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Surface active agents and their application in bacteriology.

Considerable interest has been generated in the use of the newer formulations that contain skin sanitizing agents for hand washing in food processing and service establishments. In some areas of the country, the degerming agents have been suggested so often by public health officials that the use of antimicrobial soaps has approached the status of a recommendation. It is the purpose of this paper to briefly review. this situation and some of the problems involved in choosing between some of the most common chemical agents that have been suggested for this purpose. Sanitization of the skin involves a limiting surface that Lane and Blank (22) have described generally as a continuous, relatively smooth layer of dead, flattened, keratinized cells made somewhat irregular by various ridges and furrows, by orifices of sweat glands, and by hair follicles and outgrowths of hair. The cutaneous glands secrete a film over these cells, and this fihn constitutes the absolute limiting boundary between man and his environment. In this fihn are included salt, urea, and other substances left behind by evaporation of sweat; sebum, which covers altareas except the palms and soles; and a nniform layer of fat. The cells contain proteins, lipids, and water. The protein is largely keratin, which is insoluble in weak acids, weak alkalies, and salt solu?ons. If the outer layers of the cells of the epidermis are brought into equilibrium with a solution that has a pH to either side of pH 3.70, the isoelectric point of keratin, swelling of the cells will occur. The skin reacts more· strongly to alkalies than to acids. Numerous measurements have shown the pH of the skin to range from 3.5 to 7.0. Although the relative amounts and kinds of the substances of the skin may vary among individuals and from time to time in each individual (as a result of changes in physiological conditions), the structure and composition of the skin generally provide a good environment for bacterial growth. Foci for the establishment of bacterial flora exist in hair follicles, the

The use of antimicrobial soaps and detergents for hand washing in food service establishments1

After the introduction of phenols of high germicidal potency as disinfectants, various laboratories began to experience discrepancies in results obtained by the F. D. A. phenol coefficient procedure. These variations were particularly marked when the test organism, Staphylococcus aureus, was used. The increased demand for disinfectants and antiseptics for war use and the increased emphasis on S. aureus as a test organism have caused these variations to become more evident and important. The U. S. Food and Drug Administration (1931) established an official pro cedure for the phenol coefficient test. Liebig's beef extract and Armour's special peptone were specifically designated as components of the culture medium for the test organisms, Eberthella typhosa and S. aureus. At the present time, Liebig's beef extract is practically unobtainable. Wright (1917) and Reddish and Burlingame (1938) have shown that different brands of peptone used in the culture medium may cause differences in coefficient values. Brewer (1943) demonstrated that different lots of the same brand of peptone caused as much as 100 per cent variation in phenol coefficient values. The English workers, Gladstone (1937), Knight (1937a, 1937b), Richardson (1936), and Fildes et al. (1936) have proved that S. aureus can grow in a synthetic medium in which amino acids furnish the sole source of nitrogen with the exception of that contained in the added growth factors. However, the use of the amino acids as a source of nitrogen is rather expensive, and, in some cases, their sterilization is laborious. Woolley and White (1943), in a study of microbial inhibition of several organisms including S. aureus, used an acid hydrolyzate of casein (\"casamino acids\"') as the main source of nitrogen for bacterial growth. The complete medium is as follows: glucose, 0.25 per cent; K2HPO4, 0.50 per cent; NaCl, 0.25 per cent; casamino acids (Difco), 0.25 per cent; 1(-)tryptophane, 25 mg per L; uracil, 5 mg per L; niacin, 1 mg per L; thiamine, 0.01 mg per L; biotin, 0.001 mg per L; and 2.5 ml per L of salt solution (Snell and Strong, 1939). As this medium seemed to have promise of being more nearly reproducible than the F. D. A. peptone medium, it was used as a starting point in this study. The various components of the mixture were studied in order to find whichwere

A Medium Containing an Acid Casein Hydrolyzate for Use in Testing Disinfectants

Quaternary Ammonium Salts: Insights into Synthesis and New Directions in Antibacterial Applications.

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George F. Reddish

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