Guiney D G, Hasegawa P, Davis C E
Plasmid. 1984 May;11(3):248-52. doi: 10.1016/0147-619x(84)90031-3.
The putative clindamycin resistance region of the Bacteroides fragilis R plasmid pBF4 was cloned in the vector R300B in Escherichia coli. This 3.8-kb EcoRI D fragment from pBF4 expressed noninducible tetracycline resistance in E. coli under aerobic but not anaerobic growth conditions. The fragment does not express tetracycline resistance in Bacteroides, a strict anaerobe. The separate tetracycline resistance transfer system in the Bacteroides host strain V479-1 has no homology to the cryptic determinant on pBF4. In addition, this aerobic tetracycline resistance determinant is not homologous to the three major plasmid mediated tetracycline resistance regions found in facultative gram-negative bacteria, represented by R100, RK2, and pBR322. A similar cryptic tetracycline resistance fragment was cloned from pCP1, a separate clindamycin resistance plasmid from Bacteroides that shares homology with the EcoRI D fragment of pBF4. This study identifies cryptic drug resistance determinants in Bacteroides that are expressed when inserted into an aerobically growing organism.
脆弱拟杆菌R质粒pBF4的假定克林霉素抗性区域被克隆到大肠杆菌的载体R300B中。来自pBF4的这个3.8kb的EcoRI D片段在有氧而非厌氧生长条件下在大肠杆菌中表达不可诱导的四环素抗性。该片段在严格厌氧菌拟杆菌中不表达四环素抗性。拟杆菌宿主菌株V479-1中单独的四环素抗性转移系统与pBF4上的隐蔽决定簇没有同源性。此外，这种需氧四环素抗性决定簇与在兼性革兰氏阴性细菌中发现的三个主要质粒介导的四环素抗性区域没有同源性，这些区域以R100、RK2和pBR322为代表。从pCP1中克隆了一个类似的隐蔽四环素抗性片段，pCP1是拟杆菌中一个单独的克林霉素抗性质粒，与pBF4的EcoRI D片段具有同源性。这项研究鉴定了拟杆菌中的隐蔽耐药决定簇，当插入到需氧生长的生物体中时会表达出来。
