Abstract:

To investigate the drug-resistance and genetic types of methicillin-resistant Staphylococcus aureus（MRSA）isolated from pneumonia in children，and provide information for clinical diagnosis and treatment. Methods　The patients with pneumonia from six hospitals in China between September 2008 and March 2009 were investigated. The MRSA strains were isolated from sputum of lower respiratory tract；the strains were identified by cefoxitin slip test；clinical information about these MRSA was also collected. The minimal inhibitory concentrations （MIC ） of 12 antibiotics against MRSA were determined by agar dilution method according to the guidelines of the clinical and laboratory standards institute，and the data were analyzed by WHONET 5.4 software. The multilocus sequence typing （MLST） of MRSA was performed as described previously ，and the SCCmec types were determined by the multiplex PCR assay. Results　Forty-seven strains of MRSA were separated from the patients with pneumonia；the most common age with pneumonia caused by MRSA was from 15d to 6 years old. The SCCmec types of most MRSA strains were type Ⅲ，type IV and typeⅤ.The most common type of MLST of MRSA-IV and MRSA-Ⅴwas ST59. All MRSA isolates were found to be resistant to penicillin and oxacillin，and susceptible to vancomycin. Resistance to other antimicrobial drugs tested was relatively higher and multidrug resistance was also observed. Conclusion　The most common age with pneumonia caused by MRSA is before school age. The SCCmec types of most MRSA strains are type III ，type IV and typeⅤ.The most common type of MLST of MRSA-IV and MRSA-Ⅴis ST59. Antimicrobial susceptibility tests show high resistance of many antimicrobials and multiple drugs.

Key words: methicillin, Staphylococcus aureus, pneumonia, children, drug-resistance, gene

摘要：

研究儿童肺炎耐甲氧西林金黄色葡萄球菌（MRSA）分离株的耐药性及基因分型，为临床诊疗提供参考。 方法　对2008年9月至2009年3月国内6家医院（中国医科大学附属盛京医院、温州医学院附属育英医院、重庆儿童医院、广东省妇幼保健院、复旦大学附属儿科医院、广州儿童医院）的47例肺炎患儿进行临床调查，采集下呼吸道的痰液标本作细菌培养，用头孢西丁纸片法鉴定MRSA，并用琼脂稀释法测定MRSA对12种抗生素的最低抑菌浓度（MIC）；对MRSA进行多位点序列分型（MLST） 检测，用多重PCR方法检测MRSA的葡萄球菌染色体盒mec（SCCmec）基因分型。 结果　从肺炎患儿中分离MRSA 47株，MRSA感染肺炎多见于低龄儿童（15 d至6岁），SCCmec基因分型中以Ⅲ型、Ⅳ型和Ⅴ型为主，Ⅴ型和Ⅳ型中MLST分型结果均以ST 59型多见。所有MRSA的分离株都对青霉素和苯唑西林耐药，对万古霉素敏感，对其他抗菌药物的耐药率较高并且存在多重耐药。结论　儿童肺炎MRSA分离株多见于学龄期之前的儿童，SCCmec基因分型以Ⅲ型、Ⅳ型和Ⅴ型常见，MLST分型以ST59为主；MRSA对多种抗菌药物具有较高的耐药性并且存在多重耐药。

关键词: 甲氧西林, 金黄色葡萄球菌, 肺炎, 儿童, 耐药, 基因