Cosmetics testing - Microbiology of cosmetics. Detection of  Staphylococcus aureus
(EN ISO 22718: 2016)
Test accredited by ENAC (Spanish National Accreditation Entity).
The test provides information about the "presence or absence" of Staphylococcus aureus in 1 g or 1 mL of the cosmetic sample. To perform the test, the cosmetic is diluted in the ratio 1:10 in an enrichment broth directly, when products are miscible in water. When testing a water non-miscible cosmetic it is premixed with a solubilizing agent (polysorbate 80) and subsequently added to the enrichment broth. The enrichment broth should contain a neutralizer when testing cosmetics containing any antimicrobial agent as a preservative. Neutralizers used must have been previously validated by a validation test. The presence or absence of Staphylococcus aureus in the cosmetic is determined after incubation for 24 to 72 hours at 32.5ºC in the enrichment broth, and reseeding in a selective and differential medium. This medium should be incubated at 32.5ºC and observed at 24 and 48 hours. If compatible colonies are observed they are identified by conventional microbiological tests.