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  • 學位論文

金黃色葡萄球菌的臨床菌株之表現型與基因型特徵研究

The characteristics of phenotype and genotype of clinical strains of Staphylococcus aureus

指導教授 : 曹世明

摘要


金黃色葡萄球菌(Staphylococcus aureus)是一種能引起人類各種疾病的常見格蘭氏陽性球菌,抗甲氧苯青黴素金黃色葡萄球菌methicillin resistant S. aureus,簡稱MRSA不但造成院內和社區感染,更因獨特的抗藥性導致罹病率與死亡率的增加。本研究企圖探討金黃色葡萄球菌的臨床菌株表現型與基因型特徵的分佈情形。因此,我們收集中山醫學大學附設醫院57株自血液分離出的金黃色葡萄球菌,使用分子生物學的方法,包括Multiplex PCRs、spa、agr、和dru偵測菌株基因型;而以自動化儀器、agar dilution方法偵測最低抑菌濃度試驗minimum inhibitory concentration (MIC),藉以瞭解金黃色葡萄球菌的表現型結果。本研究結果顯示,分子生物學的方法可以清楚的分出社區型community acquired MRSA (CA-MRSA)和院內型hospital acquired MRSA (HA-MRSA),而臨床表現型卻發現有八株MRSA,對oxacillin的MIC呈現感受性,必須藉由cefoxitin辨別;然而,其中三株 MRSA 不但 oxacillin 的MIC呈現感受性,cefoxitin也具感受性。這種容易造成臨床誤判的菌種,臺灣也有學者發表相同的發現,但不同的是本研究只有一株是CA-MRSA,另兩株卻為HA-MRSA。 本研究充分反映金黃色葡萄球菌的臨床菌株表現型與基因型的差異,藉助各種分子生物學的基因型偵測可以輔助臨床實驗室未臻完美之處,更提供了解金黃色葡萄球菌抗藥性演化的線索。

並列摘要


Staphylococcus aureus (S. aureus) can cause a range of illness from minor skin infection to life threaten disease. The emergence of antibiotic-resistant forms of pathogenic S. aureus [e.g. methicillin resistant S .aureus (MRSA)] is a worldwide problem in clinical medicine. To investigate the characteristics of S. aureus, we collected 57 clinical blood isolates from Chung Shan Medical University Hospital during 2011 and 2012. Genotype was detected by Multiplex PCRs、spa、agr and dru methods. While autonomic BD Phoenix and VITEKR 2 machines and agar dilution method were used to discover their phenotypes. In Contrast with phenotyping, using genotyping is able to distinguish clearly the different strains among methicillin sensitive S. aureus (MSSA), community acquired MRSA (CA-MRSA) and hospital acquired MRSA (HA-MRSA). Although “cefoxitin minimum inhibitory concentration (MIC)” can be a surrogate for detection phenotypes of MRSA, three isolates with mec gene were misidentified to be MSSA, one of isolates has the characteristics of CA-MRSA strains and the other two are HA-MRSA. Thus, we conclude the molecular methods to detect genotype of MRSA are helpful for clinical medicine to understand the mechanisms of misidentification and antibiotic resistance.

並列關鍵字

MRSA genotype phenotype MIC

參考文獻


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