治疗耐甲氧西林金黄色葡萄球菌感染的5种抗菌药物的应用评价

介绍5种治疗耐甲氧西林金黄色葡萄球菌（MRSA）感染的药物在临床上的使用特色,应结合各药物特点作个体化选药与给药方案制定,这对MRSA感染治疗的安全性、有效性至关重要。     

万古霉素与替考拉宁治疗肝移植术后MRSA菌血症疗效与安全性比较

目的：比较万古霉素和替考拉宁治疗重症监护病房肝移植术后耐甲氧西林金黄色葡萄球（MRSA）感染的疗效和安全性。方法：将12例肝移植术后MRSA感染病人随机分为万古霉素治疗组和替考拉宁治疗组,比较两组病人应用抗生素后的治愈率和不良反应。结果：万古霉素与替考拉宁治疗MRSA的治愈率分别为71．4％和60．0％,细菌清除率分别为88．2％和86．7％,不良反应发生率为28．5％和60％,两组间MRSA治愈率有显著性差异（P〈0．05）。结论：万古霉素对重症监护病房肝移植术后MRSA感染的早期治疗效果优于替考拉宁,可以作为此类病人的首选用药。     

Retrospective case-control analysis of patients with staphylococcal infections receiving daptomycin or glycopeptide therapy

Glycopeptides have been considered the antimicrobials of choice for serious meticillin-resistant Staphylococcus aureus (MRSA) and meticillin-resistant coagulase-negative staphylococci (MR-CoNS) infections for several years. Daptomycin is a new option for the treatment of these infections, including those exhibiting reduced susceptibility to glycopeptides. The aim of this study was to compare glycopeptides and daptomycin for the treatment of infections caused by MRSA or MR-CoNS. Data for 106 patients with bloodstream infections (bacteraemia or infective endocarditis) or skin and soft-tissue infections (SSTIs) were retrospectively reviewed, of which 43 were treated with daptomycin (DAP group) and 63 were treated with vancomycin or teicoplanin (GLYCO group). Patients included in the two comparison groups were homogeneous in terms of age, risk factors and clinical severity. Aetiology was mainly represented by MRSA in both groups, followed by various species of MR-CoNS. Daptomycin was used more frequently in patients with central venous catheter-associated bacteraemia or pacemaker-associated infection. Patients with SSTIs included in the GLYCO group had a longer mean duration of antibiotic therapy (18.2 days vs. 14.6 days; P = 0.009) and a longer mean length of hospital stay (28.2 days vs. 19.6 days; P = 0.01) compared with those included in the DAP group. A longer mean duration of antibiotic therapy was also observed in patients with bloodstream infections receiving glycopeptide therapy (25.6 days vs. 18 days; P = 0.004). In conclusion, the good clinical efficacy of daptomycin is associated with a more rapid resolution of the clinical syndrome and a reduced length of hospitalisation. This latter aspect may have important pharmacoeconomic implications, promoting the use of daptomycin in the clinical setting.     

万古霉素产生菌的选育与发酵培养基优化

万古霉素产生菌东方拟无枝酸菌（Amycolatopsis orientalis）5－13经紫外线（30W，253.7nm，距离30cm，照射50s）诱变后，在含万古霉素1000μg/ml的浓度梯度平板上筛选万古霉素抗性变株，得到一株万古霉素抗性变株A.orientalis 6-21，其摇瓶效价较出发菌株提高23％，对万古霉素的抗性提高200％。传代试验表明该变株的高产性能遗传特性较稳定。用正交试验法对万古霉素发酵培养基进行了优化，与原发酵培养基相比，万古霉素的摇瓶发酵效价提高了14.3%。     

异质性万古霉素中介金黄色葡萄球菌的检测方法和耐药性分析

目的 研究比较异质性万古霉素中介金黄色葡萄球菌(hVISA)的几种筛查方法,制定出适合的hVISA的筛查方法.方法 收集2018年1月—2019年12月江南大学附属医院临床标本中分离出的耐甲氧西林金黄色葡萄球菌株(MRSA),采用宏量E-test法(MET法)、BHIV3V、BHIV6V及MHA5T法筛查hVISA,最...     

Effects of Helichrysum italicum extract on growth and enzymatic activity of Staphylococcus aureus

Helichrysum italicum G. Don (Compositae) is a shrub commonly found in dry, sandy and stony areas of Mediterranean regions. This plant is known for its anti-inflammatory, anti-allergic and antimicrobial activity. The aim of this study was to evaluate the effect of the diethyl ether extract on growth of Staphylococcus aureus (ATCC 6538P, MRSA and MSSA isolates) and the influence of subminimum inhibitory concentrations (subMICs) on some enzymes which are considered virulence factors. The results indicate that the H. italicum extract had an inhibitory effect on S. aureus strains reducing both their growth and some of the enzymes such as coagulase, DNAse, thermonuclease and lipase. Helichrysum italicum extract could be a novel antimicrobial agent, less toxic to human skin and tissues, worthy of further studies.     

The effect of Nepeta cataria extract on adherence and enzyme production of Staphylococcus aureus

Nepeta cataria L., commonly known as catnip, is a perennial herb with a considerable folkloric reputation. A diethyl ether extract of this plant has been shown to have antimicrobial activity against fungi and Gram-positive bacteria. The aim of this work was to study the activity of N. cataria extract on 44 Staphylococcus aureus strains, some resistant to methicillin, and S. aureus 6538P (American Type Culture Collection) by evaluating the effect of subminimum inhibitory concentrations on coagulase, DNAse, thermonuclease and lipase production, and on in-vitro adherence. DNAse, thermonuclease and lipase were inhibited by concentrations equal to 1/2 and 1/4 MIC. A reduction of adherence was also observed.     

Metabolism of rabbit kidney cells incubated in vitro with phospholipase C from Staphylococcus aureus and Clostridium perfringens

An established cell line of rabbit kidney cells (RK-13) was treated with subcytotoxic concentrations of two highly purified toxic bacterial phospholipases C, beta-toxin from Staphylococcus aureus and alpha-toxin from Clostridium perfringens. Although the concentrations used did not increase the number of cells stained with nigrosin, a decrease in active uptake of ⁸⁶Rb and increase of leakage out of the cell of ⁸⁶Rb was noted within 60 min of incubation at 37°C with 40 hemolytic units of beta-toxin and 10 enzymatic units of alpha-toxin. Binding of ouabain to the cells was also impaired. Cl. perfringens alpha-toxin caused in general much greater damage to the cells than the staphylococcal beta-toxin, which is in accordance with the broader substrate specificity of the former enzyme. Cell metabolism was also studied up to 8 hr after incubation with the toxins for 1 hr. Staphylococcal beta-toxin temporarily inhibited the uptake of ³H-glycine, but not ³H-thymidine or ³H-uridine. Cl. perfringens alpha-toxin, on the other hand, affected first the uptake of ³H-thymidine and later the uptake of ³H-glycine. The intracellular content of cyclic AMP was doubled after 1 hr, but declined in a few hr below the control value. It is concluded that the cytoplasmic membrane was affected by these two enzymatic toxins in subcytotoxic doses, and that the different membrane functions investigated varied as to their dependence upon an intact phospholipid milieu.     

Epidemiology of meticillin-resistant Staphylococcus aureus (MRSA) in Latin America

Meticillin-resistant Staphylococcus aureus (MRSA) has become a serious threat to public health worldwide. Ongoing surveillance is essential to support infection control committees and clinicians in the prevention and treatment of infection. However, in Latin America, resources for monitoring the changing epidemiology of MRSA remain limited. In this article, we review the current situation of MRSA in Latin America in order to highlight the need for a more harmonised effort to improve its management. Literature in the PubMed and SciELO databases as well as the website of the Pan American Health Organization were searched for articles and information about the epidemiology of MRSA in Latin America. MRSA is already the leading cause of nosocomial infection in the Latin American region, and the number of reports of community-acquired MRSA infections is also rising. However, the extent of the problem is not fully understood, especially since data tend to come from large hospitals whereas much of the population is served by small community healthcare centres that do not have extensive facilities for performing microbiological surveillance. In conclusion, wider-reaching and co-ordinated programmes to provide regular MRSA surveillance reports are required across the Latin American region.     

万古霉素敏感性减低葡萄球菌筛选及抗生素耐药相关基因检测

目的 了解万古霉素敏感性减低葡萄球菌临床分离株对-内酰胺类、氨基糖苷类、四环素以及万古霉素耐药相关基因存在状况.方法 采用含61tg/mL万古霉素脑心浸液琼脂从临床分离的葡萄球菌中筛选万古霉素中介葡萄球菌和万古霉素耐药葡萄球菌;采用菌谱分析法筛选异质性万古霉素耐药葡萄球菌:E-test法和琼脂稀释法检测其MIC值;PCR技术扩增mecA,aac(6')/aph(2'),aph(3)-Ⅲ,tetM,vanA.vanB和vanC基因,并对阳性扩增产物进行测序.结果 从100株临床分离葡萄球菌中检出7株异质性万古霉素耐药葡萄球菌,并从部分菌株中检出耐药基因,mecA,aac(6')/aph(2'),aph(3')-川基因检出率分别为85.7%,57.1%和85.7%,没有检出tetM,vanA,vanB和vanC.对PCR阳性扩增产物进行测序,BLASTn比对分析,与已登录基因库的相同基因序列具有高度同源性.结论 同甲氧西林耐药葡萄球菌相似,万古霉素敏感性减低葡萄球菌携带多种耐药基因,耐药表型与基因分析支持该菌株多药耐药,该类菌株的检测对于指导临床合理用药具有积极意义.     

Influence of adjunctive ticlopidine on the treatment of experimental Staphylococcus aureus endocarditis

Antiplatelet therapy has been shown to reduce the size of aortic vegetations in a rabbit model of Staphylococcus aureus endocarditis. In addition, adjunctive aspirin improved the sterilization rate as compared with antibiotic treatment alone. To study the influence of ticlopidine, another potent inhibitor of platelet aggregation, infected animals received either vancomycin (Vm) alone or in combination with ticlopidine. When ticlopidine was given prior to and during antimicrobial therapy, a reduction in vegetation weight was observed. Ticlopidine administered with antimicrobial therapy, not only caused a reduction in vegetation weight, but also improved the rate of sterilization. This study provides additional data regarding the potential clinical role of antiplatelet agents in the treatment of endocarditis.     

Investigation of methicillin-resistant Staphylococcus aureus showing reduced vancomycin susceptibility isolated from a patient with infective endocarditis

A patient with infective endocarditis (IE) caused by methicillin-resistant Staphylococcus aureus (MRSA) was treated with vancomycin (VAN). VAN was ineffective, although therapeutic drug monitoring (TDM) indicated that the recommended trough level was maintained. Five MRSA isolates obtained at various times were analyzed to determine the minimum inhibitory concentration (MIC) and were subjected to population analysis, simulation analysis pulsed-field gel electrophoresis (PFGE). MRSA susceptible to VAN was isolated before and during the early stage of treatment, while an MRSA strain showing reduced VAN MIC was isolated during treatment. Simulation analysis indicated that the viable bacterial count only decreased to 10⁻³ to 10⁻⁴ cells after 72 h of incubation. The five MRSA strains isolated at various times were identical by PFGE.     

Dosage recommendation of vancomycin during haemodialysis with highly permeable membranes.

The standard dosage of vancomycin in haemodialysis patients is usually 1 gram, once a week. The aim of our study was to investigate vancomycin clearance by two highly permeable membranes and to determine whether dosage adjustment is necessary in regular haemodialysis settings when using these type of dialyzers.12 patients on regular haemodialysis and treated with vancomycin either prophylactically or therapeutically were prospectively randomised to either dialysis with a polyacrylonitril parallel membrane (AN69®) or a celluloseacetate hollow fiber membrane. After administering vancomycin to the patient vancomycin plasma levels were measured at different intervals. The vancomycin clearance by the dialyzer was calculated from blood samples taken 1 hour after commencing dialysis. The data were used for pharmacokinetic computer simulation in order to develop a vancomycin dosage regimen for patients on regular haemodialysis with highly permeable membranes. The mean vancomycin dialysis clearance was 46 ± 5 ml/min and did not differ between the two artificial kidneys. Dialysis clearance of vancomycin was independent of blood flow rate.Together with the dialyzer data a pharmacokinetic profile of each patient was calculated from the plasma samples. The average nonrenal clearance was 3.3 ml/min/1.73 m2 while renal vancomycin clearance, as a fraction of creatinine clearance, was found to be 0.83 ± 0.20. The computer calculations predicted that, irrespective of residual renal function, in most patients on regular haemodialysis and treated with these type of artificial kidneys, therapeutic and nontoxic vancomycin levels could be obtained by giving 1000 mg of vancomycin intravenously as a loading dosage and 500 mg during every subsequent dialysis.     

Inhibitory efficacy of various antibiotics on matrix and viable mass of Staphylococcus aureus and Pseudomonas aeruginosa biofilms

Both bacteria and the matrix are essential for the development of biofilms. Antimicrobials should therefore be tested against both components. The aim of this study was to determine the structure–activity relationships of different antibiotics against biofilm-forming Staphylococcus aureus and Pseudomonas aeruginosa strains using in vitro biofilm discriminatory assays. Only four of twelve antibiotics showed efficacy against S. aureus biofilms. Rifampicin had a 50% inhibitory activity both against the matrix and bacteria at 16× the minimum bactericidal concentration (MBC). Polymyxin B killed nearly all bacteria at 8× MBC, but left the matrix undisturbed. Both P. aeruginosa biofilms responded differently to antibiotic treatment. Rifampicin showed the greatest activity, with 100% killing of microorganisms combined with 91% destruction of the matrix at the MBC. In conclusion, rifampicin showed the highest activity on biofilm matrix and bacteria in S. aureus and P. aeruginosa biofilms. Our results also indicated that biofilm viable mass was more susceptible to treatment than the biofilm matrix, which is mainly responsible for biofilm persistence. Future research should specifically focus on compounds destroying the matrix that can be used as an adjunct to antibiotic therapy.     

耐甲氧西林金黄色葡萄球菌血流感染危险因素的系统评价

目的 系统评价耐甲氧西林金黄色葡萄球菌（MRSA）血流感染危险因素,为各级医疗机构预防MRSA血流感染提供依据。方法 计算机检索中国学术期刊全文数据库（CNKI）、万方数据库（Wanfang Data）、维普中文期刊全文数据库（VIP）、中国生物医学文献数据库（CBM）、PubMed、Embase等数据库,检索时限为建库至2023年6月6日,收集国内外MRSA血流感染危险因素的病例对照研究,采用RevMan 5.3软件进行Meta分析。结果 共纳入16篇病例对照研究,涉及感染危险因素49个。结果显示年龄（年龄≥65、60岁）,医院感染,合并脑梗死、慢性肝胆疾病、消化性溃疡、感染性休克、肺部感染,中心静脉置管、留置导尿管、气管插管,入住ICU,感染前使用碳青霉烯类、糖肽类、第3代头孢菌素类,感染来源于呼吸道、皮肤软组织、腹腔、导管、感染来源大于2个部位,住院时间,MRSA血流感染组与甲氧西林敏感金黄色葡萄球菌（MSSA）血流感染组相比,差异有统计学意义（P<0.05）。结论 MRSA血流感染危险因素多,临床诊疗活动中应重视患者基础疾病,规范化进行侵入性操作,重视病区环境的消杀和医务人员手卫生,合理使用抗菌药物,动态评估患者生命体征,根据危险因素制定感控策略,从而降低MRSA血流感染发生率。     

藏药二十五味鬼臼丸对金黄色葡萄球菌的抑菌作用及机制研究

目的 研究藏药二十五味鬼臼丸对金黄色葡萄球菌的抑菌作用,初步探讨相关抑菌机制。方法 采用琼脂平板打孔法,测定二十五味鬼臼丸（50、100、200mg·mL^-1）对金黄色葡萄球菌的抑菌圈大小。通过微量肉汤稀释法,测定最小抑菌浓度（MIC）。调整肉汤培养基中的二十五味鬼臼丸浓度为0.5MIC、1.0MIC和2.0MIC,分别加入1.0×10⁸CFU·mL^-1菌悬液,以不含药液而含菌量相同的培养基作为对照组,在37℃、120r·min^-1恒温培养箱中振荡培养,每小时取样,用紫外可见分光光度计在600nm处测定吸光度（A₆₀₀）值,绘制细菌的生长曲线;每2小时取样,离心取上清液,试剂盒法测定碱性磷酸酶（AKP）活性;每小时取样,离心取上清液,用紫外可见分光光度计在260nm处测定A₂₆₀值,以A₂₆₀值表示DNA/RNA大分子相对量;每小时取样,离心取上清液,加入考马斯亮蓝G250溶液,于595nm处测定A₅₉₅值,检测胞外可溶性蛋白含量;培养8h后,离心留沉淀,进行SDS-PAGE电泳,检测菌体蛋白含量。结果 二十五味鬼臼丸50、100、200mg·mL^-1对金黄色葡萄球菌的抑菌圈直径分别为（12.33±0.75）、（16.33±0.41）、（19.17±0.68）mm;对金黄色葡萄球菌的MIC为100mg·mL^-1;与对照组相比,二十五味鬼臼丸组的金黄色葡萄球菌生长显著减缓（P＜0.05）,胞外的AKP活性显著升高（P＜0.05）,胞外DNA/RNA大分子相对量显著升高（P＜0.01）,胞外可溶性蛋白含量显著升高（P＜0.01）,菌体总蛋白表达量明显减少。结论 二十五味鬼臼丸对金黄色葡萄球菌具有抑菌作用,其抗菌作用可能与致细菌细胞壁、细胞膜结构破损,且对菌体蛋白具有一定抑制作用有关。     

Expression, crystallization, and preliminary X-ray crystallographic analysis of putative SpoVG from Staphylococcus aureus

SpoVG, originally identified in spore-forming Bacillus subtilis was known to be involved in spore formation of B. subtilis stationary phase cells at stage V. Later, close homologues of SpoVG of B. subtilis are shown to be present in the genomes of several nonsporulating bacteria as well. Especially in Staphylococcus aureus, SpoVG is speculated to be the major factor of the yabJ-spoVG operon required for capsule formation and methicillin and glycopeptides resistance. The putative SpoVG from S. aureus, a homodimeric protein consisting of two identical 100-residue subunits, has been overexpressed in Escherichia coli with a C-terminal purification tag and crystallized at 293 K using a precipitant solution consisting of 1.9 M (NH₄)₂SO₄, 100 mM Tris-HCl, pH 7.5. X-ray diffraction data were collected to 3.10 ? at 100 K. The crystals belong to the primitive tetragonal space group P41 (or P4₃), with unit cell parameters of a = b = 92.239, c = 98.588 ?, α = β = γ = 90°. Two dimers are present in the crystallographic asymmetric unit, with a calculated crystal volume per protein weight (V_M) of 4.37 ?³Da⁻¹ and a solvent content of 71.9%.     

Effectiveness of teicoplanin versus vancomycin lock therapy in the treatment of port-related coagulase-negative staphylococci bacteraemia: a prospective case-series analysis

The aim of this study was to analyse the effectiveness of teicoplanin versus vancomycin lock therapy in the treatment of coagulase-negative staphylococci (CoNS) venous access port-related bloodstream infection (BSI). The study included 44 consecutive patients during a 36-month prospective case-series study. The primary endpoint was failure to cure. Treatment was successful in 39 patients. At the end of the study, the cumulative port survival rate was 100% in the teicoplanin lock group compared with 77% in the vancomycin lock group (P = 0.06). In the Cox regression analysis, fever beyond 48 h of treatment was a significant predictor of treatment failure (P = 0.02). Use of vancomycin or teicoplanin locks had an effectiveness of 88.6% in the treatment of CoNS port-related BSI. Teicoplanin locks reduced the failure rate from 18.5% to 0% compared with vancomycin locks. The presence of fever after beginning antimicrobial lock therapy was associated with treatment failure.     

Typing of consecutive methicillin-resistant Staphylococcus aureus isolates from intensive care unit patients and staff with pulsed-field gel electrophoresis

Six consecutive methicillin-resistant Staphylococcus aureus (MRSA) isolates obtained in a 2-month period from tracheal aspirates of six intensive care unit (ICU) patients with nosocomial pneumonia and two MRSA isolates from nasal carriers among staff were typed to determine whether one or more strains were involved and whether nasal carriage was the source of the outbreak. Pulsed-field gel electrophoresis (PFGE) of chromosomal DNA was used to type MRSA isolates. The typing showed that the outbreak was caused by a single epidemic MRSA clone. The MRSA strain isolated from the staff was unrelated to the outbreak strain and was therefore not the source of the outbreak in this study. The source was apparently the index patient followed by transfer of MRSA to other patients on medical equipment or on the hands of staff who did not adhere strictly to infection control measures.     

Sensitive and specific colorimetric ELISAs for Staphylococcus aureus enterotoxins A and B in urine and buffer

We present here simple, sensitive and accurate colorimetric capture ELISAs for staphylococcal enterotoxins A and B. Standard curves were linear over the range 0.5–1 ng/mL, and toxins could be accurately measured at 0.5 ng/mL in assay buffer or 0.1 ng/mL in human urine. Cross-reactivity between serotypes was negligible. Detection in serum was complicated by the presence of specific antibodies to SE’s in most normal sera. These assays offer a viable, cost-effective method for analysis of these ubiquitous toxins. Further, their sensitivity in undiluted urine makes them ideal candidates for evaluating human exposure.