多重抗藥性包氏不動桿菌臨床分離株之分子特性

Molecular Characterization of Clinical Multidrugresistant Acinetobacter baumannii isolates

目的：包氏不動桿菌(A cinetobacter baumannii)，是革蘭氏陰性之球桿菌，爲一常見的環境微生物，亦是人類皮膚與黏膜上的正常菌叢之一，近年來卻因其抗藥性所帶來之問題趨嚴重，而成爲院内感染的重要病原菌，且已陸續出現對多種抗生素具抗藥性的菌株(Multidrug-resist-ant Acinetobacter baumannii; MDR-Ab)。近年來在台灣也頻頻出現MDR-Ab，因而喚起國内外對包氏不動桿菌抗藥性之問題的注意與關切。材料與方法：本研究以中部某區域醫院中所收集的MDR-Ab臨床菌株之流行病學資料爲基礎，探討其抗藥性基因是否經水平傳播的方式散佈於各菌株間之可能性。使用的臨床菌株是民國九十一年六月一日到民國九十二年五月三十一日止，在中部某區域醫院分離出的12株Multidrug-resistant包氏不動桿菌爲材料，分別再以Disk diffusion experiment與VITEK 2 Advance Expert System等抗生素藥物敏感性測試來測定這12株菌株的抗生素抗藥性表現型。另經脈衝電場電泳(PFGE)電泳後，用圖譜分析軟體－－BioNumerics進行比對，描繪菌株親緣關係。此外，以聚合酶連鎖反應(PCR)方法進行水平傳播平台Integron内含的integrase基因來分析。結果：PFGE結果顯示可將這12株MDR-Ab菌株，分成2個群組(cluster A、B)。且這12株MDR-Ab菌株均帶有一個約160-bp fragment的第一類integrase gene。結論：這12株MDR-Ab菌株均帶有一個約160-bp fragment的第一類integrase gene，所以都具有第一類integron，而integron是一種genetic element，能幫助抗藥gene在不同細菌中散播，這結果顯示出這12株MDR-Ab菌株的抗藥基因有水平傳播的可能性。

Purpose: Acinetobacter baumannii, a coccobacilli, is a common environmental microbe as well as one of the normal floras on the skin and mucous membranes of human bodies. Due to the serious problems resulted from drug resistance of such germ for the past few years, it becomes a critical pathogenic bacteria causing infections in the hospitals. Multidrug-resistant Acinetobacter baumannii (MDR-Ab), a strain that resists multidrug, has appeared. Recently, MDR-Ab was also discovered in Taiwan very frequently. Therefore, awareness of such problems and finding out proper solutions have become critical issues both in our country and overseas. Materials and Methods: Based on the epidemic information on clinical MDR-Ab strains collected by a regional hospital located in central Taiwan.. In addition, the possibility of whether the drug-resistant gene diffuses among strains in a horizontal way is explored. The twelve imipenem-resistant Acinetobacter baumannii strains used in this study were isolated from a regional hospital located in central Taiwan from June 1, 2002 to May 31, 2003. They were further conducted an antibiotic susceptibility test by the Disk diffusion experiment and VITEK 2 Advance Expert System to explore the phenotype of these twelve multidrug-resistant strains. Furthermore, the 'BioNumerics' analysis software was applied after PFGE to compare and locate the genetic/phylogenesis relationship among the strains. Besides, those Integrase genes of Integron, a horizontal diffusion platform, were analyzed with the PCR method. Results:The PFGE result indicated these twelve MDR-Ab strains could be divided into two clusters (Cluster A & Cluster B). And, there was a type 1 Integrase gene of about 160-bp fragment existed in all these twelve MDR-Ab strains. Conclusion:There was a type 1 Integrase gene of about 160-bp fragment existed in all these twelve MDR-Ab strains. So,all have type 1 Integron..We know integron,a genetic element which facilitates gene dissemination among bacteria of different species and perhaps genera. The result revealed the possibility of horizontal transfer of the drug-resistant genes of all these twelve MDR-Ab strains.