OVERVIEW OF THE OECD

HARMONIZATION EFFORTS

Michele E. Wingfield, Senior Science Advisor

Antimicrobials Division

UDM/OECD Workshop

November 16, 2011

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TOPICS

 Background and Milestones

 Role of the Validation Management Group

 Report on OECD Meeting in Paris

 Key Features of the Method

 Results of the Ring Trials

 Test Guidelines and Guidance Documents

 Changes Due to Comments Received

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BACKGROUND AND MILESTONES

 1998 – The Taskforce on Biocides surveyed 

OECD member countries on approaches to 

regulating biocides. A great deal of interest was 

expressed in harmonizing efficacy test methods.

 2002 – EPA hosts OECD Workshop

 2003/2004 – Call for tender issued by the 

European commission

 2006 – Validation Management Group (VMG) 

established.

 2007/2008 – Ring-trial designed and executed.

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BACKGROUND AND MILESTONES

 2008 – Meeting of the VMG to discuss the 

validation report.

 2009 - TFB agrees to progress the methods to 

the Working Group of the National Coordinators 

of the Test Guideline Program (WNT).

 2010/2011 – Two commenting rounds completed 

on the 4 draft Test Guidelines and the Guidance 

Document.

 2011 – Test Guidelines and Guidance Document 

fail to gain approval at the WNT meeting

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OECD MEETING OF EXPERTS AND 

REGULATORS 

 Held in Paris, France on September 13 & 14, 

2011.

 Objectives: to discuss and resolve issues raised at 

the April 2011 WNT Meeting.

 Major Issues

 Reference standards and proficiency testing

 Applicability to other product types

 Compliance with MAD

 Purpose of the Guidance Document

 Contact time

 Neutralization assay

 Performance Standards 5
OECD MEETING OF EXPERTS AND 

REGULATORS

 Presentations given by Dr. Syed Sattar, Mrs. 

Rhonda Jones and Dr. Stephen Tomasino, on 

background of the method; concerns raised by 

ADBAC/DDAC Consortia; and, BEAD 

collaborative study, respectively.

 Issues resolved: reference standard and 

proficiency testing, other product types, 

compliance with MAD, guidance document, 

contact time, neutralization assay and contact 

time.

 Unresolved issues: Performance standards

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OECD MEETING OF EXPERTS AND 

REGULATORS

 Other issues addressed.

 Carrier quality

 Pseudomonas aeruginosa growth medium

 Reproducibility issues with the inoculum

 Impact of method on concentrates vs. ready-to use 

products

 Pre-collaborative studies

 BEAD collaborative studies and timeline

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KEY FEATURES OF THE METHOD

 Test design is fully 

quantitative and “closed” to 

avoid wash-off of viable 

microorganisms.

 Brushed stainless steel 

disks as the carrier. 

Simulates surfaces in 

healthcare settings.

 Default diluent – 375 ppm 

hard water.

 5 minute contact time to 

reflect the realities of field 

applications.

 Sets 20 2oC as default air 

temperature.

 Includes a standard soil 

load.

 5% mixture of high 

molecular weight protein, 

low molecular weight 

protein and mucin

 Uses surrogates for all 

classes of microorganisms 

– Hierarchy Approach

 Log reduction measure of 

performance.

 Promotes data sharing, 

review sharing, rapid 

response to pandemics

 Readily amenable to 

modification

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RESULTS OF THE RING-TRIAL

 27 Laboratories participated in the ring-trial.

 Test Organisms

 Bacteria

 Pseudomonas aeruginosa, Staphylococcus aureus, 

Enterococcus hirae

 Virus

 Adenovirus

 Mycobacteria

 Mycobacterium terrae

 Fungus

 Aspergillus niger

 Bacterial Spore

 Bacillus subtilis

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RESULTS OF THE RING-TRIAL

PHASE 1

 Very much learning by doing

 Initiated without training 

 Perhaps overly ambitious in number of compounds 

and organisms

 Positive outcome but high variability

 Drove design of Phase 2

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RESULTS OF RING-TRIAL

PHASE 2

Improved technical clarity for 

technicians, changes flowed through 

to all 5 tests

Inter-lab variability on par with Phase 1

Intra-lab variability was lower in Phase 

2

Variability decreased with experience

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CONTENT OF GUIDANCE DOCUMENT

 Background for Test Guideline development and 

validation

 Discussion of other product types

 Non-foaming aerosols, pump sprays, foams and 

towelettes 

 Study Design

 Carriers, soil load, diluent, contact time, concentration 

and additional microorganisms

 Number of test runs and test days

 Performance standards

 Test Reports

 Proficiency Testing 12
CHANGES MADE DUE TO 

COMMENTS RECEIVED

 Annexes – Have been put in order according to the use in the Test Guideline – this is to make 

them more user friendly. 

 Defined terms made more consistent throughout 

the methods (i.e. test organism, working culture)

 Clarified carrier count range to align with 

performance criteria for log reduction (must be at 

least 0.5-1.5 log higher than performance standard for log reduction)

 Added language to check desiccator system if 

drying takes longer than 60 minutes

 Added terms to the Material and Equipment 

sections for each Test Guideline

 Reference to Guidance Document added to the 

Test Guidelines

 Revised neutralization confirmation assay 13
GUIDELINE VS. GUIDANCE 

DOCUMENT

 Test Guidelines are subject to the Mutual 

Acceptability of Data (MAD)rules.

 Meaning, data generated with an OECD Test 

Guideline, must be accepted by an OECD 

member country.

 Guidance documents are not subject to MAD.

 Guidance documents can be used by member 

countries to develop their own guidelines.

 If the Test Guidelines are not approved, they may 

become Guidance Documents.

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GUIDELINES VS. GUIDANCE 

DOCUMENTS

 Major impact if Test Guidelines are not 

approved.

 Loss of harmonization

 No one test, one time for the world

 Loss of time conducting 27 laboratory ring-trial

 Option if Test Guidelines are not approved –

AOAC method

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QUESTIONS ?

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