• 대한의생명과학회지
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• 제24권2호
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• pp.108-115
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• 2018

In the present study, results of the identification of Gram-positive bacilli (GPB) were analyzed by using the MALDI-TOF MS technique to score each 2-year blood culture at a university hospital. In addition, 16S rRNA sequence analyses and MALDI-TOF MS results are compared to targeting strains that had been isolated two or more times within the same patient, to evaluate the usefulness of MALDI-TOF MS in GPB identification. According to the cut-off (${\geq}1.7$) criteria, there were 410 (57.5%) reliable strains and 303 (42.5%) non-identified strains among the GPB identification results of 713 strains, using a microflex MALDI Biotyper (Bruker Daltonik GmbH, Bremen, Germany). The isolation appeared most often in the following order: Corynebacterium striatum, Bacillus cereus, Bacillus subtilis, Paenibacillus urinalis, and Listeria monocytogenes. Nearly three-fourths, 66 out of 89 (74.2%) of the strains for Corynebacterium striatum; 44 out of 60 (73.3%) strains for Bacillus cereus; and all (25 out of 25, 100%) Listeria monocytogenes strains were identified by their high scores of 2.0 or higher. Most (293 strains out of 303) non-identified strains were strains isolated only once and not significant as infectious bacilli. A total of 43 out of 50 (86.0%) strains matched and were able to be identified based on the 16 rRNA sequencing comparison results of strains that were isolated twice or more within the same patient and significant as infection bacilli. Non-matching among 5 out of 7 strains was not identified, even with MALDI-TOF MS. In conclusion, GPB can be identified in blood cultures using MALDI-TOF MS. This can be done accurately with ease, rapidly, and at a low cost. It is also thought to be helpful in GPB diagnosis and treatment.

• 대한임상검사과학회지
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• 제50권4호
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• pp.414-421
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• 2018

본 연구에서는 일개 대학병원에서 2년간 분리된 혈액배양 양성배지에서 MALDI-TOF MS system을 이용하여 Gram-positive bacilli를 동정한 결과를 균종별, 분기별로 분석하였다. Corynebacterium striatum은 총 89균주 중 66균주 (74.2%), Bacillus cereus는 60균주 중 44 균주 (73.3%), Listeria monocytogenes는 25균주 중 25균주 (100%)로 2.0이상의 높은 스코어에서 동정되었다. 미 동정 된 균주는 303균주 중 293균주는 혈액배양에서 1회 분리 균주로 감염균으로서의 의의가 없는 오염 균주로 간주되었다. 감염균으로서 의의가 있는 동일 환자 2회 이상 분리 균주 대상 16S-rRNA sequencing 비교결과 총 50균주 중 43균주가 일치해 86.0% 동정이 가능하였다. 일치하지 않은 7균주 중 5균주는 MALDI-TOF MS로도 동정이 되지 않았다. 결론적으로 혈액배양에서 Gram-positive bacilli가 동정되는 경우, 일차적으로 MALDI-TOF MS를 이용하여 동정해보고 이를 활용한다면 어렵고 비용이 많이 들던 Gram-positive bacilli 동정이 저비용으로 더욱 간편하고 정확해지며, Gram-positive bacilli에 의한 감염 진단에도 도움이 될 것으로 판단된다.