Discovery and Properties - Discovered in 1949 by microbiologist Selman Waksman and student Hubert Lechevalier at Rutgers University - Produced naturally by the bacterium Streptomyces fradiae - Synthesis requires specific nutrient conditions in either stationary or submerged aerobic conditions - Isolated and purified from the bacterium - Neomycin was discovered over 50 years ago - Neomycin is an antibiotic active against streptomycin-resistant bacteria - It has been used in pharmaceutical manufacturing - Neomycin can induce hypersensitivity reactions in some individuals

Medical Uses - Typically applied topically, such as in Neosporin - Can be administered orally, often combined with other antibiotics - Used as a preventive measure for hepatic encephalopathy and hypercholesterolemia - Effective against streptomycin-resistant bacteria and Mycobacterium tuberculosis - Used to treat small intestinal bacterial overgrowth

Spectrum - Excellent activity against gram-negative bacteria - Partially effective against gram-positive bacteria - Relatively toxic to humans, with allergic reactions as a common adverse reaction - Physicians sometimes recommend antibiotic ointments without neomycin - Minimum inhibitory concentration (MIC) susceptibility data for medically significant gram-negative bacteria

Side Effects - Fifth-most-prevalent allergen in patch test results - Known GABA antagonist, responsible for seizures and psychosis - Ototoxic, causing tinnitus, hearing loss, and vestibular problems - Affects the cochlea in the inner ear - Patients with existing tinnitus or hearing loss should consult a healthcare practitioner

Molecular Biology - Antibacterial activity through binding to the 30S subunit of the prokaryotic ribosome - High binding affinity for phosphatidylinositol 4,5-bisphosphate (PIP2) - Resistance conferred by kanamycin kinase genes - Neomycin-resistant bacteria research ongoing - Biosynthetic pathway and composition of neomycin