This medium is recommended for determining efficiency of containers, equipment surfaces, water miscible cosmetics and for inactivation of cephalosporins of first, second, third and fourth generation. Lecithin and polysorbate 80 neutralizes quaternary ammonium compounds and parahydroxy benzoates. β lactamase II added in the medium will inactivate the β-lactam antibiotics thus enabling recovery of organisms from the environment of cleanrooms where production of antibiotics is carried out.