Comment by alphazard

It's specifically Quinolones which can harm mitochondria. There's no ongoing concern for something like Penicillin. We also shouldn't expect there to be mitochondrial risk from a fungi-derived chemical like Penicillin, since fungi also have mitochondria.

In general you want the weakest and most targeted antibiotic for the job. Most people will never need a Quinolone, and you should be skeptical whenever sophisticated antibiotics are prescribed. Why not Penicillin? should have an answer involving the name of a bacteria, not the doctor's personal preference, or a relationship with a company.

https://en.wikipedia.org/wiki/Quinolone_antibiotic#Cellular_...