We typically think of plasma as being extremely hot gas. Wikipedia defines cold plasma as nonthermal plasma which is not in thermal equilibrium. While not a precise term, cold plasma can mean the plasma discharge of a much hotter plasma. In order for plasma to exist, ionization is necessary. There must be free electrons.
A blast of cold plasma kills drug-resistant bacteria explains that high energy and temperatures are required to produce plasma - like the sun or lightning. Recall there must be ionization to create a plasma. The trick seems to be to ionize only a small portion of the molecules and then those molecules distribute energy to the other particles in the mixture to produce room temperature plasma.
The plasma seems to be very effective against bacteria, even the dreaded MRSA (or superbug) bacteria. A zap of cold plasma reduces harmful bacteria on raw chicken in Drexel study explains that food processing scientists are excited about the possibilities.
Mmm. I could not find how the plasma is so effective against bacteria. I'm guessing it is because the ionization disturbs the cell walls of the bacteria. But ionization can also produce DNA damage or mutation. I will be watching for more details on cold plasma.