Journal of Analytical & Bioanalytical Techniques
Open Access

Research Article

Changes in the Matrix Markedly Enhance the Resolution and Accurate Identification of Human Pathogens by MALDI-TOF MS

Renata A. Culak, Min Fang, Shurene Bishop Simon, Itaru Dekio, Lakshani K. Rajakaruna and Haroun N. Shah^*

Department for Bioanalysis and Horizon Technologies, Health Protection Agency Microbiology Services, London NW9 5EQ

*Corresponding Author:

Haroun N. Shah
Head, Molecular Identification Services Unit
Department for Bioanalysis and Horizon Technologies
Health Protection Agency Microbiology Services, Colindale
61 Colindale Avenue, London NW9 5EQ
Tel: 02083276749
E-mail: Haroun.shah@hpa.org.uk

Received date: March 29, 2012; Accepted date: May 11, 2012; Published date: May 16, 2012

Citation: Culak RA, Fang M, Simon SB, Dekio I, Rajakaruna LK, et al. (2012) Changes in the Matrix Markedly Enhance the Resolution and Accurate Identification of Human Pathogens by MALDI-TOF MS. J Anal Bioanal Tech S2:002. doi: 10.4172/2155-9872.S2-002

Copyright: © 2012 Culak RA, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

The mass spectral profiles of three major/emerging Gram positive pathogens belonging to the genera Clostridium, Listeria and Propionibacterium were investigated using four MALDI-TOF (Matrix-Assisted Laser Desorption/ Ionization- Time of Flight) Mass Spectrometers from Waters, Shimadzu, Bruker and Ciphergen Biosystems. These instruments have been extensively used for developing a diagnostic platform for high throughput, low cost, near sample-free preparation for microbial identification. The results demonstrate the marked effect of spectral quality obtained by altering the matrix and the added value of simple preparative extraction procedures. While microbial spectral data are generally collected in the mass range 2 to 20 kDa for diagnostic signatures, most of the significant mass ions are <10 kDa. The change from the traditional use of CMBT (5-chloro-2-mercaptobenzothiazole) to DHB (2-(2, 5-DiHydroxyBenzoic acid) enabled successful identification of C. difficile whereas the substitution of CHCA (alpha-cyano-4-hydroxycinnamic acid) for DHB (2,5-dihydroxybenzoic acid) improved the identification of Listeria species. By contrast, the use of SELDI-TOF-MS (Surface Enhanced Laser Desorption/Ionization- Time of Flight- Mass Spectrometry), which employs affinity pre-capture of specific classes of molecules and analysed using sinapinic acid, showed a fivefold extension of the mass range of analytes, extending the potential for biomarker discovery and higher resolution strain typing of P. acnes.