Abstract
Antibiotic 6640 has an in vitro spectrum similar to gentamicin with a potency equal to or twice that of gentamicin, particularly against Pseudomonas. Antibiotic 6640 is more active at an alkaline pH but is little affected by the presence of serum. MBC values are near MIC values. Antibiotic 6640 has up to 5 times the activity of gentamicin in therapeutic and prophylactic antibacterial tests in mice. Serum levels of the two antibiotics are similar in mice, rats and dogs. Results of comparative ataxia tests in cats are reported.
