ST6型金黄色葡萄球菌食物中毒菌株的毒力因子分析

目的检测食物中毒优势型ST6型菌株的毒力基因特征,为食品安全风险评估、食源性病原菌的监测和致病性研究提供依据。方法选取深圳地区7次食物中毒收集的32株ST6型菌株进行全基因组测序,利用VFDB数据库进行毒力因子分析,并通过序列比对进行SEA亚型分析。结果第1-4起食物中毒ST6菌株携带的毒力因子谱完全相同;第5-7起食物中毒中,同一起食物中毒的暴发菌株携带的毒力因子一致,而非暴发菌株与暴发菌株携带的毒力因子不完全一致。在32株ST6型菌中,与粘附、酶和Ⅶ型分泌系统相关的毒力基因具有较高的携带率,α-溶血素(hly/hla)、β-溶血素(hlb)、δ-溶血素(hld)、γ-溶血素基因(hlgA、hlgB、hlgC)、肠毒素A基因(sea)和表皮剥脱毒素A基因(eta)的携带率均为100%,双组分白细胞毒素LukDE基因(lukD和lukE)的携带率为96.8%。所有菌株携带的肠毒素A均为SEA1亚型。结论32株ST6型食物中毒相关菌株携带多个毒力因子基因,以cna、sea、eta、lukD、lukE毒力基因携带率较高,编码的毒力因子可能对ST6型菌株的致病性产生影响。     

金黄色葡萄球菌VII型分泌系统研究进展

细菌分泌系统是细菌依赖分泌通路进行蛋白质的跨胞浆膜转运系统,该分泌系统中存在的蛋白或蛋白性质的毒力因子与细菌的生存、繁殖和扩散紧密相关。已发现的几种分泌系统中,VII型分泌系统主要存在于革兰氏阳性菌中,其不仅与细菌的生长和致病性密切相关,而且可能在细菌毒力分泌方面发挥关键作用。本文将对金黄色葡萄球菌VII型分泌系统类型、分泌底物结构、对金黄色葡萄球菌的毒力调控机制等方面进行论述。     

耐甲氧西林金黄色葡萄球菌对万古霉素敏感性的变迁

目的　通过对近年来耐甲氧西林金黄色葡萄球菌 (MRSA)临床分离株对万古霉素抑菌圈直径的分析 ,研究MRSA对万古霉素敏感性的变化。方法　药敏试验采用纸片扩散法 (K B法 ) ,抑菌圈直径的比较采用t检验。结果　 1994～ 2 0 0 0年每年收集的临床分离的MRSA菌株数分别为 2 18、187、2 92、2 37、35 1、886和 6 5 2 ,各年菌株对万古霉素抑菌圈的平均直径 (mm)分别为 19 9、19 1、18 6、17 4、18 4、18 2和 17 8。 2 0 0 0年的 6 5 2株MRSA对万古霉素抑菌圈的平均直径 (17 8mm)明显小于1994年 2 18株MRSA的平均直径 (19 9mm) ,差异有显著性 (P <0 0 0 1)。 2 0 0 0年分离的MRSA对氯霉素、环丙沙星、红霉素、庆大霉素、四环素和复方新诺明等常用抗生素的耐药率均很高 ,其耐药百分率分别为 44 0 %、73 7%、89 1%、6 5 7%、6 1 0 %和 6 7 0 %。结论　 1994年到 2 0 0 0年MRSA对万古霉素的敏感性在逐年降低 ,加强金黄色葡萄球菌对万古霉素敏感性的监测非常必要。     

耐甲氧西林金黄色葡萄球菌（MRSA）感染机制研究进展

耐甲氧西林金黄色葡萄球菌（MRSA）是一种新型金黄色葡萄球菌,它会造成严重感染性疾病。MRSA对p内酰胺类抗生素耐药性的产生及毒力的加强使得它成为了临床治疗的-大痼疾。一些虽然低效但较少产生耐药的抗生素的出现使得MRSA治疗有了新的选择。同时,研究者正在逐渐阐明MRSA基因突变和病原学特征（耐药性、毒力等）的相关性。这些成果都将为今后MRSA的临床治疗以及新药和疫苗的开发提供宝贵的理论支持与指导。     

金黄色葡萄球菌isdA基因对宿主上皮细胞免疫指标的影响

目的 对金黄色葡萄球菌IsdA的编码基因缺失前后与宿主上皮细胞共孵育后的免疫学进行研究,为进一步研究金葡菌感染机制及抗金葡菌制剂的研究提供依据。方法 金黄葡萄球菌野生株Newman和IsdA缺失株NewmanΔIsdA分别作用于上皮细胞Hacat,运用实时荧光定量PCR、ELISA及Western Blot方法检测细胞促炎性细胞因子和趋化因子的分泌情况。结果 PCR结果表明,金黄色葡萄球菌IsdA+/-均能提高上皮细胞分泌促炎性细胞因子(IL-8、TNF-α和IL-6),趋化因子MCP-1,表面受体TLR2和TLR4,C型植物血凝素-1(dectin-1)及抗菌肽LL-37的表达,而IsdA-/-诱导上皮细胞释放细胞因子的能力要低于IsdA+/+,但IsdA-/-组上皮细胞因子水平高于正常对照组;通过ELISA、Western Blot检测与PCR结果一致。结论 研究表明,受金黄色葡萄球菌缺失株NewmanΔIsdA作用的上皮细胞促炎症因子分泌减少,细胞表面受体蛋白的表达和转录水平也相应降低,暗示了该缺失株的侵袭力降低,为进一步研究金葡菌感染机制及抗金葡菌制剂提供依据。     

夫西地酸治疗37例耐甲氧西林金黄色葡萄球菌性呼吸机相关性肺炎临床观察

目的 观察夫西地酸治疗耐甲氧西林金黄色葡萄球菌性呼吸机相关性肺炎临床疗效.方法 选择耐甲氧西林金黄色葡萄球菌性呼吸机相关性肺炎患者37例.应用夫西地酸钠0.5 g加入0.9%氯化钠注射液250 ml中,静脉滴注,1次/8 h,60 min滴入,连用10～14 d,观察其临床疗效、细菌清除率、肝肾功能变化、不良反应.结果夫西地酸治疗耐甲氧西林金黄色葡萄球菌性呼吸机相关性肺炎临床治愈率为67.6%,有效率为86.5%.细菌清除率为62.2%;治疗过程中对肝肾功能无明显影响;无明显不良反应.结论 夫西地酸作为一种安全性较高的药物,对耐甲氧西林金黄色葡萄球菌性呼吸机相关性肺炎效果较好.对于老年和(或)肾功能不良(或潜在不良)患者,可选择该药治疗.     

金黄色葡萄球菌对万古霉素耐药机制的初步研究

目的了解金黄色葡萄球菌对万古霉素耐药机制。方法按照美国临床实验室标准化委员会(NCCLS)标准,应用琼脂平板稀释法及MRSA特异性基因mecA的扩增鉴定MRSA,诱导产生万古霉素耐药株,然后以超声破碎法提取外膜蛋白(OMP),经聚丙烯酰胺凝胶电泳(SDS-PAGE)分析OMP的成分,分光光度法扫描仪测定相关膜蛋白的相对含量。结果耐万古霉素金葡菌菌株中,分子量为45KD和14KD的膜蛋白的相对含量较金葡菌ATCC25923株和对万古霉素敏感的MRSA少。结论提示45KD和14KD膜蛋白减少或缺失与金葡菌对万古霉素耐药可能有密切关系。     

体外诱导万古霉素耐药金葡菌及耐药菌株抗生素敏感性变化分析

目的诱导对万古霉素耐药金葡菌,分析金葡菌对万古霉素耐药后其他的药物敏感性变化情况。方法在体外用万古霉素对15株金葡菌进行诱导;诱导过程中检测23SrRNA基因对菌种进行鉴定;诱导出万古霉素耐药金葡菌后,检测耐药菌株其他抗生素药物敏感性并与诱导前进行比较。结果诱导出3株对万古霉素中介耐药金葡菌;诱导前后菌株都扩增出金葡菌23SrRNA基因;对万古霉素耐药后金葡菌对其他抗生素药物敏感性也发生改变。结论万古霉素体外很难诱导完全耐药菌株,但可以诱导出中介耐药菌株;对万古霉素耐药后金葡菌对其他抗生素耐药性也增加。     

养殖源耐甲氧西林金黄色葡萄球菌的SCCmec耐药元件、毒力危害和流行性分析

金黄色葡萄球菌(Staphylococcus aureus)是一种常见的人兽共患病病原菌,其分泌的外毒素如溶血素、杀白细胞素、脱皮毒素、肠毒素等可引发人或养殖动物多种疾病。耐甲氧西林金黄色葡萄球菌(Methicillin-resistant Staphylococcus aureus, MRSA)是携带含mec基因簇的葡萄球菌盒氏染色体(Staphylococcal chromosome cassette mec, SCCmec)遗传元件的多重耐药菌。SCCmec对MRSA的多重耐药性起重要作用。SCCmec元件中mecA基因介导了MRSA对β-内酰胺类药物的耐药性,而SCCmec元件的可变区插入的耐药基因对MRSA的多重耐药性具有重要作用。近年来,欧洲、北美等国家陆续报道在养殖业环境及动物中检测到多重耐药的养殖源MRSA(Livestock-associated MRSA,LA-MRSA),且LA-MRSA可以通过养殖环境等途径传播到人,对人的健康和公共卫生安全构成潜在威胁。本文综述了S. aureus的耐药性变化、MRSA的SCCmec耐药元件和SCCmec型别变迁以及LA-MRSA的毒力危害和流行状况,对了解S. aureus耐药性和SCCmec分型以及控制和预防LA-MRSA在人兽间传播、感染具有一定的指导意义。     

Cannula-associated Staphylococcus aureus bacteraemia: outcome in relation to treatment

BACKGROUND: Despite the frequency of cannula-associated Staphylococcus aureus bacteraemia (CASAB) there is uncertainty regarding the duration of treatment required. AIM: To determine the relationship between the duration and type of treatment for CASAB and subsequent relapse with deep-seated S. aureus infection. METHODS: We prospectively studied 276 patients with CASAB. Patients were followed for at least 8 weeks after completion of antibiotic treatment. Initial and subsequent isolates of S. aureus were compared using molecular methods to determine strain similarity. Results: Initial mortality was 9% (26 of 276) and a complicating focus of infection presented during initial treatment in 6% (15 of 250) of the survivors. There were nine relapses of deep-seated infection from the strain causing the original infection. Relapses were equally common following peripheral CASAB and central CASAB. There was no relationship between the duration of treatment and the rate of relapse of deep-seated infection (P = 0.24). This observation held true regardless of whether the duration of treatment was analysed as < or = 7 versus > or = 8, < or =10 versus > or =11, or < or=14 versus > or =15 days (P = 0.62, 0.87 and 0.16, respectively). Conclusion: Episodes of peripheral CASAB pose an equal risk of relapse to central cannula-related episodes. Although further studies are needed to determine the optimal treatment of CASAB, our study strongly suggests that more than 14 days treatment is excessive for most patients who respond promptly to cannula removal and antibiotic treatment.     

耐甲氧西林金葡菌的临床分离率及其耐药性分析

目的 了解成都地区耐甲氧西林金黄色葡萄球菌（MRSA）耐药情况。方法 应用琼脂平皿二倍稀释法，测定万古霉素等12种抗菌药物对成都地区分离到的272株金黄色葡萄球菌（SA）的最低抑菌浓度（MIC）。结果 MRSA占临床分离SA的31.6%。MSSA除对青霉素，克拉霉素，氧氟沙星和环丙沙星部分耐药外，对其他所测抗菌药物均基本敏感，MRSA除对万古霉素敏感外，对其它抗生素均显示出不同程度的耐药。结论 MRSA对克拉霉素的耐药率最高（95.4%)，以下依次为环丙沙星（55.8%)，氧氟沙星（50.0%)，氨苄青霉素/舒巴坦（39.5%)。头孢唑啉以下依次为环丙沙星（55.8%)。氧氟沙星（50.0%)。氨苄青霉素/舒巴坦（39.5%)。头孢唑啉（36.1%)，头孢噻肟（30.3%)。利福平（27.9%)亚胺培南(17.5%)和阿米卡星（8.1%)。     

下呼吸道感染金葡菌耐药性分析

目的调查我院住院病人下呼吸道感染金黄色葡萄球菌（SA）的耐药现状。方法对101例下呼吸道感染sA的住院病人临床资料进行分析,并比较甲氧西林敏感金黄色葡萄球菌（MSSA）与耐甲氧西林金黄色葡萄球菌（MRSA）对抗生素的耐药性差异。结果共101例下呼吸道感染患者,分离出MRSA71例,分离率70．30％。下呼吸道sA感染发生于基础疾病较多,接受侵入性操作,长时间使用抗生素的患者;药敏结果显示,MRSA对多种抗菌药物的产生高度耐药,且耐药率明显高于MSSA（P〈0．01）,但对替加环素、万古霉素、利奈唑胺敏感率为100％。结论下呼吸道感染sA多发生于危险因素较多的患者;MRSA分离率高,对常用抗菌药物呈多重耐药。     

Staphylococcus aureus binds to the N-terminal region of corneodesmosin to adhere to the stratum corneum in atopic dermatitis

Staphylococcus aureus colonizes the skin of the majority of patients with atopic dermatitis (AD), and its presence increases disease severity. Adhesion of S. aureus to corneocytes in the stratum corneum is a key initial event in colonization, but the bacterial and host factors contributing to this process have not been defined. Here, we show that S. aureus interacts with the host protein corneodesmosin. Corneodesmosin is aberrantly displayed on the tips of villus-like projections that occur on the surface of AD corneocytes as a result of low levels of skin humectants known as natural moisturizing factor (NMF). An S. aureus mutant deficient in fibronectin binding protein B (FnBPB) and clumping factor B (ClfB) did not bind to corneodesmosin in vitro. Using surface plasmon resonance, we found that FnBPB and ClfB proteins bound with similar affinities. The S. aureus binding site was localized to the N-terminal glycine–serine-rich region of corneodesmosin. Atomic force microscopy showed that the N-terminal region was present on corneocytes containing low levels of NMF and that blocking it with an antibody inhibited binding of individual S. aureus cells to corneocytes. Finally, we found that S. aureus mutants deficient in FnBPB or ClfB have a reduced ability to adhere to low-NMF corneocytes from patients. In summary, we show that FnBPB and ClfB interact with the accessible N-terminal region of corneodesmosin on AD corneocytes, allowing S. aureus to take advantage of the aberrant display of corneodesmosin that accompanies low NMF in AD. This interaction facilitates the characteristic strong binding of S. aureus to AD corneocytes.

Atopic dermatitis (AD) is a chronic inflammatory skin disorder, affecting 15 to 20% of children (1, 2). During disease flares, patients experience painful inflamed skin lesions accompanied by intense itch. Epidermal barrier dysfunction, increased type 2 immune responses, and recurrent skin infections are features of AD (3). The most common cause of infection is Staphylococcus aureus. This bacterium colonizes the skin of the majority of AD patients (4, 5). Isolates representing several S. aureus lineages are recovered from AD skin; however, strains from the clonal complex 1 (CC1) lineage are the most frequently isolated (6–9). The burden of S. aureus on lesional and nonlesional skin correlates with severity of the disease (10, 11). S. aureus directly influences pathogenesis, and several factors produced by the bacterium increase inflammation and exacerbate AD symptoms, including staphylococcal superantigen B and delta-toxin (12–15).Despite the clear association between S. aureus colonization and AD disease severity (11), the bacterial and host factor determinants underlying colonization are poorly understood (16). Adhesion is a critical early step in the colonization process. S. aureus adheres to corneocytes in the stratum corneum of AD skin (6, 17, 18). We previously found that clumping factor B (ClfB), a cell wall-anchored protein displayed on the surface of S. aureus, can mediate adhesion to corneocytes from AD patients (6). ClfB also binds to the alpha chain of fibrinogen and to the cornified envelope proteins loricrin and cytokeratin 10 (K10) in desquamated nasal epithelial cells (19–21). To date, ClfB is the only bacterial factor known to promote adherence to corneocytes in AD. However, a ClfB-deficient mutant retained the ability to bind to corneocytes (6), suggesting that additional bacterial factors are at play.Filaggrin deficiency is common in patients with established AD and is either genetic or caused by down-regulation of gene expression by Th-2–type cytokines (22–24). Filaggrin deficiency causes epidermal barrier defects and a loss of the hygroscopic filaggrin breakdown products that normally contribute to the natural moisturizing factor (NMF) in corneocytes (25). NMF comprises a collection of humectants, including filaggrin breakdown products urocanic acid and pyrrolidone acid, along with urea, citrate, lactate acid, and sugars, and is responsible for regulating hydration in the skin (26). Low-NMF levels are associated with a loss of hydration, increased disease severity, and abnormal corneocyte morphology (27). We showed recently that S. aureus binds more strongly to low-NMF AD corneocytes than to corneocytes with normal levels of NMF (18).Corneocytes with low NMF have very different surface topography when compared with corneocytes with normal levels of NMF (27). Aberrant “villus-like” projections (VPs) protrude from the surface of low-NMF corneocytes (18, 27). The protein corneodesmosin (CDSN) is confined to the cell–cell junctions between corneocytes in healthy skin, where homophilic interactions between the CDSN proteins on adjacent cells facilitate cell–cell cohesion (28). In AD patients, however, CDSN decorates the tips of the VPs on low-NMF corneocytes (27).This study aimed to elucidate a key component of S. aureus colonization by identifying the molecular determinants of adherence to AD corneocytes. We recognized that the occurrence of VPs on low-NMF corneocytes presents a different colonization surface to the bacterium and postulated that the accessibility of CDSN on the tips of VPs could influence pathogen adherence. We show that S. aureus can interact with CDSN and identify the S. aureus proteins promoting adherence to this host protein. We use single-cell and single-molecule atomic force microscopy (AFM), surface plasmon resonance (SPR), and ex vivo bacterial adherence studies with patient corneocytes to characterize this interaction. This study expands the repertoire of ligands for S. aureus and, crucially, links bacterial interactions with a host protein (CDSN) to binding to corneocytes taken from patients. Thus, our findings provide insights into the adhesion process and develop our understanding of the mechanisms underlying colonization of the skin of AD patients by S. aureus.     

耐甲氧西林金黄色葡萄球菌检出动态及对万古霉素的耐药性变迁

目的 观察耐甲氧西林金黄色葡萄球菌(MRSA)在临床标本中的检出动态及对万古霉素的耐药性变化趋势。方法 检测1966年～2001年各年度各种临床标本中MRSAR的分离率，测量万古霉素对MRSA的抑菌环直径大小。结果 1996～2000年5年内MRSA检出率有逐年上升趋势，2001年通过筛查MRSA携带者并采取消毒隔离措施后，2001年MRSA检出率为32．1％，与2000年(45．9％)、1999年检出率(38．5％)比较明显降低，与1998年(30．2％)接近。随着时间推移，各年度MRSA对万古霉素的抑菌圈直径逐年减小。结论 通过筛查MRSA携带者并采取严格的消毒隔离措施，可使MRSA的检出率下降。MRSA对万古霉素的敏感程度在逐年降低。     

社区获得性耐甲氧西林金黄色葡萄球菌肺炎临床分析

目的 探讨社区获得性耐甲氧西林金黄色葡萄球菌肺炎的临床特点.方法 对16例确诊病例的临床资料进行回顾性研究.结果 16例确诊病例,13例无基础性疾病,9例合并休克,7例合并急性呼吸窘迫综合征,4例死亡;死亡者从出现症状入院至死亡平均时间为(5.9±6.1)d,生存者平均住院时间为(21.6±11.1)d;8例有流感样症状,7例有咯血,5例有白细胞减少,16例C-反应蛋白明显升高,平均为(211.1±121.9) mg/L,13例有多肺叶病变,9例有胸腔积液.结论 社区获得性耐甲氧西林金黄色葡萄球菌肺炎病情凶险,应提高对其临床特点的认识,优化综合治疗方案.     

Metastatic Complications of Staphylococcus aureus Septicemia. To Seek is to Find

Summary Improvement in the high mortality from Staphylococcus aureus septicemia must address the individualized treatment (surgery and/or prolonged antibiotic treatment) of metastatic complications. The aim of this study was to evaluate the results of a comprehensive diagnostic monitoring for metastatic complications in S. aureus septicemia. 68 consecutive patients with S. aureus septicemia were prospectively followed. The performance rate and results of chest X-ray, echocardiography, bone scintigraphy and leukocyte scintigraphy are described. Metastatic complications were found in 53% of the 68 patients, endocarditis in 26%. Positive findings resulted in surgical intervention in 23 patients. The total mortality defined as all deaths within 12 weeks was 24%; 81% of the deceased were ≥ 60 years of age. Non-endocarditis patients with peripheral septic metastases had good prognosis. An active monitoring for metastatic complications in S. aureus septicemia is a necessary prerequisite for optimizing treatment and to improve survival rate. Received: October 5, 1999 · Revision accepted: February 8, 2000     

Investigation of a cluster of Staphylococcus aureus invasive infection in the Top End of the Northern Territory

Introduction: Staphylococcus aureus invasive infection remains a serious condition associated with considerable morbidity and mortality. Following notification of five cases at Royal Darwin Hospital (RDH), we searched for related cases, determined their epidemiological characteristics and attempted to identify the source of this apparent cluster. Methods: We reviewed RDH microbiology records between June 1996 and April 1997 for S. aureus isolates with similar antibiograms to notified cases. We used antibiotic resistance patterns, bacteriophage typing and two molecular typing techniques to subtype implicated isolates. Hospital records were reviewed for admission details and associated costs were estimated. Results: Fifty-four cluster-related isolates occurred in 47 separate presentations. The peak incidence was in the wet season. The most important risk factor for staphylococcal invasive infection was the presence of skin sores/scabies in 17/54 cases (31%), followed by intravascular line use in 14/54 (26%), open trauma in 11/54 (20%), underlying end stage renal failure and alcoholism each in ten of 54 (18%). The mean admission length was 30 days and antibiotics were given for an average of 23 days. Death due to S. aureus infection occurred in eight of 47 (17%) presentations. S. aureus pneumonia was community acquired in 12/13 patients (92%) and six of 13 (46%) died. Ten of 13 (80%) pneumonia patients had at least one other focus of S. aureus infection. The cost of antibiotics and hospital bed per presentation was approximately $16,000. Presentations with skin sores/scabies cost considerably more ($31,000). No common epidemiologic features were found for community or hospital acquired cases. Conclusion: Considerable mortality and cost was attributable to cases of S. aureus invasive infection during this cluster; particularly those with community acquired pneumonia or skin sores/scabies. Staphylococcal antibiotic cover should be considered early for unwell patients presenting to hospital with pneumonia and other signs of potential S. aureus infection. It is appropriate to target public health efforts to prevent skin sores and to provide adequate treatment when they occur.     

Osmolyte transport in Staphylococcus aureus and the role in pathogenesis

Osmolyte transport is a pivotal part of bacterial life, particularly in high salt environments. Several low and high affinity osmolyte transport systems have been identified in various bacterial species. A lot of research has centered on characterizing the osmolyte transport systems of Gram-negative bacteria, but less has been done to characterize the same transport systems in Gram-positive bacteria. This review will focus on the previous work that has been done to understand the osmolyte transport systems in the species Staphylococcus aureus and how these transporters may serve dual functions in allowing the bacteria to survive and grow in a variety of environments, including on the surface or within humans or other animals.