Laboratorio de Referencia e Investigación en Resistencia a Antibióticos e Infecciones Relacionadas con la Asistencia Sanitaria, Centro Nacional de Microbiología, Instituto de Salud Carlos III, Majadahonda, Madrid, Spain; Spanish Network for Research in Infectious Diseases (REIPI RD16/0016), Instituto de Salud Carlos III, Madrid, Spain.
Laboratorio de Referencia e Investigación en Resistencia a Antibióticos e Infecciones Relacionadas con la Asistencia Sanitaria, Centro Nacional de Microbiología, Instituto de Salud Carlos III, Majadahonda, Madrid, Spain.
Int J Antimicrob Agents. 2020 Jun;55(6):105977. doi: 10.1016/j.ijantimicag.2020.105977. Epub 2020 Apr 22.
The emergence of linezolid-resistant Enterococcus spp. (LRE) due to transferable resistance determinants is a matter of concern. To understand the contribution of the plasmid-encoded optrA and poxtA genes to the emergence of LRE, clinical isolates from different Spanish hospitals submitted to the Spanish Reference Laboratory from 2015-2018 were analysed. Linezolid resistance mechanisms were screened in all isolates by PCR and sequencing. Genetic relatedness of Enterococcus spp. carrying optrA and poxtA was studied by PFGE and MLST. Antimicrobial susceptibility was tested by broth microdilution using EUCAST standards. A total of 97 LRE isolates were studied, in 94 (96.9%) of which at least one resistance determinant was detected; 84/97 isolates (86.6%) presented a single resistance mechanism as follows: 45/84 (53.6%) carried the optrA gene, 38/84 (45.2%) carried the G2576T mutation and 1/84 (1.2%) carried the poxtA gene. In addition, 5/97 isolates (5.2%) carried both optrA and the G2576T mutation and 5/97 (5.2%) carried both optrA and poxtA. The optrA gene was more frequent in Enterococcus faecalis (83.6%) than Enterococcus faecium (11.1%) and was mainly associated with community-acquired urinary tract infections. Carriage of the poxtA gene was more frequent in E. faecium (13.9%) than E. faecalis (1.6%). Among the optrA-positive E. faecalis isolates, two main clusters were detected by PFGE. These two clusters belonged to ST585 and ST480 and were distributed throughout 11 and 6 Spanish provinces, respectively. This is the first description of LRE carrying the poxtA gene in Spain, including the co-existence of optrA and poxtA in five isolates.
由于可转移的耐药决定因素，出现了耐(linezolid)屎肠球菌属 (LRE)，这令人担忧。为了了解质粒编码的 optrA 和 poxtA 基因对 LRE 出现的贡献，分析了 2015-2018 年期间从西班牙不同医院提交给西班牙参考实验室的临床分离株。所有分离株均通过 PCR 和测序筛查利奈唑胺耐药机制。通过 PFGE 和 MLST 研究携带 optrA 和 poxtA 的肠球菌属的遗传相关性。采用 EUCAST 标准的肉汤微量稀释法检测抗菌药物敏感性。共研究了 97 株 LRE 分离株，其中 94 株（96.9%）至少检测到一种耐药决定因素；84/97 株（86.6%）呈现单一耐药机制，如下所示：45/84 株（53.6%）携带 optrA 基因，38/84 株（45.2%）携带 G2576T 突变，1/84 株（1.2%）携带 poxtA 基因。此外，5/97 株（5.2%）携带 optrA 和 G2576T 突变，5/97 株（5.2%）携带 optrA 和 poxtA。optrA 基因在屎肠球菌（83.6%）中比粪肠球菌（11.1%）更常见，主要与社区获得性尿路感染有关。poxtA 基因在粪肠球菌（13.9%）中比屎肠球菌（1.6%）更常见。在 optrA 阳性屎肠球菌分离株中，通过 PFGE 检测到两个主要聚类。这两个聚类属于 ST585 和 ST480，分布在 11 个和 6 个西班牙省份。这是西班牙首次描述携带 poxtA 基因的 LRE，包括五个分离株中同时存在 optrA 和 poxtA。
