PEC Chromogenic Agar

For cosmetics and other topical products, the detection of skin pathogens such as Staphylococcus aureus, Pseudomonas aeruginosa and Candida albicans may be relevant because they can cause skin or eye infection. The detection of other kinds of microorganisms might be of interest since these microorganisms (including indicators of faecal contamination, e.g. Escherichia coli) suggest hygienic failure during the manufacturing process.

The medium contains peptone, which provides nitrogen, vitamins, minerals and amino acids essential for growth. The addition of tryptophan to the medium allows the performance of the Indole test for further E. coli confirmation. The mixture of chromogenic substrates allows the identification of the different species and the bacteriological agar is the solidifying agent.

Typical formula in g/L, adjusted and/or supplemented as required to meet performance criteria.

Preparation

Suspend 47.5 grams of the medium in one liter of distilled water. Mix well and dissolve by heating with frequent agitation. Boil for one minute until complete dissolution. AVOID OVERHEATING. DO NOT AUTOCLAVE. Cool to 45-50 °C, mix well and dispense into plates.

Instructions for use

1. Prepare the sample.
2. Subculture by streaking on a plate of PEC Chromogenic Agar, and incubate at 37 ± 1 °C for 24-48 h.
3. Confirm by identification tests.

• Geissler K., Manafi M., Amoros I., Alonso J.L. Quantitative determination of total coliforms and Escherichia coli in marine waters with chromogenic and fluorogenic media. J. Appl. Microbiol. 2000, 88 pp. 280-285.
• ROBIN, T. & J.M. JANDA (1984) Enhanced recovery of P. aeruginosa from diverse clinical specimens on a new selective agar. Diag. Microbiol. Infect Dis. 2:207.
• ISO 18415:2017 Cosmetics - Microbiology - Detection of specified and non-specified microorganisms.