Benzalkonium chloride and cetylpyridinium chloride are used as disinfectants of surgical instruments and surfaces such as floors and bench tops. Because they are effective against most bacteria and fungi and are not irritating, they are also used as antiseptics. However, when used on the skin, the antimicrobial action of these agents is antagonized by soaps and multivalent cations. The CDC has recommended that benzalkonium chloride and similar quaternary compounds not be used as antiseptics because outbreaks of infection have resulted from growth of gram-negative bacteria (eg, Pseudomonas) in such anticeptic solutions