Jørgensen S T
Antimicrob Agents Chemother. 1978 May;13(5):710-5. doi: 10.1128/AAC.13.5.710.
The plasmids in 19 chloramphenicol-resistant Escherichia coli strains of three pig pathogenic antigen types were studied in conjugation and transduction experiments. The plasmids had identical resistance patterns: streptomycin, spectinomycin, sulfonamides, and chloramphenicol (Sm, Sp, Su, Cm) and belonged to IncFII. One plasmid carried ampicillin resistance in addition. Restriction enzyme analysis of the deoxyribonucleic acid from five of the plasmids originating from the same herd showed that their digestion patterns with EcoRI were indistinguishable. EcoRI cleaved the deoxyribonucleic acid of a sixth plasmid from the same herd and displayed nine of the ten bands of the other five plasmids plus an additional six. It appears that the five plasmids with identical restriction patterns have a common origin and may be copies of the same plasmid from which the sixth may have developed. Four strains carried two plasmids each. In two of these strains, a plasmid with a tetracycline marker (Tc), or possibly the tetracycline marker alone, recombined frequently with the Sm Sp Su Cm plasmid without destroying any known function of the latter. The possibility that Tc is carried on a translocation sequence is discussed.
对来自三种猪致病抗原类型的19株耐氯霉素大肠杆菌菌株中的质粒进行了接合和转导实验研究。这些质粒具有相同的耐药模式：链霉素、壮观霉素、磺胺类药物和氯霉素（Sm、Sp、Su、Cm），属于IncFII。其中一个质粒还携带氨苄青霉素抗性。对来自同一猪群的5个质粒的脱氧核糖核酸进行限制性内切酶分析表明，它们经EcoRI酶切后的图谱无法区分。EcoRI酶切来自同一猪群的第六个质粒的脱氧核糖核酸，显示出其他5个质粒的10条带中的9条以及另外6条带。看来具有相同限制性图谱的这5个质粒有共同的起源，可能是同一个质粒的拷贝，而第六个质粒可能是由其演变而来。4个菌株各携带两个质粒。在其中两个菌株中，一个带有四环素标记（Tc）的质粒，或者可能仅四环素标记本身，经常与Sm Sp Su Cm质粒重组，而不破坏后者的任何已知功能。文中讨论了Tc携带在易位序列上的可能性。
