The invention provides a method of overcoming resistance to at least one antibiotic in a multidrug resistant bacterium, said method comprising contacting said bacterium with an alginate oligomer together with the antibiotic. The multidrug resistant bacterium may be on an animate or inanimate surface and both medical and non-medical uses and methods are provided. In one aspect the invention provides an alginate oligomer for use together with at least one antibiotic in treating a subject infected, suspected to be infected, or at risk of infection, with a multidrug resistant bacterium to overcome resistance to the antibiotic in said multidrug resistant bacterium. In another aspect the method can be used to combat contamination of a site with multidrug resistant bacteria, for disinfection and cleaning purposes.
