耐甲氧西林金黄色葡萄球菌分子流行病学研究

发布时间：2018-12-11 05:51

【摘要】： 目的： 用脉冲场凝胶电泳(Pulsed Field Gel Electrophoresis, PFGE)及多重PCR技术对天津市南开医院临床分离的耐甲氧西林金黄色葡萄球菌(Methicillin-resistant Staphylococcus aureus, MRSA)株进行染色体指纹图谱分析和葡萄球菌染色体mec基因盒(Staphylococcal Cassette Chromosome mec, SCCmec)基因分型,以了解该院院内感染MRSA菌株的流行特征。 方法： (1)临床送检标本按常规方法初步鉴定为葡萄球菌属,然后根据血浆凝固酶及生化反应的结果鉴定金黄色葡萄球菌,再进行头孢西丁药敏试验,确定MRSA,质控菌株为金黄色葡萄球菌ATCC25923。 (2)耐甲氧西林金黄色葡萄球菌药物敏感试验采用K—B纸片扩散法,测试其对14种抗菌药物的敏感性,药敏结果按NCCLS(2004年版)的标准判读。 (3)对40株MRSA进行PFGE分析、mecA基因检测及SCCmec基因分型。 结果： (1)菌株来源：40株MRSA中28株来源于痰液,占70%；来自腹水或腹腔引流液的7株(17.5%)；伤口引流液和血液各2株(5.0%)；咽拭子1株(2.5%)。 (2) SCCmec分型：Oliveira法和Zhang法将40株MRSA分为四个型别,Ⅲ型为主,共33株,占82.5%；V型5株(12.5%)；Ⅰ型和Ⅳ型均为1株(2.5%)。 (3) PFGE分型：40株MRSA可被分为A—E五个型别,其中A型21株,52.5%；B型8株(20.0%)；C型4株(10.0%)；D型6株(15.0%)；E型]株(2.5%)。 (4) PFGE各型别与耐药谱：除对共同的5种抗生素(克林霉素、红霉素、头孢西丁、苯唑西林、青霉素)耐药外,各型还另对其他种类的药物耐药,如A型对6种,B型对2种,C型对4种,D型对5种,E型对4种药物耐药。 (5)通过分析不同PFGE型别的院内感染MRSA菌株的时间和空间分布,可清晰地追溯各型菌株在该院的分布和传播情况。 结论： (1)本研究所用菌株来源于住院患者的不同感染部位,但痰液的MRSA检出率最高,这显然与呼吸道为葡萄球菌的主要定植部位有关。 (2)在07至08两年的时间里,仅收集到40株院内感染MRSA,这40株菌又分属于A-E五个PFGE型别,说明天津市南开医院住院患者所感染的MRSA不是来自同一克隆株,故呈散发流行。 (3)所有40株MRSA菌株均为多重耐药,但表现出各PFGE型菌株共有耐药性和型相关性耐药表型；这种耐药谱的差别对指导用药有参考意义。 (4)本研究所涉及的MRSA菌株,SCCmec分型以Ⅲ型为主,符合院内感染MRSA菌株的特征。PFGE分型和SCCmec分型分别从不同方面研究这组MRSA菌株,通过综合两方面的研究结果,可在分子水平对医院内分离到的MRSA菌株进行分析,从而确定相关院内感染病原菌的遗传学特征、感染来源、传播途径及分布规律,为院内感染的监控提供可靠的依据。
[Abstract]:Objective: to study the clinical isolation of methicillin resistant Staphylococcus aureus (Methicillin-resistant Staphylococcus aureus,) by pulsed field gel electrophoresis (Pulsed Field Gel Electrophoresis, PFGE) and multiple PCR techniques in Nankai Hospital of Tianjin City. The MRSA strain was analyzed by chromosome fingerprinting and (Staphylococcal Cassette Chromosome mec, SCCmec) genotyping of staphylococcus chromosome mec gene box in order to understand the epidemic characteristics of MRSA strains infected in hospital. Methods: (1) Staphylococcus aureus was preliminarily identified as Staphylococcus by routine method, and then staphylococcus aureus was identified according to the results of plasma coagulase and biochemical reaction. The drug sensitivity test of cefoxitin was carried out to determine the MRSA, of Staphylococcus aureus. The quality control strain is Staphylococcus aureus ATCC25923. (2) the susceptibility of methicillin-resistant Staphylococcus aureus to 14 antimicrobial agents was tested by K-B disk diffusion method. The results were interpreted according to the standard of NCCLS (2004 edition). (3) 40 MRSA strains were analyzed by PFGE, mecA gene and SCCmec genotyping. Results: (1) strain sources: 28 out of 40 strains of MRSA were from sputum (70%), 7 strains (17. 5%) from ascites or peritoneal drainage, 2 strains from wound drainage and 2 strains from blood (5.0%). Throat swabs 1 strain (2.5%). (2) SCCmec typing: 40 strains of MRSA were classified into four types by Oliveira and Zhang, 33 strains were classified as type 鈪，

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