Huang Bin, Zhang Lei, Zhang Weizheng, Liao Kang, Zhang Shihong, Zhang Zhiquan, Ma Xingyan, Chen Jialong, Zhang Xiuhong, Qu Pinghua, Wu Shangwei, Chen Cha, Tang Yi-Wei
Department of Laboratory Medicine, First Affiliated Hospital of Sun Yat-sen University, Guangzhou, China.
Department of Laboratory Medicine, Memorial Sloan Kettering Cancer Center, New York, New York, USA.
J Clin Microbiol. 2017 May;55(5):1488-1495. doi: 10.1128/JCM.02549-16. Epub 2017 Mar 1.
Rapid and accurate detection and identification of microbial pathogens causing urinary tract infections allow prompt and specific treatment. We optimized specimen processing to maximize the limit of detection (LOD) by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) and evaluated the capacity of combination of MALDI-TOF MS and urine analysis (UA) for direct detection and identification of bacterial pathogens from urine samples. The optimal volumes of processed urine, formic acid/acetonitrile, and supernatant spotted onto the target plate were 15 ml, 3 μl, and 3 μl, respectively, yielding a LOD of 1.0 × 10 CFU/ml. Among a total of 1,167 urine specimens collected from three hospital centers, 612 (52.4%) and 351 (30.1%) were, respectively, positive by UA and urine culture. Compared with a reference method comprised of urine culture and 16S rRNA gene sequencing, the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of MALDI-TOF MS alone and MALDI-TOF MS coupled with UA were 86.6% versus 93.4% (χ = 8.93; < 0.01), 91.5% versus 96.3% (χ = 7.06; < 0.01), 81.5% versus 96.4% (χ = 37.32; < 0.01), and 94.1% versus 93.1% (χ = 0.40; > 0.05), respectively. No significant performance differences were revealed among the three sites, while specificity and NPV of MALDI-TOF MS for males were significantly higher than those for females (specificity, 94.3% versus 77.3%, χ = 44.90, < 0.01; NPV, 95.5% versus 86.1%, χ = 18.85, < 0.01). Our results indicated that the optimization of specimen processing significantly enhanced analytical sensitivity and that the combination of UA and MALDI-TOF MS provided an accurate and rapid detection and identification of bacterial pathogens directly from urine.
快速准确地检测和鉴定引起尿路感染的微生物病原体，有助于进行及时且针对性的治疗。我们优化了样本处理流程，以通过基质辅助激光解吸电离飞行时间质谱（MALDI-TOF MS）最大化检测限（LOD），并评估了MALDI-TOF MS与尿液分析（UA）相结合直接检测和鉴定尿液样本中细菌病原体的能力。处理后点样到靶板上的最佳尿液体积、甲酸/乙腈体积和上清液体积分别为15 ml、3 μl和3 μl，检测限为1.0×10 CFU/ml。在从三个医院中心收集的总共1167份尿液样本中，分别有612份（52.4%）和351份（30.1%）通过UA和尿液培养呈阳性。与由尿液培养和16S rRNA基因测序组成的参考方法相比，单独的MALDI-TOF MS以及MALDI-TOF MS与UA联用的灵敏度、特异性、阳性预测值（PPV）和阴性预测值（NPV）分别为86.6%对93.4%（χ = 8.93；P < 0.01）、91.5%对96.3%（χ = 7.06；P < 0.01）、81.5%对96.4%（χ = 37.32；P < 0.01）和94.1%对93.1%（χ = 0.40；P > 0.05）。三个地点之间未发现显著的性能差异，而MALDI-TOF MS对男性的特异性和NPV显著高于女性（特异性，94.3%对77.3%，χ = 44.90，P < 0.01；NPV，95.5%对86.1%，χ = 18.85，P < 0.01）。我们的结果表明，样本处理的优化显著提高了分析灵敏度，并且UA与MALDI-TOF MS的结合能够直接从尿液中准确快速地检测和鉴定细菌病原体。
