Improved bacterial identification directly from urine samples with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry
Improved bacterial identification directly from urine samples with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry
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DOI：
10.1002/jcla.22301
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发表时间：
2018-03-01
影响因子：
2.7
通讯作者：
Fujisawa, Masato
中科院分区：
文献类型：
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作者：
Kitagawa, Koichi;Shigemura, Katsumi;Fujisawa, Masato
基质辅助激光解吸/电离飞行时间质谱仪(MALDI-TOF MS)在临床上有助于快速鉴定病原体，但在引起复杂尿路感染(UTI)的革兰阳性球菌(GPC)中表现不佳。本研究的目的是探讨MALDI-TOF MS作为一种直接从尿路感染患者尿液中直接鉴定细菌的快速方法在临床应用的可能性。结果在133株尿培养阳性菌中，MALDI-TOF MS与标准样品制备(方法1)的GPC培养符合率为16.7%，而改良样品制备(方法2)显著提高了这一符合率为52.2%(P=.045)。方法2还将革兰氏阴性杆菌(GNR)的鉴定准确率从77.1%提高到94.2%(P=0.022)。改良的方法2能显著提高GPC的MALDI评分，从1.4080.153分提高到2.166+/-0.045分(P=.000)，GNR的MALDI评分从2.107+/-0.061分轻微提高到2.164+/-0.037分。结论改良的MALDI-TOF MS样品制备方法可以提高复杂UTI病原菌的鉴定准确度。这一简单的改进为尿路感染提供了一种快速而准确的常规诊断方法，并有可能替代尿培养。
BackgroundMatrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) contributes to rapid identification of pathogens in the clinic but has not yet performed especially well for Gram-positive cocci (GPC) causing complicated urinary tract infection (UTI). The goal of this study was to investigate the possible clinical use of MALDI-TOF MS as a rapid method for bacterial identification directly from urine in complicated UTI.MethodsMALDI-TOF MS was applied to urine samples gathered from 142 suspected complicated UTI patients in 2015-2017. We modified the standard procedure (Method 1) for sample preparation by adding an initial 10minutes of ultrasonication followed by centrifugation at 500g for 1minutes to remove debris such as epithelial cells and leukocytes from the urine (Method 2).ResultsIn 133 urine culture-positive bacteria, the rate of corresponded with urine culture in GPC by MALDI-TOF MS in urine with standard sample preparation (Method 1) was 16.7%, but the modified sample preparation (Method 2) significantly improved that rate to 52.2% (P=.045). Method 2 also improved the identification accuracy for Gram-negative rods (GNR) from 77.1% to 94.2% (P=.022). The modified Method 2 significantly improved the average MALDI score from 1.4080.153 to 2.166 +/- 0.045 (P=.000) for GPC and slightly improved the score from 2.107 +/- 0.061 to 2.164 +/- 0.037 for GNR.ConclusionThe modified sample preparation for MALDI-TOF MS can improve identification accuracy for complicated UTI causative bacteria. This simple modification offers a rapid and accurate routine diagnosis for UTI, and may possibly be a substitute for urine cultures.