How can I tell if MRSA is gone? It's not sore, but it is quite red around drain incision and pulses off and on (not painful) can't tell if it's warm

Question unclear. You may not be able to tell if the organism is "gone". You may have to wait until the area has healed up to know if the infection has resolved. It is not clear whether the treatment was just incision and drainage or involved antibiotics. This is a complex subject and need more information to answer your question accurately.