耐甲氧西林金黄色葡萄球菌PFGE分型与医院感染暴发的分子流行病学研究

目的了解医院感染耐甲氧西林金黄色葡萄球菌(MRSA)的同源性及院内流行特征,为临床控制MRSA感染、制定合适的预防控制措施提供依据。方法收集2011年6-7月全院患者各类标本中分离出的MRSA 36株,金黄色葡萄球菌鉴定采用法国生物梅里埃公司的VITEK-2全自动微生物分析系统,根据美国CLSI标准用头孢西丁K-B法确认MRSA;运用脉冲场凝胶电泳(PFGE)对医院感染MRSA进行基因分型,并进行流行病学分析。结果临床分离的36株MRSA,PFGE分型为6型8个亚型,其中以A型为主;在研究期间,NICU及ICU发生两次MRSA感染暴发。结论 MRSA在NICU及ICU易发生交叉感染;PFGE是医院感染暴发及流行病学的较好的研究手段。     

47株金黄色葡萄球菌临床血流感染分离株的基因分型研究

目的 研究金黄色葡萄球菌临床血流感染分离株的分子流行病学特征.方法 收集2006年1月至2008年12月解放军总医院分离的临床血流感染金黄色葡萄球菌菌株(共47株),标本来源均为患者静脉血.采用琼脂稀释法检测所有菌株对多种抗生素的耐药性,PCR方法 检测pvl毒素基因,DiversiLab~(TM)Rep-PCR分型系统分析菌株的同源性;对耐甲氧西林金黄色葡萄球菌(MRSA)进行葡萄球菌染色体/mec(SCCmec)分型以及ST239型别的快速筛查;综合分型和药敏试验结果,挑选部分代表菌株进行多位点序列分型(MLST).结果 47株血流感染金黄色葡萄球菌中,pvl基因检出率为4.3%.MRSA占51.1%.MRSA均为SCCmec Ⅲ型菌株;Rep-PCR分为A～L共12个型,其中A型为最主要的型,共22株(46.8%),所有的MRSA均属于A、B两型.结论 47株临床血流感染金黄色葡萄球菌中的MRSA绝大部分为多重耐药克隆ST239-MRSA-SCCmecⅢ型.     

医院感染金黄色葡萄球菌的分型

目的 用脉冲场凝胶电泳(PFGE)和药敏试验对医院感染金黄色葡萄球菌(SA)进行分型，并了解其分子流行病学特征。方法 从华西医院2000年4～11月住院患中分离SA，收集临床资料，用PFGE对医院感染株分型，并检测其对12种抗菌药物的体外敏感性。结果 在31例发生医院感染的患中，分离出34株SA。菌株经PFGE分为24型，经药敏试验分为17型。SA感染散布于各病房，在ICU、肿瘤科、神经外科、皮肤科病房有小型传播，其聚集性发生更多见于甲氧西林耐药金黄色葡萄球菌(MRSA)。SA的PFGE分型与其药敏无对应关系。结论 华西医院2000年4～11月SA医院感染以多克隆散发为主，聚集性发生多见于MRSA。PFGE是一种理想的SA分型方法。     

MRSA分子流行病学研究

目的采用脉冲场凝胶电泳(PFGE)分型及多重聚合酶链反应(PCR)SCCmec分型技术对耐甲氧西林金黄色葡萄球菌(MRSA)进行基因分型,以了解医院感染MRSA的流行情况。方法收集天津市南开医院2007年1月-2008年12月住院患者送检标本分离的MRSA 40株,进行耐药谱分析、PFGE分型和SCCmec分型。结果 40株菌耐药谱高度相似,可被分为A-E5个PFGE型,其中A型21株,B型8株,C型4株,D型6株,E型1株;SCCmec分型:Ⅰ型1株,Ⅲ型33株,Ⅳ型1株,Ⅴ型5株。通过对医院内菌株发生的时间和空间分析,明确了感染的发生和传播情况,即在2007年1月-2008年12月存在MRSA散发感染。结论 PFGE可有效鉴定菌株间的亲缘关系,SCCmec分型对是否为医院感染菌株有提示作用,两种分型方法相结合可更好地鉴定流行菌株的特征,为医院感染的监控提供依据。     

耐甲氧西林金黄色葡萄球菌基因分型与同源性分析

目的研究襄阳地区耐甲氧西林金黄色葡萄球菌(MRSA)的检出率及金黄色葡萄球菌染色体mec(SCCmec)基因型与同源性特征。方法采用苯唑西林/头孢西丁筛选法、mecA基因单一PCR扩增对2013年4-10月间湖北省襄阳地区4所三级医院门诊及住院患者标本分离的金黄色葡萄球菌进行MRSA筛选和确认;用多重PCR扩增(m-PCR)及脉冲场凝胶电泳(PFGE)进行SCCmec基因分型及同源性分析,并用单一PCR扩增法进行PVL基因的检测。结果从80株金黄色葡萄球菌菌株中分离出MRSA 43株;多重PCR分型结果显示,39株为SCCmecⅢ型,4株为SCCmecⅣa型;单一PCR法获得8株PVL阳性菌株,占18.6%,其中SCCmecⅢ型4株,SCCmecⅣa型4株;PFGE检测结果显示,43株MRSA中有A、B、C、D、E 5种类型,其中以A型为主,A型中又分为A1、A2、A3 3种亚型。结论襄阳地区MRSA以SCCmecⅢ型和A型克隆株为主,PVL基因的携带率较高,应加强感染控制,防止此类菌株的播散。     

青岛地区医院内感染耐甲氧西林金黄色葡萄球菌分子分型研究

目的 探讨青岛地区医院内感染的耐甲氧西林金黄色葡萄球菌(MRSA)分子流行病学特征及脉冲场凝胶电泳(PFGE)型别与菌株表型、一般临床资料间的关系.方法 收集2003-2007年间青岛地区主要医院内感染MRSA 360株,Sma Ⅰ酶切菌株染色体DNA后,进行PFGE电泳,用Bionumericus 2.0软件对电泳图谱进行比较和聚类分析,绘制进化树.同时对患者的性别、年龄、菌株来源等进行多变量统计分析.应用纸片扩散法测定分离菌株的药物敏感谱,并与PFGE型别进行比较分析.PCR扩增不同PFGE型别MRSA代表株25株分离株的7个管家基因进行序列测定和多位点测序分型分析(MLST).结果 所有菌株经PFGE电泳后共分为5型(M0～M4型),其中M1型为优势菌型,M2型次之,M4型相对少见,M0为独特型,明显不同于其他已知PFGE型别.统计学分析发现5种PFGE型别在患者性别、年龄分布上的差异无统计学意义,但在菌株分离部位、来源有统计学的差异:M2型多分离自伤口感染,而M3型菌株多来自ICU病房,5种PFGE型在不同医院间及医院内的分布存在差异.M1与M2两型构成各医院分离菌株的主要型别.抗生素敏感性测定中未发现万古霉素耐药菌株,亦未发现某种PFGE型别与某种特定抗生紊抗性之间的直接相关性.MIST分型发现优势型M1与M3共属于国内常见ST239型,M2型则归类于ST5,M4型属于ST240,独特型中的2种PFGE谱型则分属于ST45及ST398.结论 ST239菌株为青岛地区医院内感染MRSA优势菌株;医院内MRSA的PFGE分型与菌株来源明显相关,与患者年龄、性别无关,MRSA感染普遍存在于各年龄人群中.     

广元市28株临床分离金黄色葡萄球菌分子分型及耐药分析

目的初步建立广元市金黄色葡萄球菌脉冲场电泳(PFGE)分型及金黄色葡萄球菌A蛋白(SPA)分型数据库,了解广元市金黄色葡萄球菌分子流行型别以及耐甲氧西林金黄色葡萄球菌(MRSA)的流行情况。方法收集广元市城区四家综合医疗机构2017-10/2018-03从临床标本中分离的金黄色葡萄球菌,分别进行SPA、PFGE分型及mecA基因检测,并对检测结果进行分析。结果 28株金黄色葡萄球菌被分为23个PFGE型,PFGE图谱相似性在44.80%以上;SPA基因型可分为15个,其中t437、t189、t701、t002四个型别占50.00%,MRSA分离率35.71%,mecA基因携带率25.00%,呼吸道来源的标本MRSA分离率较高。结论广元市临床分离金黄色葡萄球菌PFGE分型较分散,SPA分型中t437等4个型别为流行优势型别,MRSA检出率及mecA基因携带率不容忽视,应持续监测MRSA流行变化,完善分子分型数据库,为金葡菌的临床感染监控以及由金葡菌引起的食源性疾病监控提供更有价值的依据。     

MRSA分子流行病学研究 FREE

目的 采用脉冲场凝胶电泳（PFGE）分型及多重聚合酶链反应（PCR）SCCmec分型技术对耐甲氧西林金黄色葡萄球菌（MRSA）进行基因分型，以了解医院感染MRSA的流行情况。方法 收集天津市南开医院2007年1月-2008年12月住院患者送检标本分离的MRSA 40株，进行耐药谱分析、PFGE分型和SCCmec分型。结果40株菌耐药谱高度相似，可被分为A-E 5个PFGE型，其中A型21株，B型8株，C型4株，D型6株，E型1株；SCCmec分型：Ⅰ型1株，Ⅲ型33株，Ⅳ型1株，V型5株。通过对医院内菌株发生的时间和空间分析，明确了感染的发生和传播情况，即在2007年1月-2008年12月存在MRSA散发感染。结论 PFGE可有效鉴定菌株间的亲缘关系，SCCmec分型对是否为医院感染菌株有提示作用，两种分型方法相结合可更好地鉴定流行菌株的特征，为医院感染的监控提供依据。     

耐甲氧西林金黄色葡萄球菌SCCmec分型的研究

目的应用多重聚合酶链反应(PCR)对临床分离的耐甲氧西林金黄色葡萄球菌(MRSA)的SCCmec基因型及亚型进行分型。方法收集医院2007年1月~2008年12月临床分离的65株MRSA用多重PCR检测MRSA的SCCmec的基因型及亚型。结果SCCmecⅠ型菌株5株(4.6%),SCCmecⅢ型菌株47株(72.3%),SCCmecⅣ型菌株2株(3.1%),未分型11株(16.9%),未检测到Ⅱ型。结论研究结果显示,医院分离的MRSA以SCCmecⅢ为主;多重PCR对MRSA进行SCCmec基因分型结果可靠,适合临床实验室。     

40株院内感染耐甲氧西林金黄色葡萄球菌的耐药性及分子分型研究

目的了解耐甲氧西林的金黄色葡萄球菌(MRSA)在医院内感染的流行病学特征,为临床MRSA的预防和控制提供依据。方法对从医院内收集的不同来源的MRSA进行生化鉴定、药敏试验及脉冲场凝胶电泳(PFGE)分子分型,并运用Bio Numeries软件分析其亲缘性关系。结果本研究共收集院内感染分离的MRSA 40株。药敏试验表明,40株MRSA对苯唑西林(100.0%)、头孢西丁(100.0%)、青霉素(100.0%)耐药性达最高,其次是红霉素(80.0%),克林霉素(75.0%);多重耐药谱显示3耐以及以上的占100.0%;PFGE分子分型表明40株MRSA共分为36个型,其中3个型别具有100.0%同源性的菌株。结论院内感染分离的MRSA的耐药性强,多重耐药谱广,PFGE带型多样,且有100.0%同源性菌株,表明MRSA在院内存在相互传播的可能。应加强对其耐药性以及溯源分析,为院内感染溯源及预警,减少MRSA的暴发和流行提供实验室的技术支撑。     

金黄色葡萄球菌感染的特征及其耐药性

目的探索金黄色葡萄球菌感染的特征及其耐药性,预防和控制MRSA流行发生。方法对2006年住院患者中金黄色葡萄球菌感染的特征及耐药性进行监测。结果2006年共分离出金黄色葡萄球菌45株,其中MRSA28株,占金葡菌的62.2%(MSSA17株,占37.8%);医院感染株和社区感染株分别占19株(42.2%)、26株(57.8%);感染部位多分布在下呼吸道、皮肤软组织和烧伤部位;在同期空气、物体表面、医务人员手等外环境中尚未检出金黄色葡萄球菌。金葡菌对阿莫西林、氨苄西林、青霉素G、阿奇霉素耐药率在70%以上,但对万古霉素敏感。基础疾病中以外伤、心脑血管病、烧伤、呼吸系统疾病、皮肤软组织疾病居前五位。结论金葡菌检出率、MRSA发生率和耐药率较高;同期外环境尚未发现有关的金葡菌菌株;金葡菌医院感染以内源性感染为主;应注意做好手卫生、物体表面消毒和合理使用抗菌药物,预防控制金葡菌交叉传播。     

Epidemiology of methicillin-resistant Staphylococcus aureus at a university hospital in the Canary Islands.

OBJECTIVES: To describe the epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) at a university hospital in Tenerife, Canary Islands, during a 40-month period and to evaluate the effectiveness of the application of control measures. DESIGN: Laboratory-based surveillance, medical charts and microbiological records review, and characterization of strains by pulsed-field gel electrophoresis (PFGE) were used to describe the epidemiology. Infection control practices were introduced as an intervention. SETTING: A 650-bed, tertiary-care university hospital. SUBJECTS: Patients with clinical and nasal isolates of MRSA and colonized staff members. RESULTS: The rate of nosocomial MRSA infections was 32.5% for 1997, 17.9% for 1998, 14.5% for 1999, and 25.6% during the first 4 months of 2000. The major sites of isolation for nosocomial MRSA infection included surgical wounds (25%) and the lower respiratory tract (24%). Intensive care units and surgical specialties had more frequent MRSA cases. Characteristics associated with nosocomial MRSA isolates included prior use of intensive antibiotic therapy, prolonged hospital stays, major underlying illness, invasive procedures, and older age. PFGE type A (subtype A1) was the strain most frequently found and the only PFGE type involved in clusters. CONCLUSIONS: Surveillance cultures and contact droplet precautions were followed by decreased rates for 2 years. Nevertheless, the spread of PFGE subtype A1 to many different areas of the hospital and the increase in incidence during the first third of 2000 indicates either that surveillance cultures were not used widely enough or that compliance with isolation measures was suboptimal.     

Epidemiology and clonality of methicillin-resistant and methicillin-susceptible Staphylococcus aureus causing bacteremia in a tertiary-care hospital in Spain.

OBJECTIVES: To describe the relative proportions of nosocomial and community-onset Staphylococcus aureus bacteremia at our institution and the epidemiologic characteristics and clonal diversity of S. aureus isolates, as determined by pulsed-field gel electrophoresis (PFGE) and antimicrobial resistance patterns. DESIGN: Retrospective cohort study of all cases of S. aureus bacteremia between October 2001 and October 2002. SETTING: A 1300-bed, tertiary-care hospital. RESULTS: One hundred sixty-two unique episodes of S. aureus bacteremia were identified. Forty-three cases (26.5%) were caused by methicillin-resistant S. aureus (MRSA). Most cases of S. aureus bacteremia, whether MRSA or methicillin susceptible (MSSA), were nosocomial in origin (77.2%) or were otherwise associated with the healthcare system (16%). Only 11 (6.8%) of the cases (all MSSA) were strictly community acquired. Thirty-five unique macrorestriction patterns were identified among the 154 isolates that were typed by PFGE. Four major genotypes were defined among the isolates of MRSA, with 36 (85.7%) represented by a single PFGE type. Of the isolates within this major clone, all (100%) were ciprofloxacin resistant and 77.8% were erythromycin resistant. In contrast, the 112 isolates of MSSA comprised 31 different PFGE types, 3 of which represented 42.9% of all MSSA isolates and were associated with both nosocomial and community-onset bacteremia. CONCLUSIONS: Most cases of S. aureus bacteremia in our healthcare region are nosocomial in origin or are acquired through contact with the healthcare system and are thus potentially preventable. To preclude dissemination of pathogenic clones, it is therefore necessary to redouble preventive measures in both the hospital and the community.     

Molecular surveillance of clinical methicillin-resistant Staphylococcus aureus isolates in neonatal intensive care units.

BACKGROUND AND OBJECTIVE: Methicillin-resistant Staphylococcus aureus (MRSA) has become an important nosocomial pathogen in our neonatal intensive care units (NICUs) and accounts for almost all S. aureus clinical isolates. The objective of this study was to assess the relatedness of these MRSA strains. DESIGN: MRSA clinical isolates were collected from infants hospitalized in our NICUs. Pulsed-field gel electrophoresis with SmaI digestion was used to fingerprint these isolates. SETTING: Level-III NICUs in a university-affiliated children's hospital. RESULTS: Between 1998 and 2000, a total of 122 MRSA clinical isolates were collected from 104 infants hospitalized in our NICUs. Fifteen infants had multiple isolates (range, 2 to 4 isolates). The sources of specimens included blood (72), pus (23), sputum (15), body fluids (3), and catheter tips (9). A total of 4 genotypes with 20 subtypes were identified. There were 2 genotypes in 1998, 2 genotypes in 1999, and 4 genotypes in 2000. All but 2 isolates belonged to either genotype A (63.1%; 7 subtypes) or genotype C (35.2%; 11 subtypes). Among the 15 infants with multiple isolates, the genotypes of the isolates from a single episode of MRSA infection were different in 2 of 12 cases, and reinfection with a new strain was noted in 3 of 5 cases with recurrent infections. CONCLUSIONS: Two predominant MRSA clones prevailed in our NICUs between 1998 and 2000. Polyclonal bacteremia and reinfection with a new strain were noted     

Frequency and diversity of molecular epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) isolates from patients of a South West German teaching hospital

We have determined the frequency and the genetic diversity of methicillin-resistant Staphylococcus aureus (MRSA) strains isolated from inpatients of a South West German teaching hospital. The frequency of primary MRSA isolates remained constant over the two-year surveillance period: 108 of the total number of 1450 S. aureus isolates (7.5%) were MRSA in 2001 and the corresponding figures were 110 MRSA out of 1412 S. aureus isolates (7.8%) in 2002. Six clusters of nosocomial MRSA infection were observed during 2001 and 2002. Cluster infections involved 65 patients on four different wards. Molecular typing of the 65 cluster isolates demonstrated that 51 (79%) belonged to a single predominant clone. The remaining 14 isolates represented seven genetically unrelated MRSA clones. Molecular typing of 50 additional non-cluster, sporadic isolates demonstrated 37 different pulsed-field gel electrophoresis (PFGE) banding patterns. Our results demonstrate that primary MRSA strains from hospitalized patients show a high degree of genetic heterogeneity. In contrast, however, MRSA isolates from nosocomial clusters were mostly derived from a single predominant clone, thus indicating a significant intra-ward and intra-hospital distribution. Molecular typing methods may lead to an improved understanding of MRSA epidemiology and thus allow the establishment of effective preventive measures.     

Molecular characterization of methicillin-resistant Staphylococcus aureus (MRSA) in a university hospital in Italy

The molecular epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) in a university hospital in Italy was studied in a five-month period in 1996, during which all S. aureus isolated were collected. All MRSA isolates (95) and a sample of methicillin-susceptible S. aureus (20) were typed with a variety of phenotypic and genotypic methods. Clonal identities were determined by pulsed-field gel electrophoresis (PFGE) of chromosomal SmaI digests and, for MRSA isolates, by probing ClaI digests with a mecA probe and a Tn554 probe. Overall, MRSA represented 32.3% of all isolates, with very high percentages from the intensive care units (adult and neonatal). PFGE after restriction with SmaI resolved genomic DNA of 95 MRSA strains into 26 major PFGE patterns. The use of southern blot hybridization of ClaI genomic digests with mecA and Tn554 allowed us a significant increase in discrimination, differentiating at least 32 different clones. Two major clones, however, each sharing common ClaI-mecA and Tn554 type and PFGE pattern as well as a common resistance phenotype, represented more than 50% of all MRSA isolates. The recovery of these two clones in the majority of the isolates of adult and neonatal intensive care units, respectively, is indicative of typical nosocomial outbreaks and clonal spread. It is concluded that intensive care units are major areas requiring preventative interventions.     

Incidence and epidemiology of methicillin-resistant Staphylococcus aureus infection in a Saudi Arabian Hospital, 1999-2003.

During 1999-2003 in a Saudi Arabian Hospital, methicillin-resistant Staphylococcus aureus constituted 6% of all S. aureus isolates; the proportion had increased from 2% in 1999, to 9.7% in 2002, to 8% in 2003. Of all MRSA isolates, 62% represented community-acquired infection, 20.4% represented healthcare-associated infection, and 17.6% represented nosocomial infection. The proportion of community-acquired isolates increased from 41.7% in 1999 to 66.6% in 2002, and the proportion representing nosocomial infection decreased from 33% in 1999 to 19% in 2003. Isolates representing nosocomial infection showed higher rates of resistance to ciprofloxacin (76.6%), clindamycin (76.6%), erythromycin (68%) and trimethoprim-sulfamethoxazole (68%) than did isolates in the other categories (P<.001).     

Rates of carriage of methicillin-resistant and methicillin-susceptible Staphylococcus aureus in an outpatient population.

OBJECTIVES: To assess the prevalence of and the clinical features associated with asymptomatic Staphylococcus aureus colonization in a healthy outpatient population, and to compare the characteristics of colonizing methicillin-resistant S. aureus (MRSA) strains with those of strains causing infection in our community and hospital. SETTING: Outpatient military clinics. METHODS: Specimens were obtained from the nares, pharynx, and axillae of 404 outpatients, and a questionnaire was administered to obtain demographic and risk factor information. MRSA strains were typed by pulsed-field gel electrophoresis (PFGE) and evaluated for antibiotic susceptibility. Antibiograms of study MRSA strains were compared with those of MRSA strains causing clinical illness during the same time period. RESULTS: Methicillin-susceptible S. aureus (MSSA) colonization was present in 153 (38%) of the 404 asymptomatic outpatients, and MRSA colonization was present in 8 (2%). Detection of colonization was highest from the nares. No clinical risk factor was significantly associated with MRSA colonization; however, a tendency was noted for MRSA to be more common in men and in those who were older or who had been recently hospitalized. All colonizing MRSA strains had unique patterns on PFGE. In contrast to strains responsible for hospital infections, most colonizing isolates of MRSA were susceptible to oral antibiotics. CONCLUSIONS: MRSA and MSSA colonization is common in our outpatient population. Colonization is best detected by nares cultures and most carriers of MRSA are without apparent predisposing risk factors for acquisition. Colonizing isolates of MRSA are heterogeneous and, unlike nosocomial isolates, often retain susceptibility to other non-beta-lactam antibiotics.