Action of Synthetic Detergents

The bactericidal and bacteriostatic actions of soaps have been recognized for many years. Detailed studies by Eggerth (1) on the germicidal action of soaps have shown the importance of such factors as length of hydrocarbon chain, chemical configuration, effect of hydrogen ion concentration, effect of serum, etc. Avery (2) demonstrated the selective germicidal action of soap on microorganisms, and recommended for the isolation of influenza bacilli a medium containing sodium oleate. He noted that "this medium prevents the growth of certain Gram-positive organisms, principally pneumococcus and streptococcus, while the growth of B. infuenzae is enhanced by the presence of this substance." The marked selectivity of soaps on bacteria has been studied further by Bayliss and Halvorson (3) and Bayliss (4). The work of Walker (5) indicates that although pneumococci and streptococci are unusually susceptible to certain soaps, staphylococci are very resistant. Because of the widespread occurrence of the staphylococcus on body surfaces, soaps have only a limited value as germicidal agents. Generally, they are employed when detergent, rather than germicidal action, is desired. In addition to their selectivity, which is a disadvantage unless one wishes to attack or differentiate specific microorganisms, soaps have certain other undesirable characteristics which limit their usefulness. Ordinary soaps have too alkaline a reaction for application on sensitive tissues. Moreover, soap is precipitated by hard water.