High Levels of mecA DNA Detected by a Quantitative Real-Time PCR Assay Are Associated with Mortality in Patients with Methicillin-Resistant Staphylococcus aureus Bacteremia
High Levels of mecA DNA Detected by a Quantitative Real-Time PCR Assay Are Associated with Mortality in Patients with Methicillin-Resistant Staphylococcus aureus Bacteremia
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DOI：
10.1128/jcm.01197-08
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发表时间：
2009-05-01
影响因子：
9.4
通讯作者：
Wang, Wei-Kung
中科院分区：
文献类型：
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作者：
Ho, Ya-Chi;Chang, Shan-Chwen;Wang, Wei-Kung
耐甲氧西林金黄色葡萄球菌(MRSA)菌血症是已知的预后不良因素。虽然最近报道了几种检测不同临床标本中MRSA的PCR方法，但定量PCR方法用于定量和监测MRSA菌血症的可能性尚未被探索。在这项研究中，我们建立了一种mecA基因的实时定量聚合酶链式反应方法，以含有mecA DNA的质粒的已知拷贝数为标准，以及前面描述的mecA特异的引物和探针(P.Francois等人，J.Clin。微生物。41：254-260,2003)。我们于2006年7月1日至2007年1月31日在国立台湾大学医院重症监护室对20例经培养证实为MRSA菌血症的成人患者的250份连续全血样本进行了检测，其中包括13名幸存者和7名死亡患者。在菌血症的3个时期(0.003~2天、3~5天、6~8天)，死亡者mecA DNA水平均显著高于存活者(经双尾Mann-Whitney U检验，P=0.003)。在抗MRSA治疗3天和7天后，死亡者mecA DNA水平均高于存活者(死亡者和存活者的中位数分别为3天、5.86和4.30个对数拷贝/ml；死亡者和存活者的中位数分别为5.21和4.36个对数拷贝/ml；经双尾Mann-Whitney U检验，分别为P=0.02和P=0.04)。综上所述，这些发现表明，血液中mecA DNA水平可能被用于监测MRSA菌血症和评估治疗反应。
Persistent methicillin-resistant Staphylococcus aureus (MRSA) bacteremia is known to be a poor prognostic factor. While several PCR assays for the detection of MRSA in various clinical samples were recently reported, the possibility that a quantitative PCR assay could be used to quantify and monitor MRSA bacteremia has not been explored. In this study, we established a quantitative real-time PCR assay for the mecA gene using known copy numbers of a plasmid containing mecA DNA as a standard and the previously described mecA-specific primers and probe (P. Francois et al., J. Clin. Microbiol. 41: 254-260, 2003). We employed this assay to examine 250 sequential whole-blood samples from 20 adult patients, including 13 survivors and 7 nonsurvivors, with culture-proven MRSA bacteremia at the intensive care units of National Taiwan University Hospital between 1 July 2006 and 31 January 2007. The levels of mecA DNA in the nonsurvivors were significantly higher than those in the survivors during the three periods of bacteremia examined (days 0 to 2, 3 to 5, and 6 to 8) (P = 0.003 by two-tailed Mann-Whitney U test). Moreover, the nonsurvivors had higher mecA DNA levels than the survivors after 3 days and 7 days of anti-MRSA therapy (medians for nonsurvivors and survivors at 3 days, 5.86 and 4.30 log copies/ml, respectively; medians for nonsurvivors and survivors at 7 days, 5.21 and 4.36 log copies/ml, respectively; P = 0.02 and P = 0.04, respectively, by two-tailed Mann-Whitney U test). Together, these findings suggest that the level of mecA DNA in blood could potentially be used to monitor MRSA bacteremia and evaluate responses to therapy.