TL;DW:
Due to various molecular configurations (aka polymorphs), currently known medicines when contaminated with a catalyst seed molecule/particle can become irreversibly unreproducible via chained-contaminations.
- the contamination can cause the existing configurations to become more stable in a negative fashion where the medicine/compounds no longer work they way we expect them to.
This system of contamination and reproduction acts in similar fashion to viral infections.
Current Solutions:
- better clean room procedures for all steps of medicine manufacturing.
- pour more money into medicine polymorph research.
Ah, it's tin pest? (I'm watching the video right now.)
Same "basic" idea, of a vicious cycle. Except you don't need reaction with an external substance, like oxygen; the catalyst for tin pest is even more tin. (That means the blob over the cube of metal is likely a piece of grey tin. You could use germanium instead but eh, it's more expensive.)