Emergence of cephalosporin resitance in cephalosporin-sensitive class A penicillin binding protein mutants in Enterococcus faecium. Enterococcus faecium

E. faecium is inherantly resistant to cephalosporins. Resistance is lost in Class A penicillin binding protein PbfF PonA mutants, but is reversible by pencillin exposure. E. faecium Affymetrix GeneChips were used to compare E. faecium expression properties of pbfF ponA mutant cells in the absence or presence of penicillin exposure. Significant differences were observed between the expression properties of mock and penicillin treated E. faecium CV571 (pbfF ponA double mutant) cells. Overall design: E. faecium strain CV571 (pbfF ponA) were grown in laboratory medium to exponential under aerobic growth conditions. Cells were either mock treated or treated with penicillin for 30 min, total bacterial RNA was isolated, labeled and applied to Affymetrix GeneChips. We sought to determine whether the transcriptional profiles of E. faecium pbfF ponA mutant cells of penicillin challenged cells differed from that of mock treated CV571 cells.

屎肠球菌（Enterococcus faecium，简称E. faecium）天然对头孢菌素类抗生素具有耐药性。该耐药性在A类青霉素结合蛋白PbfF与PonA的突变体中会丧失，但可通过青霉素暴露使其恢复。本研究使用屎肠球菌Affymetrix基因芯片（Affymetrix GeneChips），对比了pbfF ponA突变体细胞在有无青霉素暴露条件下的基因表达特征。结果显示，经青霉素处理与空白对照处理的屎肠球菌CV571（pbfF ponA双突变体）细胞的基因表达特征存在显著差异。

实验设计概述：将屎肠球菌菌株CV571（pbfF ponA双突变体）于有氧培养条件下在实验室培养基中培养至指数生长期。将细胞分为两组，一组进行空白对照处理，另一组用青霉素处理30分钟；随后提取总细菌RNA，进行标记后与Affymetrix基因芯片杂交。本研究旨在探究经青霉素刺激的pbfF ponA突变体细胞的转录组谱，与空白对照处理的CV571细胞是否存在差异。