Factors To Consider When Designing A Disinfectant … · Factors To Consider When Designing A Disinfectant Efficacy Study Rachel Blount Global Validation Manager (CC) October 2014

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2014It Matters Here. Now.

Factors To Consider When Designing A Disinfectant Efficacy Study Rachel Blount

Global Validation Manager (CC)

October 2014

Proprietary Information of Ecolab

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Introduction - Objectives

y  Requirements for Validation

y  Points to consider when designing an efficacy test protocol

y  To give an overview of the different test methods and how they are performed

y  To give an insight into the challenges associated with efficacy testing and factors affecting disinfectant performance


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Regulatory Requirements PIC/S-6 Recommendation on the Validation of Aseptic Processes

“The effectiveness of disinfectants and the minimum contact time on different surfaces should be validated”

Specific instruction to validate disinfectant efficacy but no clear instructions as to how this should be performed


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Regulatory Requirements USP <1072> Antiseptics and Disinfectants

Provides some very useful theoretical and practical information regarding the use and testing of disinfectants in a pharmaceutical setting

The test design should take into account:

y  Representative model organisms from standard cultures

y  Common environmental isolates

y  Predominant surfaces in the cleanroom

y  Performed under “clean” conditions


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What is Validation of a Disinfectant?

Demonstration that the chosen disinfectant can reduce environmental

bioburden to an acceptable level


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Efficacy Requirements Different disinfectants are effective against different types of organisms

y What technical data is available to prove the efficacy claims – is it from testing of actual product (not published data for the active only)?

y Is the spectrum of activity appropriate to the type of organisms you expect to find in your cleanroom?

y What support can your supplier offer for your in-house validation?


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Supplier Qualification y  How is the product manufactured, what certification does the

manufacturer hold? y  Will you be notified of changes to product formulation,

specification, manufacturing process etc.? y  Is the product supplied with a CoA or CoC? QC testing should

be considered for product supplied without a CoA y  Grade of water used and method of production (e.g. Ph Eur.

WFI vs. USP WFI) y  Sterility assurance for products used in Grade A/B areas (prior

to use and in-use) y  Data to support efficacy claims y  Stability data. How has the shelf life of the product been

validated?


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Stages of Disinfectant Validation All or some of the following steps may occur during validation of a disinfectant: 1.  Screening tests (various disinfectants/different

concentrations)

2.  Challenge tests using cleanroom surfaces and EM isolates

3.  Field Trial - Study of organisms isolated (frequency and type) before and after implementation of a new cleaning/disinfection regime

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Establishing Disinfectant Efficacy Specific EN Methodology


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Types of Disinfection Efficacy Test There are 3 basic types of disinfectant efficacy testing:

y Suspension Test

y Surface Tests

y Carrier Tests

All tests involve exposure of a test inoculum to a biocide under controlled conditions. The biocidal activity is a measure of the difference between the test inoculum count and the number of surviving organisms Each test type has advantages and disadvantages and may be more or less suitable depending on the intention of the testing


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The CEN Standards (Industrial Area)

• Phase 1 – Basic suspension tests • EN 1040/1275/14347

• Phase 2, Step 1 – Quantitative suspension tests • EN 1276/1650/13704/14476

• Phase 2, Step 2 – Surface test and hand wash/rub methods • EN 13697/1499/1500

• Phase 3 – Field tests under practical conditions


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Phase 1 – Basic Suspension Tests

y  Uses only 2 organisms

y  Has no interfering substance

y  Pass criteria: 5 log reduction within 5 minutes or less for bacteria, 4 log reduction within 15 minutes or less for fungi and spores

y  Data should be available from the manufacturer

y  Preliminary screening for next step


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Phase 2, Step 1 – Quantitative Suspension tests y  Take into account environmental parameters

§  Water hardness §  Organic soiling

y  Simulated “Clean” and “dirty” conditions using Bovine Serum Albumin (BSA)

y  Pass criteria: 5 log reduction for bacteria, 4 log reduction for fungi and 3 log reduction for spores


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Standard Organisms used in Industrial Methods y  EN 1276/EN 13697 Bactericidal

§  S. aureus ATCC 6538 §  E. hirae ATCC 10541 §  P. aeruginosa ATCC 15442 §  E. coli ATCC 10536

y  EN 1650/EN 13697 Fungicidal §  C. albicans ATCC 10231 §  A. brasiliensis ATCC 16404

y  EN 13704 Sporicidal §  B subtilis ATCC 6633 Spores

y  EN 14476 Virucidal §  Adenovirus-5 and poliovirus-1


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Observed Practices For sterile drug manufacture:

y Surface/coupon testing is performed

y Most commonly encountered surfaces included

y Organism test panel includes in-house isolates


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Phase 2, Step 2 – Quantitative Surface Test (EN 13697) y Simulates practical in-use conditions as far as possible

y Organisms dried onto a stainless steel surface prior to the application of the disinfectant and recovery

y  Is performed under “Clean” OR “Dirty” conditions

y Uses the same organisms as EN 1276/1650

y Pass criteria: 4 log reduction in 5 minutes for bacteria, 3 log reduction in 15 minutes for fungi

y No provision in the surface method or acceptance criteria for testing bacterial spores


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Surface Testing

Neutraliser Biocide

Inactivation of biocide by

immersion in neutraliser

Recovery by shaking with glass

beads

Calculate survivors vs. inoculum

Recovery of survivors (filtration/

plating)

Coupon dried

100µL of biocide pippetted onto

coupon > Contact Time

Test Organism + Interfering Substance


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Surface Testing

y  The number of survivors when treated with water is compared to the number of survivors when treated with biocide = Log Reduction

y  The amount of inoculum dried onto the carrier is known

y  The amount of biocide used is known

y  Reflects how the biocides are used in practice (organisms dried onto a surface, surfaces wetted with biocide and allowed to dry, the in-use dilution of biocide is used)


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Points to Consider – Acceptance Criteria The standard methods were not designed for cleanroom disinfectants – a lower log reduction than that specified by the standards may be acceptable in practice. Acceptance criteria should be set accordingly:

EN 13697 (Surface) y  Fungi - 3 log

y  Bacteria - 4 log

EN 13704 (Suspension)

y  Spores - 3 log

USP <1072> y  Bacteria - 3 log

y  Spores - 2 log


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Points to Consider – Acceptance Criteria USP <1072> “The disinfectant efficacy test must have realistic acceptance criteria”

Reduced acceptance criteria are permitted because:

y Disinfectants are less effective against the high numbers of organisms used during testing than against the low numbers expected in a cleanroom environment

y Stressed environmental organisms are not easier to kill than the standard cultures using in testing

y  In reality disinfectants are applied by wiping/mopping which physically removes organisms enhancing the “kill”


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Points to Consider – Acceptance Criteria The log reduction obtained will be impacted by the starting inocculum.

In both examples below a log 2 reduction is achieved but the actual number of organisms killed is very different:

TEST A

y  Test inoculum: 1 X 107cfu

y  Survivors: 1 X 105cfu

y  Log reduction: 2 log

y  Organisms killed: 9.9 x 106

cfu

TEST B

y  Test inoculum: 1 X 105cfu

y  Survivors: 1 X 103cfu

y  Log reduction: 2 log

y  Organisms killed: 9.9 x 104

cfu


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Points to Consider – Test Controls Each of the different efficacy tests will include the following controls:

y  Control to check that the test conditions are not lethal to the test organisms (i.e. that the organisms will not die anyway without biocide contact and cause a false positive result)

y  Control to check that the neutraliser is working effectively (i.e. that the effect of the biocide is quenched and that the intended contact time is controlled)


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Points to Consider – Soiling y  The presence of organic soiling can reduce the efficacy of a

biocide

y  “Clean” and “dirty” conditions may be simulated by adding BSA to the test culture

y  EN Norms include some interfering substance in testing of all disinfectants. “Clean” conditions more accurately reflect level of soiling of cleanroom surfaces

“Clean” conditions = 0.03% “Dirty” conditions = 0.3%


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Points to Consider – Other y  Temperature

The efficacy of biocides is temperature dependant. Standard test methods are conducted at 20°C. Use of biocides at lower temperatures may require longer contact times (e.g. in refrigerated store rooms etc.)

y  Water for Dilution of Biocide Concentrates The EN Norms use “water of standard hardness”. This should be substituted for the water which will be used in practice (e.g. WFI, DI, PWTR etc.)


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Points to Consider – Other y  Test Organisms

The standard methods specify certain organisms which should be supplemented with environmental isolates. Organisms should be selected carefully and in accordance with manufacturer’s claims. The method of culture preparation is crucial to obtaining consistent results.

y  Test Surfaces Surfaces must be non-porous. Porous surfaces will soak up the test suspension/biocide so that the test conditions can not be adequately controlled. In addition, porous surfaces are not appropriate for a cleanroom environment.


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Contact Times y  The time needed for the required level of kill to be achieved y  A product may have different contact times depending on the

target organisms (e.g. extended contact time for sporicidal action)

y  Whether a “wet” contact time is required depends on how efficacy validation was performed. NOTE: the surface is not re-wetted during the contact time for EN 13697 testing

y  To achieve longer “wet” contact times re-wetting may be required. Surface does not need to be completely saturated

y  Alcohol is very fast acting, some customers have validated full bactericidal activity at >1min contact


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Field Trials The equivalent of “PQ” testing of disinfectants

y  Verifies that the cleaning agents/disinfectants, frequencies and method of application are appropriate

y  Ideally conducted under worst case conditions (e.g. after shut-down/break in asepsis)

y  A baseline is established prior to and then during implementation of the new regime using intensive EM* sampling.

y  Statistical evaluation of the EM data before and after implementation of the new regime (results should be equivalent or better)

* Contact plates should contain validated neutralisers appropriate for disinfectants being used


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Requirement for Re-validation Efficacy validation is not a one-off exercise. Re-validation should be considered when there is:

y  A significant change in the number and/or type of organisms identified

y  Change to the predominant surface types in the cleanroom (e.g. refurbishment, new equipment)

y  Change to the formulation of the biocide


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Summary

y Disinfectant validation is a regulatory expectation

y There are a variety of test methods to choose from

y The USP requirements for biocidal action are lower than those specified in the standard test methods

y The test can be modified to be more realistic to your application if justified


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Questions?

Thank you!

Documents

Factors To Consider When Designing A Disinfectant … · Factors To Consider When Designing A Disinfectant Efficacy Study Rachel Blount Global Validation Manager (CC) October 2014