ASTM D7907-14

Standard Test Methods for Determination of Bactericidal Efficacy on the Surface of Medical Examination Gloves

Manufacturers sometimes incorporate medical examination gloves with bactericidal properties. ASTM D7907 specifies 2 quantitative methods to evaluate the surface bactericidal efficacy of these types of gloves.

The difference between the 2 methods lies in how the bacterial load is presented to the gloves. Method A uses a saline or buffered saline solution and Method B uses a saline or buffered saline solution containing an organic load.

Test Conditions

The standard refers to the parameters to be observed when determining the bactericidal efficacy on the surface of medical examination of gloves. This includes the test microorganism, contact time and interfering substance.

Test microorganism refers to the mandatory list of microbes that must be used in the test to determine the antimicrobial activity of the product. The mandatory microorganisms are assumed to represent all microbes in its group.
Contact time refers to the minimum duration a product must remain in contact with the microbes for the product to be effective.
Interfering substance refers to substance used in the test to simulate the possible contaminants that co-occur with microbes in the actual environment.

Test Method A

First, 10⁸ CFU/mL bacterial suspension is prepared in sterile saline or phosphate buffered saline. This is the challenge inoculum for the gloves to be tested. Next, 20µL of the challenge inoculum is transferred to 10cm² test specimen, dispersed and held in place by a sterile coverslip. The challenge inoculum must contain a minimum titer of 10⁶ target bacteria to ensure there is sufficient viable bacteria to achieve at least a 4-log reduction.

After the specified contact time, the test specimen is transferred with its coverslip into a 50 mL sterile conical centrifuge tube containing 10 mL of qualified neutralizer solution. The solution is vortexed for 15 seconds. The neutralizer must have been validated through ASTM E 1054 test method. If a suitable neutralizer cannot be identified, the solution will be neutralized using filtration method. Serial dilution is performed on the neutralizer, plated and incubated at appropriate temperature for 1-2 days.

The result is compared to challenge inoculum and control specimen (identical to test specimen but without the antibacterial agents).

Test Method B

First, 10⁸ CFU/mL bacterial suspension (challenge inoculum) is prepared in sterile saline or phosphate buffered saline with 5% bovine serum albumin (BSA). All test and control specimens are exposed to 5% BSA prior to challenge inoculation.

Next, 20uL of the challenge inoculum is transferred to 10cm² test specimen, dispersed and held in place by a sterile coverslip. The challenge inoculum must contain a minimum titer of 10⁶ target bacteria to ensure there is sufficient viable bacteria to achieve at least a 4-log reduction.

After the specified contact time, the test specimen is transferred with its coverslip into a 50 mL sterile conical centrifuge tube containing 10 mL of qualified neutralizer solution. The solution is vortexed for 15 seconds. The neutralizer must have been validated through ATSM E 1054 test method. If a suitable neutralizer cannot be identified, the solution will be neutralized using filtration method. Serial dilution is performed on the neutralizer, plated and incubated at appropriate temperature for 1-2 days.

The result will be compared to challenge inoculum and control specimen (identical to test specimen but without the antibacterial agents).

Performance Criteria