耐甲氧西林金黄色葡萄球菌SCCmec基因分型研究与耐药基因检测

目的了解耐甲氧西林金黄色葡萄球菌(MRSA)的葡萄球菌盒染色体(SCCmec)基因型分布特点和耐药基因的携带状况。方法采用多重聚合酶链反应(PCR)对医院分离的125株MRSA进行SCCmec基因型分型,普通PCR对其中的50株MRSA进行6种耐药基因扩增。结果检测的125株MRSA中124株SCCmec基因型为Ⅲ型,1株不能分型,6种耐药基因的阳性率分别为aac(6′)/aph(2″)98%、aph(3′)Ⅲ基因46%t、etM基因72%、erm基因86%,未扩增出TEM和ant(4′、4″)基因。结论引起感染的MRSA的基因型基本为SCCmecⅢ型,SC-CmecⅢ型的MRSA对氨基糖苷类、红霉素类、四环素类耐药基因有较高的携带率,多重PCR法可以有效的用于大批量临床分离的MRSA的SCCmec分型研究。     

儿童社区获得性、金黄色葡萄球菌肺炎的分子分型研究

目的了解金黄色葡萄球菌杀白细胞毒素(PVL)的分布特征以及耐甲氧西林金黄色葡萄球菌(MRSA)染色体mec(SCCmec)基因盒的分型情况。方法收集2015年1-3月在该院诊断为社区获得性肺炎患儿的非重复性金黄色葡萄球菌菌株141株(痰标本);用多重聚合酶链反应对金黄色葡萄球菌进行PVL基因检测和spa分型,对MRSA进行甲氧西林耐药决定子A(mecA)基因检测和SCCmec基因分型。结果 MRSA检出率为9.2%,均检出mecA基因;将141株金黄色葡萄球菌全部进行PVL基因检测,共检测PVL阳性菌株26株,其中从138株甲氧西林敏感的金黄色葡萄球菌(MSSA)中检出25株,占19.5%;从13株MRSA中检出1株,占7.7%。SCCmec分型结果 1株携带PVL基因的MRSA属于SCCmecⅢ型,其余12株MRSA有2株属于SCCmecⅢ型、10株属于SCCmecⅣ型。未检出SCCmecⅠ、Ⅱ和Ⅴ型。13株MRSA的spa分型未见典型的型别,比较分散;128株MSSA的spa分型以t132为主要型别,其次为t141、t124和t210。结论 MSSA携带PVL基因的阳性率高于MRSA,该院儿童社区获得MRSA以SCCmecⅣ型为主。Spa分型分析显示未见某一型菌株克隆流行,呈散发状态。     

2009－2015年深圳市不同来源样本中金黄色葡萄球菌毒力耐药特征及分子分型研究

目的 研究2009－2015年深圳市不同来源样本中金黄色葡萄球菌(Staphylococcus aureus,SA)携带毒力、耐药基因、耐药表型情况和分子型别研究。 方法 2009－2015年期间,86株SA分离自医院病人、医院环境涂抹样、食物中毒等样品。PCR方法检测毒力基因、耐药基因以及耐甲氧西林金黄色葡萄球菌(methicillin-resistant Staphylococcus aureus,MRSA)的SCCmec基因型,进行蛋白A基因多态性(single locus DNA-sequencing of the repeat region of the Staphylococcus protein A gene,Spa)以及多位点序列分型(multilocus sequencing typing,MLST)研究。按照美国临床和实验室标准协会(Clinical and Laboratory Standards Institute,CLSI)方法,对抗菌药物进行药敏试验。 结果 检出21种毒力基因,55株(64.0%)携带mecA基因。SCCmec分型结果,Ⅲ型为优势型别(60.0%,33/55)。86株SA分为24种Spa型,MRSA菌株Spa优势型别为t030与t437,甲氧西林敏感金黄色葡萄球菌菌株(methicillin sensitive Staphylococcus aureus,MSSA)的优势型别为t091与t127。86株SA分为23种 MLST型,形成3个克隆复合体CC239(27.9%)、CCnew3(27.9%)与CC188(11.6%)。 结论 优势型别为ST239(Spa-t030)、STnew3(Spa-t437)具有多药耐药的特征,且携带多种毒力基因。MRSA流行株、非流行株与MSSA在携带毒力与耐药基因之间均存在差异。需要加强监测SA中的优势型别及MRSA菌株.关注其耐药的动态变化。     

中山地区耐甲氧西林金黄色葡萄球菌的耐药性分析及基因分型研究

目的 了解中山地区耐甲氧西林金黄色葡萄球菌(MRSA)临床分离株耐药性及基因型,为MRSA治疗及感染控制提供数据及分子生物学支持。方法 收集2015年1月至2015年10月中山市7家医院临床分离到的MRSA,采用WOHONET 5.6对耐药数据进行统计分析,PCR检测MRSA耐药基因mecA携带情况,采用多重PCR对分离株进行葡萄球菌染色体mec基因盒(SCCmec)分型。结果 2015年1月至2015年10月7家医院共分离到50株MRSA,所有MRSA分离株均检出mecA基因,检出率为100%。SCCmec各分型数量依次为I型1株(2%),II型2株(4%),III型28株(56%),IV型6株(12%),V型12株(24%),有1株不能分型。中山市古镇人民医院分离MRSA株主要为SCCmecIII型,其他6家医院主要为SCCmecIV型及V型。MRSA对青霉素耐药率为100%,对红霉素(90%)、庆大霉素(86%)、左氧氟沙星(84%)、诺氟沙星(84%)、克林霉素(76%)耐药率较高,对奎奴普丁/达福普丁(4%)耐药率较低,未检出替考拉宁及万古霉素耐药株。SCCmec III型菌株对庆大霉素、利福平、左氧氟沙星、诺氟沙星、复方新诺明、克林霉素、红霉素、奎奴普丁/达福普丁及四环素耐药率高于SCCmec V型菌株。结论 mecA是MRSA携带最常见的耐药基因,中山地区分离MRSA株在规模较大的医院主要以SCCmec III型为主,基层医院以SCCmec IV及V型为主,SCCmec III型对常用抗菌药敏感性较差,耐药机制较为复杂,临床科室及医院感染控制部门应重点监控该型细菌,避免院内感染暴发。     

耐甲氧西林金黄色葡萄球菌基因诊断及多重PCR SCCmec基因分型方法的建立

目的建立对临床分离的耐甲氧西林金黄色葡萄球菌(MRSA)基因诊断和金黄色葡萄球菌染色体mec基因盒(SCCmec)基因分型的方法。方法对临床分离的11株金黄色葡萄球菌采用双重PCR(femA和mecA)鉴定,再将鉴定为MRSA的临床菌株和3株标准株用多重PCR方法在一个反应体系(针对MRSA的8个基因)中进行SCCmec基因分型。结果临床分离株中有6株鉴定为MRSA,对其和MRSA标准株的多重PCR基因分型结果显示,两株临床株为SCCmecⅡ型,4株为Ⅲ型,标准株SA-w2为Ⅰ型,MRSA252为Ⅱ型。结论该研究可以很好地对临床MRSA进行基因诊断和分型,对MRSA的诊断和分型、耐药研究以及分子流行病学有重要意义。     

耐甲氧西林金黄色葡萄球菌pvl及tst基因分布与感染类型研究

目的了解耐甲氧西林金黄色葡萄球菌(MRSA)临床菌株携带杀白细胞毒素(PVL)编码基因pvl和中毒休克综合征毒素-1(TSST-1)编码基因tst情况、流行特征及感染类型,为该类感染的临床治疗提供依据。方法收集2012年1-12月临床分离的MRSA 96株,采用PCR检测96株MRSA中pvl和tst基因,采用全自动微生物分析仪检测11种临床常用抗菌药物的敏感性,采用多重PCR对携带pvl基因(pvl+)或tst基因(tst+)的MRSA进行mec分型(SCCmec),了解与分析pvl+或tst+MRSA感染类型。结果 96株MRSA中20株检出pvl基因占20.8%,13株检出tst基因占13.5%,未发现同时携带pvl和tst基因的菌株;除左氧氟沙星和莫西沙星外,pvl+/tst+MRSA对其他抗菌药物耐药率与pvl-/tst-菌株相似;20株pvl+MRSA中7株社区获得性感染菌株、13株医院获得性感染菌株,其中17株分离自皮肤和软组织感染患者脓液,13株tst+MRSA均为医院获得感染菌株,其中8株分离自肺部感染患者痰液;20株pvl+MRSA中,SCCmecⅢ型11株、SCCmecⅣa型5株、SCCmecII型2株,2株未能分型;13株tst+MRSA均为SCCmecⅢ型。结论 pvl+MRSA在社区和医院内均有流行,主要引起皮肤和软组织感染;tst+MRSA仅在医院内流行,主要引起肺部感染;pvl+和tst+MRSA均以SCCmecⅢ型为主。     

耐甲氧西林金黄色葡萄球菌SCCmec分型与耐药性研究

目的研究临床分离的耐甲氧西林金黄色葡萄球菌(MRSA)耐药性,检测MRSA葡萄球菌染色体mec盒(SCCmec)基因型,并进行杀白细胞素(PVL)毒力基因检测。方法采用标准平皿两倍稀释法测定250株MRSA对多种抗菌药物最低抑菌浓度(MIC),采用多重PCR方法对MRSA进行SCCmec基因分型,单一PCR方法对MRSA菌株进行PVL毒力基因检测。结果 250株MRSA经多重PCR方法检测SCCmec基因型,SCCmecⅡ-dcs型菌株30株,占12.0%,Ⅱ型的亚型1株,占0.4%,Ⅲ型62株,占24.8%,含有342 bp(dcs)额外扩增条带的Ⅲ型菌株141株,占56.4%,Ⅳ型7株,占2.8%,Ⅳa型1株,占0.4%,Ⅴ型1株,占0.4%,7株细菌未能分型,占2.8%,未发现Ⅰ型;单一PCR方法获得PVL呈阳性的菌株共2株,占临床分离MRSA的0.8%;各基因型对多种抗菌药物呈现不同程度的耐药。结论临床分离的MRSA以SCCmecⅢ型为主;其次为SCCmecⅡ型;有少量SCCmecⅣ型,少数菌PVL毒力基因阳性。     

某院ICU医院获得性肺炎患者痰分离MRSA耐药基因和pvl基因携带情况

目的了解医院获得性肺炎患者痰中耐甲氧西林金黄色葡萄球菌(MRSA)耐药基因和毒力因子pvl基因携带情况。方法对来源于某院重症监护病房(ICU)医院获得性肺炎患者痰中的46株MRSA,采用聚合酶链反应(PCR)检测细菌耐药基因(mecA、aacA-D、tetK、tet M、msrA、msrB、ermA、ermC、vatA、vatB、vatC、femB和linA)和毒力因子pvl基因,并以PCR法分析MRSA菌株SCCmec型别。结果 46株MRSA中,耐药基因mecA、aacA-D、tetK、msrA、ermA、ermC、femB和linA的检出率分别为100%、54.35%、36.96%、13.04%、36.96%、52.17%、71.74%和10.87%,所有菌株均未检出tet M、msrB、vatA、vatB和vatC基因;毒力基因pvl携带率为65.22%。46株MRSA共检出4种SCCmec基因型,其中SCCmecⅡ型、Ⅲ型、IVc型、V型分别为26.09%、52.17%、2.17%和2.17%。结论医院获得性肺炎患者痰中MRSA携带多种耐药基因,且毒力基因pvl携带率较高,SCCmec基因型以Ⅲ型为主,临床医务人员对此情况应高度重视。     

mecA基因在金黄色葡萄球菌中的分布及对耐药性的影响

目的 探讨mecA基因在金黄色葡萄球菌中的分布以及对其耐药性的影响.方法 收集金黄色葡萄球菌临床分离菌株47株,用琼脂扩散法进行敏感性检测,提取分离株DNA,通过聚合酶链反应(PCR)对mecA基因进行扩增,分析mecA基因和金黄色葡萄球菌耐药性的关系.结果 47株金黄色葡萄球菌中,有33株为耐甲氧西林金黄色葡萄球菌(MRSA),占70.2%;甲氧西林敏感金黄色葡萄球菌(MSSA)有14株,占29.8%;在33株MRSA中,只有3株对除替考拉宁、万古霉素等糖肽类以外的抗菌药物敏感,占9.1%;14株MSSA中只有2株对全部12种抗菌药物敏感,仅占14.3%;PCR结果 显示,在33株MRSA中,32株携带mecA基因,占97.0%;而在14株MSSA中有3株携带mecA基因,3株携带mecA基因的MSSA耐药性较不携带mecA基因MSSA的耐药性严重.结论 金黄色葡萄球菌中MRSA具有较高的分离率,MRSA的耐药性非常严重,万古霉素等糖肽类抗菌药物是惟一有效的抗菌药物,绝大多数的MRSA携带有mecA基因,mecA基因在金黄色葡萄球菌的耐药机制中发挥重要作用,携带mecA基因的MSSA耐药情况比不携带mecA基因的MSSA严重.     

2014—2022年湖南省病人来源猪链球菌2型鉴定及毒力基因分析

目的 了解2014—2022年湖南省人感染猪链球菌病病人分离株型别分布与毒力基因携带情况,为人感染猪链球菌病的防控提供依据。方法 收集2014—2022年湖南省人感染猪链球菌病临床分离株,通过传统生化反应和聚合酶链反应(polymerase chain reaction, PCR)检测猪链球菌种特异性基因16S rRNA,同时用PCR对2型血清型鉴定基因(兼荚膜多糖毒力基因)cps2J和7种毒力基因进行扩增,用毛细管电泳检测扩增产物,分析病人来源猪链球菌的型别与毒力基因携带情况。结果 2014—2022年湖南省38株人感染猪链球菌病临床分离株中,1株为羊链球菌,32株为猪链球菌2型,5株生化鉴定为2型的菌株经分子分型鉴定为猪链球菌其他型别。32株猪链球菌2型菌株中,46.88%的菌株携带全部8种毒力基因,40.63%的菌株携带除mrp外的7种毒力基因。携带cps2J、fbps、ef、gdh、orf2、gapdh 6种毒力基因与携带cps2J、sly、gdh、orf2、gapdh 5种毒力基因的菌株均占3.13%,6.25%的菌株携带cps2J、gdh、orf2、gapdh 4种毒力基因...     

ICU患者分离金黄色葡萄球菌的耐药性及分子流行病学特征

目的了解某院重症监护病房（ICU）金黄色葡萄球菌的耐药特点及分子流行病学特征。方法收集2014年1—12月该院ICU分离的金黄色葡萄球菌,进行细菌鉴定及药物敏感性试验,采用金黄色葡萄球菌A蛋白(spa)分型及多位点序列分型(MLST)方法进行分型。结果160株金黄色葡萄球菌中耐甲氧西林金黄色葡萄球菌（MRSA）120株（占75.00%）。MRSA对红霉素、克林霉素、左氧氟沙星的耐药率均＞80%;MSSA对头孢唑林敏感,对红霉素、克林霉素、左氧氟沙星的耐药率分别为62.50%、35.00%、10.00%。spa分型和MLST结果显示,120株MRSA主要为ST239 t030、ST239 t037、ST5 t2460 3种型别,其中ST239 t030（105株,87.50%）为主要流行菌株,8个ICU均有检出;MSSA存在较多型别,ST59 t437仅在神经内科(8株)和消化科（2株）检出,ST6 t701、ST398 t3625、ST398 t1793和ST121 t2092分别仅在神经内科（7株）、麻醉科（5株）、神经外科（4株）和心外科（4株）检出。结论该院ICU MRSA分离率较高,以ST239 t030克隆株为主,存在医院内流行;不同型别MSSA在各科室内存在流行趋势。     

Genomic diversity of mec regulator genes in methicillin-resistant Staphylococcus aureus and Staphylococcus epidermidis.

Low-affinity penicillin-binding protein PBP-2a encoded by mecA is closely related to methicillin resistance in staphylococci, and expression of PBP-2a is controlled by regulator elements encoded by mecR1 and mecI which are located adjacent to mecA on the chromosome. Deletion or mutation which occurred in mec regulator gene is considered to be associated with constitutive production of PBP-2a. The distribution of the mec regulator genes in 176 strains of Staphylococcus aureus and 33 strains of S. epidermidis isolated from a single hospital was studied by polymerase chain reaction amplification. Most clinical isolates of methicillin-resistant S. aureus (MRSA) (94.3%) and S. epidermidis (MRSE) (83.9%) possessed both mecI and mecR1 genes (type I), whereas no mec regulator genes were detected in mecA-negative isolates. In contrast, 7 MRSA and 5 MRSE isolates were found to have incomplete regulator genes, and they were classified into three groups; strains which lacked only mecI gene (type II), strains which lacked mecI and 3''-end of mecR1 gene (type III), and strains which lacked both regulator genes (type IV). Analysis of mecI gene from all the strains having mecI by restriction fragment length polymorphism after Mse I digestion indicated that three MRSA strains possessed one of the known point mutations identified previously. These findings indicated the predominance of a single type of MRSA possessing both mecI and mecR1 in the study period and also suggested a high genomic diversity in mec regulator region of staphylococci.     

Coagulase gemne variants associated with distinct populations of Staphylococcus aureus

An identifying characteristic of Staphylococcus aureus is the production of staphylocoagulase (coagulase). The aim of this study was to determine the clonal distribution of coagulase gene (coa) variants within populations of S. aureus defined by multilocus sequence typing (MLST), pulsed-field gel electrophoresis (PFGE), and protein A variation. The N-terminal region of the coa gene from 43 methicillin-susceptible (MSSA) and 252 methicillin-resistant (MRSA) S. aureus human isolates and 9 animal S. aureus isolates was amplified and digested with HinfI. Twelve types were identified amongst the MSSA isolates and the majority (93%) of MRSA isolates were assigned to 5 of the 12 types. MLST and PFGE analysis identified epidemic populations of MRSA and each epidemic population was characterized by a different coagulase type. Nine of the 12 MLST-defined clonal complex ancestral genotypes recently described each carried a different coagulase type suggesting that coagulase evolution and the evolution of the clonal complexes are intimately related.     

医院获得性耐甲氧西林金黄色葡萄球菌中PSM-α基因检测及相关研究

目的了解某地区耐甲氧西林金黄色葡萄球菌(MRSA)中α型-酚溶调制蛋白(PSM-α)基因携带情况及对人外周血中性粒细胞的影响,为指导临床治疗及明确该地区MRSA致病机制提供理论依据。方法收集临床标本中分离并经SCCmec分型的MRSA90株,采用聚合酶链反应(PCR)方法扩增PSM-α基因,并通过细胞形态学方法研究PSM-α对人外周血中性粒细胞的影响。结果 86株医院获得性MRSA(HA-MRSA)中,PSM-α基因阳性者78株,PSM-α阳性率为90.70%;4株社区获得性MRSA(CA-MRSA)中,2株为PSM-α基因阳性,阳性率为50.00%;PSM-α阳性组中性粒细胞死亡率与生理盐水组、PSM-α阴性组和ATCC25923组间比较,差异有统计学意义。PSM-α阳性组死亡率高于其他3组,而PSM-α阴性组和ATCC25923组差异无统计学意义。结论该地区HA-MRSA携带PSM-α基因,且PSM-α基因阳性的MRSA菌株分泌的PSM-α具有促进中性粒细胞溶解的活性。     

Characteristics of patients with healthcare-associated infection due to SCCmec type IV methicillin-resistant Staphylococcus aureus.

OBJECTIVE: Methicillin-resistant Staphylococcus aureus (MRSA) with the staphylococcal cassette chromosome mec (SCCmec) type IV allele is most commonly associated with community-acquired MRSA (CA-MRSA) infection; however, such organisms have also been identified in the healthcare setting. The objective of the present study was to characterize the epidemiology of and clinical outcomes associated with SCCmec-IV MRSA infection acquired in the healthcare setting, compared with infection caused by MRSA of other SCCmec types. DESIGN: We evaluated a cohort of 100 inpatients with MRSA infection that met the Centers for Disease Control and Prevention definition for healthcare-associated infection and compared the patients' demographic characteristics, the antimicrobial susceptibilities of the MRSA isolates, the infection types, and the associated clinical and microbiological outcomes. For each MRSA isolate, the SCCmec type and the presence of Panton-Valentine leukocidin (PVL) were determined by polymerase chain reaction methods. RESULTS: SCCmec-IV MRSA isolates were isolated from 53 patients (42% of these isolates were positive for PVL), and SCCmec-II or SCCmec-III MRSA was isolated from 47 patients (3% of these isolates were positive for PVL). No differences were noted between the patients in the SCCmec-II/III group and the patients in the SCCmec-IV group with respect to age (median, 55 vs 50 years); sex (77% vs 64% of patients were male); medical service (surgical service, 60% in both groups; ICU admission, 55% vs 53%), Acute Physiology and Chronic Health Evaluation II score (median, 8 vs. 7); infection type; or underlying comorbidities, except for presence of a burn wound (13% vs 2%; P < .04). Patients in the SCCmec-II/III group were more likely to have multiple sites of infection (P = .006) and a longer length of stay (LOS) prior to detection of MRSA than were patients in the SCCmec-IV group (median, 4 vs 1 days; P < .001). Total LOS was significantly greater for patients in the SCCmec-II/III, compared with those in the SCCmec-IV group (P = .006). Multiple logistic regression identified liver disease and longer LOS prior to detection of MRSA as predictors of infection with SCCmec-II/III MRSA. Rates of susceptibility to clindamycin, gentamicin, ciprofloxacin, levofloxacin, and tetracycline was significantly greater among SCCmec-IV MRSA isolates, compared with type II/III isolates (P < or = .05). Compared with SCCmec-IV isolates acquired in the community, the susceptibility rates among healthcare-associated SCCmec-IV isolates was significantly less for clindamycin, gentamicin, and levofloxacin, indicating that these organisms may quickly acquire resistance to non- beta -lactam antibiotics, as do SCCmec-II/III strains. CONCLUSIONS: SCCmec-IV MRSA appears to have become established in hospitals. The onset of infection caused by SCCmec-IV strains is earlier than the onset of infection with SCCmec-II/III strains; however, associated types of infection are similar. Infection with SCCmec-II/III MRSA is currently associated with an adverse impact on outcome, compared with infection with SCCmec-IV MRSA. Further research is warranted to determine the impact of SCCmec type IV strains in hospital settings.     

Molecular epidemiology and antibiotic resistance of methicillin-resistant Staphylococcus aureus circulating in the Russian Federation

The aim of this study was to investigate the patterns of antimicrobial resistance and molecular features of methicillin-resistant Staphylococcus aureus (MRSA) isolates in Russia. Isolates recovered from hospital patients (n = 480), healthy medical personnel (n = 25), and healthy carriers (n = 13) were included in the study. Hospital-acquired MRSA (HA-MRSA) demonstrated high resistance to ciprofloxacin, gentamicin, and chloramphenicol (76%–92%), moderate – to tetracycline, erythromycin, clindamycin, and rifampicin (38%–54%), and low – to fusidic acid, co-trimoxazole, mupirocin, and daptomycin (2%–7%). Elevated MIC (2.0 μg/ml) of vancomycin was detected in 26% of isolates. All isolates were susceptible to linezolid and tigecycline. Multilocus sequence typing (MLST) revealed that CC8 isolates (ST8 + ST239) constituted 83.1% of HA-MRSA and that this genetic lineage dominated in all regions from Krasnoyarsk to Saint Petersburg. A local ST239 variant harboring the tst gene (ST239_Kras) was detected in Krasnoyarsk. The other HA-MRSA isolates belonged to clonal complex 5 (CC5) (21 isolates, 12.2%) and CC22 (2, 1.2%). The majority of CC5 isolates were affiliated with sequence type 228 (ST228) and were characterized with decreased susceptibility to ceftaroline (MIC = 2 μg/ml). We also detected, for the first time in Russia, livestock-associated MRSA (LA-MRSA) from clusters CC398 and CC97 in humans. Among the 2053 healthy persons screened for nasal carriage of S. aureus, the bacteria were isolated from 426 (21%); among them, 13 carried isolates identified as community-associated MRSA (CA-MRSA). Eleven of 13 CA-MRSA isolates belonged to ST22 (spa types t223, t3243, and t3689; SCCmec types IVa and IVc, agr type I, tst-positive) and were similar to the EMRSA-15/Middle Eastern variant (Gaza strain).     

徐州地区116株MRSA耐药性分析与分子流行病学调查

目的了解耐甲氧西林金黄色葡萄球菌(MRSA)感染现状和耐药机制,为临床合理用药提供依据。方法收集徐州地区2012—2015年各类标本中分离的金黄色葡萄球菌(SA),用头孢西丁纸片扩散法初筛MRSA菌株,扩增mecA基因进行确认,K-B法检测MRSA对药物的敏感性,E-test法测定万古霉素的最低抑菌浓度(MIC),采用多重PCR进行葡萄球菌染色体mec(SCCmec)基因分型。结果 2012—2015年210株SA共检出MRSA116株,其中mecA基因阳性114株,MRSA总检出率为55.24%。MRSA对万古霉素、奎奴普丁/达福普汀、替考拉宁和利奈唑胺的敏感率均为100%,对氯霉素和呋喃妥因的耐药率最低,分别为15.52%、1.72%,MRSA对10种抗菌药物的耐药率80%;MRSA对青霉素类、氨基糖苷类、红霉素、喹诺酮类、磺胺类、利福平、四环素、克林霉素的耐药率高于甲氧西林敏感金黄色葡萄球菌(MSSA)。2012—2015年万古霉素对MRSA的MIC均为1.0μg/mL,MIC90均为1.5μg/mL,2015年发现1株MRSA的万古霉素MIC为2.0μg/mL。116株MRSA分型结果显示,SCCmecII型11株(9.48%),SCCmecIII型85株(73.28%),SCCmecIV型4株(IVa和IVb型各2株,均为1.72%),未分型MRSA16株(13.79%),未检出SCCmecI和V型。结论 MRSA呈严重的多重耐药,对万古霉素MIC无漂移,临床MRSA分离株以SCCmecIII型为主,临床应采取感染控制措施,控制MRSA感染。     

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.     

Distribution of erm genes among MRSA isolates with resistance to clindamycin in a Chinese teaching hospital

The objective of this study was to analyze erythromycin and clindamycin resistance patterns among different MRSA lineages in China. Antimicrobial susceptibility testing, resistance determinant screening, plasmid electroporation and sequence comparisons were performed. High rates of clindamycin (92.5%, 270/292) and erythromycin (92.8%, 271/292) resistance were observed. Additionally, 88.2% (60/68) of the ST59 MRSA isolates and 78.9% (15/19) of the ST239 MRSA isolates had constitutive resistance to clindamycin, while 82.0% (123/150) of the ST5 MRSA isolates showed inducible clindamycin resistance. The ermB gene was identified in 80.9% (55/68) of the ST59 isolates but was not detected in ST5 and ST239 MRSA isolates. Detection rates of ermA were high in the ST5 (99.3%, 149/150) and ST239 (89.5%, 17/19) MRSA isolates, but no ermA-positive ST59 MRSA isolates were identified. The ermC gene, observed to be harbored on similar, transmissible plasmids ranging in size from 2402 to 2473 bp, were found in different MRSA lineages. Summarily, high erythromycin and clindamycin resistance rates were observed in MRSA isolates. ST59 and ST239 MRSA isolates primarily exhibited constitutive resistance, while ST5 MRSA isolates showed inducible resistance phenotypes. ermA and ermB genes were frequently carried by specific MRSA clones, while ermC gene was present within small transmissible plasmids in all lineages. Erythromycin and clindamycin resistance genes transfer between MRSA isolates in healthcare settings remains a problem, and infection control procedures should be applied.     

临床分离金黄色葡萄球菌的耐药特点和MRSA分子分型

目的研究耐甲氧西林金黄色葡萄球菌(MRSA)的耐药性及其基因分型。方法收集某院2014年1月—2015年11月检出的非重复金黄色葡萄球菌967株,检测其药敏结果及mecA抗性基因、杀白细胞素(PVL)基因;MRSA菌株经多重PCR进行葡萄球菌盒式染色体mec(SCCmec)分型、多位点序列分型(MLST)、金黄色葡萄球菌蛋白A基因(spa)分型、金黄色葡萄球菌附属因子调节子(agr)分型。结果 967株金黄色葡萄球菌共检出210株MRSA,MRSA检出率为21.72%;痰标本MRSA检出率高于皮肤软组织标本(68.09%vs 11.83%,P0.05);金黄色葡萄球菌中未发现对万古霉素和利奈唑胺耐药菌株,MRSA对庆大霉素、四环素、红霉素、克林霉素、左氧氟沙星、环丙沙星、莫西沙星、呋喃妥因、利福平的敏感率均低于MSSA,差异均有统计学意义(均P0.05);MRSA对复方磺胺甲口恶唑的敏感率高于MSSA,差异有统计学意义(P0.05)。皮肤软组织分离的MRSA对庆大霉素、左氧氟沙星、环丙沙星、莫西沙星、利福平的敏感率为86.90%~95.24%,而痰分离的MRSA仅为1.56%~15.63%。967株金黄色葡萄球菌检测出210株携带mecA基因,10株携带PVL基因,210株MRSA中有8株未分型,占3.81%。MLST主要以ST239(177株)为主;SCCmec分型主要以Ⅲ型(177株)为主;spa分型主要以t 030(177株)为主;agr分型主要以Ⅰ型(196株)为主。结论该院MRSA菌株主要流行克隆ST239-MRSA-SCCmecⅢ-t030,耐药形势严峻,应加强医院内耐药菌株的监测。