Ma Xiao-xue, Luo En-jie
Department of Medical Microbiology and Parasitology, College of Basic Medical Sciences, China Medical University, Shenyang 110001, China.
Zhonghua Liu Xing Bing Xue Za Zhi. 2011 Aug;32(8):804-7.
To investigate the nasal colonization of Staphylococcus (S.) aureus strains among medical university students in Shenyang and to study the molecular epidemiological characteristics of methicillin resistant S. aureus (MRSA) strains.
Sterilized nasal swabs were used to collect nasal bacteria from both nares of the students. Nasal specimens were further identified as S. aureus strains, sensitive or resistant to methicillin through a series of tests. Molecular related methods including staphylococcal cassette chromosome mec (SCCmec) typing, pulsed- field gel electrophoresis (PFGE), coagulase isotyping and minimum inhibitory concentration (MIC) determination etc. were used to characterize the isolates. Prevalence of the panton-valentine leukocidin (pvl) genes (lukS and F-PV) among the isolates was also assessed.
Staphylococci were found in 488 specimens from 977 participants through the surveillance program, conducted in 2009. Of the 488 specimens being tested, 364 were identified as coagulase-negative staphylococci (CoNS) and 124 as S. aureus. MRSA strain among the S. aureus isolates was accounted for 3.4%. In the surveillance program conducted in 2010, staphylococci grew in 310 specimens from 657 participants. Of the 310 specimens tested, 195 were identified as CoNS and 115 as S. aureus. The percentage of MRSA strains among the S. aureus isolates was 7.7%. In total, 239 students carried S. aureus, and the percentage of MRSA carriers among the total specimens tested in this study was 5.1%. Most of the MRSA strains could be classified into one of the five types of SCCmec elements. Type IV a SCCmec strains were most frequent seen overall (10 isolates). A total of 11 pulsotype were identified among the MRSA strains and were classified into 7 major groups (A to G) by the mutual correlations of their banding patterns. Ten MRSA strains were identified as pvl positive strains.
An MRSA clone (IV a SCCmec pulsotype A) carrying pvl toxin gene was found to be prevalent in the nares of the healthy university students.
调查沈阳医科大学学生金黄色葡萄球菌的鼻腔定植情况，并研究耐甲氧西林金黄色葡萄球菌（MRSA）菌株的分子流行病学特征。
使用无菌鼻拭子从学生双侧鼻孔采集鼻内细菌。通过一系列检测，将鼻标本进一步鉴定为金黄色葡萄球菌菌株，对甲氧西林敏感或耐药。采用葡萄球菌盒式染色体mec（SCCmec）分型、脉冲场凝胶电泳（PFGE）、凝固酶同型分型和最低抑菌浓度（MIC）测定等分子相关方法对分离株进行特征分析。还评估了分离株中杀白细胞素（pvl）基因（lukS和F-PV）的流行情况。
通过2009年开展的监测项目，在977名参与者的488份标本中发现了葡萄球菌。在检测的488份标本中，364份被鉴定为凝固酶阴性葡萄球菌（CoNS），124份为金黄色葡萄球菌。金黄色葡萄球菌分离株中的MRSA菌株占3.4%。在2010年开展的监测项目中，657名参与者的310份标本中培养出了葡萄球菌。在检测的310份标本中，195份被鉴定为CoNS，115份为金黄色葡萄球菌。金黄色葡萄球菌分离株中MRSA菌株的比例为7.7%。共有239名学生携带金黄色葡萄球菌，本研究中检测的所有标本中MRSA携带者的比例为5.1%。大多数MRSA菌株可归类为五种SCCmec元件类型之一。IV a型SCCmec菌株总体上最常见（10株）。在MRSA菌株中总共鉴定出11种脉冲型，并根据其条带模式的相互关系分为7个主要组（A至G）。10株MRSA菌株被鉴定为pvl阳性菌株。
发现携带pvl毒素基因的MRSA克隆（IV a SCCmec脉冲型A）在健康大学生的鼻腔中流行。
