The action of trimethoprim and rifampicin in combination against Gram-negative rods resistant to gentamicin

Abstract

The combined action of trimethoprim and rifampicin was measured against 61 strains of Gram-negative rods resistant to gentamicin. No antagonism was observed with this combination and it was synergistic against 26strains(43%). ‘Useful synergy’, judged by readily obtainable serum levels, was only obtained against 2 strains but judged by attainable urine levels, useful synergistic action was found against 24 strains. Useful synergy at urinary levels was found in 5 of 6 multiple resistant flavobacteria.