After a brief outside ride I will re-use a chamois, and after “real” rides I will sometimes conserve some energy & wash with either handwashing detergent or soap before finally tossing them into the laundry after a second and even third ride (can’t take five pairs along on a week’s training camp, and have no washing machine there)

Even as a microbiologist I don't get all worked up about MRSA; however, the amount of perspiration in a spin class justifies washing shorts. But even then a quick rinse in soapy water might be ok for another go.

My laundry machine has a sportswear cycle that takes half as long as a regular cycle...