Datta N, Hughes V M
Nature. 1983;306(5943):616-7. doi: 10.1038/306616a0.
Conjugative plasmids were common in enterobacteria isolated before the medical use of antibiotics. Plasmid F of Escherichia coli K-12 was one example and we identified others in over 20% of a collection of strains isolated between 1917 and 1954, the Murray collection. In the past 25 years, conjugative plasmids encoding antibiotic resistances have become common in bacteria of the same genera as those of the Murray Collection--Salmonella, Shigella, Klebsiella, Proteus, Escherichia. The present study was made to show whether the 'pre-antibiotic' plasmids belonged to the same groups, as defined by incompatibility tests (Inc groups), as modern R plasmids. Of 84 such plasmids established in E. coli K-12, none with antibiotic resistance determinants, 65 belonged to the same groups as present resistance (R) plasmids. Thus the remarkable way in which medically important bacteria have acquired antibiotic resistance in the past 25 years seems to have been by the insertion of new genes into existing plasmids rather than by the spread of previously rare plasmids.
接合质粒在抗生素用于医学之前分离出的肠杆菌中很常见。大肠杆菌K-12的F质粒就是一个例子，我们在1917年至1954年间分离的一组菌株（默里菌株集）中，超过20%的菌株中鉴定出了其他接合质粒。在过去25年里，编码抗生素抗性的接合质粒在与默里菌株集相同属的细菌（沙门氏菌、志贺氏菌、克雷伯氏菌、变形杆菌、大肠杆菌）中变得很常见。本研究旨在表明，通过不相容性试验（Inc组）定义，“抗生素使用前”的质粒是否与现代R质粒属于同一组。在大肠杆菌K-12中建立的84个此类质粒中，没有一个带有抗生素抗性决定簇，其中65个与目前的抗性（R）质粒属于同一组。因此，在过去25年里，医学上重要的细菌获得抗生素抗性的显著方式似乎是通过将新基因插入现有质粒，而不是通过以前罕见质粒的传播。
