Amikacin is an injectable bactericidal antibiotic meaning that it kills bacteria that are susceptible to it and stops it from growing. Most effective against gram-negative bacteria, amikacin is not effective against fungus, viruses, or anaerobic bacteria (bacteria that doesn’t need oxygen). It’s in the same family as gentamicin, but amikacin is less toxic to the kidneys and some bacteria are resistant to gentamicin where they are still susceptible to amikacin.