Rubens C E, Farrar W E, McGee Z A, Schaffner W
J Infect Dis. 1981 Feb;143(2):170-81. doi: 10.1093/infdis/143.2.170.
At the Vanderbilt University Medical Center, Nashville, Tennessee, resistance to gentamicin was encountered with increasing frequency among several species of gram-negative bacilli between 1973 and 1977. Representative strains were screened for plasmid DNA content using agarose gel electrophoresis. In strains of Pseudomonas aeruginosa and Serrati marcescens isolated early in the outbreak, gentamicin resistance was mediated by a common 9.8-megadalton nonconjugative plasmid. Either an 80- or a 100-megadalton transferable plasmid coexisted with the nonconjugative plasmid in the isolates of Serratia. Transposition between the 100- and 9.8-megadalton plasmids in this species resulted in the formation of a 105-megadalton conjugative plasmid that mediated gentamicin resistance; this was observed in strains of Serratia and Klebsiella isolated in 1976-1977. Thus, during this five-year investigation separate outbreaks of nosocomial infections that were caused by different bacterial species were shown to be related by the presence of plasmids that contained a common transposable DNA sequence.
在田纳西州纳什维尔的范德比尔特大学医学中心，1973年至1977年间，几种革兰氏阴性杆菌对庆大霉素的耐药性出现频率不断增加。使用琼脂糖凝胶电泳对代表性菌株的质粒DNA含量进行筛选。在疫情早期分离出的铜绿假单胞菌和粘质沙雷氏菌菌株中，庆大霉素耐药性由一个常见的9.8兆道尔顿非接合性质粒介导。在沙雷氏菌分离株中，一个80或100兆道尔顿的可转移质粒与非接合性质粒共存。该物种中100兆道尔顿和9.8兆道尔顿质粒之间的转座导致形成了一个介导庆大霉素耐药性的105兆道尔顿接合性质粒；在1976 - 1977年分离出的沙雷氏菌和克雷伯氏菌菌株中观察到了这一现象。因此，在这项为期五年的调查中，由不同细菌物种引起的医院感染单独暴发被证明与含有共同可转座DNA序列的质粒的存在有关。
