Gentamicin is an unusual antiobiotic with two properties that make it particularly useful in plant cell culture: it is autoclavable so is added to media before autoclaving/sterilization, and it is active against mycoplasmas as well as gram positive and gram negative bacteria. Over the last week, I too have been getting it. I discovered this way other unusual properties: while nearly any other drug is metabolized in the body, gentamicin is excreted unchanged. There is also much more than the usual fuss in prescribing it: careful does correlation of ‘lean body weight’ against dose (7mg/kg up to 640mg max daily) , and blood testing after the first dose to check the excretion rate: it will bind to many molecules so travels slowly out of the system. It is given intravenously, diluted in c. 100ml of 0.9% saline, as it is not absorbed orally, so is a drug restricted to hospitals.