Interestingly, there are more than 2,600 types
or serotypes of salmonella, most of which
are not pathogenic to humans. Of those 2,600
types, only about a dozen serotypes of salmonella,
including SE, are considered harmful to
humans. This same phenomena (e.g., some
types being pathogenic and some types being
harmless) is true for most types of bacteria,
including E. coli.