It is widely suspected that the anaerobic bacterial species Propionibacterium acnes ( P. acnes ) contributes to the development of acne, but its exact role is not well understood.  There are specific sub-strains of P. acnes associated with normal skin, and moderate or severe inflammatory acne.  It is unclear whether these undesirable strains evolve on-site or are acquired, or possibly both depending on the person. These strains have the capability of changing, perpetuating, or adapting to the abnormal cycle of inflammation, oil production, and inadequate sloughing of dead skin cells from acne pores. Infection with the parasitic mite Demodex is associated with the development of acne.   It is unclear whether eradication of the mite improves acne. 
Dermal fillers are a neat way to treat acne scars. They work by injecting one of many different sorts of filler into a scar. This basically ‘plumps up’ the area bringing it in line with the rest of your unscarred skin. This can significantly reduce the visibility of your scar and even disguise it completely in some cases. Of course, this technique only works for depressed scars such as ice pick and boxcar scars. Raised, hypertrophic, keloid scars are definitely not suitable for the treatment and moderate-to-severe acne scarring will almost certainly not be either. Dermal fillers are quick and easy to insert and have little-to-no recovery time. The biggest downside is that they are not permanent as your body breaks down the injected fillers over time. You will need to have the treatment regularly to maintain the effect. This can become seriously expensive over a lifetime.