This study aims to explore the antimicrobial activity and resistance mechanism of radezolid against Enterococcus faecium, and to compare it with linezolid. A total of 232 E. faecium isolates were collected, and the minimal inhibitory concentrations of radezolid and linezolid were determined. The radezolid- or linezolid-nonsusceptible isolates were selected by passage in vitro under antibiotic pressure. Oxazolidinone-resistant chromosomal genes and plasmid-borne genes cfr, optrA, and poxtA were detected by PCR and sequenced. Radezolid MIC₉₀ was 4 times lower than linezolid in the 232 E. faecium isolates, including the linezolid-nonsusceptible isolates. This study found that 6.5% (15/232) of the E. faecium isolates carried the plasmid-borne genes cfr and 9.5% (22/232) carried the optrA gene, but only one of these isolates had a linezolid MIC ≥ 4 mg l⁻¹. Among the 13 isolates with linezolid MIC ≥ 4 mg l⁻¹ or radezolid MIC ≥ 1 mg l⁻¹, genetic mutations in the V domain of 23S rRNA were only found in four isolates. The MICs of linezolid or radezolid against three E. faecium isolates increased to 4–16 times of the initial MICs after 140 days of daily passage in drug-containing medium. The radezolid MICs remained 8–16 times lower than linezolid in those linezolid-induced resistant isolates. Conversely, the radezolid MICs increased while the linezolid MICs remained unchanged in the most of the radezolid-induced resistant isolates. Radezolid exhibits excellent antimicrobial activity against E. faecium, and has minimal cross resistance with linezolid.

本研究旨在探讨雷地唑胺对粪肠球菌的抗菌活性和耐药机制，并将其与利奈唑胺进行比较。总共收集了232株粪肠球菌的分离物，并确定了雷克唑利德和利奈唑胺的最低抑菌浓度。通过在抗生素压力下体外传代选择雷迪唑烷或利奈唑胺不敏感的分离株。通过PCR检测抗恶唑烷酮的染色体基因和质粒携带的基因cfr，optrA和poxtA并进行测序。Radezolid MIC ₉₀在232 E.粪便中比利奈唑胺低4倍分离株，包括利奈唑胺不敏感分离株。这项研究发现，粪肠球菌中有6.5％（15/232）带有质粒携带的基因cfr，而粪便中有9.5％（22/232）带有optrA基因，但是这些分离株中只有一种的利奈唑胺MIC≥4 mg l ^-1。在13株利奈唑胺MIC≥4 mg l ^-1或雷克唑利MIC≥1 mgl ^-1的分离株中，仅在4个分离株中发现23S rRNA V域的遗传突变。利奈唑胺或雷地唑胺对三种粪肠球菌的MIC在含药物的培养基中每天通过140天后，分离株的分离度增加到初始MIC的4-16倍。在那些由利奈唑胺诱导的耐药菌株中，雷尼唑利酯的MIC仍比利奈唑胺低8-16倍。相反，在大多数由雷佐唑胺诱导的抗性菌株中，雷佐唑胺的MIC增加，而利奈唑胺的MIC保持不变。Radezolid对屎肠球菌具有出色的抗菌活性，并且与利奈唑胺的交叉耐药性最小。