https://scholars.lib.ntu.edu.tw/handle/123456789/145794
標題: | Ciprofloxacin抗藥性鼠傷寒及豬霍亂型沙門氏桿菌之分子流行病學及抗藥機轉 Molecular Epidemiology and Resistance Mechanisms of Ciprofloxacin-Resistant S. typhimurium and S. choleraesuis |
作者: | 曾嵩斌 Tseng, Sung-Pin |
關鍵字: | 沙門氏桿菌;抗藥;quinolone;drug resistance;PFGE | 公開日期: | 2004 | 摘要: | Salmonella enterica為一常見引起腹瀉的致病菌,由於在台灣其對quinolone類藥物抗性的增加顯著上昇,為了解此抗藥現象,因此收集台大醫院分離 (1996~2000)、2001年三月到八月所收集的全省菌株 ( SMART study ) 以及1997~2002年從養豬場的豬隻身上收集到的15株菌株加以分析。利用PFGE分析其基因型,發現同一血清型的菌株其在基因上多屬於同一來源,由此可推測這些菌株的出現可能為一抗藥菌株散播的結果。為了探知這些菌株的來源,因此再分析從各地所得的動物菌株,發現有些菌株基因型與人體分離菌株相同,可證實由於食用具抗藥菌株的家畜家禽導致這些菌株傳播到人體的推測。 細菌對quinolone類藥物抗藥機轉目前認為主要是topoisomerase上發生突變以及efflux pump的活化所造成。首先以核酸定序的方式知道topoisomerase上QRDR (quinolone resistant-determining region)的位置的確有發生突變,故此應為造成抗藥的原因之一。再測量菌株對有機溶劑的忍受度以及對ciprofloxacin的累積程度,結果也說明抗藥菌株確實有efflux的活化。進一步以北方墨點法以及西方墨點法分析S. cholerasuis主要efflux pump AcrA在RNA以及蛋白表現上的差異,結果發現抗藥菌株比具感受性菌株來的多,同時在基因序列上也發現它的抑制蛋白基因acrR在Gln78Stp (CAG→TAG)發生點突變可能會導致AcrR無法產生,進而促進efflux的活化。而在S. typhimurium內並沒有發現到相同的結果推測其efflux pump AcrAB活化可能是由於上游基因 (marRAB, soxRS regulons)調控所致,需要再進一步的研究。 Salmonella enterica is one of the human pathogens that causes diarrhea and salmonellosis. Fluoroquinolones are often the choice of tratment in the case of salmonellosis. Unfortunately, the quinolone resistant strains significantly increased in recent year. To elevate the dissemination of this strain, clinical isolates from 1996-2001 were collected and analyzed. Pulsed-Field Gel Electrophoresis (PFGE) showed that majority of these clones that with identical serotype of S. enterica sharing similar PFGE pattern. This result suggested that these clinical pathogens were disseminated by similar source. In other word, this is the result of clone spreading effect. In addition, we collected animal infection strains and the result was compared with those clinical isolates. Interestingly, we found that some of the animal infection strains sharing the identical pulsoltype with clinical isolated, suggested that swine served as a reservoir for these resistant strains. Recent study shows that the point mutation of topoisomerase and highly expressed of efflux pumps, such as acrAB operon, causes the bacteria increased the resistant ability to quinolone. Our sequencing results demonstrated the point mutation regions in quinolone resistance determination region (QRDR). Furthermore, organic solvent tolerance assay and ciprofloxacin accumulation assay showed the increasing activity of efflux pump in resistance strains. Northern blotting and Western blotting results confirmed the significantly increased expression level of acrA revealed that the activation of efflux pumps expression leads to the resistance effect in Taiwan. Besides, the stop codon mutation of acrR, an inhibitor of acrA, lost its function to inhibit acrA expression level resulting the over-expression of this efflux pumps. We also could not obtained the similar result in Salmonella typhimurium as S. enterica elevated that, except acrR, an unknown genes which might be involved in acrA regulatory system in resulting acrAB regulon increased its expression levels. |
URI: | http://ntur.lib.ntu.edu.tw//handle/246246/62822 | 其他識別: | zh-TW |
顯示於: | 醫學檢驗暨生物技術學系 |
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ntu-93-R90424008-1.pdf | 23.31 kB | Adobe PDF | 檢視/開啟 |
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