Hygromycin A (also known as totomycin) is a modified cinnamic acid flanked by a furanose sugar and aminocyclitol (not to be confused with hygromycin B, belonging to an unrelated class of antibiotics, aminoglycosides).

Hygromycin A was discovered in a soil sample from a forest near Indianapolis, Indiana in 1953 by Waksman and Henrici.

[citation needed] Little further research was performed on totomycin for decades afterwards due to its weak activity against most bacteria, and as of 2021 its safety or efficacy in humans have not been assessed in any preclinical or clinical trials, although some initial results in mice were promising.

[2][3] It was thought that the strongest antibiotic activity of totomycin was against Staphylococcus haemolyticus, in which growth was inhibited by concentrations of 2 μg/mL.

Bait laced with hygromycin A could be used to eliminate Lyme disease in the wild.