万古霉素中介和耐万古霉素金黄色葡萄球菌（hVISA）在 9 家美国医院血流感染中的发生情况。
Occurrence of vancomycin-tolerant and heterogeneous vancomycin-intermediate strains (hVISA) among Staphylococcus aureus causing bloodstream infections in nine USA hospitals.
机构信息
JMI Laboratories, North Liberty, IA, USA.
出版信息
J Antimicrob Chemother. 2009 Nov;64(5):1024-8. doi: 10.1093/jac/dkp319. Epub 2009 Sep 10.
BACKGROUND
The bactericidal activities of vancomycin and daptomycin were evaluated in a large collection of methicillin-resistant Staphylococcus aureus (MRSA) bacteraemia strains from nine major USA medical centres.
OBJECTIVES
To evaluate the occurrence of heterogeneous vancomycin-intermediate S. aureus (hVISA) among MRSA strains tolerant to vancomycin and/or with increased vancomycin or daptomycin MIC values. The accuracy of the macro Etest method (MET) compared with population analysis profiling (PAP) for the detection of hVISA was also assessed.
METHODS
A total of 1800 MRSA strains were collected from bloodstream infections at the nine sites (40 strains per year, per medical centre during the 2002-06 study period). Vancomycin and daptomycin MIC testing was performed by reference broth microdilution (all strains) and MBC tests on 50% of strains (randomly selected). A subset of isolates (n = 268) having an increased vancomycin MBC (> or =16 mg/L), an increased vancomycin MIC (> or =1 mg/L) and/or an increased daptomycin MIC (>0.5 mg/L) were tested for susceptibility to vancomycin and teicoplanin by MET.
RESULTS
Overall, 181 of 900 (20.1%) MRSA tested exhibited vancomycin tolerance, varying from 10% to 43% among the medical centres evaluated, and from 11.7% in 2004 to 27.8% in 2005. No resistance trend was observed in any medical centre or in the overall study data. Daptomycin showed bactericidal activity against all strains tested. The accuracy of MET for identifying hVISA strains varied significantly with the criteria applied for positivity.
CONCLUSIONS
The most frequently used criteria to define hVISA, i.e. MET reading values > or =8 mg/L for both vancomycin and teicoplanin or > or =12 mg/L for teicoplanin only, detected 20 of 36 PAP-positive strains (55.6% sensitivity), indicating that the prevalence of hVISA could be higher than currently appreciated. Daptomycin was bactericidal against hVISA strains.
背景
从美国 9 个主要医疗中心的 1800 株耐甲氧西林金黄色葡萄球菌（MRSA）菌血症分离株中评估了万古霉素和达托霉素的杀菌活性。
目的
评估对万古霉素耐药和/或万古霉素或达托霉素 MIC 值升高的耐甲氧西林金黄色葡萄球菌（MRSA）株中异质性万古霉素中介金黄色葡萄球菌（hVISA）的发生率。还评估了宏 E 试验（MET）方法与群体分析蛋白图谱（PAP）检测 hVISA 的准确性。
方法
在 2002-06 年研究期间，从 9 个地点的血流感染中收集了总共 1800 株 MRSA 菌株（每个医疗中心每年 40 株）。使用参考肉汤微量稀释法（所有菌株）和 MBC 试验（随机选择的 50%菌株）检测万古霉素和达托霉素 MIC。选择一组分离株（n=268），其万古霉素 MBC（>或=16 mg/L）、万古霉素 MIC（>或=1 mg/L）和/或达托霉素 MIC（>0.5 mg/L）升高，用 MET 检测对万古霉素和替考拉宁的敏感性。
结果
总体而言，900 株 MRSA 中有 181 株（20.1%）表现出万古霉素耐药性，在评估的医疗中心中从 10%到 43%不等，2004 年为 11.7%，2005 年为 27.8%。在任何医疗中心或整个研究数据中均未观察到耐药趋势。达托霉素对所有测试菌株均显示出杀菌活性。用于确定 hVISA 菌株的 MET 准确性随阳性标准的应用而显著变化。
结论
最常使用的定义 hVISA 的标准，即万古霉素和替考拉宁的 MET 读数值>或=8 mg/L 或替考拉宁的>或=12 mg/L，检测到 36 株 PAP 阳性株中的 20 株（55.6%的敏感性），表明 hVISA 的流行率可能高于目前的认识。达托霉素对 hVISA 株具有杀菌活性。
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