Im not a big fan of cutting. Usually the plant just gets horribly ugly or eventualy trows the heavily infected parts of. I have a cactus which is infected with dryrot bacteria an spores for allready 5 years!! The plant looks like its been beaten by aliens but every year it grows and blooms with pride
Adjusting conditions from ideal to near perfect can most of the time help plants defeat the pathogens on their own. Using all kinds of antbiotic chemicals may weaken the plant helping getting a step closer to its end. Dryness of air and wet dry types of wattering really helps well for me.
I do not have experience with antipathogenic chemicals so I have no clue if they help and how to use them.
good luck both