ASTM D7907 is useful for the evaluation of bactericidal efficacy against a wide range of germs and circumstances, allowing manufacturers to compare performance. There are four specific bacteria listed against which antibacterial efficacy is compared.
In ASTM D7907, two test methods are intended to measure the amount of bactericidal efficacy of gloves under various conditions. In test method A, challenge bacteria are suspended in a phosphate buffer saline. A sterile coverslip is used to inoculate the aliquot of the bacterial challenge onto a test specimen. In test method B, the test surface is first exposed to organic loading for stimulating the glove contamination. The protein present in an organic load then neutralizes multiple bactericides. Once the organic conditioning is done, the site is challenged with target bacteria containing the organic load. The log reduction from the control specimen as well as from the challenge population recovered from the inoculum is determined per unit of time.
Video 01: Method to test antimicrobial agents
Bacteria incubation time must be 24 to 48 h at optimal temperature. Microbial counts must be >90%.
In ASTM D7909 testing, the log and percent reduction of the bacteria resulting from contact with the specimen is calculated using the following formula:
(A) Log reduction from control specimen titer = SC – TS expressed in log10 scale (10x)
(B) % bacterial reduction efficacy compared to control specimen = [(SC – TS) ÷ SC] × 100
ASTM D7907 is useful for the evaluation of bactericidal efficacy against a wide range of germs and circumstances, allowing manufacturers to compare performance.