Abstract
The therapeutic potencies of colistin methanesulfonate (CLM) was assessed quantitatively in acute infection of mice with clinically isolated strains of Escherichia coli and Pseudomonas czeruginosa, and effect of different routes of administration was compared. There was no detectable difference in the therapeutic effect of CLM when intramuscular (im) or intravenous (iv) administration was initiated one hour after the infection. On the other hand, a significant difference in ED50 given by im and iv administrations was observed, indicating the superiority of iv administration, when the treatment started 4-6 hours after the infection. No difference in the therapeutic effect of polymyxin B (PMB) and tetracycline (TC) administered via either im or iv route was found even in the delayed administration. In contrast to PMB and TC, lower toxicity of CLM was determined when it was administered iv rather than im.
