耐甲氧西林金黄色葡萄球菌检测方法应用评价

目的:评价四种检测耐甲氧西林金黄色葡萄球菌(MRSA)的实验方法.方法:收集107株金黄色葡萄球菌临床分离株,分别采用乳胶凝集实验法、头孢西丁纸片法、盐琼脂筛选法和聚合酶链反应(PCR)法进行实验检测.结果:PCR法是检测MRSA的金标准,特异性和灵敏度均为100%.头孢西丁纸片法和乳胶凝集法实验特异性均为100%,灵敏度是97.9%.盐琼脂筛选法特异性为91.4%,灵敏度为95.9%.结论:各级实验室需针对自身条件选择相应的实验方法,为临床提供准确的实验诊断.     

医院耐甲氧西林葡萄球菌感染的生态学特征

目的研究葡萄球菌医院感染的生态学特征，为β-内酰胺类抗生素过度使用导致的医院内肺感染提供预防措施。方法以多重耐药凝固酶阴性葡萄球菌作为主要研究对象，采用临床追踪、痰微生物种群定量分析、苯唑西林和头孢西丁耐药表型筛选以及mecA基因检测及序列同源性比较。结果30％（56／185）重症监护病人分离到耐药表型符合研究对象的葡萄球菌；感染与住院时间、病种、头孢哌酮／舒巴坦和亚胺培南使用有关，常与多重耐药鲍曼不动杆菌、阴沟肠杆菌、粪肠球菌、铜绿假单胞菌同时出现；当葡萄球菌超过细菌总数的50％时，应高度警惕继发感染和菌群失调；13％（24／185）病例以菌群交替为特征；64％（36156）的病例凝固酶阴性葡萄球菌出现在亚胺培南或头孢哌酮／舒巴坦使用1周后；所有耐甲氧西林葡萄球菌菌株含1个533bp的mecA基因；17株溶血葡萄球菌mecA基因间同源性为99．74％；56株葡萄球菌mecA基因的同源性是97．9％。结论从生态学的3个层面：宏观生态（医院环境、病人条件、抗生素使用等情况）、微生物生态（呼吸道微生物种群变化）、分子生态（mecA基因耐药基因同源性分析）分析葡萄球菌医院感染的特征，为控制医院感染提供新的思路。     

应用ED—PCR技术快速检测耐甲氧西林葡萄球菌

应用ＥＤ－ＰＣＲ技术从临床分离的７６株葡萄球菌中鉴定出耐甲氧西林金黄色葡萄球菌９株，耐氧西林血浆凝固酶阴性的葡萄球菌１１株。此结果与药物敏感性检测结果相符。ＥＤ－ＰＣＲ法具有简便，特异，省时，耗资少等优点，宜在临床检验室推广应用。     

甲氧西林耐药葡萄球菌SCCmec研究

目的明确甲氧西林耐药金黄色葡萄球菌（MRSA）和溶血性葡萄球菌（MRSH）所包含的葡萄球菌染色体mec盒（staphylococcal cassette chromosome mec，SCC mec）类型，并比较两者的差异。方法分别收集本院住院患者临床标本中分离的60株MRSA和88株MRSH。共设计10对引物，采用PCR法分别扩增mec复合体和ccr复合体的各个特征序列，分析其SCCmec类型。结果60株MRSA均为Ⅲ型SCCmec；88株MRSH中7株为V型SCCmec，1株为Ⅲ型SCCmec，其余均为新的组合或是无法分型。结论SCCmec在MRSA和MRSH中分布特点差别较大，MRSH中可能存在较多新的型别。     

检测耐甲氧西林葡萄球菌及其耐药性分析

为了解我院耐甲氧西林葡萄球菌（MRS）的感染情况及其耐药性,为临床治疗MRS感染提供实验室依据和有效的用药措施．用微生物鉴定仪检测了142株葡萄球菌对13种抗生素的MIC,对苯唑青霉素MIC＞2ug／ml的菌株,采用K－B纸片法,补充检测对苯唑青毒素纸片的耐药性,共筛选出80株MPS,其中耐甲氧西林金黄色葡萄球菌（MRSA）20株,耐甲氧西林表皮葡萄球菌（MRSE）33株,其它耐甲氧西林葡萄球菌27株,说明感染我院的MRS种类不断增加,应引起重视．药散结果表明MRS对万古霉素（Van）100％敏感,对其他抗生素的敏感性明显低于对甲氧西林敏感的葡萄球菌（MSS）,因此,临床上应区分MRS与MSS,选择性地用药．     

一起耐甲氧西林金黄色葡萄球菌医院感染的调查

目的分析一起耐甲氧西林金黄色葡萄球菌医院感染的危险因素,探索有效的控制措施。方法查看病房环境、回归性病例分析,利用PFGE方法对耐甲氧西林金黄色葡萄球菌（MRSA）菌株进行同源性分析。结果2007年6～7月MRSA感染9例,罹患率为15%;病房分布有聚集性;9份菌株药敏结果基本相同;5份菌株具有高度同源性;主要的危险因素有抗菌素的频繁使用、大面积的烧伤、与感染者同房、换床、陪护和探视等。结论合理使用抗生素,尽量减少侵袭性操作、严格隔离MRSA感染者、严格控制人员尤其探视人员进入、加强医护人员的手部卫生、加强器械及环境消毒、及时采样送检是预防和控制MRSA感染的关键。     

社区相关性耐甲氧西林金黄色葡萄球菌致病性研究进展

社区相关性耐甲氧西林金黄色葡萄球菌(CA-MRSA)自从上世纪八十年代出现以来,得到了全世界的普遍关注。CA-MRSA较强地适应外界环境的能力和定植能力对于其致病性起到了十分重要的作用,近期在CA-MRSA-USA300型菌株的基因组中发现的可移动精氨酸代谢元件(ACME),以及该段DNA编码的精氨酸脱亚胺酶(arginine deiminase)对MRSA在人体中的定植起到了重要作用。     

干部病房高龄老人耐甲氧西林金黄色葡萄球菌感染调查及控制措施

对21例耐甲氧西林葡萄球菌(MRSA) 感染的高龄老年病人进行治疗和护理.17例MRSA 病人痰培养相继转为阴性,1 例因心力衰竭死亡,1 例因主动脉夹层瘤破裂大出血死亡,2例死亡.提示严格按MRSA的流程进行处置,加强医务人员的预防意识、增加医护人员的洗手依从性、严格执行消毒隔离制度,合理应用抗生素,可有效控制MRSA 流行.     

耐甲氧西林金黄葡萄球菌小鼠菌血症感染模型的建立与评估

目的 本研究采用临床分离鉴定的ST-239型耐甲氧西林金黄葡萄球菌(MRSA)感染BALB/c小鼠,建立菌血症感染模型.方法 从小鼠的临床症状、生存曲线和主要组织器官的病理学变化进行了时相性监测,并用该模型验证万古霉素对小鼠菌血症的治疗效果.结果 ST-239型MRSA感染的小鼠血液中细菌含量较高,小鼠炎症反应严重并伴有心、肺等多组织器官的损伤;对小鼠使用万古霉素后可显著降低血液中的细菌量,动物存活率明显提高,主要组织器官的病理学症状减轻.结论 该模型的建立将为进一步研究临床分离的MRSA的病原特性、发病机制、治疗方法等提供可靠的实验动物模型.     

耐甲氧西林葡萄球菌的耐药状况分析

目的 分析耐甲氧西林葡萄球菌的耐药状况,了解葡萄球菌耐药的流行病学特征.方法 对251株临床分离的葡萄球菌进行耐药性检测,分析其药敏试验结果.结果 251株葡萄球菌中,金黄色葡萄球菌162株,其中耐甲氧西林金黄色葡萄球菌(methicillin-resistant Staphylococcus aureus,MRSA) 62株,阳性率为38.3%;凝固酶阴性葡萄球菌89株,其中耐甲氧西林凝固酶阴性葡萄球菌(methicillin-resistant coagulase negative Staphylococcus,MRCNS) 63株,阳性率为70.8%;所有菌株对万古霉素均敏感.结论 耐甲氧西林葡萄球菌对抗生素的耐药状况较为严重;未分离出万古霉素耐药株.     

Characterization of SCCmec elements in methicillin-resistant Staphylococcus epidermidis isolated from blood cultures from neonates during three decades

Staphylococcus epidermidis is a major cause of nosocomial infections in immunocompromised patients and the predominant pathogen in catheter-related infections and bloodstream infections. Approximately 70-80% of S. epidermidis carry the mecA gene encoding methicillin resistance. The mecA gene is located on a mobile genetic element, the staphylococcal cassette chromosome mec (SCCmec). The aim of this study was to characterize the SCCmec elements as well as the adjacent arginine catabolic mobile element (ACME) in 30 clinical blood isolates of mecA positive S. epidermidis obtained from neonates and collected over a period of three decades. The ccr and mec gene complexes were identified using PCR. The SCCmec elements were found among 29/30 isolates and 13 different combinations of ccr gene complexes and mec gene complexes were identified. Staphylococcus epidermidis regularly carried multiple copies of ccr gene complexes, but only one class of mec gene complex. Three isolates could be assigned the SCCmec type III (3A). The combinations of ccr gene complexes and the mec gene complexes differed among the three decades. The most frequent combination was class B mec in combination with ccr1 and ccr2. Staphylococcus epidermidis may constitute a large reservoir for SCCmec elements, and frequent exchange of mobile genetic elements between staphylococcal species may explain the emergence of new MRSA strains.     

Detection of diverse SCCmec variants in methicillin-resistant Staphylococcus aureus and comparison of SCCmec typing methods

Non-duplicate methicillin-resistant Staphylococcus aureus (MRSA) isolates (n = 436), collected from four hospitals located in three Korean cities between 2001 and 2005, were investigated by SCCmec typing and multilocus sequence typing (MLST). Variations within SCCmec, especially type II, were detected in 165 (37.8%) isolates, and these variants were characterised using four different SCCmec typing methods. The predominant SCCmec type was a type II variant that differed from type II by the absence of a pUB110 insertion. MLST analysis showed that most of the isolates carrying SCCmec variants belonged to ST5.     

Prevalence of methicillin-resistant Staphylococcus aureus in infected and uninfected diabetic foot ulcers

This study investigated the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) in infected and uninfected diabetic foot ulcers of 84 patients with the two types of diabetes. S. aureus was the most common pathogen among the Gram-positive bacteria isolated from ulcers, and almost 50% of S. aureus isolates were MRSA. The prevalence of MRSA was significantly higher in patients with infected foot ulcers. MRSA infection or colonisation was not associated with factors (previous hospitalisation, use of antibiotics, etc.) known to predispose to MRSA colonisation or infection. The high prevalence of MRSA in patients with foot ulcers may reflect the increased prevalence of MRSA in the community.     

PCR for the identification of methicillin-resistant Staphylococcus aureus (MRSA) strains using a single primer pair specific for SCCmec elements and the neighbouring chromosome-borne orfX

The chromosomal location of the SCCmec elements containing mecA allows the identification of methicillin-resistant Staphylococcus aureus (MRSA) strains by PCR amplification of a sequence covering the right junction of the SCCmec elements and the adjacent chromosomal region encoding the species-specific ORFX. MRSA strains can be identified specifically using one forward primer, with only one or two mismatches, targeting the SCCmec elements of different types, and one reverse primer targeting the orfX region.     

A new multiplex PCR for easy screening of methicillin-resistant Staphylococcus aureus SCCmec types I–V

A multiplex PCR with four primer-pairs was designed to identify the five main known SCCmec types. A clear and easily discriminated band pattern was obtained for all five types. The SCCmec type was identified for 98% of 312 clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA). SCCmec type IV was by far the most common SCCmec type among both hospital- and community-acquired MRSA isolates in Denmark.     

耐甲氧西林金黄葡萄球菌高变区基因分型及其与耐药性的关系

目的 调查本地区耐甲氧西林金黄葡萄球菌(MRSA)的高变区(HVR)基因分型,分析HVR基因型与MRSA耐药谱的关系,并初步探讨其在分子流行病学分析中的作用.方法 收集80株MRSA,采用PCR方法扩增MRSA的HVR,并根据扩增片段大小进行基因分型.同时统计各MRSA菌株对多种抗菌药物的药敏结果,并分析基因型与耐药性的关系.结果 根据PCR产物片段大小,80株MRSA被分为A、B、C、D、E 5种基因型,其中以D和E型多见,分别占61.25%和21.25%,A(3.75%)、B(5.00%)、C(8.75%)型少见.各基因型MRSA除对万古霉素敏感外,对头孢唑啉、庆大霉素、红霉素、阿奇霉素、克林霉素、环丙沙星、复方新诺明、阿米卡星的耐药率为61.5%～100%.结论 MRSA的HVR基因分型是一种快速、简单、可靠的分型方法,适用于MRSA感染的流行病学调查,有利于抗菌药物的选用.     

Two clones of methicillin-resistant Staphylococcus aureus in Poland

Objective: To evaluate relatedness among methicillin-resistant Staphylococcus aureus (MRSA) strains isolated in Poland.
Method: Ninety-three MRSA hospital isolates were collected from different regions in Poland from 1990 to 1992. Strains were analyzed with respect to heterogeneity of methicillin resistance, phage types, resistance patterns, crystal violet staining, chromosomal DNA Sma I restriction patterns by PFGE, ERIC1 and ERIC2 AP-PCR types and DNA repeat polymorphism within the protein A gene. Resistance to methicillin was confirmed by the detection of the mecA gene by PCR.
Results: The combined results of typing methods demonstrate that all MRSA strains analyzed could be easily divided into two distinct clones (clonally related strains). The first consisted of strains with clear heterogeneous expression of resistance to methicillin (34 isolates) and the second showed more homogeneous resistance (59 isolates). In this study the best method for epidemiologic analysis of MRSA was found to be PFGE. A good correlation between the epidemic behavior of MRSA and a high number of repetitive DNA units within the protein A gene was observed.
Conclusions: Results show that in Poland two distinct clones of epidemic MRSA have circulated in the past, easily discriminated by pheno and genotyping methods, and both could be found together in a single hospital.     

Spread of old and new clones of epidemic methicillin-resistant Staphylococcus aureus in Poland

Objective: To study the relatedness among methicillin-resistant Staphylococcus aureus (MRSA) isolates originating from two regions of Poland using different epidemiologic typing methods.
Methods: Forty-five MRSA isolates (19 from Warsaw and 26 from the Grajewo region) were collected between 1995 and 1996. For phenotypic epidemiologic analysis, antimicrobial susceptibility testing (AST) with a panel of 19 antibiotics was performed. For genotypic epidemiologic analysis, pulsed-field gel electrophoresis (PFGE) of Smal-digested chromosomal DNA, restriction endonuclease analysis of plasmid (REAP) DNA digested by Hin dIII, random amplification of polymorphic DNA (RAPD) and binary typing (BT) of genomic DNA by hybridization with five different RAPD-generated strain-specific DNA probes, were used.
Results: Six clusters of clonally related strains were found among the MRSA isolates analyzed. Three of these, identified in both regions, were related to previously described Polish epidemic clones, designated HeEMRSA-Pol1 (heterogeneously methicillin resistant—18 isolates) and HoEMRSA-Pol1 (homogeneously resistant—two clones, six isolates each). The remaining three clones, identified in the Grajewo region only, are previously undescribed. One of these, represented by 11 isolates, appears to be new epidemic heterogeneous MRSA clone (HeEMRSA-Pol2). Results of PFGE and BT in general showed good correlation, and, in some cases, RAPD using AP1 and AP7 primers could discriminate between isolates belonging to single PFGE or BT types. Broad AST and REAP can provide useful additional information concerning relatedness.
Conclusion: Evidence for the spread of previously recognized epidemic MRSA clones in Poland and the presence of a new epidemic heterogeneously resistant clone of MRSA in hospitals outside Warsaw is documented.     

Methicillin-resistant Staphylococcus aureus nasal carriage and infection among patients with diabetic foot ulcer

PurposeTo evaluate the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) nasal carriage in patients with diabetic foot ulcer (DFU) in Taiwan, and to assess the concordance between colonizing and clinical MRSA isolates from the patients.MethodA total of 354 nasal specimens were collected from 112 to 242 diabetic patients with and without foot ulcer, respectively. MRSA clinical isolates from DFU wound cultures were collected for comparison.ResultsNasal carriage rate of S. aureus and MRSA was similar between diabetic patients with and without foot ulcer (15.2% vs. 16.9% for S. aureus and 5.4% vs. 1.7% for MRSA). Nasal S. aureus colonization was an independent predictor for wound S. aureus infection (Odds ratio [OR]: 5.33, 95% confidence interval [CI]: 1.61–17.59), so did nasal MRSA colonization (OR: 19.09, 95% CI: 2.12–171.91). The levels of glycated hemoglobin, and the usage with immunosuppressant agent were associated with S. aureus nasal colonization while oral hypoglycemic agent usage a protective factor. Sequence type 59/staphylococcal chromosome cassette mec IV or V, the local endemic community-associated clone, accounted for 42% and 70% of the clinical and colonizing isolates, respectively. Six of 10 patients with paired colonizing and clinical isolates, either MRSA or methicillin-sensitive S. aureus, had a genetically identical strain from a single patient.ConclusionLess than one-fifth of patients with DFU have nasal S. aureus, including MRSA, colonization; however, the colonization is significantly associated with S. aureus diabetic foot infection. Screening for S. aureus colonizing status in DFU patients might have a potential clinical implication.     

Feasible identification of Staphylococcus epidermidis using desferrioxamine and fosfomycin disks

Coagulase-negative Staphylococcus spp. (CoNS) have emerged as predominant pathogens in hospital-acquired infections, as well as reservoirs of antimicrobial resistance, increasing the necessity of developing reliable methods for identification of the most frequent species. The aim of this study was to propose a simplified method for identification of Staphylococcus epidermidis. A total of 490 isolates of CoNS were identified by Bannerman's method. Taking into account distinct approaches for identification of S. epidermidis, among CoNS, we proposed the use of only two disks: desferrioxamine for the initial trial, and fosfomycin to match the final identification. Of the 320 isolates susceptible to desferrioxamine, Bannerman's method identified 238 S. epidermidis and 73 S. hominis, while we achieved identification of 239 S. epidermidis and 76 S. hominis. Compared to Bannerman's method, the method proposed here obtained a sensitivity of 99.5%, and had a positive predictor value of 99.2%. We also used a genotypic method for identification of S. epidermidis by polymerase chain reaction (PCR) targeting the tuf gene. In conclusion, the method proposed here has proved to be useful for the identification of S. epidermidis, the most frequent species of CoNS isolated from blood cultures in clinical microbiology laboratories.