肺炎链球菌致病的分子机理

肺炎链球菌致病机理的研究，内容上包括细菌结构成分，粘附机制，宿主免疫等几个方面；水平上包括毒力基因和毒力蛋白。本篇就Spn的主要结构，毒力因子，粘附加入侵方面的最新研究作一综述报道。     

肺炎链球菌致病的分子机理

肺炎链球菌致病机理的研究 ,内容上包括细菌结构成分、粘附机制、宿主免疫等几个方面 ;水平上包括毒力基因和毒力蛋白。本篇就Spn的主要结构、毒力因子、粘附和入侵方面的最新研究作一综述报道。     

肺炎链球菌蛋白质类的毒力因子

本文综述了肺炎锭球菌蛋白持类毒力因子的生物学性质和参与致病的可能机制，近年来肺炎链球菌与致病有关的蛋白虎来越受到重视，通过研究这些蛋白质类的毒力因子可以进一步弄清肺炎锭球菌的致病机理，并从中筛选疫苗的候选者，发展新一代多价疫苗，预防肺炎锭球菌杂性疾病的发生，以克服目前英膜多糖疫苗存在的两个主要缺点。     

颅内感染青霉素结合蛋白PBP1A、PBP2B和PBP2X同时变异的肺炎链球菌

肺炎链球菌拥有6种青霉素结合蛋白(PBPs),其中分子质量80000～90000的PBPs2X、2B、1A、1B和2A具有转肽酶的作用,在细胞壁肽聚糖的连接中起重要作用。β-内酰胺类药物与PBPs靶向结合,通过灭活转肽酶作用和影响细胞壁合成来抑制肺炎链球菌的生长。肺炎链球菌对青霉素耐药主要是因     

肺炎链球菌蛋白质类的毒力因子

本文综述了肺炎链球菌蛋白质类毒力因子的生物学性质和参与致病的可能机制。近年来肺炎链球菌与致病有关的蛋白质越来越受到重视。通过研究这些蛋白质类的毒力因子可以进一步弄清肺炎链球菌的致病机理．并从中筛选疫苗候选者，发展新一代多价疫苗，预防肺炎链球菌感染性疾病的发生，以克服目前荚膜多糖疫苗在在的两个主要缺点。     

肺炎链球菌重组PrtA蛋白克隆与表达的相关研究

目的 构建携带PrtA基因的原核表达载体,诱导表达具有活性的重组PrtA融合蛋白.方法 根据GenBank中肺炎链球菌表面蛋白细胞壁相关丝氨酸蛋白酶A(PrtA)蛋白基因序列,设计合成了一对特异性引物,扩增目的 片段,建立了RT-PCR检测方法.应用RT-RCR方法 扩增得到PrtA蛋白基因,并克隆到pMD18-T载体上,筛选、鉴定阳性重组子pMD18-T-PrtA,然后克隆到原核表达载体pET-30a(+)上,经双酶切、PCR鉴定,获得重组表达质粒pET-30a-PrtA.将含有pET-30a-PrtA的重组菌,经终浓度为0.6 mmol/L的IPTG诱导后,重组PrtA蛋白获得高效表达.通过Western blot检测结果,检测表达的重组PrtA蛋白的反应原性.结果 所获PrtA基因与GenBank的基因序列同源性为99%;重组质粒经IPTG诱导,不同浓度的IPTG均能诱导重组蛋白表达,且IPTG终浓度为0.6 mmol/L时,目的 蛋白的表达量最高,约占菌体总蛋白的18%.通过抗-His标签单克隆抗体在IPTG诱导6 h的重组菌蛋白中检测到一条大小约为40×103的特异性清晰条带,与预期结果 相符,表明表达的蛋白为肺炎链球菌重组PrtA蛋白.结论 成功地克隆和表达了肺炎链球菌表面蛋白细胞壁PrtA,为进一步研究以PrtA蛋白作为免疫原预防和治疗由肺炎链球菌引起的疾病奠定基础.     

肺炎链球菌生物膜形成的调节

肺炎链球菌是社区获得性肺炎的常见病原菌,近年来,该菌耐药性不断增加,其中生物膜(biofilm)的形成与肺炎链球菌在人体定植、反复感染密切相关.生物膜形成不仅使细菌对抗生素不敏感,还使细菌逃避宿主的免疫系统.现就外界环境因素、菌株自身特点、细胞外基质及信号调节等方面对肺炎链球菌生物膜形成的影响作一综述. 一、生物膜的基本概念 生物膜概念的提出最早可以追溯到20世纪80年代.1976年Marshall提到生物膜主要指细胞外多聚纤维,可以帮助细菌黏附到物质表面.随着对生物膜研究的深入,人们不仅认识到生物膜中细菌具有不可逆地黏附到物质表面且埋藏于基质中的特征,而且还认识到膜内细菌所发生的不同于浮游菌的生长速度与基因表达的改变.     

肺炎链球菌新型疫苗研究进展

肺炎链球菌是引起肺炎的主要病原体,肺炎链球菌性疾病是全球严重的公共卫生问题之一,每年约导致160万人死亡。目前,已明确的肺炎链球菌血清型高达100种,已上市的预防肺炎链球菌感染的疫苗只覆盖了部分肺炎链球菌血清型,无法预防非疫苗血清型和不可分型肺炎链球菌感染。因此,新型“通用型”肺炎链球菌疫苗的研发迫在眉睫,本综述旨在总结目前在用或在研究疫苗策略的优势和局限性,为进一步研发肺炎链球菌疫苗提供新的参考思路。     

肺炎链球菌感染的耐药性探讨

目的：了解临床分离肺炎链球菌对青霉素等抗生素的耐药性。方法：常规方法鉴定肺炎链球菌，纸片扩散法测试肺炎链球菌对9种抗生素敏感性。当苯唑西林抑菌圈≤19mm时以E-test浓度梯度法测定其对青霉素敏感性。白血液分离的菌株均以E-test法测定青霉素及万古霉素的MIC值。结果：从呼吸道、血液及眼分泌物共检出42株肺炎链球菌。苯唑西林筛纸片筛选耐药率达35，7％，进一步经青霉素E-test检测，耐青霉素肺炎链球菌(PRP)检出率实际为19．0％。PRP株耐药率及多重耐药性明显高于非PRP株。结论：苯唑西林纸片测试肺炎链球菌敏感性有一定重要误差(假耐药率)；PRP检出率虽比邻国报道低，但其发展趋势值得关注。     

肺炎链球菌243株耐药性研究

肺炎链球菌是引起儿童肺炎和败血症的常见致病菌 ,随着抗生素的广泛使用 ,肺炎链球菌耐药现象日益严重 ,如中国周边一些国家青霉素不敏感肺炎链球菌 (penicillin nonsensitivestreptococcuspneumoniae ,PNSP)的发生率高达57 9%～ 79 7% [1],而在儿童中的耐药率更是高于成人[2 ]。中国关于肺炎链球菌的研究相对较少 ,为此我们对浙江大学附属儿童医院分离的 2 43株肺炎链球菌进行了耐药性研究。一、材料与方法1.菌株来源 :2 0 0 1年 8月～ 2 0 0 2年 7月浙江大学医学院附属儿童医院从临床标本分离的 2 43株肺炎链球菌 ,2 12株分离自肺部感染…     

Mortality changes for patients with pneumococcal pneumonia from 2012 to 2017 in Japan

IntroductionPneumococcal pneumonia has a high morbidity and mortality in adults, especially those ≥65 years old. In the past decade, pneumococcal vaccination programs have been initiated worldwide, however, few data concerning mortality changes are available in pneumococcal pneumonia patients and there are no reports clarifying these current changes in Japan.MethodsJapanese patients ≥65 years old hospitalized with pneumococcal pneumonia between April 2012 and March 2018 were analyzed using the Diagnostic Procedure Combination database. In-hospital mortality was evaluated, and the odds ratios for this outcome in each fiscal year compared with that in 2012 was analyzed using multivariable logistic regression models.ResultsBetween 2012 and 2017, data of 47,375 pneumococcal pneumonia patients ≥65 years old were extracted. The incidence per 1000 person-years for in-hospital mortality was 60.4 in 2012, 56.8 in 2013, 63.2 in 2014, 56.1 in 2015, 73.0 in 2016, and 67.4 in 2017 and the odds ratios for in-hospital mortality in 2013, 2014, 2015, 2016, and 2017 compared with that in 2012 were 1.00, 1.05, 1.04, 1.06, and 0.98, respectively. There were no significant differences between 2012 and each year from 2013 to 2017. Low BMI; low ADL score; high A-DROP score; comorbid malignancy and heart failure; the coexistence of invasive pneumococcal infection; and the use of invasive mechanical ventilation were independent risk factors for in-hospital mortality.ConclusionsThere were no changes in in-hospital mortality in pneumococcal pneumonia patients between 2012 or each year from 2013 to 2017 and further epidemiological observations are necessary.     

Complement component 5 contributes to poor disease outcome in humans and mice with pneumococcal meningitis

Pneumococcal meningitis is the most common and severe form of bacterial meningitis. Fatality rates are substantial, and long-term sequelae develop in about half of survivors. Disease outcome has been related to the severity of the proinflammatory response in the subarachnoid space. The complement system, which mediates key inflammatory processes, has been implicated as a modulator of pneumococcal meningitis disease severity in animal studies. Additionally, SNPs in genes encoding complement pathway proteins have been linked to susceptibility to pneumococcal infection, although no associations with disease severity or outcome have been established. Here, we have performed a robust prospective nationwide genetic association study in patients with bacterial meningitis and found that a common nonsynonymous complement component 5 (C5) SNP (rs17611) is associated with unfavorable disease outcome. C5 fragment levels in cerebrospinal fluid (CSF) of patients with bacterial meningitis correlated with several clinical indicators of poor prognosis. Consistent with these human data, C5a receptor-deficient mice with pneumococcal meningitis had lower CSF wbc counts and decreased brain damage compared with WT mice. Adjuvant treatment with C5-specific monoclonal antibodies prevented death in all mice with pneumococcal meningitis. Thus, our results suggest C5-specific monoclonal antibodies could be a promising new antiinflammatory adjuvant therapy for pneumococcal meningitis.     

The prevalence and antimicrobial susceptibility of Streptococcus pneumoniae isolated from patients at Jikei University Hospitals after the implementation of the pneumococcal vaccination program in Japan

Studies have shown that pneumococcal vaccination reduces the incidence of Streptococcus pneumoniae infections but does not change the prevalence of S. pneumoniae nasopharyngeal colonization. To comprehensively and longitudinally assess the epidemiology of S. pneumoniae after the introduction of pneumococcal vaccination, we monitored the prevalence and antimicrobial susceptibility of S. pneumoniae, irrespective of its serotypes or pathogenicity, by analyzing specimens collected from a large number of patients at Jikei University Hospitals from 2009 to 2017. A total of 5763 S. pneumoniae isolates were identified out of 375,435 specimens from various sources of patients in different age groups. The prevalence of S. pneumoniae isolated only from patients <5 years old was significantly reduced with the widespread use of pneumococcal vaccines, although this reduction differed by areas where patients resided. The incidence of pneumococcal infections, including bacteremia and otitis media, clearly decreased among patients <5 years old after the introduction of pneumococcal vaccination, while the prevalence of S. pneumoniae isolated from blood specimens of patients 15–64 years old increased, suggesting the involvement of non-vaccine serotypes in the incidence of invasive pneumococcal infections. The antimicrobial susceptibility of S. pneumoniae improved after the introduction of pneumococcal vaccination. Our results show that pneumococcal vaccination has a suppressive effect on the prevalence of S. pneumoniae and the incidence of pneumococcal infections, at least for children <5 years old, in association with an improvement in the antimicrobial susceptibility of S. pneumoniae. However, further measures will be needed to control invasive pneumococcal infections caused by non-vaccine serotypes.     

Demonstration of cryoprecipitable immune complexes in pneumococcal pneumonia.

Cold-insoluble protein complexes (cryoprecipitates) can be found in the serum in a variety of infectious diseases. We studied serum cryoprecipitates isolated from three patients with pneumococcal pneumonia by counterimmunoelectrophoresis (CEP) and immunofluorescent technics for the presence of immune complexes. The cryoprecipitates and supernatant serum were tested for pneumococcal capsular polysaccharide (PCP) by CEP at 37 C and 56 C with the appropriate controls. Antibodies against PCP in the cryoprecipitates and the supernatant serum were detected as follows. Streptococcus pneumoniae from each case was fixed onto slides. The slides were incubated with each cryoprecipitate and supernatant serum at 37 C, and further incubated with fluorescein isothiocyanate-conjugated antisera to human IgG, IgM, and IgA. The slides were examined with an immunofluorescent microscope. PCP was demonstrated in all of the cryoprecipitates. IgG antibodies against PCP were detected in all of the cryoprecipitates, while IgM antibodies were detected in Cases 1 and 2, and IgA antibodies in Case 1 only. Complement components of C3 and C4 also were demonstrated in the cryoprecipitates by CEP. These findings suggest that some patients with pneumococcal pneumonia have cryoprecipitable-immune complexes consisting of PCP and its antibodies.     

Pneumococcal conjugated vaccine: PHiD-CV

At the beginning of a new century, we have gained significant achievements against pneumococcal infections by using conjugated pneumococcal vaccines. In January 2009, the EMEA issued a positive opinion about, and recommended the approval of, GlaxoSmithKline’s pediatric pneumococcal candidate vaccine, which is indicated for active immunization against invasive pneumococcal disease (IPD) and acute otitis media caused by Streptococcus pneumoniae in infants and children from 6 weeks up to 2 years of age. The approved 10-valent pneumococcal vaccine (PHiD-CV) contains all serotypes in 7-valent pneumococcal conjugate vaccine (PCV-7) plus serotypes 1, 5 and 7F. Protein D from nontypeable Haemophilus influenzae is the carrier protein for eight serotypes, while tetanus and diphtheria toxins are in the carrier proteins for the remaining two serotypes. It has also been proved that PHiD-CV is immunogenic, safe and well-tolerated in children. This vaccine can be coadministered with routinely used pediatric vaccines. Noninferiority criteria of PHiD-CV compared with PCV-7 were established in shared serotypes, except for serotypes 6B and 23F, and PHiD-CV is immunogenic for additional serotypes as assessed by the percentage of subjects with antibody concentrations. PHiD-CV is also immunogenic for ten serotypes as assessed by post-primary and post-booster dose opsonophagocytic activity responses. Vaccine efficacy against IPD and other conditions should be monitored for shared serotypes and also additional serotypes during the postmarketing period. Optimal scheduling, safety and immunogenicity data in children with different risk factors for IPD, or whether it will provide herd immunity, are the questions waiting for answers in the postmarketing period. Further studies are needed to assess the potential advantages of protein D as a carrier and the potential efficacy of this new vaccine against H. influenzae. The potential public health efficacy of PHiD-CV in low-income countries, where IPD and pneumonia are a major public health problem, is a major concern.     

Pneumococcal vaccine and opsonic pneumococcal antibody

Streptococcus pneumoniae is a major human pathogen responsible for the majority of bacterial pneumonia cases as well as invasive pneumococcal diseases with high mortality and morbidity. Use of conjugate vaccines targeting the pneumococcal capsule has dramatically reduced the incidence of invasive diseases, and there are active efforts to further improve the conjugate vaccines. However, in children new pneumococcal vaccines can no longer be tested with placebo-based clinical trials because effective vaccines are currently available. Thus, vaccine studies must depend on surrogate markers of vaccine efficacy. Although traditional antibody levels (e.g., ELISA) are useful as a surrogate marker of protection, they have limitations, and a bioassay measuring the capacity of antibodies to opsonize pneumococci has been developed. This opsonophagocytosis assay (OPA) replicates the in vivo mechanism of antibody protection and should therefore better reflect protection by vaccine-induced antibodies. Technical improvements of OPA have made this bioassay rapid, multiplexed, and practical for analyzing small samples including those from children. Strong correlations between ELISA and OPA have been observed in many studies of young children. However, poor correlations have been found in some important clinical situations (such as determination of protection by cross-reactive antibodies) and populations (such as elderly adults and immunodeficient patients). In these settings, OPA has become a useful supplementary measure of pneumococcal vaccine immunogenicity. Current efforts to standardize OPA will further expand its uses.     

Emergence of Streptococcus pneumoniae with very-high-level resistance to penicillin

Penicillin resistance threatens the treatment of pneumococcal infections. We used sentinel hospital surveillance (1978 to 2001) and population-based surveillance (1995 to 2001) in seven states in the Active Bacterial Core surveillance of the Emerging Infections Program Network to document the emergence in the United States of invasive pneumococcal isolates with very-high-level penicillin resistance (MIC > or = 8 microg/ml). Very-high-level penicillin resistance was first detected in 1995 in multiple pneumococcal serotypes in three regions of the United States. The prevalence increased from 0.56% (14 of 2,507) of isolates in 1995 to 0.87% in 2001 (P = 0.03), with peaks in 1996 and 2000 associated with epidemics in Georgia and Maryland. For a majority of the strains the MICs of amoxicillin (91%), cefuroxime (100%), and cefotaxime (68%), were > or =8 microg/ml and all were resistant to at least one other drug class. Pneumonia (50%) and bacteremia (36%) were the most common clinical presentations. Factors associated with very highly resistant infections included residence in Tennessee, age of <5 or > or =65 years, and resistance to at least three drug classes. Hospitalization and case fatality rates were not higher than those of other pneumococcal infection patients; length of hospital stay was longer, controlling for age. Among the strains from 2000 and 2001, 39% were related to Tennessee(23F)-4 and 35% were related to England(14-)9. After the introduction of the pneumococcal conjugate vaccine, the incidence of highly penicillin resistant infections decreased by 50% among children <5 years of age. The emergence, clonality, and association of very-high-level penicillin resistance with multiple drug resistance requires further monitoring and highlights the need for novel agents active against the pneumococcus.     

Pneumococcal Infection — Low Awareness as a Potential Barrier to Vaccination: Results of a European Survey

Introduction

Elderly people and adults with chronic disease or compromised immune status are at increased risk of pneumococcal infection, with pneumonia being the most common serious presentation and a significant cause of morbidity and mortality. Most European countries have recommendations for pneumococcal vaccination but vaccination rates have remained low. In the present article, the authors present the results of a European survey that investigated the current level of awareness of pneumococcal infection among primary care physicians and specialists, and attitudes to vaccination in these physicians and members of the general public aged >50 years.

Methods

Primary care physicians (n = 1,300) and specialists (n = 926) from 13 Western European countries participated in online/face-to-face interviews, and a further 6,534 individuals aged >50 years from a population sample reflecting local socio-demographic structure participated in telephone/face-to-face interviews.

Results

Pneumonia was the most well-known of the pneumococcal infections amongst primary care physicians and specialists. However, there was a relatively low awareness of the term invasive pneumococcal disease (IPD), with only 50% of primary care physicians and 71% of specialists reporting knowledge of the term IPD. Key factors influencing a physician’s decision to prescribe pneumococcal vaccination were the patient’s health condition, recommendations from health authorities, and the tolerability of the vaccine. Perceptions regarding vaccination were good amongst the members of the general public; individuals did not fear vaccines or their side effects. The main drivers for vaccination were recommendations from a healthcare professional and, to a lesser extent, that vaccination provides reassurance against contracting a disease.

Conclusion

These findings highlight the low awareness of the term IPD in comparison with individual pneumococcal conditions. Given the importance of physician recommendations in encouraging patients to be vaccinated, primary care physicians need to be vigilant of patients at risk of pneumococcal infections in order to increase vaccination rates.