Protective effect of liposomal gentamicin against systemic acute murine brucellosis.

Liposomes of the stable multilamellar type, which previously demonstrated great efficiency in antibiotic transport [Vitas et al: Antimicrob Agents Chemother 1996;40:146-151] were used in this study as carriers of gentamicin for treatment of mice lethally infected with Brucella abortus. Treatment with gentamicin in positively charged liposomes produced a protective effect when it was administered 1 day after lethal challenge (70% of protection). On the other hand, the use of free gentamicin or in liposomes with a negative net charge did not produce a protective effect. Moreover, the results reported here also indicated that cationic liposomes themselves had a therapeutic effect on the course of the infection (up to 50% of protection). In conclusion, we observed that cationic liposomal encapsulation of gentamicin resulted in an enhancement of the therapeutic activity of free gentamicin in this mouse model of acute infection.