and yet copper and it's alloys (ie. brass, zinc, ) have deleterious effects on bacteria.
below is one of many fine articles on the antimicrobial efficacy of copper and brass compounds on "Listeria Monocytogenes" -- a food born pathogen, but I thought it just might ellicit a corroborating affirmative from the medical professionals that Brass Doorknobs and BRASS Instruments already have an antimicrobial factor permanently or inherently built in to their design based upon the METAL they were/are made of!!!
((ps. not arguing that people shouldn't clean their instruments --just saying they should not become HYPER-PARANOID of the DANGERS of playing an instrument in which the bodily fluids eminating from them are being put into the instrument)) ---