Kanamycin

Kanamycin is an aminoglycoside antibiotic produced by the bacterium Streptomyces kanamyceticus. It inhibits bacterial protein synthesis by binding irreversibly to the 30S ribosomal subunit, causing misreading of mRNA and blocking initiation, which leads to bactericidal effects against susceptible organisms.

The antibiotic has good activity against many Gram-negative bacteria, including Enterobacteriaceae and Pseudomonas species, with variable activity against Gram-positive bacteria. It is not active against most anaerobes. Because uptake of aminoglycosides requires oxygen, anaerobic bacteria are inherently resistant.

Administration and use: Kanamycin is poorly absorbed from the gastrointestinal tract, so systemic infections are treated with parenteral administration (intramuscular or intravenous). It is not suitable for treating intestinal infections when given orally. In some settings, topical or ophthalmic formulations are used. Historically used for a range of severe infections, its current role is more limited and it is often reserved as a second-line injectable for certain multidrug-resistant infections and as part of regimens for drug-resistant tuberculosis, typically in combination with other agents.

Adverse effects and safety: Major toxicities include nephrotoxicity and ototoxicity (cochlear and vestibular), which can be dose- and duration-dependent. Neuromuscular blockade is a potential, though less common, risk, especially with concurrent neuromuscular agents or in susceptible patients. Monitoring of renal function and drug levels is advised when used. The drug is generally avoided in pregnancy unless benefits outweigh risks.

Resistance: Bacteria may develop resistance through aminoglycoside-modifying enzymes, methylation of the ribosomal target, or reduced uptake, which can limit efficacy and guide careful use alongside susceptibility testing.