Mutational analysis of reduced telithromycin susceptibility of Streptococcus pneumoniae isolated clinically in Japan.
Mutational analysis of reduced telithromycin susceptibility of Streptococcus pneumoniae isolated clinically in Japan.
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DOI：
10.1111/j.1574-6968.2010.01962.x
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发表时间：
2010-06
影响因子：
2.1
通讯作者：
A. Takaya;Naomi Kitagawa;Yukano Kuroe;Kikutarou Endo;M. Okazaki;E. Yokoyama;A. Wada;Tomoko Yamamoto
中科院分区：
文献类型：
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作者：
A. Takaya;Naomi Kitagawa;Yukano Kuroe;Kikutarou Endo;M. Okazaki;E. Yokoyama;A. Wada;Tomoko Yamamoto
对2005年至2006年在日本收集的132株肺炎链球菌分离株进行了泰利霉素（TEL）和大环内酯类药物敏感性检查。对大环内酯类的总体耐药率为80%。在分离株中，128株具有低水平的TEL敏感性（最小抑菌浓度[MIC] 0.03-1 μ g mL（-1）），这表明对TEL敏感性降低的肺炎球菌在没有预先暴露于药物的情况下出现，尽管没有分离株被指定为TEL耐药（断点，>或= 4 μ g mL（-1））。对其中8株（MIC 0.5-1 μ g mL（-1））进行了大环内酯类药物耐药决定因素和遗传相关性分析。它们都携带mefE-mel，编码大环内酯外排遗传组装，三个还携带ermB，编码rRNA甲基化酶。临床分离株中相应基因的等位基因置换突变显示，S.肺炎链球菌感染可能仅由mefE-mel元件的获得引起，并且另外由ermB决定子赋予。
A total of 132 Streptococcus pneumoniae isolates collected between 2005 and 2006 in Japan were examined for susceptibility to telithromycin (TEL) and macrolide. The overall resistance to macrolide was 80%. Among the isolates, 128 strains had low-level TEL susceptibility (minimal inhibitory concentrations [MICs] 0.03-1 microg mL(-1)), suggesting that pneumococci with reduced susceptibility to TEL have appeared without prior exposure to the drug, although none of the isolates were assigned as TEL-resistant (breakpoint, > or = 4 microg mL(-1)). Eight of these isolates (MIC 0.5-1 microg mL(-1)) were analyzed for macrolide resistance determinants and genetic relatedness. They all carried mefE-mel, which encodes the macrolide efflux genetic assembly, and three also harbored ermB, which encodes rRNA methylase. Allele replacement mutagenesis of the corresponding genes in the clinical isolates revealed that reduced TEL susceptibility (MIC 1 microg mL(-1)) in S. pneumoniae may be caused by acquisition of the mefE-mel element only and additionally conferred by the ermB determinant.