Choi Ji Seon, Kim Jayoung, Kim Han-Soo, Kwon Chang-Wan, Kim Min-Sung, Choi Seong-Hyeok
Department of Laboratory Medicine, International St. Mary's Hospital, Catholic Kwandong University, Incheon, Korea.
Institute for Integrative Medicine, International St. Mary's Hospital, Catholic Kwandong University, Incheon, Korea.
J Clin Lab Anal. 2018 Mar;32(3). doi: 10.1002/jcla.22280. Epub 2017 Jun 26.
We evaluated the analytical performance of a NaOH-HCl neutralization protocol for identifying uropathogens directly from urine samples by a Bruker MS system (Bruker Daltonics, German) and sought to establish a protocol for integrating the method with conventional screening.
Among all urine samples requested for Gram staining, UF-1000i, and urine cultures by physicians, we selected samples that were positive by both Gram staining and UF-1000i testing. Urine was prepared by neutralization using 0.01M NaOH-HCl, and the samples were processed by Bruker MS. For the low detection limit, one strain each of Escherichia coli and Enterococcus faecium was inoculated in sterile deionized water and sterile urine specimens at sequential dilutions.
In a total of 1270 urine samples, 125 samples (9.8%) were positive by both Gram staining and UF-1000i. Of 94 samples showing a single morphotype on agar plates, 82 samples had colony counts ≥10 CFU/mL and most uropathogens (95.1%, 78 of 82) had UF-1000i counts ≥10 bacteria/mL. Among them, Bruker MS correctly identified 86.6% (71/82) of all isolates, 89.2% (66/74) of Gram-negative bacteria (GNB), and 62.5% (5/8) of Gram-positive cocci (GPC) with higher average scores for GPC (mean score 2.013) and GNB (mean score 2.110).
Bruker MS with urine preparation by NaOH-HCl neutralization provides a simple, cost-effective, and accurate method for identifying uropathogens directly from urine. Using Bruker MS when single morphotype Gram staining and the UF-1000i count as ≥10 bacteria/mL may improve the efficiency of bacterial identification in routine practice.
我们评估了一种氢氧化钠-盐酸中和方案的分析性能，该方案用于通过布鲁克质谱系统（德国布鲁克道尔顿公司）直接从尿液样本中鉴定尿路病原体，并试图建立一种将该方法与传统筛查相结合的方案。
在医生要求进行革兰氏染色、UF-1000i检测和尿培养的所有尿液样本中，我们选择了革兰氏染色和UF-1000i检测均为阳性的样本。尿液通过用0.01M氢氧化钠-盐酸中和制备，样本由布鲁克质谱仪处理。对于低检测限，将一株大肠杆菌和一株粪肠球菌分别接种于无菌去离子水和无菌尿液标本中，并进行连续稀释。
在总共1270份尿液样本中，125份样本（9.8%）革兰氏染色和UF-1000i检测均为阳性。在94份在琼脂平板上显示单一形态型的样本中，82份样本的菌落计数≥10⁵CFU/mL，并且大多数尿路病原体（95.1%，82份中的78份）的UF-1000i计数≥10⁵细菌/mL。其中，布鲁克质谱仪正确鉴定了所有分离株的86.6%（71/82）、革兰氏阴性菌（GNB）的89.2%（66/74）和革兰氏阳性球菌（GPC）的62.5%（5/8），GPC的平均得分（平均得分2.013）和GNB的平均得分（平均得分2.110）更高。
采用氢氧化钠-盐酸中和法制备尿液的布鲁克质谱仪为直接从尿液中鉴定尿路病原体提供了一种简单、经济有效且准确的方法。当单一形态型革兰氏染色且UF-1000i计数≥10⁵细菌/mL时使用布鲁克质谱仪可能会提高常规实践中细菌鉴定的效率。
