Experiment Principle:

According to the possible pollution (primary and secondary pollution) in the process of cosmetics production and consumer use, quantitative known bacteria are added to the product to regularly observe the growth of microorganisms in the product and evaluate the anti-corrosion effect of the preservative, which is the antiseptic efficacy test.

Test Method:

Disposable culture method: The volume of the suspension inoculum used is 1.0% of the volume of the product to minimize potential effects on the product. The concentration of test microorganisms that is added to the product  is such that the final concentration of the test preparation after inoculation is between 1×105 and 1×106 cfu/mL of the product.The initial concentration of viable microorganisms in each test preparation is estimated based on the concentration of microorganisms in each of the standardized inocula as determined by the plate-count method. Incubate the inoculated containers at 22.5±2.5°. Determine, by the plate-count procedure, the number of cfu present in each test preparation for every week. Plate counts will be conducted using a minimum of duplicate plates, with the cfu averaged before determination of deduced cfu/mL. Using the calculated concentrations of cfu/mL present at the start of the test, calculate the change in log values of the concentration of cfu/mL for each microorganism at the applicable test intervals, and express the changes in concentration in terms of log reductions.

Triple culture method: In the same way, the operation process is the same as above. The initial bacterial concentration in the sampleis between 106-107cfu/g of the product ; The initial concentration of yeast and mold is between105-106cfu/g of the product . The experiment period is 42 days, the inoculation time is once every 14 days, and a total of 3 inoculations are required. Determine, by the plate-count procedure, the number of cfu present in each test preparation for every week.

Test Strains:

Bacteria: Escherichia Coli(ATCC 8739), Pseudomonas Aeruginosa(ATCC 9027), Staphylococcus Aureus(ATCC 6538)

Fungi: Aspergillus Niger(ATCC  16404), Candida Albicans(ATCC 10231)

Reference Standards: 

United States Pharmacopeia USP43<2020> Chapter 51    

PCPC Microbiology Guidelines(Section 20  M-3)

Criteria for Antimicrobial Effectiveness: 

Disposable culture method: from USP43(51) Table 1 and Table 3