FIG 4.

Overlaid, preprocessed spectra of 31 A. baumannii clinical isolates using MS data, preprocessed by taking the third-order derivative with a filter width of 15, followed by mean centering (A), and Raman spectroscopic data preprocessed by truncation of data between the 600 and 1,800 cm⁻¹ Raman spectral region, baseline removal using a sixth-order polynomial, and normalization to the 1,445 cm⁻¹ Raman spectral band (B). Spectra are colored according to their resulting strain type (based on PFGE type indicated by classes 1, 2, 3, and 4).