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Volume 24, Number 3—March 2018
Research

Capsule Typing of Haemophilus influenzae by Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry1

Viktor MånssonComments to Author , Janet R. Gilsdorf, Gunnar Kahlmeter, Mogens Kilian, J. Simon Kroll, Kristian Riesbeck2, and Fredrik Resman2
Author affiliations: Lund University, Malmö, Sweden (V. Månsson, K. Riesbeck, F. Resman); University of Michigan, Ann Arbor, Michigan, USA (J.R. Gilsdorf); Växjö Hospital, Växjö, Sweden (G. Kahlmeter); Aarhus University, Aarhus, Denmark (M. Kilian); Imperial College London, London, UK (J.S. Kroll)

Main Article

Figure 4

Biomarker analysis of matrix-assisted laser desorption/ionization time-of-flight mass spectra of encapsulated Haemophilus influenzae. Analysis was performed on all encapsulated isolates in the evaluation set (n = 83) and capsule transformants (n = 4). Rows are peaks (2,000–20,000 m/z in descending order), and columns are groups of encapsulated H. influenzae. A total of 124 peaks with discriminatory power (p<0.05) between different capsule types and genetic lineages were identified. Peak expre

Figure 4. Biomarker analysis of matrix-assisted laser desorption/ionization time-of-flight mass spectra of encapsulated Haemophilus influenzae. Analysis was performed on all encapsulated isolates in the evaluation set (n = 83) and capsule transformants (n = 4). Rows represent peaks (2,000–20,000 m/z in descending order), and columns represent groups of encapsulated H. influenzae. A total of 124 peaks with discriminatory power (p<0.05) between different capsule types and genetic lineages were identified. Peak expression is indicated by shades of black (black >75%, gray >25% but <75%, and white <25% of isolates in the group express the peak). Several peaks conserved within capsule types and genetic lineages with the possibility for separation were observed, as indicated by the mosaic of peak patterns. Capsule transformants showed similar peak patterns, and lacked many of the capsule type-specific peaks for their respective phenotypic capsule types. KR1130 expressed different peaks than Hif of the ST124-related lineage. Hia, H. influenzae type a; Hib, H. influenzae type b; Hic, H. influenzae type c; Hid, H. influenzae type d; Hie, H. influenzae type e; Hif, H. influenzae type f; ST, sequence type.

Main Article

1Preliminary results from this study were presented at the IDWeek 2016 Conference, October 26−30, 2016, New Orleans, Louisiana, USA.

2These senior authors contributed equally to this article.

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