614 E. M. Staal and A. C. Noordzij Table IV. Time of sampling Total lipophylic micro-organisms/cm • on the scalp Subject 1 Subject 2 Subject 3 Subject 4 After 1 week 7'1 x 10 • 2-6 x 106 5.4 x 10 • 6-9 x 10 • After 2 weeks 1'9 x 10 • 1'4 x 106 5'8 x 10 • 4'4 x 10 • After 3 weeks 4-4 x 10 • 1-6 x 106 1.1 x 10 • 2-9 x 10 • After 4 weeks 3.8 x 10 • 1.7 x 106 1.9 x 10 • 9.4 x 10 • After 5 weeks 4.8 x 10 • 3.0 x 10 • 1.6 x 10 • 7.5 x 10 • those given in the literature (28, 29). We also noticed that the ratio between aerobic and anaerobic micro-organisms did not change as a function of the quantity of washing fluid. CONCLUSION The Water-Pik method has been tested as a method to quantify the number of micro- organisms in the axilla and on the scalp. In these areas of the human skin, which are important for the study of the effectiveness of a deodorant or antidandruff preparation, the Water-Pik method appeared to be a suitable tool. The Water-Pik method is easy to handle and gives little discomfort for the subjects. Not only for cosmetic research but also for medical or dermatological studies the described method can be recommended for the quantitative sampling of the skin popu- lation. REFERENCES 1 Williamson, P. Quantitative estimation of cutaneous bacteria. In: Maibach, H. I. & Hildick-Smith, G. Skin Bacteria and their Role in Infection. 3 (1965) McGraw Hill, New York. 2 Kligman, A.M. The bacteriology of normal skin. In: Maibach, H. I. & Hildick-Smith, G. Skin Bacteria and their Role in Infection. 13 (1965) McGraw Hill, New York. 3 Woodroffe, R. C. S. and Shaw, D. A. Natural control and ecology of microbial populations on skin and hair. In: Skinner, F. A. and Cart, J. G. The normal microbial flora ooeman. 13 (1974) Academic Press, London. 4 Marples, M. J. The normal microbial flora of the skin. In: Skinner, F. A. and Can', J. G. The Normal Microbial Flora of Man. 7 (1974) Academic Press, London. 5 Gibbs, B. M. and Stuttard, L. W. Evaluation of skin germicides. J. Appl. Bacteriol. 30 66 (1967). 6 Selwyn, S. and Ellis, H. Skin bacteria and skin disinfection reconsidered. Brit. Med. J. 1 136 (1972). 7 Parker, M. S. Skin bacteria: myth and reality. Soap, Perrum. Cosmet. 45 296 (1972). 8 Holt, R. J. Aerobic bacterial counts on human skin after bathing. J. Med. Microbiol. 4 319 (1971). 9 Holt, R. J. Pad culture studies on skin surfaces. J. Appl. Bacteriol. 29 625 (1966•, 10 Dixon, H. and Paneza, A. K. Microbiological applications of novel replipad skin sampler. J. Soc. Cosmet. Chem. 28 21 (1977). 11 McGinley, K. J., Leyden, J. J., Marpies, R. R., Path, M. R. C. and Kligman, A.M. Quantitative microbiology of the scalp in non-dandruff, dandruff and seborrheic dermatitis. J. Invest. Dermatol. 64 401 (1975). 12 Leyden, J. J., McGinley, K. J., Mills, O. H. and Kligman, A.M. Age related changes in the resident bacterial flora of the human face. J. Invest. DermatoL 65 379 (1975). 13 Shehadeh, N.J. and Kligman, A.M. The effect of topical antibacterial agents on the bacterial flora of the axilla. J. Investigative Dermatology 40 61 (1963) 14 Ulrich, J. A. Techniques of skin sampling for microbial contaminants. Health Lab. Sci. 1 133 (1964).

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