- 期刊
Molecular Characterization of R-Plasmids Pst1 and Pst2 From Salmonella Typhimurium S24
鼠傷寒桿茵S24的抗藥性質體pST1和pST2之分生物學特性
摘要
鼠傷寒桿茵S24是於1986年9月在高雄醫學院附設中和紀念醫院從腹瀉病患的糞便中分離得到。該茵所表現的多重抗藥性與期茵體內所帶有兩個質體有相關。利用接合作用(conjugation)，鼠傷寒桿茵S24所帶有的兩個抗藥性質體，會分別轉移到受體細胞(RE-CIPIENT STRAIN) E.coli 14R525茵體中。於接合轉移茵(trancsconjugant) E.coli D39茵體中，帶有一個130 kilobase (kb)的質體，稱之為質體pST1。而另一個接合轉移茵 E. coli D39茵體中則帶有一個56kb的質體，稱之為質體pST2。這兩個抗藥性質體，分別屬於不同的互不相容性的組別〔incompatibility (Inc) group〕。質體pST1於IncFI組別，而質體pTS2則為 IncN組。由於質體pST1和pST2分別決定了不同的抗藥性。故鼠傷寒桿茵S24的多重抗藥性，是這兩個抗藥性質體pST1和PST2共同表現的特性。利用核酸探針雜交技術(DNA PROBE HYBRIDIZATION)，發現質體pST1帶有一個腸內茵第二型氯黴素乙醯基轉移酶〔enteric type Ⅱ chloramphenicol acetyltransfe-rase(CAT)〕的基因，一個第C型四環黴素抗藥性〔class C tetracycline resistance(TetＲ)〕的基因和一個第III型雙氫葉酸基還原酶〔type Ⅲ dindrofolate reductase(DHFR)〕的基因。以上這三重基，分別導致對chlorampheni-col，tetracycline和trimethoprim造成抗藥性。利用對基質的作用形式(substrate profiles)之不同，發現質體pST1和pST2均帶有一個同屬於Richmond氏分類法中第三型的青黴素酶(Richmond's type Ⅲ penicllinase)。這個青黴素酶會導致對ampicillin, amoxicillin, car-benicillin, piperacillin, sulbenicillin和ticarcillin呈現高度的抗藥性。質體pST2尚具有一個新型的氨基糖苷類6'-N- acetyltransferase〔AAC(6')〕的基因。此基因會表現對kanamycin, amika-cin, dibekacin, tobramycin, gentamicin, netilimi-cin和sisomicin具抗藥性。
關鍵字
無資料並列摘要
Salmonella typhimurium S24 was isolated in September 1986 Kaohsiung Medical College Hospital, Kaohsiung, Taiwan, from a patient suffering from gastroenteritis during an outbreak of salmonellosis. Two conjugative R-plasmids have been isolated from Escherichia coli K-12 14R525, which was mated with S.typhimurium S24. The two R-plasmids found in S. typhimurium S24.By DNA probes hybridization, plasmid pST1 was shown to carry an enteric type Ⅱ chlor-amphenicol acetyltransferase (CAT) gene, a class C tetracycline resistance (TetＲ) gene and a type Ⅲ dihydrofolate reductase (DHFR) gene, all of which confer re-sistance to chloramphenicol, tetracycline, and trimethoprim respectively. A Ri-chmond's type Ⅲ -lactamase gene was located on each plasmid of pST1 and pST2. -lactamases specified by both plasmids pST1 and pST2 conferred high level resistance to amoxicillin, carbeniciliin, piperacillin, sulbenicillin, ticaricillin in addition to ampicillin. A novel aminoglycoside 6'-N-acetyltransferase [AAC(6')] was demonstrated on plasmid pST2. This AAC(6') enzyme modified kanamycin, amikacin, dibekacin, tobramycin, gentamicin, netilmicin, sisomicin, butirosin and ribostamycin.