Lincosamides are naturally occurring antibiotics that are effective against a variety of different types of bacterial infections. However, they possess a sulfur atom at a key location that makes them vulnerable to rapid metabolism in both animals and humans, reducing their usefulness in the clinic. Efforts to make a synthetic version without the sulfur atom have failed to generate a new antibiotic that is both long-lived and effective, and all the synthetic versions that do work still have the key sulfur.