THE IN VIVO ACTIVITY OF NEOMYCIN

Abstract

Neomycin, in concns. of 2000 to 5000 U., injd. subcut. into mice weighing 15-20 g., was well tolerated. These concns. were at least 20-50 times the protective concn. of this antibiotic. Neomycin did not exert any serious toxic effects when instilled into the rabbit''s eye, a toxicity test characteristic for strepto-thricin. Neomycin was (1) more effective than streptomycin in suppressing Staphylococcus aureus infection of both streptomycin-resistant and streptomycin-sensitive strains of mice; (2) more effective than streptomycin by oral admn. in protecting mice infected intraperit. with S. aureus; (3) more effective than streptomycin in suppressing infections caused in mice and in chick embryos by Salmonella schottmiilleri, including both streptomycin-resistant and streptomycin-sensitive strains; (4) far more effective than streptomycin in suppressing infection of chick embryos with S. pullorum; (5) highly bactericidal upon S. pullorum as measured by injecting embryos with mixtures of 24-hr. - old cultures of the organism and neomycin; and (6) highly effective, much more so than streptomycin, on typhoid bacteria injd. into mice.