Netilmicin: new aminoglycoside effective against bacterial endophthalmitis.

Bacterial endophthalmitis is difficult to treat because antibiotics administered systemically, subconjuctivally or topically cannot be delivered in bactericidal amounts to the infected tissues. Netilmicin, a new aminoglycoside, is active against Pseudomonas aeruginosa, Staphylococcus and most Enterobacteriaceae, including Escherichia coll, Klebsiella and Enterobacter, that have been resistant to other aminoglycosides. In rabbits an intravitreal injection of 250 mu g/0.1 ml rapidly provided a bactericidal concentration (greater than 10 mu g/ml) in the vitreous, and this level was maintained for 100 hours. This dose was not toxic to ocular tissues, unlike higher doses (1000 to 2000 mu g). Intravenous, subconjunctival and topical administration yielded only low concentrations of the drug in the vitreous, although subconjunctival injection yield significant concentrations in the aqueous for 4 hours. Experimentally induced Staphylococcus aureus endophthalmitis was quickly eradicated by a single intravitreal dose of netilmicin without detectable sequelae in 9 to 10 eyes studied. A solution of netilmicin infused during vitrectomy and lensectomy prevented infection.