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UDM/OECD Technical Workshop –Highlights from the Regulatory Sessions

(November 15th, 2011: Post Registration Testing, AOAC Committee M, etc) 

Method/Activity Aspect Suggestion/recommendation

Regulatory Overviews 

Front End Process for the 

Antimicrobial Testing 

Program 

See PowerPoint presentation entitled “2011 UDM/OECD 

Technical Workshop/Post-Registration Testing”, Joan 

Harrigan-Farrelly

Group discussed product receipt, chain of custody, 

development of test parameters

Suggestion made to have company include a “test 

parameter” chart in future data submissions. 

Inquiry on process for responding to AD regarding 

products that registrants believe were tested using 

incorrect parameters. Registrants are to contact AD. 

Resolution may involve sending in new sample. In many 

cases, the data used to develop parameters were very old. 

AD and BEAD have listened to concerns of industry and 

have re-evaluated some products already.

Suggestion made to adjust performance standards for the 

AOAC Germicidal Spray Products as Disinfectants test as 

well.

EPA has limited resources. Resources are being directed 

to furthering the OECD method for determining efficacy 

of hospital disinfectants. EPA encourages industry lab 

involvement in terms of volunteer labs for collaborative 

studies.

Action Item-CSPA to present the option of providing 

the test parameters for products to members

for consideration 

AOAC Committee M Meeting 

See PowerPoint presentation entitled “AOAC Committee 

M/September 2011/Annual Meeting”, Dan Klein.

Question was raised about AOAC support once the EPA 

contract with AOAC expires (July 2012) . Industry may 
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approach AOAC. 

EPA Method Revision 

Activities 

See PowerPoint presentation entitled “Modifications to 

Existing AOAC Official Methods”, Jafrul Hasan.

Status of Clostridium difficile

Agency presented the data on C. difficile spore 

preparation protocol and media study – refer to the Power 

Point presentation on this topic, entitled “An Update on 

EPA’s Initiatives and Activities of AOAC Expert Review 

Panel on Clostridium difficile: Is C. difficile Becoming 

Less Difficile?”, Jafrul Hasan. 

Inquiry on how the Agency was conducting post 

registration testing of C. difficile claims. Agency is 

following the registrant protocol incorporating any 

scientifically sound changes when there is data (for 

example, use of appropriate recovery media for 

enumeration – recovery media data developed, submitted, 

reviewed and accepted by the AOAC Expert Review 

Panel). 

What will Agency do if data indicates that different 

chemistries may require different spore/media 

combinations. Currently few actives are registered so 

this has not been an issue to date Agency will review on 

a case by case basis. 

Recommendation to do a multi-lab study of spore 

preparation protocol coupled with efficacy testing using a 

few actives. Min/max carrier counts need to be defined. 

The performance standard is defined in EPA’s interim 

guidance for C. difficile claims. 
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Quantitative Petri Dish 

Method (QPM) 

Agency presented the QPM method using Power Point 

presentation entitled “ASTM Work Item 32908: Standard 

Test Method for Quantitative Petri Plate Method (QPM) 

for Testing Antimicrobial Towelette Products”, Jafrul 

Hasan. 

The issue of a requirement for a Scientific Advisory 

Panel review was raised. Suggestion by industry that if 

an SAP is required for the QPM that it be coupled with 

the OECD method. 

Clarification requested on the scraping procedure – the 

procedure was reviewed with the meeting participants. 

Issue of spreading the inoculum was raised (per 

discussion at the 2011 AOAC Annual Meeting). The 

preference by the Agency in order to ensure uniformity 

across all labs and tests is to dispense the inoculum 

without spreading due to inconsistency in drying, removal 

of inoculum etc.

Discussion on impact of pressure applied during wiping, 

from analyst to analyst. Method indicates to apply 
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Quantitative Petri Dish 

Method (QPM)

moderate and gentle pressure. May need to further refine 

language and technique, but group agreed that this 

method was better than the current methodology.

In developing current proposed method, towelette 

workgroup (members from Agency, industry, and testing 

labs) considered evaluating the active ingredient 

separately from the towelette and the expressed liquid. 

Presented the proposal to industry and the response was 

that evaluating the liquid separately from the wipe was 

inconsistent with how the towelette is used by the 

consumer. Efficacy is based on both physical (wiping) 

and chemical (active ingredient) action.

The carrier counts should be within a log of the 

performance standard for the QPM. For example, if the 

Agency considers a five log standard, the carrier count 

range should be between 5.5 and 6.5 log.

Comment – Current methodology and proposed QPM 

method do not take into account wipe label directions that 

indicate to wipe surface multiple times if necessary to 

keep wet for the duration of the contact time. Wipe test 

should reflect product label directions.

AOAC GSPT Revisions

See PowerPoint presentation entitled “Improvements to 

the AOAC Germicidal Spray Products as Disinfectants 

Test - A Carrier Enumeration Procedure and 

Establishment of a Log Density Range for Test Microbes 

on Inoculated Carriers”, Jafrul Hasan.

Agency presented a method for determining carrier 

counts for the AOAC GSPT, and a proposal to establish a 

carrier count range (5 to 6.5 logs) based on historical data 

collected by 4 labs over 11 years.

Agency will propose procedural revision to method 
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AOAC GSPT Revisions

961.02 to include carrier enumeration method and carrier 

count range for S. aureus and P. aeruginosa.

Persistence data presented in the PowerPoint was 

developed using organisms (S. aureus and P. aeruginosa) 

grown in nutrient broth.

Comment–More data may need to be developed to 

determine impact of using synthetic broth on carrier 

counts and persistence.

Procedural changes for S. enterica to be considered at a 

later time

UDM Data 

EPA presented data on maximum carrier count proposal, 

UDM collaborative data, reassessment of the performance 

standard, and the schedule of activities. Refer to the 

Power Point presentations entitled “Establishment of 

Maximum Log Density Value for Test Microbes on 

Inoculated Carriers,” “Reassessment of UDM 

Performance Standard,” and “Updated Revision 

Schedule”; Stephen Tomasino. 

Comment – valuable to have this workshop – industry 

suggested future workshops on the spray and towelette 

methods. Suggestion made to have an industry lab lead a 

workshop as well. Action Item – CSPA to discuss with 

their members. 

Request made to have a copy of the chart outlining the 

UDM method modifications and schedule. Action Item –

the chart was posted to the docket. 

Confidence around the registration versus post 

registration testing. Registration requires 3 different lots; 

one aged. Post-registration will require 1 lot, three 

replications using separate test cultures. Statistics should 

bring it to the same point. 
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UDM Data

Decision tree for three replications for post-registration 

testing– if any one test fails to meet the performance 

standard, the product efficacy will be deemed a failure. 

Staphylococcus will be run first; then Pseudomonas. All 

replications can be done in one lab. This is easier 

logistically and within lab variability is typically less than 

between lab variability.

The Agency will act upon any “red flags” in postregistration testing (e.g., product passes one day with 0+ 

carrier sets and fails the next day with 30+ carrier sets). 

The industry suggested that if a product fails the first of 

three tests, the Agency should automatically proceed 

with the second test to be assured that the product fails 

consistently.

Inquiry about distribution of current ATP data – pie chart 

was shared – the data is not broken out by test method but 

EPA will work on doing so.

Changes in post-registration testing requirements and 

performance standards are meant to be an interim 

measure during the OECD method implementation phase. 

UDM/OECD Technical Workshop – Highlights from Regulatory Sessions

(November 16th, 2011: OECD Method)

11/16/11

OECD Regulatory Overview

Q&A Session on 

Reassessment of UDM 

Performance Standards

Stephen Tomasino reiterated the performance standard 

proposal for the AOAC UDM (presented 11/15/11) and 

answered a variety of questions from the audience.

Implementation of the new performance standard and 

changes to post-registration testing will be transparent.

Comment – The confidence level resulting from testing 

three separate lots of product (registration requirement) 

may be higher than testing one lot of product three times 

(proposal for post-registration testing). Some registrants 
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create three distinct batches of product for testing, in 

which the product ingredients are from differing batches.

EPA is exploring the possibility of posting draft versions 

of performance standard-related papers on the docket 

concurrent with AOAC review. 

Overview of the OECD 

Harmonization Effort

See PowerPoint presentation entitled “Overview of the 

OECD Harmonization Efforts,” Michele Wingfield.

Ring trial did not include work on S. enterica because it 

is more sensitive to disinfectants than P. aeruginosa. 

Agency is not likely to do any work on S. enterica.

The Agency committed to communicating with the states 

regarding the harmonization efforts. 

Implementation Strategy

Agency presented information on the OECD 

implementation strategy, performance standards, default 

test conditions, and a timeline for transition. Refer to the 

Power Point presentation entitled “OECD Implementation 

Strategy”, Michele Wingfield.

Question arose regarding how CSPA could best assist 

EPA with implementation efforts. The Agency responded 

that industry can help by participating in the upcoming 

collaborative study and providing suggestions and 

feedback on the OECD implementation process.

Proposed standardized contact time of hospital 

disinfectants in the OECD method is 5 minutes. 

The OECD method includes an option for testing spray 

products. The product is sprayed into a sterile vessel. 

The liquid is collected and used for testing.

There will be no bridging study for towelette-based 

products. Agency would most likely use the QPM for 

testing of towelettes.

Question regarding submissions for DCI. The Agency 

will evaluate DCI plans with respect to the proposed 

changes to the performance standard. For submission of 
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data in response to a DCI, the age of data cited is not 

important. What matters is that data meets today’s 

scientific standards (e.g., the elements present in the 

latest version of the AOAC UDM and adequate carrier 

counts).

Lunchtime Discussion of 

OECD Collaborative Study

Proposed Collabortive Study 

of the OECD Bactericidal 

Method

See PowerPoint presentation entitled “Collaborative 

Evaluation of the Draft OECD Test Guidelines for 

Bactericidal Activity,” Stephen Tomasino.

S. Tomasino presented the general study plan, timeline, 

and potential outcomes for the collaborative study.