Then R L, Angehrn P
Antimicrob Agents Chemother. 1986 Nov;30(5):684-8. doi: 10.1128/AAC.30.5.684.
Mutants of Enterobacter cloacae, selected in vitro with ceftriaxone, ceftazidime, carumonam, or aztreonam, fell into several distinct classes. Three mutants highly resistant to nearly all beta-lactam antibiotics were stably derepressed for beta-lactamase production. Although no other changes could be detected, virulence in a mouse septicemia model was decreased in two of these mutants. One mutant, 908-Ssi, showed selectively decreased susceptibility to ampicillin and cefotetan. A change in beta-lactamase expression was thought to be responsible for this. Alterations in the production of two outer membrane proteins with molecular sizes of 36.5 and 39 kilodaltons were responsible for multiple antibiotic resistance in two mutants, both of which acquired a low level of resistance to beta-lactam antibiotics. Whereas one of the mutants, AMA-R, simultaneously acquired resistance to chloramphenicol and trimethoprim, the other, AZT-R, became hypersusceptible to these and other hydrophobic agents. Both strains had drastically reduced virulence in mice.
用头孢曲松、头孢他啶、卡芦莫南或氨曲南在体外筛选出的阴沟肠杆菌突变体可分为几个不同的类别。三个对几乎所有β-内酰胺类抗生素高度耐药的突变体，其β-内酰胺酶的产生处于稳定的去阻遏状态。尽管未检测到其他变化，但其中两个突变体在小鼠败血症模型中的毒力有所下降。一个突变体908-Ssi对氨苄西林和头孢替坦的敏感性选择性降低。据认为，β-内酰胺酶表达的变化是造成这种情况的原因。两个分子大小分别为36.5和39千道尔顿的外膜蛋白产量的改变导致了两个突变体的多重耐药性，这两个突变体均获得了对β-内酰胺类抗生素的低水平耐药性。其中一个突变体AMA-R同时获得了对氯霉素和甲氧苄啶的耐药性，另一个突变体AZT-R则对这些及其他疏水性药物变得高度敏感。这两种菌株在小鼠中的毒力均大幅降低。
