Tait-Kamradt A, Clancy J, Cronan M, Dib-Hajj F, Wondrack L, Yuan W, Sutcliffe J
Department of Antibacterials, Pfizer, Inc., Groton, Connecticut 06340, USA.
Antimicrob Agents Chemother. 1997 Oct;41(10):2251-5. doi: 10.1128/AAC.41.10.2251.
Recently, it was shown that a significant number of erythromycin-resistant Streptococcus pneumoniae and Streptococcus pyogenes strains contain a determinant that mediates resistance via a putative efflux pump. The gene encoding the erythromycin-resistant determinant was cloned and sequenced from three strains of S. pneumoniae bearing the M phenotype (macrolide resistant but clindamycin and streptogramin B susceptible). The DNA sequences of mefE were nearly identical, with only 2-nucleotide differences between genes from any two strains. When the mefE sequences were compared to the mefA sequence from S. pyogenes, the two genes were found to be closely related (90% identity). Strains of S. pneumoniae were constructed to confirm that mefE is necessary to confer erythromycin resistance and to explore the substrate specificity of the pump; no substrates other than 14- and 15-membered macrolides were identified.
最近的研究表明，相当数量的耐红霉素肺炎链球菌和化脓性链球菌菌株含有一种通过假定的外排泵介导耐药性的决定簇。从三株具有M表型（对大环内酯类耐药但对克林霉素和链阳菌素B敏感）的肺炎链球菌菌株中克隆并测序了编码耐红霉素决定簇的基因。mefE的DNA序列几乎完全相同，任意两株菌的基因之间仅有2个核苷酸差异。当将mefE序列与化脓性链球菌的mefA序列进行比较时，发现这两个基因密切相关（同一性为90%）。构建了肺炎链球菌菌株以证实mefE是赋予红霉素耐药性所必需的，并探索该泵的底物特异性；未鉴定出除14和15元大环内酯类以外的其他底物。
