In vivo potentiation of the action of polymyxin B by Gramicidin dubos

Abstract

Gramicidin potentiated the efficacy of polymyxin B by 2-to 3-fold in curing Aerobacter aerogenes infections and 2-fold in Salmonella typhi infections, when both the antibiotics are administered either immediately after infection or 4 hr thereafter. Enhanced therapeutic effects are obtained to an extent of 7-fold and 9-fold in case of A. aerogenes and S. typhi infections, respectively, when the animals are protected by prior administration of gramicidin, with polymyxin B administration at the time of infection. The combined action of these antibiotics in vivo is compared with the known in vitro effectiveness.