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October 2019

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Subject:
From:
"Dr. Michael J. Miller" <[log in to unmask]>
Reply To:
The Pharmaceutical Microbiology Forum Email List <[log in to unmask]>
Date:
Thu, 3 Oct 2019 16:34:36 -0400
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It also did not help that the B&L formulation was just barely passing disinfection efficacy testing against Fusarium. Once the product starts to age in the field all bets are off. And that was evident with the failure of this formulation. 

 

Ophthalmic products, including contact lens solutions, are expected to be tested against ISO disinfection and preservative effectiveness tests, which in some cases are more stringent than the USP tests. For example, the AET test utilizes a rechallenge procedure. But Fusarium is only challenged in the disinfection efficacy test. 

 

Always a great conversation is the development of biofilms in contact lens cases and adherence of organisms to the lenses before being inserted onto the eye. This was the basis for my PhD thesis and publications back in the 80’s. Those were fun times. Michael 

 

From: The Pharmaceutical Microbiology Forum Email List <[log in to unmask]> on behalf of Tony Cundell <[log in to unmask]>
Reply-To: The Pharmaceutical Microbiology Forum Email List <[log in to unmask]>
Date: Wednesday, October 2, 2019 at 10:00 PM
To: <[log in to unmask]>
Subject: Re: [PMFLIST] USP <51> AET Cultures - Fresh vs Premade

 

Richard I was going to stay that it is well known to microbiologists that

microorganisms in a biofilm are more resistant to both antibiotics and

antimicrobial preservatives but perhaps it is not.

 

One of the limitations of the USP <51> is it only tests for the log

reduction of so-called pelagic bacteria and fungi and does not address the

resistance of microorganisms in a biofilm that is more critical for medical

devices than drug products.

 

The classic example that include in my industry presentations is the

reformulated B&L contact lens solution that failed to control extrinsic

Fusarium biofilms on lenses resulting in a nationwide ocular fungal

outbreak where many victim required coronal transplants.

 

Tony

 

On Wed, Oct 2, 2019 at 12:07 PM Richard Albert <[log in to unmask]>

wrote:

 

I will take this opportunity to share the following.  The question I have

always had about USP <51> is how 'real' world it is.  Real world

microbiology is not a microbe growing in a Petri dish.  I have seen

formulations containing preservatives be very effective when evaluated

according to USP <51>.  However the preservatives were not effective when

the microbial growth was as a biofilm.  Has anyone else observed something

similar or evaluated preservative effectiveness against microbial growth as

a biofilm.

 

Richard A. Albert

Senior Microbiologist

Kleen Test Products

 

 

 

On Tue, Oct 1, 2019 at 5:04 PM Robert Pritchett <

[log in to unmask]> wrote:

 

> Hello all,

> 

> USP <51> AET has the following text regarding preparation of test

strains:

> 

> "Use standardized suspensions of test strains or prepare as stated

below."

> "The viable microorganisms used in the procedure should be part of a

> freshly growing culture (e.g., in logarithmic growth phase) with the

> exception of A. brasiliensis spores."

> 

> I've encountered at least one contract lab who uses pre-made commercially

> available lyophilized cultures specifically marketed for AET. The

> lyophilized cultures are hydrated and then used for testing and that lab

> tells me they consider this the mentioned "standardized suspensions" from

> the USP text. The contract laboratory does perform proper method

> suitability using the premade AET cultures with passing results and I

have

> seen the validation work for using AET pre-made cultures, but I still

> question the acceptability of the practice.

> 

> My personal opinions/talking points are as follows:

> - Why? It's simpler and more cost effective to start a fresh culture and

> any analyst with the title microbiologist should be able to adjust

> suspensions accordingly

> - Introducing recently desiccated, starved, frozen, and stressed cells as

> a challenge to a preservative system seems like a very bad idea - a weak

> preservative system might pass when it would otherwise fail when

challenged

> with fresh cultures

> - The validation work cannot possibly represent the varied materials and

> preservative systems that may be tested for AET

> 

> At this time, I've requested laboratories performing AET for my site to

> always use fresh cultures.

> 

> With that said, I'm open to hear what others may say on the topic. Can

> anybody defend using pre-made commercial cultures for AET?

> 

> -RP

> 

> 

> 

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> Veltek Associates, Inc - http://www.sterile.com

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Science Advisory Board https://www.scienceboard.net/

 

Steris - http://www.sterislifesciences.com/

 

Charles River Laboratories - http://www.criver.com/

 

Veltek Associates, Inc - http://www.sterile.com

 

Microbiologics, Inc. - http://www.microbiologics.com

 

BD Industrial Media - http://www.bd.com/ds/

 

Boston Analytical http://www.bostonanalytical.com/

 

Associates of Cape Cod, Inc. - http://www.acciusa.com/

 

 

=================================

The nature of this service is to provide a medium for communication.  The

specific statements and endorsements of individuals participating in the

discussions are not necessarily those of The Microbiology Network, Inc.,

the PMF, or the sponsors of the list.

 

 

 

-- 

Tony Cundell, Ph. D.

Consulting Microbiologist

Email: [log in to unmask]

Phone: 914 725-3947

Cell: 914 841-0074

 

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Science Advisory Board https://www.scienceboard.net/

 

Steris - http://www.sterislifesciences.com/

 

Charles River Laboratories - http://www.criver.com/

 

Veltek Associates, Inc - http://www.sterile.com

 

Microbiologics, Inc. - http://www.microbiologics.com

 

BD Industrial Media - http://www.bd.com/ds/

 

Boston Analytical http://www.bostonanalytical.com/

 

Associates of Cape Cod, Inc. - http://www.acciusa.com/

 

 

=================================

The nature of this service is to provide a medium for communication.  The specific statements and endorsements of individuals participating in the discussions are not necessarily those of The Microbiology Network, Inc., the PMF, or the sponsors of the list.

 


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The PMFList (http://microbiologynetwork.com/pmflist.asp) is operated from
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Please take a second to visit our sponsors' web sites and say thank you for their support of this service.
If your company would be interested in sponsoring this community, please contact [log in to unmask]



Science Advisory Board https://www.scienceboard.net/

Steris - http://www.sterislifesciences.com/

Charles River Laboratories - http://www.criver.com/

Veltek Associates, Inc - http://www.sterile.com

Microbiologics, Inc. - http://www.microbiologics.com

BD Industrial Media - http://www.bd.com/ds/

Boston Analytical http://www.bostonanalytical.com/

Associates of Cape Cod, Inc. - http://www.acciusa.com/


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The nature of this service is to provide a medium for communication.  The specific statements and endorsements of individuals participating in the discussions are not necessarily those of The Microbiology Network, Inc., the PMF, or the sponsors of the list.

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