2008—2013年北京市17株伤寒和副伤寒沙门菌耐药和分子分型研究

目的分析2008—2013年北京市17株伤寒、副伤寒沙门菌耐药及分子分型。方法对2008-2013年通过对北京市肠道门诊监测系统分离到的17株伤寒、副伤寒沙门菌进行生化鉴定、血清分型并运用纸片法进行药敏检测;利用脉冲场凝胶电泳(PFGE)进行分子分型。结果 17株伤寒、副伤寒沙门菌对三代头孢菌素类药物头孢他啶敏感率达100%,头孢噻肟和头孢曲松敏感率均为93.75%,对氟喹诺酮类药物环丙沙星敏感率为93.75%,萘啶酸耐药率达31.25%。其中16株伤寒、副伤寒沙门菌可分为15种PFGE带型,带型分布较分散。结论北京市伤寒、副伤寒沙门菌分离株对3代头孢类抗生素及环丙沙星敏感;PFGE分子型别较多,无聚集性。     

Persistence of blood (DNA/RNA) on shoe soles under varying casework related conditions

Blunt force traumas by footwear can result in severe and even fatal head and upper body injuries. Oftentimes, footwear impressions are only partially available and evidential value is limited. DNA evidence on shoe soles could provide crucial evidence helping to solve crimes by linking target DNA to the activity of interest. Little is known about the persistence and detectability of biological material post such offenses and the interplay of factors affecting the analytical success. In this study, we assessed the persistence of blood on shoe soles under varying parameters such as blood location, different sneakers, weather condition, gait, amount of blood, underground and step count. We applied an optimized DNA/RNA workflow adapted to micro-traces without constraints for the primary DNA pipeline. There is a high probability to link donor DNA to the shoe sole for up to 300–400 steps, regardless of the underground, blood location, and amount of blood. Depending on the sole material and the degree of abrasion of the sole, a longer blood persistence can be observed. Considering blood, 98.2% of the initial DNA amount (1 μl initial blood volume) was lost after 100 steps walked on sole areas that are in constant contact with the ground. Proportion of foreign DNA was marginal (avg. 4.4 alleles), minimizing the probability of unintentional DNA transfer in this context. RNA typing showed high specificity but lower sensitivity than presumptive tests used for body fluid identification (BFI). Luminol is essential for targeted sampling on shoe soles, as latent blood traces (>100–200 steps) provided sufficient biological material for DNA/RNA typing. The generated data help to address the activity of interest and evaluate probabilities about prevalence of target DNA important for casework implications and assessments on activity level.     

Identification of HLA-DRB1 Alleles Associated with Graves' Disease in Koreans by Sequence-Based Typing

The human leukocyte antigen (HLA) region, particularly class II genes, plays a primary role in the susceptibility to development of GD. We investigated the allelic polymorphism of HLA class II DRB1 genes to examine its association with GD in Koreans. We performed the high resolution polymerase chain reaction-sequence based typing (PCR-SBT) of HLA-DRB1 in 133 patients with GD and 200 healthy controls. Compared to healthy controls, the patients with GD had increased frequencies of DRB1*030101 (4.9% vs.1.8%, p = 0.034), DRB1*080201 (5.3% vs. 2.3%, p = 0.050) and DRB1*140301 (3.4% vs. 1.0%, p = 0.043). In contrast, the frequencies of DRB1*070101 (3.0% vs. 7.3%, p = 0.024) and DRB1*130201 (4.1% vs. 9.0%, p = 0.010) were decreased in the patients with GD. However, the corrected p values were not significant in above all alleles. Patients with DRB1*040301 were significantly older than controls (45 years vs. 35 years, p = 0.017). DRB1*040301, DRB1*150201, DRB1*120101 and DRB1*120201 were associated with male predominance, strong familial associations, thyroid ophthalmopathy and radioactive iodine therapy, respectively. In conclusion, there were no significant HLA-DRB1 alleles associated with GD in Koreans, although some alleles were correlated with the clinical characteristics.     

Escherichia coli clonal group A causing bacteraemia of urinary tract origin

Escherichia coli clonal group A (CgA) causes disease in humans. This is the first study investigating the prevalence of CgA among E. coli from non-urine, extraintestinal infections in a northern European country. E. coli blood (n = 196) and paired urine (n = 195) isolates from the same patients with bacteraemia of urinary tract origin were analysed. The isolates were collected from January 2003 through May 2005 at four hospitals in Copenhagen, Denmark. Pulsed-field gel electrophoresis (PFGE) patterns, antimicrobial resistance and patient characteristics were determined for all CgA isolates; presence of virulence-associated genes (VAGs) and serotypes were determined for the blood CgA isolates. Thirty blood isolates (15%) belonged to CgA. CgA blood isolates were associated with female patients and sulfamethoxazole-trimethoprim resistance and they harboured a distinctive VAG profile. The blood and urine isolates from each pair were found to be related in 26 of 27 CgA blood/urine pairs, confirming a urinary tract origin of infection. Furthermore, a relationship between the PFGE patterns of CgA blood/urine isolates and CgA isolates from UTI patients in general practice and a CgA isolate from a community-dwelling human reported previously, was found, suggesting a community origin of CgA. The finding of CgA strains in 15% of the E. coli bloodstream infections with a urinary tract origin in Denmark suggests that CgA constitutes an important clonal lineage among extraintestinal pathogenic E. coli. A reservoir of this pathogenic E. coli group in the community causing not only UTI but also more severe infections such as bacteraemia has implications for public health.     

Updated model of group A Streptococcus M proteins based on a comprehensive worldwide study

Group A Streptococcus (GAS) M protein is an important virulence factor and potential vaccine antigen, and constitutes the basis for strain typing (emm-typing). Although >200 emm-types are characterized, structural data were obtained from only a limited number of emm-types. We aim to evaluate the sequence diversity of near-full-length M proteins from worldwide sources and analyse their structure, sequence conservation and classification. GAS isolates recovered from throughout the world during the last two decades underwent emm-typing and complete emm gene sequencing. Predicted amino acid sequence analyses, secondary structure predictions and vaccine epitope mapping were performed using MUSCLE and Geneious software. A total of 1086 isolates from 31 countries were analysed, representing 175 emm-types. emm-type is predictive of the whole protein structure, independent of geographical origin or clinical association. Findings of an emm-type paired with multiple, highly divergent central regions were not observed. M protein sequence length, the presence or absence of sequence repeats and predicted secondary structure were assessed in the context of the latest vaccine developments. Based on these global data, the M6 protein model is updated to a three representative M protein (M5, M80 and M77) model, to aid in epidemiological analysis, vaccine development and M protein-related pathogenesis studies.     

不同分型的肝硬化门静脉血栓的临床特点

目的探讨不同分型的肝硬化门静脉血栓(PVT)的临床特点及差异。方法回顾性分析2016年8月至2019年8月昆明医科大学第二附属医院消化内科收住的肝硬化合并PVT患者107例,依据解剖因素将其分为3组:单纯门静脉主干血栓形成组(主干组,n=17)、单纯分支血栓形成组(分支组,n=35)和门静脉主干并分支血栓形成组(主干+分支组,n=55)。分别从一般临床资料、实验室指标、影像学指标、肝储备及相关评分等方面对不同PVT部位进行比较分析。检验水准取α=0.05,采用分割χ²检验时,校正为α′=0.0125。结果主干+分支组患者更易合并消化道出血,主干组次之,分支组最低,三组间比较差异有统计学意义(χ²=27.832,P<0.01),两两比较示,分支组与主干+分支组、主干组与主干+分支组差异有统计学意义(P<0.0125);主干+分支组D-二聚体水平最高,主干组次之,分支组最低,三组间比较(H=37.439,P<0.01)及两两比较差异均有统计学意义(P<0.05,P<0.01);主干+分支组血浆D-二聚体和纤维蛋白原比值(D/F)最高,主干组次之,分支组最低,三组间比较(H=33.973,P<0.01)及两两比较差异均有统计学意义(P<0.05,P<0.01)。结论血栓累及主干+分支的肝硬化PVT患者,发生消化道出血的风险最高,主干次之,分支最低。D-二聚体、D/F水平的高低可能对不同部位的肝硬化PVT诊断有一定的参考价值。     

临床与环境标本分离的大肠埃希菌blaCTX-M-14基因环境和菌株同源性分析

目的分析临床与环境标本分离的大肠埃希菌blaCTX-M-14基因环境和菌株同源性。方法收集2014年6月至2014年8月我院临床与环境标本分离的大肠埃希菌共255株,PhoenixTM-100鉴定细菌种类并测定最小抑菌浓度,纸片扩散法测定超广谱β-内酰胺酶表型,PCR扩增blaCTX-M-14基因;接合实验、质粒复制子分型分析质粒特征;脉冲场凝胶电泳和多位点序列分型对菌株分型。结果 blaCTX-M-14基因的阳性共26株。多数菌株(42.3%,11/26)含有F型质粒,且多具有可转移性。多位点序列分型多为ST131(30.8%,8/26)。仅有4株菌能在环境或大便标本中找到同源株。多数菌株(61.5%,16/26)blaCTX-M-14基因环境均具有相同的模式:上游有ISEcp1,同时下游有IS903。结论 blaCTX-M-14基因可通过医院环境或体内移位获得,但其广泛传播的原因可能与其编码在F型质粒上及其基因环境中存在ISEcp1和IS903有关。     

短串联重复序列基因座在石蜡包埋组织中的应用

目的探讨3种STR基因座分型系统在石蜡包埋组织基因座分型的差异。方法采用Qiagen法对保存1个月的石蜡包埋组织进行DNA提取,用Identifiler系统、PowerPlex 21系统及Investigator HDplex系统对STR基因座进行聚合酶链反应复合扩增、毛细管电泳、荧光检测及片段分析,比较3种系统的STR基因座检出率,并且采集组织同一个体的血液、毛发、口腔拭子等样本进行STR基因座分型,比较同一个体不同器官组织STR基因座分型的差异。结果经紫外分光光度计测定石蜡包埋组织的DNA浓度为6~85ng/μL,纯度1.7~2.2,Identifiler系统能够在DNA浓度大于15ng/μL时得到完整的基因座分型,PowerPlex 21系统在DNA浓度为85ng/μL时得到完整的基因座分型,而HDplex系统在石蜡组织检测中均未获得完整的基因座分型。石蜡包埋组织与其他器官组织分型结果存在差异,其中D6S474、D4S2366和D21S2055基因座存在等位基因不平衡或基因座丢失现象。结论石蜡包埋组织中DNA的浓度和纯度是STR基因座分型的重要影响因素,遗传信息丢失现象与检验对象的性状有关,也与所采用的检测系统有关,Identifiler系统对石蜡包埋组织的STR基因座分型具有较高的实用价值。     

Neutral microepidemic evolution of bacterial pathogens

Understanding bacterial population genetics is vital for interpreting the response of bacterial populations to selection pressures such as antibiotic treatment or vaccines targeted at only a subset of strains. The evolution of transmissible bacteria occurs by mutation and localized recombination and is influenced by epidemiological as well as molecular processes. We demonstrate that the observed population genetic structure of three important human pathogens, Streptococcus pneumoniae, Neisseria meningitidis, and Staphylococcus aureus, can be explained by using a simple evolutionary model that is based on neutral mutational drift, modulated by recombination, and which incorporates the impact of epidemic transmission in local populations. The predictions of this neutral "microepidemic" model are found to closely fit observed genetic relatedness distributions of bacteria sampled from their natural population, and it provides estimates of the relative rate of recombination that agree well with empirical estimates. The analysis suggests the emergence of neutral bacterial population structure from overlapping microepidemics within clustered host populations and provides insight into the nature and size distribution of these clusters. These findings challenge the assumption that strains of bacterial pathogens differ markedly in relative fitness.     

副溶血性弧菌病原学和分子流行病学流行特征研究进展

副溶血性弧菌是导致我国细菌性食物中毒事件的首要原因.临床分离株和环境分离株的病原学特征有着明显的差异.临床分离株以O3:K6血清型为主,tdh和(或)trh基因携带率较高,一般在80%以上,脉冲场凝胶电泳(PFGE)基因图谱具有明显的优势图谱,并且与血清分型具有一致性.而环境分离株(包括食品)多无优势血清型和优势PFGE图谱,tdh和(或)trh基因携带率远低于临床分离株,多在6%以下.各地临床分离株的耐药性差异较大,但对氨苄西林等早期药物耐药率均较高.环境分离株较临床分离株的耐药性更为严重和复杂.