04 Feb

Intestinal Pathogens

The intestinal pathogens of the most medical importance are the salmonella and shigella and pathogenic strains of Escherichia coli.  They cause gastroenteritis, bacillary dysentery, foodborne illness, and diarrhea in humans.  Right now the taxonomic differences of salmonella are being revised.  In the first edition of Bergey’s Manual of Systematic Bacteriology, Salmonella is divided into two species, S. choleraesuis and S. bongori.  S. choleraesuis is divided further into six subspecies based on different taxonomic and nucleic acid differences.  If you base the classification system on antigenic differences the Salmonella can be divided into 2500 different serovars or serotypes, most of them belong to S. choleraesuis.  A serovar is a strain that has similar biochemical characteristics but differ in their antigenic composition.  It is important to identify serovars in order to determine the identity of the pathogen causing outbreaks of Salmonella infections.