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KMID : 0829320160190030065
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Korean Journal of Clinical Microbiology
2016 Volume.19 No. 3 p.65 ~ p.69
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Application of Matrix-Assisted Laser Desorption Ionization Time-of-Flight Mass Spectrometry to Screen the Extended-Spectrum β-Lactamase-Producing ST131 Escherichia coli Strains
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Kim Young-Ah
Yong Dong-Eun
In Yong-Ha
Park Hyung-Soon
Lee Kyung-Won
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Abstract
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Background: Sequence type 131 (ST131) O25b serogroup Escherichia coli, producing CTX-M type extended-spectrum β-lactamase (ESBL), is a major clone involved in worldwide pandemic spread in both community- and healthcare-associated infections. Recently, matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) has become a routine tool for the identification of bacteria in many laboratories. This study aimed to assess the performance of MALDI-TOF MS for the screening of ESBL-producing E. coli ST131 in a rapid, inexpensive, and simple way.
Methods: A total 26 clinical E. coli, isolated from blood between 2013 and 2014, were used. The characteristics are ST131-O25b ESBL producers (n=6), ST131-O16 ESBL producers (n=4), non-ST131 ESBL producers (n=11), and non-ST131 non-ESBL producers (n=5). Specific biomarker peaks to distinguish the ST131 clonal group from others were investigated by MicroIDSys (ASTA, South Korea) and ASTA Tinkerbell 2.0 software.
Results: A peak at 9,713 m/z peak is useful to screen for ST131 E. coli, regardless of serogroup O25 or O16, showing a sensitivity of 100%, specificity of 56.2%, positive predictive value of 58.8%, and negative predictive value of 100% when using a relative intensity cutoff of 15%.
Conclusion: We can screen for ST131 E. coli using MicroIDSys (ASTA), MALDI-TOF MS in a rapid, inexpensive, and simple way. However, other confirmatory tests are needed to confirm ST131 E. coli due to the low specificity of this method.
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KEYWORD
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Escherichia coli, Extended-spectrum β-lactamase, Matrix-assisted laser desorption ionization time-of-flight mass spectrometry, Sequence type 131, Serogroup O16, Serogroup O25b
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