Since 1897, when the renowned French dermatologist Raymond Sabouraud first noted that material from acne lesions contained bacteria, it has been assumed that killing that bacteria would clear acne. What M. Sabouraud did not realize is that all pores, whether afflicted with acne or clear, contain those same bacteria.
Bacteria does not cause acne. The excess shedding of skin cells within the pores causes acne. Bacteria does play a part in the inflammation process, but oral