This International Standard gives general guidelines for the detection and identification of the specified micro-organism Pseudomonas aeruginosa in cosmetic products. Micro-organisms considered as specified in this International Standard might differ from country to country according to national practices or regulations. In order to ensure product quality and safety for consumers, it is advisable to perform an appropriate microbiological risk analysis to determine the types of cosmetic product to which this International Standard is applicable. Products considered to present a low microbiological risk include those with low water activity, hydro-alcoholic products, extreme pH values, etc. The method described in this International Standard is based on the detection of Pseudomonas aeruginosa in a non-selective liquid medium (enrichment broth), followed by isolation on a selective agar medium. Other methods may be appropriate, depending on the level of detection required. NOTE For the detection of Pseudomonas aeruginosa, subcultures can be performed on non-selective culture media followed by suitable identification steps (e.g. using identification kits). Because of the large variety of cosmetic products within this field of application, this method may not be appropriate in every detail for some products (e.g. certain water immiscible products). Other International Standards (ISO 18415 [10]) may be appropriate. Other methods (e.g. automated) may be substituted for the tests presented here provided that their equivalence has been demonstrated or the method has been otherwise validated.