Linezolid (LNZ) is one of the most important antimicrobial agents against infections caused by gram-positive bacteria, including enterococci. In a layer operation system, antimicrobial resistance can be transferred to commercial layers via the fecal-oral route. This study investigated the presence and distribution of LNZ-resistant Enterococcus faecalis and Enterococcus faecium in a layer operation system. Among 117 E. faecalis and 154 E. faecium, 10 (8.5%) E. faecalis and 5 (3.2%) E. faecium isolates showed resistance to LNZ and chloramphenicol, and they exhibited multidrug resistance against 5 or more classes of antimicrobial agents. Among the resistant isolates, 9 (90.0%) and 2 (20.0%) E. faecalis harbored optrA and cfr genes, respectively. The optrA and fexA genes were not detected in five LNZ-resistant E. faecium. None of the 15 LNZ-resistant isolates harbored the fexA gene, and no mutations were observed in the genes encoding domain V of 23S ribosomal RNA (rRNA) and ribosomal proteins L3 (rplC) and L4 (rplD). Transferability was identified in three of the nine optrA-positive LNZ-resistant isolates. The tetM, tetL, and ermB genes were cotransferred with the optrA gene in all optrA-positive transconjugants. The results indicate that optrA is well-distributed in E. faecalis, implying a greater level of transferability. Thus, enhanced surveillance efforts are needed to monitor the emergence and spread of optrA in enterococci in layer operation system.

中文翻译：

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韩国产蛋运行系统中耐利奈唑胺粪肠球菌和粪肠球菌分离株的检测

利奈唑胺 (LNZ) 是对抗革兰氏阳性菌（包括肠球菌）引起的感染的最重要的抗菌药物之一。在蛋鸡运营系统中，抗菌素耐药性可以通过粪口途径转移到商业蛋鸡。本研究调查了蛋鸡操作系统中耐 LNZ粪肠球菌和粪肠球菌的存在和分布。在 117株粪肠球菌和 154株粪肠球菌中，10 株（8.5%）粪肠杆菌和 5 株（3.2%）粪肠杆菌分离株对 LNZ 和氯霉素表现出耐药性，并对 5 类或更多类抗菌药物表现出多药耐药性。在耐药菌株中，9 个（90.0%）和 2 个（20.0%）粪肠球菌分别带有optrA和cfr基因。在五个耐 LNZ屎肠球菌中未检测到optrA和fexA基因。15 个 LNZ 抗性分离株中没有一个具有fexA基因，并且在编码 23S 核糖体 RNA (rRNA) 域 V 和核糖体蛋白 L3 ( rplC ) 和 L4 ( rplD )的基因中没有观察到突变。在九个optrA中的三个中确定了可转移性-阳性LNZ抗性分离株。tetM、tetL和ermB基因与所有optrA阳性转导结合体中的optrA基因共转移。结果表明optrA在E. faecalis中分布良好，这意味着更高水平的可转移性。因此，需要加强监测工作，以监测蛋鸡操作系统中肠球菌中optrA的出现和传播。