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Rapid identification of Burkholderia mallei and Burkholderia pseudomallei by intact cell Matrix-assisted Laser Desorption/Ionisation mass spectrometric typing.
BMC Microbiol. 2012 Oct 10; 12:229.BM

Abstract

BACKGROUND

Burkholderia (B.) pseudomallei and B. mallei are genetically closely related species. B. pseudomallei causes melioidosis in humans and animals, whereas B. mallei is the causative agent of glanders in equines and rarely also in humans. Both agents have been classified by the CDC as priority category B biological agents. Rapid identification is crucial, because both agents are intrinsically resistant to many antibiotics. Matrix-assisted laser desorption/ionisation mass spectrometry (MALDI-TOF MS) has the potential of rapid and reliable identification of pathogens, but is limited by the availability of a database containing validated reference spectra. The aim of this study was to evaluate the use of MALDI-TOF MS for the rapid and reliable identification and differentiation of B. pseudomallei and B. mallei and to build up a reliable reference database for both organisms.

RESULTS

A collection of ten B. pseudomallei and seventeen B. mallei strains was used to generate a library of reference spectra. Samples of both species could be identified by MALDI-TOF MS, if a dedicated subset of the reference spectra library was used. In comparison with samples representing B. mallei, higher genetic diversity among B. pseudomallei was reflected in the higher average Eucledian distances between the mass spectra and a broader range of identification score values obtained with commercial software for the identification of microorganisms. The type strain of B. pseudomallei (ATCC 23343) was isolated decades ago and is outstanding in the spectrum-based dendrograms probably due to massive methylations as indicated by two intensive series of mass increments of 14 Da specifically and reproducibly found in the spectra of this strain.

CONCLUSIONS

Handling of pathogens under BSL 3 conditions is dangerous and cumbersome but can be minimized by inactivation of bacteria with ethanol, subsequent protein extraction under BSL 1 conditions and MALDI-TOF MS analysis being faster than nucleic amplification methods. Our spectra demonstrated a higher homogeneity in B. mallei than in B. pseudomallei isolates. As expected for closely related species, the identification process with MALDI Biotyper software (Bruker Daltonik GmbH, Bremen, Germany) requires the careful selection of spectra from reference strains. When a dedicated reference set is used and spectra of high quality are acquired, it is possible to distinguish both species unambiguously. The need for a careful curation of reference spectra databases is stressed.

Authors+Show Affiliations

Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Institute of Molecular Biology, Südufer 10, Greifswald-Insel Riems D-17493, Germany.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Evaluation Study
Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

23046611

Citation

Karger, Axel, et al. "Rapid Identification of Burkholderia Mallei and Burkholderia Pseudomallei By Intact Cell Matrix-assisted Laser Desorption/Ionisation Mass Spectrometric Typing." BMC Microbiology, vol. 12, 2012, p. 229.
Karger A, Stock R, Ziller M, et al. Rapid identification of Burkholderia mallei and Burkholderia pseudomallei by intact cell Matrix-assisted Laser Desorption/Ionisation mass spectrometric typing. BMC Microbiol. 2012;12:229.
Karger, A., Stock, R., Ziller, M., Elschner, M. C., Bettin, B., Melzer, F., Maier, T., Kostrzewa, M., Scholz, H. C., Neubauer, H., & Tomaso, H. (2012). Rapid identification of Burkholderia mallei and Burkholderia pseudomallei by intact cell Matrix-assisted Laser Desorption/Ionisation mass spectrometric typing. BMC Microbiology, 12, 229. https://doi.org/10.1186/1471-2180-12-229
Karger A, et al. Rapid Identification of Burkholderia Mallei and Burkholderia Pseudomallei By Intact Cell Matrix-assisted Laser Desorption/Ionisation Mass Spectrometric Typing. BMC Microbiol. 2012 Oct 10;12:229. PubMed PMID: 23046611.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Rapid identification of Burkholderia mallei and Burkholderia pseudomallei by intact cell Matrix-assisted Laser Desorption/Ionisation mass spectrometric typing. AU - Karger,Axel, AU - Stock,Rüdiger, AU - Ziller,Mario, AU - Elschner,Mandy C, AU - Bettin,Barbara, AU - Melzer,Falk, AU - Maier,Thomas, AU - Kostrzewa,Markus, AU - Scholz,Holger C, AU - Neubauer,Heinrich, AU - Tomaso,Herbert, Y1 - 2012/10/10/ PY - 2012/03/22/received PY - 2012/09/25/accepted PY - 2012/10/11/entrez PY - 2012/10/11/pubmed PY - 2013/5/15/medline SP - 229 EP - 229 JF - BMC microbiology JO - BMC Microbiol VL - 12 N2 - BACKGROUND: Burkholderia (B.) pseudomallei and B. mallei are genetically closely related species. B. pseudomallei causes melioidosis in humans and animals, whereas B. mallei is the causative agent of glanders in equines and rarely also in humans. Both agents have been classified by the CDC as priority category B biological agents. Rapid identification is crucial, because both agents are intrinsically resistant to many antibiotics. Matrix-assisted laser desorption/ionisation mass spectrometry (MALDI-TOF MS) has the potential of rapid and reliable identification of pathogens, but is limited by the availability of a database containing validated reference spectra. The aim of this study was to evaluate the use of MALDI-TOF MS for the rapid and reliable identification and differentiation of B. pseudomallei and B. mallei and to build up a reliable reference database for both organisms. RESULTS: A collection of ten B. pseudomallei and seventeen B. mallei strains was used to generate a library of reference spectra. Samples of both species could be identified by MALDI-TOF MS, if a dedicated subset of the reference spectra library was used. In comparison with samples representing B. mallei, higher genetic diversity among B. pseudomallei was reflected in the higher average Eucledian distances between the mass spectra and a broader range of identification score values obtained with commercial software for the identification of microorganisms. The type strain of B. pseudomallei (ATCC 23343) was isolated decades ago and is outstanding in the spectrum-based dendrograms probably due to massive methylations as indicated by two intensive series of mass increments of 14 Da specifically and reproducibly found in the spectra of this strain. CONCLUSIONS: Handling of pathogens under BSL 3 conditions is dangerous and cumbersome but can be minimized by inactivation of bacteria with ethanol, subsequent protein extraction under BSL 1 conditions and MALDI-TOF MS analysis being faster than nucleic amplification methods. Our spectra demonstrated a higher homogeneity in B. mallei than in B. pseudomallei isolates. As expected for closely related species, the identification process with MALDI Biotyper software (Bruker Daltonik GmbH, Bremen, Germany) requires the careful selection of spectra from reference strains. When a dedicated reference set is used and spectra of high quality are acquired, it is possible to distinguish both species unambiguously. The need for a careful curation of reference spectra databases is stressed. SN - 1471-2180 UR - https://www.unboundmedicine.com/medline/citation/23046611/Rapid_identification_of_Burkholderia_mallei_and_Burkholderia_pseudomallei_by_intact_cell_Matrix_assisted_Laser_Desorption/Ionisation_mass_spectrometric_typing_ L2 - https://bmcmicrobiol.biomedcentral.com/articles/10.1186/1471-2180-12-229 DB - PRIME DP - Unbound Medicine ER -