Aminoglycoside is a medicinal and bacteriologic category of traditional Gram-negative antibacterial therapeutic agents that inhibit protein synthesis and contain as a portion of the molecule an amino-modified glycoside (sugar); the term can also refer more generally to any organic molecule that contains aminosugar substructures. Aminoglycoside antibiotics display bactericidal activity against gram-negative aerobes and some anaerobic bacilli where resistance has not yet arisen, but generally not against Gram-positive and anaerobic Gram-negative bacteria. They include the first-in-class aminoglycoside antibiotic streptomycin (images at right) derived from Streptomyces griseus, the earliest modern agent used against tuberculosis, and an example that lacks the common 2-deoxystreptamine moiety (image right, below) present in many other class members. Other examples include the deoxystreptamine-containing agents kanamycin, tobramycin, gentamicin, and neomycin (see below).