This is why I am trying to choose my words a bit carefully. It seems that most arrows point to trauma of some type (surgery, needle sticks, fractures, etc) as a precursor to RSD developing. Infection can follow trauma, and certainly that work-ups that we all go through in the attempt to find answers can turn up positives which may or may not be pertinent. Outside of those infections, using the term "infection" can really mean anything and I think sends a message which can panic people and lend less credence to those who are trying to prove a causing event (WC, med mal) to be compensated for their medical bills. If we REALLY think it's infection of any sort, the virulence itself would make RSD much more well-recognized than it is.
Just my opinion