residual effectiveness, ASTM E2752, Standard Guide for Evaluation of Residual Effectiveness, antimicrobial efficacy testing, evaluation of residual efficacy

Evaluation of Residual Effectiveness of Antibacterial Personal Cleansing Products

QACS provides Residual Antimicrobial Efficacy testing to demonstrate the effectiveness of antibacterial personal cleansing and disinfectant products both immediately and after prolonged exposure, for the substantiation of the relevant claim.  More specifically, the following Protocols can be applied:

ASTM E2752: Standard Guide for Evaluation of Residual Effectiveness

This test is conducted on a panel of healthy adult participants. Every participant is tested at two test areas. Each test areas, usually forearms, are washed multiple times with the product under test and a vehicle or control formulation. After the washing procedure, the test areas are inoculated with a marker micro-organism (usually Staphylococcus aureus or Escherichia coli) and occluded for a specified period of time, after which, the test areas are sampled and enumerated for the marker micro-organism. Activity of the product under test is measured by comparing microbial counts from treated areas to those derived from the areas treated with vehicle/control formulation or to an untreated baseline organism count.

Tailor made protocols based on European Normatives EN 1499, EN 1500 & EN12791

This approach involves applying either live test organisms (Escherichia coli K12) to the hands of healthy adult volunteers or use the present transient microbial flora of hands.

Initially, the micro-organisms present on hands are recovered, to obtain a baseline count. The test or reference disinfectant product is then applied to the hands, according to instructions of product’s label. Immediately after wash procedure and drying, the remaining flora of one hand is enumerated and the other hand is protected from extraneous contamination by donning a sterile surgical glove to be removed after 2-3 h.   The procedure is repeated with the product under test. The following samples are taken from the hands, for enumeration of bacterial counts:

  • immediately after the handrub or –wash procedure; for immediate effect
  • 2-3 h after the handrub or –wash procedure; for sustained/for residual effect

The organisms are enumerated, counts transposed to the Log system and the difference between the numbers recovered from the test or reference, and baseline counts are established and statistically analyzed.

In order to ensure the safety of our volunteers, the above services are applicable for products which have been met the criteria of EN 1499, EN 1500 or EN 12791.

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