Department of Clinical Pathology Cleveland Clinic, 9500 Euclid Avenue/L40, Cleveland, OH 44195, USA.
J Clin Microbiol. 2011 Dec;49(12):4203-7. doi: 10.1128/JCM.01152-11. Epub 2011 Oct 5.
The prevalence of heterogeneous intermediate-level resistance to vancomycin (hVISA) in Staphylococcus aureus was assessed by screening a large collection of recent isolates. Susceptibility testing by the Clinical and Laboratory Standards Institute broth microdilution method and the Etest GRD (glycopeptide resistance detection) method (bioMérieux) was performed on 4,210 clinically significant S. aureus isolates obtained in 2009 from 43 U.S. centers. Isolates with Etest GRD-positive results for hVISA were evaluated further by repeat GRD testing and population analysis profiling-area under the curve (PAP-AUC) analysis. No VISA (vancomycin MIC, 4 to 8 μg/ml) or vancomycin-resistant (MIC ≥ 16 μg/ml) strains were detected. The Etest GRD screen for hVISA was initially positive for 68 isolates (1.6%; all by teicoplanin MIC ≥ 8 μg/ml at 24 or 48 h). Among those 68 isolates, 45 were reproducibly GRD positive. PAP-AUC testing confirmed only 11 isolates as hVISA (all had reproducible GRD-positive results). The 11 hVISA isolates were from nine medical centers and appeared genetically diverse (ten different PFGE types). The rates of resistance (including intermediate) for hVISA were as follows: oxacillin, 82%; erythromycin, 82%; clindamycin, 73%; levofloxacin, 73%; trimethoprim-sulfamethoxazole, 9%; and daptomycin, 9%. All hVISA isolates were susceptible to linezolid, tigecycline, and ceftaroline. Our data suggest that the overall prevalence of hVISA in the United States is low (0.3%). The hVISA isolates represented 10.5% of isolates with vancomycin MICs of 2 μg/ml and 0.1% of isolates with vancomycin MICs of 1 μg/ml. The positive predictive value of GRD Etest for hVISA was 16.2% for initial screen positive and 24.4% for reproducibly positive results.
通过筛选大量近期分离株，评估了金黄色葡萄球菌中万古霉素中介水平耐药（hVISA）的流行情况。对 2009 年从美国 43 个中心获得的 4210 株临床意义重大的金黄色葡萄球菌分离株，采用临床和实验室标准协会肉汤微量稀释法和 Etest GRD（糖肽耐药检测）法（bioMérieux）进行了药敏试验。对 Etest GRD 检测 hVISA 阳性的分离株进行了进一步的重复 GRD 检测和群体分析谱-曲线下面积（PAP-AUC）分析。未检测到 VISA（万古霉素 MIC，4-8μg/ml）或万古霉素耐药（MIC≥16μg/ml）菌株。hVISA 的 Etest GRD 筛选最初对 68 株分离株呈阳性（1.6%；所有分离株均以替考拉宁 MIC≥24 或 48 小时 8μg/ml 为特征）。在这 68 株分离株中，有 45 株 GRD 检测结果可重复。PAP-AUC 检测仅证实 11 株为 hVISA（所有分离株均具有可重复的 GRD 阳性结果）。11 株 hVISA 分离株来自 9 个医疗中心，表现出遗传多样性（10 种不同的 PFGE 类型）。hVISA 的耐药率（包括中介耐药）如下：苯唑西林，82%；红霉素，82%；克林霉素，73%；左氧氟沙星，73%；甲氧苄啶-磺胺甲恶唑，9%；达托霉素，9%。所有 hVISA 分离株均对利奈唑胺、替加环素和头孢洛林敏感。我们的数据表明，美国 hVISA 的总体流行率较低（0.3%）。hVISA 分离株占万古霉素 MIC 为 2μg/ml 的分离株的 10.5%，占万古霉素 MIC 为 1μg/ml 的分离株的 0.1%。GRD Etest 对初始筛选阳性的 hVISA 的阳性预测值为 16.2%，对可重复阳性结果的阳性预测值为 24.4%。
