Flamm Robert K, Mendes Rodrigo E, Hogan Patricia A, Streit Jennifer M, Ross James E, Jones Ronald N
JMI Laboratories, North Liberty, Iowa, USA
JMI Laboratories, North Liberty, Iowa, USA.
Antimicrob Agents Chemother. 2016 Mar 25;60(4):2273-80. doi: 10.1128/AAC.02803-15. Print 2016 Apr.
Thelinezolidexperience andaccuratedetermination ofresistance (LEADER) surveillance program has monitored linezolid activity, spectrum, and resistance since 2004. In 2014, a total of 6,865 Gram-positive pathogens from 60 medical centers from 36 states were submitted. The organism groups evaluated wereStaphylococcus aureus(3,106), coagulase-negative staphylococci (CoNS; 797), enterococci (855),Streptococcus pneumoniae(874), viridans group streptococci (359), and beta-hemolytic streptococci (874). Susceptibility testing was performed by reference broth microdilution at the monitoring laboratory. Linezolid-resistant isolates were confirmed by repeat testing. PCR and sequencing were performed to detect mutations in 23S rRNA, L3, L4, and L22 proteins and acquired genes (cfrandoptrA). The MIC50/90forStaphylococcus aureuswas 1/1 μg/ml, with 47.2% of isolates being methicillin-resistantStaphylococcus aureus Linezolid was active against allStreptococcus pneumoniaestrains and beta-hemolytic streptococci with a MIC50/90of 1/1 μg/ml and against viridans group streptococci with a MIC50/90of 0.5/1 μg/ml. Among the linezolid-nonsusceptible MRSA strains, one strain harboredcfronly (MIC, 4 μg/ml), one harbored G2576T (MIC, 8 μg/ml), and one containedcfrand G2576T with L3 changes (MIC, ≥8 μg/ml). Among CoNS, 0.75% (six isolates) of all strains demonstrated linezolid MIC results of ≥4 μg/ml. Five of these were identified asStaphylococcus epidermidis, four of which containedcfrin addition to the presence of mutations in the ribosomal proteins L3 and L4, alone or in combination with 23S rRNA (G2576T) mutations. Six enterococci (0.7%) were linezolid nonsusceptible (≥4 μg/ml; five with G2576T mutations, including one with an additionalcfrgene, and one strain withoptrAonly). Linezolid demonstrated excellent activity and a sustained susceptibility rate of 99.78% overall.
利奈唑胺经验及耐药性准确测定（LEADER）监测项目自2004年起对利奈唑胺的活性、抗菌谱及耐药性进行监测。2014年，来自36个州60家医疗中心的共6865株革兰氏阳性病原体被送检。评估的微生物类别包括金黄色葡萄球菌（3106株）、凝固酶阴性葡萄球菌（CoNS；797株）、肠球菌（855株）、肺炎链球菌（874株）、草绿色链球菌（359株）及β溶血性链球菌（874株）。监测实验室采用参考肉汤微量稀释法进行药敏试验。对利奈唑胺耐药的分离株通过重复试验进行确认。进行聚合酶链反应（PCR）及测序以检测23S rRNA、L3、L4及L22蛋白的突变以及获得性基因（cfr和optrA）。金黄色葡萄球菌的MIC50/90为1/1 μg/ml，47.2%的分离株为耐甲氧西林金黄色葡萄球菌。利奈唑胺对所有肺炎链球菌菌株及β溶血性链球菌均有活性，MIC50/90为1/1 μg/ml，对草绿色链球菌的MIC50/90为0.5/1 μg/ml。在对利奈唑胺不敏感的耐甲氧西林金黄色葡萄球菌菌株中，一株仅携带cfr（MIC，4 μg/ml），一株携带G2576T（MIC，8 μg/ml），一株同时含有cfr和G2576T且L3有改变（MIC，≥8 μg/ml）。在CoNS中，所有菌株的0.75%（6株分离株）利奈唑胺MIC结果≥4 μg/ml。其中5株被鉴定为表皮葡萄球菌，4株除核糖体蛋白L3和L4存在突变外还含有cfr，这些突变单独或与23S rRNA（G2576T）突变同时存在。6株肠球菌（0.7%）对利奈唑胺不敏感（≥4 μg/ml；5株有G2576T突变，其中1株还含有cfr基因，1株仅含optrA）。利奈唑胺显示出优异的活性，总体持续敏感率为99.78%。
