Can Restylane Injections Cause Infections?

Restylane is prepared from a fermentation process using a bacteria Streptococcus equi. This particular strain was chosen because it produces copious amounts of hyaluronic acid. It is then cross linked using a small amount of BDDE (butanediol diglycidyl ester). Since Restylane uses esterification in its process, it tends to be a bit "stiffer" than its Juvederm cousin. Also, the rare allergic reaction stems from a tiny remnant of BDDE which might be left over.
There is no danger of a bacterial infection since Q Med, the Swedish company that produces Restylane, uses the hyaluronic acid produced by the bacteria and not the bacteria itself.
Certainly you can get an infection. The skin should be properly cleansed and sterile technique employed rigorously. You certainly could get an infection from the dental block if this is performed. ( I received one when I was undergoing dental work last year myself.).
Also, as Dr. Janjua mentioned, you can develop an outbreak of herpes labialis since we are working around the mouth. This hopefully would be recognized early and treated appropriately.

Restylane is derived, in the lab, from the fermentation of equine streptococcus, which is a form of beta-hemolytic strep. The important point is that the bacteria are used to create the chemical that is then processed into Restylane. There are no streptococci in Restylane, just like there is not Botulinum bacteria in Botox and no bread mold in penicillin.
Any filler can result in an infection. However that would most likely be the result of bacteria on your skin or in your system, not the bacteria used to create the product. Fortunately, infections following hyalauronic acid fillers are very rare.
Hope this is helpful.