金黄色葡萄球菌的鉴定上升到“亚型”的高度,16S核糖体RNA测序和核糖体分型技术可为食源性致病菌的风险监测提供有力的技术支持.     

广东省食物中毒暴发疫情中沙门菌和金黄色葡萄球菌自动化核糖体基因分型研究

目的 为了解广东省常见食源性致病菌沙门菌和金黄色葡萄球菌（金葡菌）的遗传物质多态性特征,探索其鉴定及溯源方法。方法运用自动化核糖体基因分型系统,用EcoRⅠ酶或PvuⅡ酶,对广东省分离的沙门菌和金葡菌进行分子分型研究。应用BioNumerics软件比对不同来源、时间和地点的分离株,分析菌株间的相关性。结果使用PvuⅡ酶对32株沙门菌酶切,分为19个核糖体型,使用EcoRⅠ酶对14株沙门菌酶切,分为2个核糖体型。使用EcoRⅠ酶对49株金葡菌酶切,分为31个核糖体型,表现出较大的遗传多样性。结论 自动化核糖体基因分型能有效鉴定沙门菌和金葡菌。沙门菌血清分型与Ribotyping分型无高度相关性,但两者结合,能更有效鉴定菌株间的亲缘关系,确定食物中毒的来源和传染途径。     

O139群霍乱弧菌的核糖体基因分型及其与药物抗性相关性研究

目的了解杭州市及浙江省部分地区O139群霍乱弧菌分离株的核糖体基因分型特征及其与抗生素抗性关系。方法对1994～2004年杭州市分离的105株及2000年浙江省部分地区分离的5株O139群菌株，PCR法检测ctxA和tcpA基因，纸片扩散法测定抗生素抗性，应用核糖体基因分型技术进行分子分型；并与1997～2001年分离的20株O1群霍乱弧菌流行株代表菌株的分子分型结果进行比较。结果杭州市105株O139群菌株中，95株ctxA阳性菌株分为8个型（Ⅰ、Ⅱ、Ⅲ、Ⅳ、Ⅴ、Ⅵ、Ⅶ和Ⅷ型），其中Ⅱ型菌株为2000年后的优势克隆群（占73．7％，70／95），并于2004年引起一起较大规模的爆发；10株ctxA阴性菌株被分为3个型（α、β和У型）。2000年浙江绍兴市4株axA阳性O139群分离株属Ⅱ型，浙江湖州市1株axA阴性分离株属У型。20株O1群流行代表菌株被分为5个型（A、B、C、D和E型），其中A型和B型分别与O139群中的Ⅵ型和Ⅶ型的带谱相同。ctxA阳性和axA阴性O139群菌株间的耐药谱显著不同。67株Ⅱ型O139群菌株中共有28种耐药谱，最少的仅对2种抗生素同时耐药，最多对11种抗生素同时耐药；分别有对11种和10种抗生素耐药的菌株在2002～2004年间成为优势菌（81．5％，22／27）。结论1994～2004年间多种核糖体基因型O139群霍乱弧菌在杭州同时或替换流行，多重耐药的核糖体基因型Ⅱ型O139群菌株于2002～2004年间成了杭州优势流行菌株。     

Molecular characterization of Vibrio cholerae O1 strains isolated in Romania

A collection of 89 Vibrio cholerae 01 strains, isolated in Romania between 1977 and 1994, and 6 strains from the Republic of Moldavia, was characterized by ribotyping, toxin gene restriction pattern (toxinogenotype) and distribution of cholera toxin gene (ctx), accessory toxin gene (ace) and zonula occludens toxin gene (zot). After BgA endonuclease restriction of chromosomal DNA, a total of 18 ribotypes and 21 toxinogenotypes were distinguished. Deletions in the core region of the toxin gene cassette were found in 20% of strains; however, with the exception of one strain, all the isolates contained the ctx gene. Used in association, the three methods of molecular typing provided an accurate characterization of V. cholerae 01 isolates.     

The emergence of community-onset Clostridium difficile infection in a tertiary hospital in Singapore: A cause for concern

Increasing rates of Clostridium difficile infection (CDI) among those without traditional risk factors have been reported mainly in Europe and North America. Here we describe the epidemiology, clinical features and ribotypes of CDI at National University Hospital (NUH), a 1000-bed tertiary care hospital in Singapore, from December 2011 to May 2012. All laboratory-confirmed CDI cases ≥21 years old who gave informed consent were included. Clinical data were collected prospectively and participants underwent an interviewer-administered questionnaire. Cases were classified by healthcare facility exposure and severity according to the SHEA guidelines. Included cases were also subjected to PCR and were classified by ribotype. In total, 66 patients participated in the study, of which 33 (50.0%) were healthcare-facility-associated hospital onset (HCFA-HO). Of the 33 community-onset (CO) cases, 14 (42.4%) were HCFA-CO, 10 (30.3%) were indeterminate and 9 (27.3%) were community-associated (CA). Of the CA cases, a majority (90.9%) had prior exposure to a healthcare facility within the last 12 weeks. Clinical characteristics, exposures and outcomes were not different between HO-CDI and CO-CDI. Diagnosis was delayed in CO-CDI compared with HO-CDI (4 days vs. 1 day; P = 0.014). There was no difference in distribution of ribotypes between CO-CDI and HO-CDI, with 053 being most prevalent in both groups. CO-CDI increasingly contributes to the burden of CDI in NUH. This may reflect a trend in other parts of Asia. Healthcare professionals should be aware of the possible role of outpatient healthcare environments to CDI risk and thus extend control measures to outpatient settings.