Nucleotide genomic signal (NGS) analysis reveals surprising regularities in the distribution of nucleotides and pairs of nucleotides, in both prokaryotes and eukaryotes. These features of genomic sequences would be difficult to identify by using only standard symbolic sequence analysis. NGS analysis is also efficient in the analysis of local structural features, in particular for the study of pathogen variability. This is important for the molecular level detection of mutations that induce drug resistance, providing the clinician with information needed for fast and accurate decisions.