A liquid antimicrobial composition is provided for use in the disinfection of the skin of a human or an animal, in particular where disinfection of a drug resistant organism is required. The composition comprises a cationic, cell membrane-disrupting biocide and a cationic dendrimer capable of inhibiting an efflux pump mechanism of said cell membrane. The cationic, cell membrane-disrupting biocide is preferably any or a combination of chlorhexidine, a polymeric biguanide, octenidine dihydrochloride and a quaternary ammonium compound. The dendrimer is provided to bind and disrupt the cell membranes of microorganisms in order to inhibit or destroy the cell's efflux pump mechanism thereby preventing microorganism strains resistant to the cationic membrane-disrupting biocide from becoming prevalent, particularly if the biocide comprises chlorhexidine. The dendrimer is preferably a G-o to G-3 dendrimer comprising any or a combination of quaternary ammonium functionalised poly(propylene imine), polylysine, dendrimers with surface groups based on a sugar and polyamide amine (PAMAM) dendrimers. The composition is preferably in the form of an aqueous or aqueous alcohol solution, dispersion or emulsion that may have been adsorbed by a wipe.L'invention concerne une composition antimicrobienne liquide à utiliser pour la désinfection de la peau d'un humain ou d'un animal, en particulier lorsque la désinfection d'un organisme résistant aux médicaments est nécessaire. La composition comprend un biocide cationique perturbant la membrane cellulaire et un dendrimère cationique capable d'inhiber un mécanisme de pompe d'efflux de ladite membrane cellulaire. Le biocide cationique perturbant la membrane cellulaire est de préférence un élément quelconque ou une combinaison d'éléments du groupe comprenant la chlorhexidine, un biguanide polymérique, le dihydrochlorure d'octénidine et un composé d'ammonium quaternaire. Le dendrimère est présent pour se lier et perturber les membranes cellulai
