320 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS The Bacillus group of organisms have been infrequent contaminants of products and when the occurrence has been investigated no reasonable explanation has been made of that occurrence. These organisms are only remarkable for the low level of contamination found but because of the contamination being in the spore phase this low level of contamination remains in the product due to the preservatives present having no sporocidal activity but merely preventing exsporulation and growth. All species isolated so far have been aerobic in spite of considerable expenditure of time in attempting the isolation of Clostridia from talcs and similar materials. Other than Ps aeruginosa classical pathogens such as E. coli, Salmonella spp. or Staphylococcus aureus have not been isolated. When required by regulation to certify products as being free from these organisms but in the absence of approved test methods the following test structures were utilized. E. coli An aliquot is taken from the product sample and is used to inoculate a primary enrichment broth (Digest or Glucose) which is incubated at 37øC for 2 days. This broth is then subcultured onto a selective media containing bile salt, lactose and indicator (MacConkey Agar) at 37øC for 24 h. Any Gram negative lactose fermenting colonies are inoculated into an equivalent broth (MacConkey Broth) and incubated at 44øC for 24 h. The production of both acid and gas at this temperature is considered to be presumptive of E. coli. Ps aeruginosa An aliquot is taken from the product sample and is used to inoculate a primary selective/inhibitory broth (Digest with 0.02•o Cetrimide) which is incubated at 37øC for 2 days. This broth is subcultured onto an equivalent agar (Nutrient with 0.03•o Cetrimide) at 37øC for 24 h. Any Gram negative colonies growing on this plate which smell of trimethylamine and display greenish pigment and/or fluorescence under a UV lamp are considered to be Ps aeruginosa. Salmonella spp. An aliquot is taken from the product sample and is used to inoculate a primary enrichment broth (Digest or Glucose) which is incubated at 37øC for 2 days. This broth is subcultured into a selective/inhibitory broth (Selenite or Tetrathionate) at 37øC for 24 h. This broth is then subcultured

MICROBIOLOGICAL QUALITY CONTROL 321 onto an inhibitory/differential agar (Wilson and Blair bismuth sulphite agar) at 37øC for 48 h. Any Gram negative colonies growing on this plate which are black or green, have a metallic sheen or a diffuse black sulphide deposit around the colony are presumed to be Salmonella spp. The most certain and rapid confirmatory test is to subculture suspect colonies onto Nutrient agar and test the colonies after 24 h growth with appropriate polyvalent antisera. Staphylococcus aureus An aliquot is taken from the product sample and is used to inoculate a primary enrichment broth (Digest or Glucose) which is incubated at 37øC for 2 days. This broth is subcultured onto an inhibitory/differential agar (Tellurite-egg or Vogel-Johnson) at 37øC for 48 h. Any Gram positive colonies growing on this plate (Vogel-Johnson) which are small, black surrounded by yellow zones are presumed to be Staph. aureus. For confirmation, subculture suspect colonies into tubes of mamma- lian plasma (0.5 ml) and incubate at 37øC. Examine at 3 and 24 h. Coagula- tion constitutes a positive test. LESSONS LEARNED FROM THE MICROBIOLOGICAL QUALITY CONTROL PROGRAMME It has been recognized that only sterile products are expected to be free from detectable organisms and it is, therefore, important to recognize that non-sterile products can and do have organisms present in any product. It is, therefore, necessary to draw up techniques of viable counting with full laboratory instructions to determine such contamination and to set limits on that contamination. The microbiological quality of any raw material that is used in the manu- facture of products should be known and determined both in the develop- ment laboratory and in the factory. It is important to draw up realistic specifications for raw materials and great assistance may be had from most suppliers in doing this. It is obvious that during the manufacture of a non-sterile product, the process should be so designed, so that the microbial content does not increase. The function of a preservative is to prevent proliferation of an accidental contamination, not to free production from rigid hygiene standards and