All life forms strategize to survive and procreate. Weeds, worms, birds, fungi and bacteria all work to sustain their own lives on this planet. In fact, we humans survive because of the biological games constantly unfolding in our mist.
Propionibacterium acnes, or p acne bacteria, are no different. They want and need to survive. Skin bacteria perform an important function. Bacteria use the secretions of our sweat and sebaceous glands (sebum is the oil that makes our skin look shiny) as nutrients. P acnes that are in balance with your body prevent colonization by more harmful bacteria.
P acne bacteria only encourage acne formations if the production of oil on the face is excessive. This surplus of oil of prompted by hormonal, nutritional, environmental and/or psychological changes in the body. So to prevent acne, you do not what to kill bacteria per se, but keep the amount of bacteria on your skin at an optimal balance. You optimize your oil secretion by understanding and controlling your response to hormonal, nutritional, environmental and/or psychological changes.
If we upset the balance of bacteria in our bodies by taking antibiotics, our resident flora is upset and this enables harmful bacteria (such as Staphylococcus aureus and Acinetobacter baumannii) to colonize our skin. What's more, antibiotics can destroy the balance of intestinal flora and cause constipation.
In short, using antibiotics on bacteria is a battle amongst intelligent parties involving the bacteria, the body, and the human mind. If we fail to appreciate the bacteria as bodily maintenance workers and continue dousing them with antibiotics, the bacteria just become more resistant to our antibiotics. The bacteria are practiced at playing dead as a tactic for survival. Even people who have used the strongest acne drug on the market, Accutane, have witnessed the cunning behavior of bacteria as zits reappear some months after using this course of acne treatment. These people have discovered that bacteria do not die; they silently and strategically multiply. If you do not want your bacteria out of balance, do not provide them an environment conducive to acne.