Today, aminoglycosides have largely replaced streptomycin for TB, just as next-generation sulfonamides and manmade flouroquinolones, are taking on urinary tract infections. Selectively targeted for infections and their sites, these treatments have greater potency than their antimicrobial ancestors, allowing for tailored dosages with fewer side effects.

If history repeats itself, however, these medications won't be any more effective than previous ones over the long haul. Since Fleming's discovery, bacterial resistance to existing drugs has driven antimicrobial research and development, making smart prescribing a continual challenge.