耐甲氧西林金黄色葡萄球菌的鉴定显示头孢他林的mic增加。
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Mendes RE, Tsakris A, Sader HS, Jones RN, Biek D, McGhee P, Appelbaum PC, Kosowska-Shick K
耐甲氧西林金黄色葡萄球菌的鉴定显示头孢他林的mic增加。
《抗菌化学杂志》2012 6;67(6):1321-4。doi: 10.1093 /江淮/ dks069。Epub 2012 3月7日。
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22398650 (PubMed视图］
- 摘要
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目的:探讨头孢他林对耐甲氧西林金黄色葡萄球菌(MRSA) mic升高的机制。方法:在2008年全球抗微生物药物耐药性评估(“AWARE”)监测项目中，从希腊雅典的不同患者身上收集的4例金黄色葡萄球菌显示头孢他林的mic为4 mg/L。这些分离株具有克隆相关性，并筛选出一株(13101)作进一步鉴定。选取头孢他啉mic分别为1 mg/L和2 mg/L的两株菌株(4981和4977)进行比较。所有菌株都来自同一家医院测定青霉素结合蛋白(PBP)对头孢他啉和比较物的亲和性。通过单位点分型(即spa分型)、多位点序列分型('MLST')和多位点可变数串联重复指纹(MLVF)对菌株进行分型。潘通-瓦伦丁亮色素和葡萄球菌盒染色体mec型的存在进行了评估。我们还对mecA(编码PBP2a)启动子和核糖体结合位点(rbs)区域以及mecR1进行了核苷酸测序。结果:头孢他林与菌株4981 (ST5-MRSA-II)的PBP2a亲和度最高(IC(50) 0.06 mg/L; MIC 1 mg/L). Strains 4977 and 13101 (both ST239-MRSA-III) showed indistinguishable MLVF profiles. Ceftaroline PBP2a binding affinity in strains 4977 (IC(50) 0.25 mg/L; MIC 2 mg/L) and 13101 (IC(50) 1 mg/L; MIC 4 mg/L) was 4- and 16-fold lower than 4981, respectively. Strain 4981 contains a wild-type PBP2a, while strains 4977 and 13101 have N(146)K and E(150)K alterations in the non-penicillin-binding domain. Additionally, 13101 has one substitution (H(351)N) in the transpeptidase domain. Alterations in the mecR1, mecA promoter or rbs regions were not observed. CONCLUSIONS: Increased ceftaroline MICs were associated with decreased PBP2a binding affinity and reflected alterations in PBP2a.