阳性报警时间预测血培养葡萄球菌评价

Evaluation of time to positivity for predicting Staphylococci in blood culture

目的探讨阳性报警时间(TTP)在预测血培养中金黄色葡萄球菌(SA)、凝固酶阴性葡萄球菌(CoNS)和甲氧西林耐药金黄色葡萄球菌(MRSA)中的价值。方法收集北京大学第一医院2008至2012年血培养阳性标本中SA、CoNS的TTP,根据SA对苯唑西林的敏感性判定为MRSA或甲氧西林敏感金黄色葡萄球菌(MSSA)。对同一患者分离的重复菌株,仅留取第1株纳入本研究。分别比较SA和CoNS的TTP差异是否具有统计学意义,MRSA和MSSA的TTP差异是否有统计学意义。用受试者工作特征(ROC)曲线分析TTP的诊断价值。结果收集到SA共101株(其中MRSA为51株,MSSA为50株),CoNS共253株。SA和CoNS的TTP分别为(16.63±7.47)h和(24.61±11.09)h,二者差异有统计学意义(P<0.05)。MRSA和MSSA的TTP分别为(18.22±8.15)h和(15.01±6.40)h,二者差异有统计学意义(P<0.05)。ROC曲线表明TTP≤16.90 h可作为区分SA和CoNS的切点,曲线下面积(AUC)为0.758。TTP>12.58 h可作为区分MRSA和MSSA的切点,AUC为0.630。结论 TTP对预测SA和CoNS的准确度为中等,对预测MRSA和MSSA的准确度较低。

Objective To investigate the significance of time to positivity （TI＇P） for predicting Staphylococcus aureus （ SA ） , coagulase negative Staphylococcus （CONS） and methicillin-resistant Staphylococcus aureus （MRSA） in blood culture. Methods The TFP for predicting SA and CoNS in blood culture from 2008 to 2012 in Beijing University First Hospital were collected. MRSA and methicillin-susceptible Staphylococcus aureus （MSSA） were judged by their susceptibility to oxacillin. Only the first isolate was included in this study for those repetitively isolated from the same patients. 3TP between SA and CoNS and TYP between MRSA and MSSA were compared statistically. Receiver operating characteristic （ROC） curve was used to analyze the diagnosis significance of ITP. Results A total of 101 isolates of SA （51 isolates of MRSA and 50 isolates of MSSA） and 253 isolates of CoNS were collected. TIP of SA and CoNS were （ 16.63 ± 7.47） h and （24.61 ± 11.09） h with statistical significance （P 〈 0.05）, and TIP of MRSA and MSSA were （ 18.22 ±8.15） h and （ 15.01±6.40） h with statistical significance （ P 〈 0.05 ）. ROC curve showed that TIP 〈 16.90 h was the cut-off point to differentiate SA and CONS, and the area under the ROC curve （AUC） was 0.758. TrP 〉 12.58 h was the cut-off point to differentiate MRSA and MSSA, and the AUC was 0. 630. Conclusions The accuracy of TIP for predicting SA and CoNS is moderate, and the accuracy of TIP for predicting MRSA and MSSA is lOW.