摘要： 目的·通过定量检测痰标本中
mecA和
Sa442基因，分析耐甲氧西林金黄色葡萄球菌（methicillin resistant
Staphylococcus aureus，MRSA）的感染状态以及临床意义。方法·痰标本经裂解获取DNA，定量PCR（quantitative PCR，qPCR）绝对定量检测
mecA和
Sa442基因；结合痰标本临床常规培养鉴定结果，分析qPCR定量值的临床意义。结果·筛选1 775例合格痰标本，以细菌培养鉴定结果为金标准，qPCR检测的灵敏度为92.19%（59/64），特异度为89.60%（1 533/1 711），阳性预测值为24.89%（59/237），阴性预测值达到99.67%（1 533/1 538）。受试者操作特征曲线分析结果显示，
mecA定量对数值和
CT值判断MRSA培养阳性的曲线下面积分别为0.755和0.770，最佳临界值分别为5.59和27.1，敏感度分别为72.4%和73.0%，特异度分别为70.2%和74.1%。仅
Sa442基因定值为阳性时，细菌培养以甲氧西林敏感的金黄色葡萄球菌为主。当
mecA定量对数值>5.59或
CT值<27.1时，可以预判MRSA培养阳性。结论·痰标本中
mecA和
Sa442基因的定量结果，可用于早期快速排除MRSA的定植和感染，协助分析不同菌种培养结果的趋势。
关键词: 耐甲氧西林金黄色葡萄球菌, 定量PCR, mecA, Sa442, 痰标本 Abstract: Objective·To analyze the infection status and clinical significance of methicillin resistant Staphylococcus aureus (MRSA) by detecting mecA and Sa442 genes.
Methods·DNA was obtained from sputum samples. The clinical significance of quantitative value of quantitative PCR (qPCR) was analyzed by combining with the results of routine culture and identification of sputum samples.
Results·There were 1 775 qualified sputum samples. The sensitivity of qPCR was 92.19% (59/64), the specificity was 89.60% (1 533/1 711), the positive predictive value was 24.89% (59/237), and the negative predictive value was 99.67% (1 533/1 538). The results of receiver operating characteristic ( ROC) curve analysis showed that the area under the curve of mecA quantitative value and CT value were 0.755 and 0.770, respectively. The best critical values were 5.59 and 27.1, respectively. The sensitivity was 72.4% and 73.0%, and the specificity was 70.2% and 74.1%, respectively. When only Sa442 gene was positive, methicillin-susceptible Staphylococcus aureus was the main bacteria. When mecA value was greater than 5.59, or CT value was less than 27.1, MRSA culture can be predicted to be positive.
Conclusion·The quantitative detection of mecA and Sa442 genes in sputum samples can be used to quickly exclude the colonization and infection of MRSA in the early stage, helping to analyze the trend of different culture results.
Key words: methicillin resistant Staphylococcus aureus (MRSA), quantitative PCR (qPCR), mecA, Sa442, sputum sample PDF全文下载地址:
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