Gentamicin belongs to the class of antibiotics called Aminoglycosides.Most of the Aminoglycosides are isolated from Streptomyces or micromonospora sp.Aminoglycosides are highly water soluble due to their polar groups (hydroxyl and amine groups) and are very well distributed through the body fluids.They are very poorly distributed to the bones, CNS, and fatty tissues due to their polar groups and have very poor oral absorption.They have a broad spectrum of action against both gram positive and gram negative bacteria, but are better against gram negative bacteria due to their polar groups which allow them to cross into the bacterial cell well through porins.