For each micro-organism, the log reduction is compared to criteria A or B (see below).
a) If all the reduction values comply with criteria A below, the formulation satisfies requirement of the preservation efficacy test and, in accordance meets the requirements of this International Standard.
b) If all the reduction values comply only with criteria B, the formulation does not satisfy all requirements of the preservation efficacy and additional justification should be provided to show that the product is sufficiently protected from microbial attack.
c) If one or more of the reduction values do not comply with criteria A or B, then the formulation does not satisfy the requirements of the preservation efficacy test. The status of the product shall be further evaluated and possibly reformulated for better microbial protection.
Criteria A
For bacteria: No less than 3.0 log reduction for the initial calculated count at 7 days, not less than 3.0 log reduction and no increase from the 7 day count at 14 days, and no increase from the 14 days’ count at 28 days.
For C. albicans: No less than 1.0 log reduction for the initial calculated count at 7 days, not less than 1.0 log reduction and no increase from the 7 day count at 14 days, and no increase from the 14 days’ count at 28 days.
For A. brasiliensis: No increase from the initial inoculum count at 14 days and no less than 1.0 log reduction from the initial inoculum count at 28 days.
Criteria B
For bacteria: No less than 3.0 log reduction for the initial calculated count at 14 days, and no increase from the 14 days’ count at 28 days.
For C. albicans: No less than 1.0 log reduction for the initial calculated count at 14 days, and no increase from the 14 days’ count at 28 days.
For A. brasiliensis: No increase from the initial inoculum count at 14 days and no increase from the 14 day count at 28 days.
