DISCRIMINATION BETWEEN METHICILLIN-RESISTANT AND METHICILLIN-SUSCEPTIBLE STAPHYLOCOCCUS-AUREUS USING PYROLYSIS MASS-SPECTROMETRY AND ARTIFICIAL NEURAL NETWORKS

Curie-point pyrolysis mass spectra were obtained from 15 methicillin-r esistant and 22 methicillin-susceptible Staphylococcus aureus strains, Cluster analysis showed that the major source of variation between th e pyrolysis mass spectra resulted from the phage group of the bacteria , not their resistance or susceptibility to methicillin. By contrast, artificial neural networks could be trained to recognize those aspects of the pyrolysis mass spectra that differentiated methicillin-resista nt from methicillin-sensitive strains. The trained neural network coul d then use pyrolysis mass spectral data to assess whether an unknown s train was resistant to methicillin. These results give the first demon stration that the combination of pyrolysis mass spectrometry with neur al networks can provide a very rapid and accurate antibiotic susceptib ility testing technique.