the bacteria thrive on the oily skin, the oily skin is some acne sufferers
response to a lack of vitamin D... probably trying to make the
precursor to vitamin D in the
skin so it can be turned to vitamin D in the liver.
But what happens when you have sufficient levels of vitamin D??? Well, your body no longer needs to make
the precursor in the skin.
It also makes sense... think about it... acne is always on the face, neck, back, shoulders, or chest.