ISO 18415:2017 gives general guidelines for the detection and identification of specified microorganisms in cosmetic products as well as for the detection and identification of other kinds of aerobic mesophilic non-specified microorganisms in cosmetic products.
The method described in this document is based on the detection of microbial growth in a non-selective liquid medium (enrichment broth) suitable to detect microbial contamination, followed by isolation of microorganisms on non-selective agar media.
In ISO 18415:2017 specific indications are given for identification of Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus and Candida albicans.
Other standards (e.g. ISO 18416, ISO 21150, ISO 22717, ISO 22718) may be appropriate.