Bacterial Pathogens

Bacterial pathogens are divided into: Gram-positive and Gram-negative, based upon their staining attributes with Gram's stain. This differentiation was a useful tool, but it provides little taxonomic resolution in this age of sophisticated molecular diagnostics and bacterial systematics. Some bacterial pathogens have very little genomic variation valuable for sub typing and strain identification. The most common cause for this lack of variation is that these organisms have only recently “emerged’’ as pathogens from a closely related bacterium in the “recent’’ past. The close bacterial relative may or may not have been a pathogen, but some genetic change presumably occurred (genes could have been gained or lost) that changed its virulence properties and converted it into a highly effective human pathogen. This situation is fairly common for bacterial pathogens encountered in biocrimes, and exists in all pathogens that rapidly expand during an epidemic. Bacterial pathogens —such as, Bacillus anthracis, Yersinia pestis, Franciscella tularensis, Brucella, melioidosis and glanders are described in the chapter. When the highest sub typing resolution is required for the most precise identification of bacterial isolates, the most diverse and mutable genomic loci are used. For example, highly mutable genomic regions are found in the Variable Number Tandem Repeat (VNTR) loci. Many different bacterial pathogens are employed in s. It is difficult to predict which pathogen will be used in the future, although availability, ease of handling, ease of weaponization, and potential impact (death or terror) are factors that might narrow the options.