IMO..I dont think is a bacterial infection, although ive seen on numerous articles that it is highly contagious..which i think its a big lie... I really think its stress related..and water conditions apply to that stress..also wether the coral likes high or low flow..)...So, I dont think either STN and/or RTN are infections. Ive seen many cases where the STNing abruptly stops and the coral begins to rejuvenate. I have a frag of a. samoensis that did this a while back and now is a beautiful baby blue color. The STNing stopped and, although the tissue never grew back on part of the base, the rest of the coral kept growing as it should be.