Public Health Ontario, Public Health Laboratory, Toronto, Canada; Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Canada.
Diagn Microbiol Infect Dis. 2013 Dec;77(4):350-3. doi: 10.1016/j.diagmicrobio.2013.08.012. Epub 2013 Oct 2.
Recent studies have described linezolid-resistant MRSA and vancomycin-resistant enterococci (VRE) occurring worldwide, including an outbreak of linezolid-resistant MRSA. The objective of this study was to determine if linezolid-resistant enterococci are present in clinical isolates in Ontario, Canada. From January 2010 to June 2012, all enterococcal isolates submitted to the Public Health Ontario Laboratory (PHOL) for confirmation of VRE and susceptibility testing were included in this study. Of 2829 enterococcal isolates tested, 12 Enterococcus faecium were found to be resistant to linezolid. All linezolid-resistant isolates were also resistant to ampicillin, ciprofloxacin, and vancomycin. In addition, 33% of isolates were non-susceptible to daptomycin, whereas 41% were resistant to quinupristin/dalfopristin. Molecular characterization of these isolates showed that 8/12 isolates (66.7%) contained the mutation G2576T in 23S rRNA, which has been associated with linezolid resistance. Amplification and sequencing of L3- and L4-coding genes did not reveal mutations associated with linezolid resistance. One isolate contained the cfr gene, which is associated with linezolid resistance, and has been found in staphylococcal species and E. faecalis. These data show that occurrence of linezolid resistance is still rare among enterococcal isolates referred to PHOL though detection of cfr in E. faecium is concerning as it has the potential to disseminate among other enterococci.
最近的研究描述了全球范围内出现的耐(linezolid) 利奈唑胺的耐万古霉素金黄色葡萄球菌 (MRSA) 和耐万古霉素肠球菌 (VRE)，包括耐(linezolid) 利奈唑胺的 MRSA 爆发。本研究的目的是确定加拿大安大略省临床分离株中是否存在耐(linezolid) 肠球菌。从 2010 年 1 月至 2012 年 6 月，所有提交给安大略省公共卫生实验室 (PHOL) 以确认 VRE 和药敏试验的肠球菌分离株均纳入本研究。在 2829 株肠球菌分离株中，发现 12 株屎肠球菌对利奈唑胺耐药。所有耐(linezolid) 的分离株对氨苄西林、环丙沙星和万古霉素也均耐药。此外，33%的分离株对达托霉素不敏感，而 41%的分离株对奎奴普汀/达福普汀耐药。这些分离株的分子特征表明，12 株分离株中有 8 株（66.7%）含有与利奈唑胺耐药相关的 23S rRNA 中的 G2576T 突变。L3 和 L4 编码基因的扩增和测序未显示与利奈唑胺耐药相关的突变。一个分离株含有与利奈唑胺耐药相关的 cfr 基因，该基因已在葡萄球菌属和屎肠球菌中发现。这些数据表明，尽管在屎肠球菌中检测到 cfr 令人担忧，因为它有可能在其他肠球菌中传播，但 PHOL 送检的肠球菌分离株中利奈唑胺耐药的发生率仍然较低。
