ASTM E1153: Procedure At a Glance
In this study, carriers/surfaces will be inoculated with 10 µl of Staphylococcus aureus and Klebsiella pneumoniae (or Enterobacter aerogenes substituted) and dried for 35 minutes at 35 ± 2ºC. The surfaces will be transferred into sterile jars, petri plates, or other appropriate sterile container using sterile forceps and covered with a pre-determined volume of sanitizer product and held for the desired contact time at ambient temperature. After the exposure time, appropriate neutralizer solution will be added into the jar containing the exposed carrier/surface and rotated vigorously for approximately 50 rotations to suspend the surviving organisms. Surviving bacteria will be quantitatively determined via pour-plate method. The number of surviving colony-forming units (CFU) on carriers/surfaces will then be compared to a non-active, parallel control to determine the percent kill of S. aureus and K. pneumoniae (or E. aerogenes substituted) by the sanitizer product. Five replicate bacteria-labeled carriers/surfaces will be tested against each of three lots of sanitizer product, all at LCL, and the non-active, parallel control for each test bacterium.
There are numerous test controls in place in this method to ensure validity of the test results. Analysis of the bacteria used to inoculate the carriers/surfaces to determine strength of the inoculum. Analysis of the carriers/surfaces after drying to measure the bacterial challenge being exposed to the sanitizer product. Parallel controls measure the amount of bacteria removed from the carriers/surfaces by the application method (i.e. spray or wipe). An average of at least 7.50×105 CFU of bacteria must be recovered from the parallel control. Neutralization controls to confirm that the neutralizing recovery method stops the antimicrobial activity of the sanitizer product at the completion of the contact time. Viability controls to confirm the neutralizer medium is not toxic to the bacteria being tested. Media sterility to confirm the sterility of the medium used in the test.
ASTM E1153: Microchem’s Expertise
Microchem Laboratory, LLC has been performing Disinfectant and Sanitizer testing in accordance with U.S. EPA OCSPP guidelines for many years. The Non-Food Contact Sanitizer Test/Surface Time Kill Test/ ASTM E1153 is among the numerous test methods listed under those guidelines. This test method can be modified for pre-saturated towlettes and spray sanitizer products. Sanitizer products can be challenged against numerous microorganisms using this method for additional claims on product label.