Open AccessImproved bacterial identification directly from urine samples with matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry
Author(s) -
Kitagawa Koichi,
Shigemura Katsumi,
Onuma Kenichiro,
Nishida Masako,
Fujiwara Mayu,
Kobayashi Saori,
Yamasaki Mika,
Nakamura Tatsuya,
Yamamichi Fukashi,
Shirakawa Toshiro,
Tokimatsu Issei,
Fujisawa Masato
Publication year - 2018
Publication title -
journal of clinical laboratory analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.536
H-Index - 50
eISSN - 1098-2825
pISSN - 0887-8013
DOI - 10.1002/jcla.22301
Subject(s) - urine , chromatography , mass spectrometry , matrix assisted laser desorption/ionization , sample preparation , gram positive cocci , urinary system , chemistry , medicine , bacteria , desorption , biology , organic chemistry , adsorption , biochemistry , genetics , staphylococcus aureus
Background Matrix‐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 . Methods MALDI ‐ 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 10 minutes of ultrasonication followed by centrifugation at 500 g for 1 minutes to remove debris such as epithelial cells and leukocytes from the urine (Method 2). Results In 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 1.408±0.153 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 . Conclusion The 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.