Antimicrobial compositions may provide varying release kinetics for the active ions in the compositions due to the different water solubilities of the ions, allowing antimicrobial release profiles to be tailored for a given application and providing for sustained antimicrobial activity over time. According to some embodiments, the antimicrobial compositions may comprise polymer compositions containing colloids including salts of one or more oligodynamic metals, such as gallium. The antimicrobial compositions may be produced, for example, by mixing a solution of the salts of one or more oligodynamic metals with a polymer solution or dispersion and precipitating a colloid of the metal salts by addition of other salts to the solution which react with the metal salts. The compositions can be incorporated into articles or can be employed as a coating on articles such as medical devices including, for example, catheters, implants, and endotracheal tubes. The coatings may be on all or part of a surface.