Bacteria are everywhere!  (Pages 324-333)

Note: not all bacteria cause disease.  Some are helpful.  We use them to make yogurt, to give wine its subtle flavors, to make hard sausages and pickles. 

Some estimates state that humans have as many bacteria living in them as they have human cells (you are 50% bacteria).  These bacteria reside on the skin and in your gut.  They do not live in your blood.  We also need them for proper digestion and to help defend us against disease causing bacteria.  For example: one kind of Staphylococcus (epidermis) helps protect us against one of our most nasty pathogens Staphylococcus aureus.  Some researchers suggest that bacteria in our gut may produce many vitamins, may compete with dangerous bacteria for living space, and may breakdown some environmental poisons.