Occurrence of vancomycin-tolerant and heterogeneous vancomycin-intermediate strains (hVISA) among Staphylococcus aureus causing bloodstream infections in nine USA hospitals
Occurrence of vancomycin-tolerant and heterogeneous vancomycin-intermediate strains (hVISA) among Staphylococcus aureus causing bloodstream infections in nine USA hospitals
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DOI：
10.1093/jac/dkp319
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发表时间：
2009-11-01
影响因子：
5.2
通讯作者：
Rybak, Michael J.
中科院分区：
文献类型：
--
作者：
Sader, Helio S.;Jones, Ronald N.;Rybak, Michael J.
背景：从美国9个主要医学中心收集大量的耐甲氧西林金黄色葡萄球菌(MRSA)菌株，评价万古霉素和达托霉素的杀菌活性。目的：评估耐万古霉素和/或增加万古霉素或达托霉素MIC值的MRSA菌株中是否存在异质性万古霉素中间金黄色葡萄球菌(HVISA)。同时比较了宏观Etest法(MET)和群体分析法(PAP)检测hVISA的准确性。方法：在2002-06年的研究期间，从9个地点的血液感染中收集1800株MRSA(每个医疗中心每年40株)。参照肉汤微量稀释法(全部菌株)进行万古霉素和达托霉素MIC试验，随机抽取50%的菌株进行MBC试验。用MET检测268株万古霉素MBC(>；=16 mg/L)、万古霉素MIC(>；=1 mg/L)和/或达托霉素MIC(>；0.5 mg/L)升高的菌株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%)对万古霉素耐药，在被评估的医疗中心中，耐药率从10%到43%不等，从2004年的11.7%到2005年的27.8%。在任何医学中心或整个研究数据中都没有观察到耐药性趋势。达托霉素对所有受试菌株均有杀菌活性。结论：最常用的hVISA标准，即万古霉素和替考拉宁的MET读数=8 mg/L或替考拉宁的MET读数=1.2 mg/L，在36株PAP阳性菌株中检出20株，敏感度为55.6%，提示hVISA的患病率可能比目前所认为的要高。达托霉素对hVISA菌株有杀菌作用。
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 (>= 16 mg/L), an increased vancomycin MIC (>= 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 >= 8 mg/L for both vancomycin and teicoplanin or >= 1 2 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.