The most common virus is the common cold, which is actually caused by several different families of viruses. Even though you may experience upper-respiratory symptoms associated with a bacterial infection, most cases of the common cold are not caused by bacteria-which make antibiotics useless against them.
Colon infection is caused when harmful bacteria resides in the colon. Normally, human immune system kills the harmful bacteria but there are some strains of bacteria that grow uninterruptedly even with strong immune system. When such bacteria overgrow in the large intestine, they can cause lot of complication.
Diverticulosis happens when pouches (diverticula ) form in the wall of the colon . If these pouches get inflamed or infected, it is called diverticulitis. Diverticulitis can be very painful. Doctors aren't sure what causes diverticula in the colon (diverticulosis). But they think that a low-fiber diet may play a role. Without fiber to add bulk to the stool, the colon has to work harder than normal to push the stool forward. The pressure from this may cause pouches to form in weak spots along the colon.