aminoglycoside

Aminoglycosides are a powerful class of antibiotics, including gentamicin, tobramycin and amikacin, reserved mainly for serious Gram-negative infections. They are like a sledgehammer in the toolbox: very effective against the right target, but heavy-handed enough that they must be used carefully and usually only when lighter tools will not do.

They kill bacteria by binding irreversibly to the 30S subunit of the bacterial ribosome, causing it to misread the genetic code and churn out faulty, non-functional proteins. This corruption is lethal, making aminoglycosides bactericidal, and their effect depends on reaching a high peak concentration. They also show a marked post-antibiotic effect and so are commonly given as a single large daily dose rather than divided.

The catch is toxicity. Aminoglycosides accumulate in the kidney and inner ear, where they can cause nephrotoxicity and irreversible damage to hearing and balance. Because the gap between an effective and a harmful level is narrow, blood concentrations are often monitored, and they are used in short courses or alongside other agents whenever possible. They also work poorly in low-oxygen environments, since their uptake into bacteria is oxygen-dependent.