Propionibacterium acnes (P.acnes) is the bacteria found in acne. A new study in the Journal of the American Academy of Dermatology has shed some light on how it wreaks its damage.

P. acnes lives in a biofilm, an aggregation of bacterial organisms and sticky extracellular substance, that allows it to stick to the wall of the hair follicle. This sticky substance also causes the skin cells to stick together, limiting their ability to shed. These stuck-together skin cells (keratinocytes) then block the hair follicle, forming a keratin plug and trapping the natural oils (sebum) below the surface. When the pressure from this trapped oil builds up, a pimple is born. The acne bacteria then live happily encased in their protective biofilm, trapped in the follicle.

This is why combination therapy is most effective against acne; if you don’t break up the keratin plug on the skin’s surface, then antibacterial medications cannot penetrate and won’t work.

Proactiv® works by employing an mild acid to break up the plugged pores and an antibacterial to kill the P. acnes. Prescription acne therapy works similarly. I often prescribe a retinoid, like Retin-A, to break-up the keratin plugs and an antibiotic, like benzoyl peroxide or clindamycin, to kill the bacteria.

Unfortunately, even with the appropriate combination therapy, it still takes up to 12 weeks to clear up your acne. On the up side, if you follow this regimen daily, you really will see results.

Burkhart, CG and Burkart, CN. Expanding the microcomedone theory and acne therapeutics: Propionibacterium acnes biofilm produces biological glue that holds corneocytes together to form plug. J Am Acad Dermatol 2007;57:22-4