FDA - Bacteriological Analytical Manual, Microbiological Methods for Cosmetics

Referring to the fact that cosmetics can be contaminated with microorganisms and that, in most cases, there is a risk for growth and reproduction of microorganisms, chapter 23 of FDA's Bacteriological Analytical Manual (BAM) was published several years before. It is supposed to partly support manufacturers in reducing the possibility of spoilage or chemical changes in cosmetic products and thus injury of the user. Since the last hard-copy version (Edition 8, Revision A /1998), it has been updated several times. The last important changes were:

• July 2017: Revision to Section H-1 and H-2.
• January 2017: Section H-1 and H-2. Additional 1 ml of 10-1 dilution is analyzed.
• May 2016: Section H-1. Changed dilution range from 10-1 - 10-6 to 10-1 - 10-3.
• May 2016: Section H-4. Deleted the entire section: Screening test for total numbers of microorganisms.
• May 2016: Section: Identification of Microbes updated: A.1. Gram-positive rods. Identify Bacillus-like rods if isolated from aerobic plates.

Detection, Isolation and enrichment culturing of microorganisms from cosmetics will be challenging in some cases, especially when the product is not soluble in Water. Therefore the manual provides some guidance with regard to equipment, media and methods. Chapter 23 in the current version of July 2017 includes the following parts relating to the cultivation of microorganisms:

• Equipment and materials
• Media for enumeration and identification of Gram-positive bacteria and fungi
• Media for identification of Enterobacteriaceae
• Media and reagents for identification of Gram-negative nonfermentative (NF) bacilli
• Other media and reagents
• Handling of cosmetic samples for microbiological analysis
• Preliminary sample preparation
• Microbiological evaluations

In a second part, the chapter gives some information about identification of microbes. For yeasts and molds the document recommends: "Molds and yeasts should be purified and yeasts identified as far as possible using kits, e.g., Vitek yeast card and API yeast assimilation strip. If necessary, send fungal isolates to Valerie H. Tournas, FDA HFS-711, 5001 Campus Drive College Park, MD 20740, for speciation."

For the identification of bacteria the following requirements are defined: "For bacteria, examine all plates and streak morpho-logically dissimilar colonial types onto MacConkey and MLA media. Prepare Gram stain of all morphologically dissimilar colonial types obtained in pure culture. With methods given here, isolates may be identified to genus level in general; tests for speciation are listed when necessary. Test results should be evaluated using Bergey's Manual (12) or Madden's methods (14). All isolates are required to be identified to the species level. Commercial identification kits, e.g., API, Roche, Vitek, Hewlett-Packard (see Appendix 1), are strongly recommended to speciate microbes recovered from enumeration plates and enrichment broth"

Therefore this part covers the following topics:

• Identification Methods (for  gram positive rods, gram positive cocci, gram negative rods and Pseudomonas aeruginosa)
• A Biochemical Results table
• Interpretation
• Cosmetic preservative efficacy

Additional details can be found directly in BAM: Bacteriological Analytical Manual, Chapter 23 Microbiological Methods for Cosmetics.