Successful treatment using gentamicin liposomes of Salmonella dublin infections in mice

Gentamicin entrapped within stable multilamellar liposomes was used to treat mice after they were infected per os with Salmonella dublin. Of 10 mice, 8 survived after a single intravenous (i.v.) injection of 2 mg of gentamicin liposomes per kg compared with 0 of 10 treated with the same amount of free gentamicin. All mice survived after treatment with a single i.v. or intraperitoneal injection of 20 mg of gentamicin liposomes per kg, whereas that dose of free drug was completely ineffective and caused neuromuscular paralysis when injected rapidly i.v. In mice treated with gentamicin liposomes, there was a steady decrease in the number of salmonellae in spleens for 2 weeks after treatment. High concentrations of gentamicin were present in the spleen for at least 10 days after treatment. Although gentamicin was not detected in the mesenteric lymph nodes of mice treated with gentamicin liposomes, bacterial counts in the nodes also decreased over time. Small numbers of bacteria remained viable in the mesenteric lymph nodes and Peyer's patches but not in the spleens of mice treated with 20 to 80 mg/kg. Mice treated with doses of gentamicin liposomes as high as 80 mg/kg showed only a transient increase in blood urea nitrogen and no rise in serum creatinine. These results confirm that gentamicin in liposomes is less toxic in mice than is free gentamicin and is extremely effective therapy for disseminated Salmonella infections in mice.