Huycke M M, Gilmore M S, Jett B D, Booth J L
Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City.
J Infect Dis. 1992 Nov;166(5):1188-91. doi: 10.1093/infdis/166.5.1188.
Pheromone-responsive plasmids are common to Enterococcus faecalis, transfer at high frequency in vitro, and carry cytolysin and other gene products implicated in the pathogenesis of enterococcal infection. A Syrian hamster model of enterococcal intestinal overgrowth was used to test for transfer of three isogenic plasmids differing in conjugative and cytolytic phenotypes. Transconjugants were found in 8 (44%) of 18 and 6 (35%) of 17 hamsters given donor strains containing cytolytic (pAM714) and noncytolytic (pAM771) pheromone-responsive plasmids. Of the 14 hamsters from which transconjugants were isolated from stool, 9 (64%) had transconjugants 1 day after donor strain inoculation. The frequency of transfer (mean +/- SD) for pAM714 and pAM771 was 1.4 +/- 2.2 x 10(-1) and 2.9 +/- 4.2 x 10(-2) transconjugants/donor, respectively (P > .20). Transconjugants were not recovered from hamsters receiving a cytolytic, nonconjugative plasmid (pAM930; transfer frequency < 2 x 10(-5) transconjugants/donor). Pheromone-responsive plasmid transfer between E. faecalis strains occurs at high frequency in the gastrointestinal tract of hamsters and may be one means by which enterococcal resistance and virulence factors disseminate.
信息素反应性质粒在粪肠球菌中很常见，在体外能高频转移，并携带与肠球菌感染发病机制有关的细胞溶素和其他基因产物。利用叙利亚仓鼠肠球菌肠道过度生长模型来检测三种在接合和细胞溶解表型上不同的同基因质粒的转移情况。在分别给予含有细胞溶解型（pAM714）和非细胞溶解型（pAM771）信息素反应性质粒的供体菌株的18只仓鼠中有8只（44%）以及17只仓鼠中有6只（35%）发现了转接合子。在从粪便中分离出转接合子的14只仓鼠中，有9只（64%）在接种供体菌株1天后出现了转接合子。pAM714和pAM771的转移频率（平均值±标准差）分别为1.4±2.2×10⁻¹和2.9±4.2×10⁻²个转接合子/供体（P>.20）。在接受细胞溶解型非接合性质粒（pAM930；转移频率<2×10⁻⁵个转接合子/供体）的仓鼠中未回收得到转接合子。粪肠球菌菌株间的信息素反应性质粒转移在仓鼠胃肠道中高频发生，可能是肠球菌耐药性和毒力因子传播的一种方式。
