Institute of Clinical Pharmacology, Peking University First Hospital, Beijing, People's Republic of China.
Institute of Clinical Pharmacology, Peking University First Hospital, Beijing, People's Republic of China.
J Glob Antimicrob Resist. 2017 Mar;8:1-5. doi: 10.1016/j.jgar.2016.09.008. Epub 2016 Nov 5.
Three linezolid-resistant coagulase-negative staphylococci (LR-CoNS), including two Staphylococcus cohnii and one Staphylococcus capitis, were isolated from 1104 clinical staphylococcal isolates across China in 2013-2014. Antibiotic susceptibilities of the bacteria were determined by the agar dilution method. PCR and DNA sequencing were performed to determine the potential molecular mechanism of linezolid resistance. The two linezolid-resistant S. cohnii isolates were subjected to pulsed-field gel electrophoresis (PFGE) to investigate their genetic relatedness. Primer walking, S1 nuclease PFGE and Southern blot hybridisation were conducted to ascertain the location and environment of the cfr gene. All three isolates were positive for the cfr gene. Amino acid mutations S158F and S158Y in the ribosomal protein L3 were identified in S. cohnii 13B289 and 13L105, respectively, both of which also had an additional substitution (D159Y) in L3. PFGE indicated that the two S. cohnii isolates belonged to diverse clonal strains. S1 nuclease PFGE and Southern blotting experiments indicated that the cfr gene of the three isolates resided on plasmids of similar size (ca. 35.4kb). The cfr-harbouring segments of S. capitis 13G350 and S. cohnii 13L105 were identical to plasmid pSS-01 reported previously. The cfr-carrying fragment of S. cohnii 13B289 was indistinguishable from the formerly described plasmid pSS-02. In conclusion, the presence of the cfr gene located on a plasmid was the main mechanism contributing to resistance to linezolid in the three staphylococcal isolates. Hence, timely detection and judicious use of antibiotics are essential to prevent further transmission of this resistance mechanism.
2013-2014 年，从中国 1104 株临床分离的葡萄球菌中分离出 3 株耐(linezolid-resistant)利奈唑胺凝固酶阴性葡萄球菌（LR-CoNS），包括 2 株科氏葡萄球菌和 1 株头状葡萄球菌。采用琼脂稀释法测定细菌的药敏性。通过 PCR 和 DNA 测序确定利奈唑胺耐药的潜在分子机制。对 2 株耐利奈唑胺的科氏葡萄球菌分离株进行脉冲场凝胶电泳（PFGE）以研究其遗传相关性。引物行走、S1 核酸酶 PFGE 和 Southern 印迹杂交用于确定 cfr 基因的位置和环境。所有 3 株分离株均为 cfr 基因阳性。在科氏葡萄球菌 13B289 和 13L105 中，核糖体蛋白 L3 中的氨基酸突变 S158F 和 S158Y 分别被鉴定出来，这两个突变在 L3 中也有一个额外的取代（D159Y）。PFGE 表明，这 2 株科氏葡萄球菌分离株属于不同的克隆株。S1 核酸酶 PFGE 和 Southern 印迹实验表明，3 株分离株的 cfr 基因位于大小相似（约 35.4kb）的质粒上。头状葡萄球菌 13G350 和科氏葡萄球菌 13L105 的 cfr 携带片段与先前报道的质粒 pSS-01 相同。科氏葡萄球菌 13B289 的 cfr 携带片段与先前描述的质粒 pSS-02 无法区分。总之，位于质粒上的 cfr 基因的存在是导致 3 株葡萄球菌对利奈唑胺耐药的主要机制。因此，及时检测和合理使用抗生素对于防止这种耐药机制的进一步传播至关重要。
