在中国东北地区发现耐甲氧西林和甲氧西林敏感金黄色葡萄球菌临床分离株中万古霉素敏感性降低。
Reduced vancomycin susceptibility found in methicillin-resistant and methicillin-sensitive Staphylococcus aureus clinical isolates in Northeast China.
机构信息
Department of Medical Microbiology and Parasitology, College of Basic Medical Sciences, China Medical University, Shenyang, People's Republic of China ; Department of Clinical Laboratory, Yixing Hospital of Traditional Chinese Medicine, Yixing, Jiangsu, People's Republic of China.
出版信息
PLoS One. 2013 Sep 12;8(9):e73300. doi: 10.1371/journal.pone.0073300. eCollection 2013.
BACKGROUND
Strains of Staphylococcus aureus with an intermediate level of resistance to vancomycin (vancomycin-intermediate S. aureus, or VISA) or which contain subpopulations of mixed susceptibility (heterogeneous VISA, or hVISA) have been reported worldwide. However, the prevalence of VISA and hVISA infections in Northeast China is unknown. From 2007 through 2010, we surveyed the vancomycin susceptibility of methicillin-resistant and methicillin-sensitive S. aureus (MRSA and MSSA, respectively) clinical isolates in Northeast China.
METHODS
S. aureus clinical isolates (369 MRSA and 388 MSSA) were screened for hVISA and VISA on brain heart infusion agar containing 3 μg/mL vancomycin, and their identity confirmed using a modified population analysis profile-area under the curve method and broth microdilution. All hVISA and VISA isolates were characterized genotypically and phenotypically.
RESULTS
Ten percent and 0.5 percent of the isolates were hVISA and VISA, respectively. The proportion of hVISA among MSSA isolates for the entire study period was 4.1%, but increased significantly year-by-year, from 1.2% in 2007 to 7.2% in 2010. The predominant sources of hVISA and VISA isolates were sputum (56.3%), pus (18.8%), and blood (8.8%). Molecular typing of hVISA and VISA strains revealed that, taken together, 80% contained the accessory gene regulator (agr) group II, and of these, 85.7% of the MR-hVISA and MR-VISA strains were staphylococcal cassette chromosome mec (SCCmec) type II. The adherence ability of all hVISA and VISA strains was reduced compared with that of vancomycin-susceptible strains, shown by biofilm assay.
CONCLUSIONS
The percentage of hVISA strains was high and increased each year. The proportion of hVISA among MSSA specifically also increased significantly each year. In isolates collected from diverse infection sites, hVISA and VISA strains were found predominantly in sputum, pus, and blood, in descending order. Testing for vancomycin susceptibility should include both MRSA and MSSA isolates collected from different clinical sites.
背景
具有中间水平耐万古霉素的金黄色葡萄球菌（万古霉素中介金黄色葡萄球菌，或 VISA）或含有混合敏感性亚群（异质性 VISA，或 hVISA）的菌株已在全球范围内报道。然而，在中国东北地区 VISA 和 hVISA 感染的流行情况尚不清楚。我们从 2007 年至 2010 年调查了中国东北地区耐甲氧西林和甲氧西林敏感的金黄色葡萄球菌（分别为 MRSA 和 MSSA）临床分离株的万古霉素敏感性。
方法
在含有 3μg/ml 万古霉素的脑心浸液琼脂上筛选 hVISA 和 VISA 的金黄色葡萄球菌临床分离株（369 株 MRSA 和 388 株 MSSA），并使用改良的群体分析轮廓-曲线下面积法和肉汤微量稀释法确认其身份。所有 hVISA 和 VISA 分离株均进行表型和基因型特征分析。
结果
10%和 0.5%的分离株分别为 hVISA 和 VISA。整个研究期间，MSSA 分离株中 hVISA 的比例为 4.1%，但呈逐年显著上升趋势，从 2007 年的 1.2%上升至 2010 年的 7.2%。hVISA 和 VISA 分离株的主要来源是痰（56.3%）、脓液（18.8%）和血液（8.8%）。hVISA 和 VISA 菌株的分子分型显示，80%共同含有辅助基因调节物（agr）组 II，其中 85.7%的 MR-hVISA 和 MR-VISA 菌株为葡萄球菌盒染色体 mec（SCCmec）类型 II。所有 hVISA 和 VISA 菌株的黏附能力均低于万古霉素敏感菌株，通过生物膜试验显示。
结论
hVISA 菌株的比例较高且逐年增加。特别是 MSSA 中 hVISA 的比例也逐年显著增加。在从不同感染部位采集的分离株中，hVISA 和 VISA 菌株主要存在于痰、脓液和血液中，依次递减。万古霉素敏感性测试应包括来自不同临床部位的 MRSA 和 MSSA 分离株。
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