Jamieson A F, Bremner D A, Bergquist P L, Lane H E
J Gen Microbiol. 1979 Jul;113(1):73-81. doi: 10.1099/00221287-113-1-73.
Gel electrophoresis of DNA from 95 clinical isolates of Shigella sonnei and Shigella flexneri resistant to antibiotics revealed a heterogeneous plasmid population. Most of the plasmids were smaller than 6 megadaltons (Mdal). Six S. sonnei isolates with the most common antibiotic resistance pattern were characterized. They had two plasmids in common: one was a self-transmissible Fi+ plasmid of 46 Mdal encoding resistance to streptomycin and sulphafurazole. In addition, several cryptic plasmids ranging in size from 1.0 to 24.5 Mdal were present. Mobilization of the 5.5 Mdal SuSm plasmid and a 1.0 Mdal cryptic plasmid was demonstrated with all six S. sonnei isolates during conjugation. This mobilization was mediated by the 46 Mdal self-transmissible Fi+ R plasmid and also by a 24.5 Mdal Fi- plasmid carrying no known drug resistance determinants.
对95株对多种抗生素耐药的宋内志贺菌和福氏志贺菌临床分离株的DNA进行凝胶电泳分析，结果显示质粒群体具有异质性。大多数质粒小于6兆道尔顿（Mdal）。对6株具有最常见抗生素耐药模式的宋内志贺菌分离株进行了特征分析。它们共有两种质粒：一种是46Mdal的自我传递性Fi +质粒，编码对链霉素和磺胺异恶唑的耐药性。此外，还存在几种大小在1.0至24.5Mdal之间的隐蔽质粒。在接合过程中，所有6株宋内志贺菌分离株均证明了5.5Mdal的SuSm质粒和1.0Mdal的隐蔽质粒的转移。这种转移由46Mdal的自我传递性Fi + R质粒介导，也由携带未知耐药决定簇的24.5Mdal Fi-质粒介导。
