Rapid identification of mycobacterial whole cells in solid and liquid culture media by matrix-assisted laser desorption ionization-time of flight mass spectrometry

J Clin Microbiol. 2010 Dec;48(12):4481-6. doi: 10.1128/JCM.01397-10. Epub 2010 Oct 13.

Abstract

Mycobacterial identification is based on several methods: conventional biochemical tests that require several weeks for accurate identification, and molecular tools that are now routinely used. However, these techniques are expensive and time-consuming. In this study, an alternative method was developed using matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). This approach allows a characteristic mass spectral fingerprint to be obtained from whole inactivated mycobacterial cells. We engineered a strategy based on specific profiles in order to identify the most clinically relevant species of mycobacteria. To validate the mycobacterial database, a total of 311 strains belonging to 31 distinct species and 4 species complexes grown in Löwenstein-Jensen (LJ) and liquid (mycobacterium growth indicator tube [MGIT]) media were analyzed. No extraction step was required. Correct identifications were obtained for 97% of strains from LJ and 77% from MGIT media. No misidentification was noted. Our results, based on a very simple protocol, suggest that this system may represent a serious alternative for clinical laboratories to identify mycobacterial species.

Publication types

  • Research Support, Non-U.S. Gov't
  • Validation Study

MeSH terms

  • Bacteriological Techniques / methods*
  • Humans
  • Mycobacterium / chemistry*
  • Mycobacterium / classification*
  • Mycobacterium / growth & development
  • Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / methods*
  • Tuberculosis / diagnosis*
  • Tuberculosis / microbiology*