Discrimination of Burkholderia Species, Brucella Biovars, Francisella tularensis and Other Taxa at the Subspecies Level by MALDI-TOF Mass Spectrometry
This chapter discusses and describes successful approaches for the identification of closely related organisms by refined statistical analysis of their matrix-assisted laser desorption/ionization-time-of-flight (MALDI-TOF) mass spectra. The emphasis is on the discrimination of select organisms such as subspecies of Francisella tularensis, different species of the Brucella genus, Burkholderia mallei and Burkholderia pseudomallei and Shiga-toxin-producing serotypes of Escherichia coli. The success of any discrimination procedure always depend on the specific conditions like the presence of prominent group-specific features, the number of isolates that is available, the number of groups that are to be discriminated in parallel, the quality of the spectra, and more factors. For the discrimination of F. tularensis subspecies, polymerase chain reaction (PCR)-based tests are available that target genetic markers like the variable number of tandem repeats (Johansson et al., 2004) or single-nucleotide polymorphisms.