Direct matrix-assisted laser desorption ionisation time-of-flight mass spectrometry identification of mycobacteria from colonies
Matrix-assisted laser desorption ionisation time-of-flight mass spectrometry (MALDI-TOF-MS) identification of mycobacteria requires a standard acetonitrile/formic acid pre-MALDI-TOF-MS. We prospectively compared this standard protocol with direct deposit with matrix for the identification of mycobac...
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Published in | European journal of clinical microbiology & infectious diseases Vol. 35; no. 12; pp. 1983 - 1987 |
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Main Authors | , , |
Format | Journal Article |
Language | English |
Published |
Berlin/Heidelberg
Springer Berlin Heidelberg
01.12.2016
Springer Nature B.V Springer Verlag |
Subjects | |
Online Access | Get full text |
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Summary: | Matrix-assisted laser desorption ionisation time-of-flight mass spectrometry (MALDI-TOF-MS) identification of mycobacteria requires a standard acetonitrile/formic acid pre-MALDI-TOF-MS. We prospectively compared this standard protocol with direct deposit with matrix for the identification of mycobacteria cultured on solid media. We first verified that
Mycobacterium tuberculosis
was killed after it was mixed with matrix. Then, 111
Mycobacterium
isolates previously identified by partial
rpo
B gene sequencing were tested in parallel by the two protocols. An identification score >1.7 was obtained in 86/111 (77.5 %) isolates after protein extraction versus 97/111 (87.4 %) isolates after direct deposit (
p
= 0.039, Chi-squared test). In a third step, we determined that direct deposit achieved identification for as few as 2.10
4
M. tuberculosis
organisms. In a fourth step, we evaluated direct deposit of one colony for 116 solid medium-cultured clinical isolates finally identified as representative of 12 species (63.8 %
M. tuberculosis
). For 114/116 (98.3 %) isolates with an identification score >1.2, the MALDI-TOF-MS identification was in complete agreement with the reference
rpo
B gene sequencing identification. One isolate with a MALDI-TOF-MS identification score of 1.22 for
M. fortuitum
was identified as
M. avium
by partial
rpo
B gene sequencing. One other isolate with a MALDI-TOF-MS identification score of 1.22 for
M. tuberculosis
was identified as
M. tuberculosis
by genotyping. All the original MALDI-TOF-MS spectra reported here have been deposited in a public database. Direct deposit of one colony on a MALDI-TOF-MS plate allows for an accurate identification of mycobacteria for an identification score >1.3. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 0934-9723 1435-4373 |
DOI: | 10.1007/s10096-016-2750-5 |