psm-mec在临床分离表皮葡萄球菌中的分布和表达  

Distribution and expression of psm-mec in clinical isolates of Staphylococcus Epidermidis

作　　者：杨永长[1] 肖代雯[1] 姜伟[1] 陈亮[1] 胡洪华[1] 周薇[1] 黄文芳[1] 

机构地区：[1]四川省医学科学院.四川省人民医院检验科,成都610072

出　　处：《成都医学院学报》2015年第5期549-552,627,共5页Journal of Chengdu Medical College

摘　　要：目的探讨psm-mec基因在临床分离表皮葡萄球菌中的分布和表达,为进一步分析psm-mec的功能奠定基础。方法收集临床分离并经过全自动微生物鉴定系统准确鉴定的表皮葡萄球菌165株,通过PCR扩增esp和mecA基因准确鉴定和区分甲氧西林敏感表皮葡萄球菌（MSSE）和甲氧西林耐药表皮葡萄球菌（MRSE）。扩增psm-mec、fudoh和p221片段确认psm-mec携带菌株,通过DNA序列比对分析psm-mec及其上游序列的变化。构建p221重组质粒制备定量检测psm-mec的标准品,提取携带psm-mec MRSE总RNA,采用荧光定量RT-PCR分析临床分离MRSE psm-mec转录水平。结果 83.64%的临床分离表皮葡萄球菌为MRSE,其中29株携带psmmec基因,携带率为17.58%,且仅分布于MRSE中。所有菌株psm-mec开放读码框序列无突变,仅4.34%菌株在psm-mec基因上游存在G〉A的点突变。临床分离携带psm-mec菌株均表达此基因,其表达水平在103~107拷贝之间,G〉A点突变不影响psm-mec转录表达。结论 psm-mec仅分布和表达于临床分离MRSE中,G〉A点突变不影响psm-mec表达。Objective To explore the distribution and expression of psm-mec in clinical isolates of Staphylococcus epidermidis and to provide foundation for its function analysis. Methods 165 strains of S.epidermidis identified accurately by full automation microbiological identification system were collected,and PCR was used to amplify esp and mecA gene to differentiate methicillin-resistant S.epidermidis（MRSE）and methicillin-sensitive S.epidermidis（MSSE）.Strains with psm-mec were validated by amplification of psm-mec,fudohand p221 fragments,and DNA sequence analysis was performed to determine mutation in psm-mec and its upstream sequences.psm-mec reference standard was obtained by construction of p221 recombinant plasmid.RNA of MRSE with psm-mec was extracted,and its mRNA level was measured by fluorescent quantitative RT-PCR.Results MRSE accounted for 83.64% of clinical isolated S.epidermidis,and 29 strains were positive to psm-mec with a rate of 17.58%,which distributed only in MRSE.No mutation was observed in psm-mec ORF sequence,but a G to A point mutation of psm-mec in 4.34% strains.psm-mec expressed with a level ranging from 103 to 107 copies in all clinical isolates of MRSE with psm-mec,and the G to A point mutation did not affect psm-mec transcription.Conclusion psm-mec distributes and expresses only in clinical isolates of MRSE,and G〉A mutation of psm-mec has no effect on its expression.

关 键 词：表皮葡萄球菌 psm-mec 分布 表达 

分 类 号：R378[医药卫生—病原生物学]