Bacterial identification

One way to identify bacterial species is to analyze the extracts of bacteria [28,29]. Several pathogenic bacterial strains, including Bacillus anthracis. Yersinia pestis, and Brucella melitensis, can be distinguished from nonpathogenic species on the basis of characteristic protein ions in the mass range 2400 to 10,000 Da [28]. Various Bacillus species (e.g., anthracis, subtilis, cerus, and thuringiensis) also exhibit distinct mass spectrometry data. The strain-specific biomarkers for six different strains of Helicobacter pylori were obtained with MALDI-MS [29]. 

Improved sample stability can extend the mass range of biomarker detection beyond 10,000 Da [33,34]. For example, a biomarker for H. pylori has been detected at m/z 58,268 and for H. mustelae at m z 49,608 and 57,231 [34]. Similarly, characteristic biomarkers have been observed at m z 10,074 and 25,478 for Campylobacter coli, at m z 10,285 and 12,901 for C. jejuni, and at miz 10,726 and 11,289 for C. fetus [34]. Thus, Campylobacter species could be readily distinguished from Helicobacter species. 

It is also feasible to use profiles of small molecules, such as fatty acids, phospholipids, glycolipids, and peptides, to distinguish among various bacterial species. For example, Francisella tularensis. Brucella melitensis. Yersinia pestis. Bacillus anthracis, and Bacillus cerus species have been discriminated on the basis of their distinct fatty acid profiles [38]. The samples can be ionized 

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Polymerase chain reaction (PCR) is one of the most important techniques for rapid bacterial identification. It consists of repeated cycles of enzymatic reactions in a thermal cycler (PCR machine) that copies DNA strands many times. The DNA amplified in one PCR cycle is used as a template for the next cycle. This results in an exponential increase of the desired target... 

Other pattern recognition strategies have been used for bacterial identification and data interpretation from mass spectra. Bright et al. have recently developed a software product called MUSE, capable of rapidly speciating bacteria based on matrix-assisted laser desorption ionization time-of-flight mass spectra.13 MUSE constructs a spectral database of representative microbial samples by using single point vectors to consolidate spectra of similar (not identical) microbial strains. Sample unknowns are then compared to this database and MUSE determines the best matches for identification purposes. In a... 

We have proposed a multi-subsystem approach to the challenge of rapid bacterial identification. The subsystems involve the following ... 

Jarman, K. H. Cebula, S. T. Saenz, A. J. Peterson, C. E. Valentive, N. B. Kingsley, M. T. Wahl, K. L. An algorithm for automated bacterial identification using matrix-assisted laser desorption/ionization mass spectrometry. Anal. Chem. 2000, 72, 1217-1223. 

An interesting variation on the whole-cell MALDI approach was recently reported in a study aimed more at FTMS than TOF MS, but the results are nevertheless interesting and important to users of both methods for analysis of bacteria 40. Wilkins s group showed both MALDI-TOF and MALDI-FTMS spectra of whole bacteria grown on isotopic media depleted in C13 and N14. Because most bacterial identification protocols involve a culture step prior to analysis, it is possible to manipulate the sample based on control of the growth media. For mass spectral analysis manipulation of the isotope profile... 

DEVELOPMENT OF SPECTRAL PATTERN-MATCHING APPROACHES TO MATRIX-ASSISTED LASER DESORPTION/ IONIZATION TIME-OF-FLIGHT MASS SPECTROMETRY FOR BACTERIAL IDENTIFICATION... 

Vaidyanathan, S. Kell, D. B. Goodacre, R. Flow-injection electrospray ionization mass spectrometry of crude cell extracts for high-throughput bacterial identification. J. Am. Soc. Mass Spectrom. 2002,13,118-128. 

Wang, Z. Dunlop, K. Long, S. R. Li, L. Mass spectrometric methods for generation of protein mass database used for bacterial identification. Anal. Chem. 2002, 74,3174-3182. 

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