Are e.coli infections severe in the elderly?

Can be: The elderly, due to diminished immune function, can react more severely to all infections, including e. Coli infections. This is also true with colds, flu's, influenza, etc. When the elderly (or very young) get sick, be more diligent in getting them to the doctor.

E.Coli: The severity of an infection is not due to the bacteria per se, it depended upon how long has been present, how is the immune system of the patient, the location of the infection etc? Any infection could be catastrophic if not treated on time. Gram negative infections like by e. Coli are commonly coming from the urinary or intestinal tract or contaminated food/ drink.