| a highly toxic broad-spectrum antibiotic mixture of related aminoglycoside substances derived from the actinomycete bacterium Micromonospora purpurea, used in its sulfate form in the treatment of severe Gram-negative infections. |

gentamicin gen·ta·mi·cin or gen·ta·my·cin (jěn'tə-mī'sĭn)
n.
A broad-spectrum antibiotic derived from an actinomycete used in the treatment of various infections.