Autoclaving is the preferred method when sharing medical instruments between different people. Boiling and alcohol would be a second choice. If she is only using the needles on herself and not sharing then she should use whatever precautions she uses with fresh needles. The major infective agents are what the needles are exposed while in use. Perhaps squirt alcohol through the needles to remove any debris picked up while inserting and then boil for 5 minutes or so. Re-sharpening can be tough...but maybe she prefers them a little dull!