UNITED STATES OF AMERICA

BEFORE THE FOOD AND DRUG ADMINISTRATION

DEPARTMENT OF HEALTH AND HUMAN SERVICES

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:

In the Matter of: :

:

Enrofloxacin for Poultry: Withdrawal : FDA DOCKET NO.

of Approval of Bayer Corporation\'s : 00N-1571

New Animal Drug Application (NADA) :

140-828 (Baytril) :

:

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Food and Drug Administration

5600 Fishers Lane

Rockville, Maryland

Tuesday, April 29, 2003

THE HEARING in the above-entitled matter commenced at 9:32 a.m.,
pursuant to notice.

BEFORE:

DANIEL J. DAVIDSON, Administrative Law Judge

APPEARANCES:

On behalf of the Center for

Veterinary Medicine (CVM):

NADINE R. STEINBERG, ESQ.

ROBERT M. SPILLER, JR., ESQ.

CLAUDIA J. ZUCKERMAN, ESQ.

U.S. Food and Drug Administration

Department of Health and Human Services

Office of the General Counsel

Office of the Chief Counsel

5600 Fishers Lane, GCF-1

Rockville, Maryland 20857

\(301\) 827-5050

On behalf of Respondent Bayer Corporation:

GREGORY A. KRAUSS, ESQ.

ROBERT B. NICHOLAS, ESQ.

McDermott, Will & Emery

600 13th Street, N.W.

Washington, D.C. 20005-3096

\(202\) 756-8263

Also present:

Dennis D. Copeland, D.V.M., Director

Stewardship - Government/Industry Relations

Research & Development

Bayer HealthCare Animal Health Division

Bayer HealthCare, LLC

P.O. Box 390

Shawnee Mission, Kansas 66201-0390

\(913\) 268-2522

C O N T E N T S

WITNESSES: DIRECT CROSS REDIRECT RECROSS

Robert D. Walker 192 194 245 253

258

GOVERNMENT EXHIBITS: IDENTIFIED RECEIVED

776-British standard 233

RESPONDENT EXHIBITS\"

1930-French standard 235

P R O C E E D I N G S

JUDGE DAVIDSON: Okay, on the record. Do we have any preliminary matters?

MR. NICHOLAS: We do. On behalf of Bayer, I\'m Robert Nicholas, and I
want to respond to CVM\'s motion yesterday with respect to the Sentinel
County study.

As I mentioned yesterday, Your Honor, Bayer has still not received the
complete documentation for the Sentinel County study, and critical
information is still missing.

For instance, Your Honor, the data set provided by CVC ‑‑ and this is
the data set provided in the SAS format ‑‑ identifies 471 isolates;
however, the turnover article, G-624, identifies 700 isolates in that
study.

Another article by Patton, which is B-589, describes the survey as 298
isolates; and another article by Sobel identifies the study, or
identifies 460 isolates.

So without complete documentation, Your Honor, we can\'t even tell what
the study is, much less understand what\'s been done there.

Neither the data set, the protocol, nor the questionnaire that we did
obtain identify all the variables in the data set. They don\'t
identify ‑‑ neither the data set, the proto-formula, or the
questionnaire identify the species of each campylobacter isolated.

We can\'t tell when the organisms were tested, whether they were tested
more than once, and we have not seen the laboratory test sheets ‑‑ data
sheets ‑‑ so we\'re still expecting a reply.

I had a conversation with a lawyer from CVC as recently as three weeks
ago and he promised that we would have the information and response to
our reply within a week. He then called me back and said he could not
make that representation any more. He believed we would get additional
information, but he couldn\'t let me know when.

So that\'s the current status, Your Honor; therefore, we object to the
introduction of this exhibit at this time.

JUDGE DAVIDSON: As I said yesterday, I haven\'t seen any of this. I
don\'t ‑‑ I don\'t know what it is that\'s there and what\'s not there.
I\'ve seen what\'s been put in the record. I only have your
representation that there are things missing, and I don\'t question
that.

So what I\'m going to do is I\'m going to require the parties, by close
of business ‑‑ and close of business means whenever we adjourn the
hearing on Friday ‑‑ to present me with the detailed information that I
need to rule on this. In other words, what is there and what\'s not
there. If you can\'t agree as to what is there and what\'s not there,
then I\'ll take separate representations in writing from both of you so
that I can then mull it over over the weekend and decide what I want to
do with it.

As of now, I don\'t know. I ruled earlier because I took your
representation at face value that they hadn\'t presented the
information; and now they claim they have, and I don\'t know. So I\'ll
have to ‑‑ that\'s it. By the time the hearing adjourns on Friday, I
expect a written representation from both sides, or jointly, explaining
to me what is missing, if anything is missing, and what is included; and
if you want to add the import of that if your argument is that it\'s not
important. Okay?

MR. NICHOLAS: Thank you, Your Honor.

JUDGE DAVIDSON: All right. Any other preliminary matters? Do you have
enough chairs today? Looks that way. Okay.

I think we\'re ready for Mr. Walker now.

MS. STEINBERG: Dr. Walker ‑‑

JUDGE DAVIDSON: I apologize. They ‑‑ okay, Dr. Walker. I meant no
disrespect; it\'s just the way they sent this list up to me. Sometimes
they put the doctor in front and sometimes they don\'t.

Whereupon,

ROBERT D. WALKER

was called as a witness and, having been first duly sworn, was examined
and testified as follows:

JUDGE DAVIDSON: Give your full name and address to the reporter.

THE WITNESS: Work or home?

JUDGE DAVIDSON: It doesn\'t matter, as long as you can be contacted
there.

THE WITNESS: My name is Robert D. Walker; I work at 8401 Merkirk Road,
Laurel, Maryland 20708.

DIRECT EXAMINATION

BY MS. STEINBERG:

Q Dr. Walker, can you state your position at CVM for the record, please?

A I\'m the director of the division of animal and food microbiology in
the office of research.

MS. STEINBERG: Your Honor, may I have permission to approach the
witness?

JUDGE DAVIDSON: Certainly.

BY MS. STEINBERG:

Q Dr. Walker, can you identify what I\'m handing you, please?

A This is my written direct testimony.

Q And the exhibit number?

A G-141.

Q Okay. And can you turn to page 10 of that exhibit? Is that a photocopy
of your signature on that page?

A Yes, it is.

Q Thank you. Since the time that you signed that testimony and submitted
it, have we had a chance to talk about that testimony?

A Yes, we have.

Q And have you identified to me a correction that you would like to make
for the record?

A Yes, I have.

Q And what is that correction?

A On page 7, beginning on line 3, where I state that the surveillance
system has used these values in the past, but in 2001 lowered their
resistance rate points for Ciprofloxacin to equal two or less or equal
to or greater than one microgram per mil? That is an error. They raised
their resistance rate point to greater than 2.

Q Thank you. Is there anything else that you would like to correct?

A No.

Q Thank you.

MS. STEINBERG: Your Honor, Dr. Walker is ready for cross-examination.

JUDGE DAVIDSON: Thank you. Mr. Nicholas?

CROSS-EXAMINATION

BY MR. NICHOLAS:

Q Good morning, Dr. Walker. I\'m Bob Nicholas. I represent Bayer in this
matter, and I\'m going to be doing the cross-examination this morning.

Now as I reviewed your testimony, attached to that was your curriculum
vitae. And as I reviewed that, it said that you have a Doctor of
Philosophy in veterinary microbiology and pathology. Is that correct?

A Yes.

Q And prior to joining the Center for Veterinary Medicine in 2000, you
were primarily at the College of Veterinary Medicine at Michigan State
University for about 15 years? Is that correct?

A Fourteen years.

Q Fourteen. And you described yourself in your testimony as a veterinary
diagnostic microbiologist with research interests in bacterial pathogen
post antimicrobial interagent interactions and research interests
involved in developing and validating standardized laboratory tests. Is
that correct?

A Yes.

Q So if I understood correctly, you\'re not a medical doctor ‑‑ either a
D.V.M. or an M.D., is that correct?

A That\'s correct.

Q I also note on your CV, attached to the government\'s Exhibit 438,
selected research support. You have many activities there, many projects
that you worked on involving various animals, primarily companion
animals and cattle.

So it would be accurate to say that the primary research focus is
veterinary medicine and not human medicine and that your research
experience does not include a significant focus on poultry. Is that
correct?

A That\'s correct.

Q I also noted on that same Exhibit G-1438, under Professional Societies
and Activities, you listed the Subcommittee on Veterinary Antimicrobial
Susceptibility Testing for NCCLS. In fact, you\'re one of the founding
members of that, is that correct?

A That\'s correct.

Q And also that you\'re the liaison between that committee, the
veterinary committee, and the subcommittee on antimicrobial
susceptibility testing. Is that correct?

A That\'s correct.

Q And if I understand this, NCCLS has these two separate committees ‑‑
the veterinary committee, the one that you\'re on, basically looks at
the development of antimicrobial susceptibility testing for organisms
isolated from animals; whereas, the human ‑‑ the other committee, the
susceptibility testing committee, focuses most on human medicine. Is
that correct?

A Would you rephrase ‑‑ repeat the first part of the question? In other
words, I\'m ‑‑

Q What are the two different committees, or ‑‑

A Yeah, the functions of the first one.

Q Well, let me do this. Would you tell me what the veterinary ‑‑ the
subcommittee on antimicrobial ‑‑ the veterinary ‑‑ the subcommittee on
veterinary antimicrobial susceptibility testing does?

A The subcommittee on veterinary animal antimicrobial susceptibility
testing is involved in generating appropriate testing methods and
interpreting criteria for vet meds specific to antimicrobial agents.

Q By the way, is Ciprofloxacin a vet med specific to antimicrobial
agents?

A (No audible response.)

Q It\'s approved ‑‑ do you know if it\'s approved for human medicine?

A Yes, it is.

Q All right. Would you expect that it would be used in poultry?

A I would expect it would not be used.

Q Thank you. Now the subcommittee on antimicrobial susceptibility
testing primarily has similar functions but with respect to human
pathogens isolated from humans. Would that be a fair statement?

A With antimicrobial agents used to treat pathogens isolated from
humans.

Q Thank you.

Now I\'d like to ask you a few questions about NCCLS. As I understand
it, that stands for the National Conference ‑‑ I\'m sorry ‑‑ Committee
on Clinical Laboratory Standards ‑‑

A For the National Committee for Clinical Laboratory Standards.

Q For the committee for clinical laboratory standards. And there\'s a
joint stipulation in this matter. I\'m not ‑‑ I don\'t know whether
you\'re aware of it, but there\'s a joint stipulation between the
parties and I can provide you a copy. These are joint stipulations
between the parties to this matter, the parties that agreed to these
matters.

And if you look at numbers 11, and 12, and 13, and those stipulations
describe in general the functions of NCCLS. Number 11 says, \"The
National Committee for Clinical Laboratory Standards, NCCLS, is a
standards-developing organization that develops and disseminates
standards, guidelines, and best practices for medical testing in
clinical laboratories.\"

Is that correct?

A That\'s correct.

Q And number 12, one stipulation ‑‑ \"NCCLS has established guidelines
for susceptibility testing of certain bacteria, certain antimicrobial
agents.\"

And number 13 reads: \"FDA is a member of NCCLS and uses the NCCLS
standards where feasible.\" Is that correct?

A Yes.

Q Now you\'ve worked with NCCLS for a number of years, have you not?

A Yes, sir.

Q And can you tell me how NCCLS defines a standard?

A A standard is a method that needs to be followed as described with no
variation, as opposed to a guideline.

Q And NCCLS also has guidelines that it ‑‑

A Guidelines, yes.

Q And guidelines sometimes describe how one develops a standard, but
once a standard is in place, the standard becomes the manner of doing
business. Is that correct?

A Guidelines describe how one generates data that can be fed into the
standards.

Q So for the purposes of several documents I\'m going to show you now,
which are NCCLS guidelines and/or standards, let me give you Exhibit
1796 ‑‑ that\'s G-1796. I believe most of these were referenced in your
testimony. 1796, 1797.

Now this is 1797, and this is entitled, \"Development of In Vitro
Susceptibility Testing Criteria and Quality Control Parameters ‑‑
Veterinary Antimicrobial Agents Approved Guidelines ‑‑ Second Edition,\"
is it not?

A Yes, sir.

Q So that would be the guideline that would be used to generate data, if
I understood what you said correctly, that would feed into the standard
to the extent that there was a standard developed as a result of that
guideline.

A This would be the procedure for the guidelines that a pharmaceutical
company would follow if they had a product that they wanted to present
to the NCCLS for either development, establishing quality control
ranges, or establishment of interpreting criteria, yes.

Q And 1796, would you please tell us what that document is?

A A performance standard for antimicrobial disk and dilution
susceptibility testing for bacteria isolated from animals, approved
standards, second edition.

Q And when was that standard approved?

A The standard was approved, I believe, in 2002. Q There is a joint
stipulation between the parties, number 29, that reads: \"An
NCCLS-approved method for animal origin campylobacter susceptibility
testing was not available to May 2002, when NCCLS published N-31-A2,
Performance Standards for Antimicrobial Disk and Dilutions
Susceptibility Tests for Bacteria Isolated from Animals.\"

Is that that standard?

A I think that\'s correct.

Q Now there are no NCCLS standards for isolation of ‑‑ I\'m sorry ‑‑
NCCLS standards for antimicrobial susceptibility testing for
isolates isolated from people, is there, for campylobacter?

A Are you saying that there are no NCCLS-standardized susceptibility
testing methods for campylobacter isolated from people?

Q That\'s correct.

A That\'s incorrect.

Q Would you tell us what standard that is?

A That is in the M-100-S-13 document, which deals ‑‑ which is a
supplement for the M-7 ‑‑ I think ‑‑ A-6 document.

Q Is it correct to say then that there\'s no NCCLS interpretive criteria
for campylobacter and Ciprofloxacin?

A That is correct.

Q Now could you tell us why it\'s important to establish standards; why
people spend a lot of time and effort and energy developing standards
such as the one we\'ve been talking about?

A There a lot ‑‑ there are a number of different laboratories that have
the capability of performing susceptibility tests. In order for those
laboratories to compare results of one set of data to another, there
needs to be a common ground.

The development of standardized testing methods enables those
laboratories to test under identical conditions and thus compare data
generated under identical testing conditions.

Q Now the methods go to how you prepare various free agents, to quality
of the materials ‑‑ basically, a fairly detailed methodology with
respect to how you conduct these tests. Is that generally true?

A There is some variation, but basically that\'s true with some
exceptions.

Q So in the absence of a standard, it is difficult to compare tests from
one laboratory to the next, even though they may be testing organisms of
the same species against the same antimicrobial? I believe that was your
testimony.

A No. Two laboratories testing identical isolates against the same drug
can always compare the data; but if there is not standards, then you
don\'t know of the reliability of the data they\'re comparing. Q And in
the absence of standards, is that potentially the same problem in a
single laboratory, which is known as intra-laboratory?

A Absolutely.

Q Now in your testimony, you basically address, if I understand it, two
aspects of antimicrobial susceptibility. The first aspect you deal with
the test, the development of laboratory standards or laboratory
standards to test various micro-organisms for susceptibility to
different antibiotics.

Is that correct?

A No.

Q Does your testimony address that issue?

A The first thing ‑‑ would you repeat your ‑‑ repeat your question.

Q Well, what I was asking you was whether there ‑‑ I was looking at your
testimony and I was trying to summarize that it essentially addresses
two issues. One is laboratory tests used to test the antimicrobial
susceptibility of micro-organisms to various antibiotics; and two, how
to interpret test results from laboratory tests in terms of
characterizing the organisms basically as susceptible or resistant.

A The first step would be to develop a testing method.

Q So your testimony describes various laboratory tests and talks about
the development of an acceptable laboratory ‑‑ the development of a
method that would be standardized?

A My test ‑‑

MS. STEINBERG: Your Honor, instead of summarizing written direct
testimony which is already in evidence, if Mr. Nicholas would ask a
question of the witness, it might go faster.

JUDGE DAVIDSON: Is that an objection?

MS. STEINBERG: It is an objection, Your Honor.

JUDGE DAVIDSON: Okay. The testimony speaks for itself, Mr. Nicholas.
I\'m going to sustain the objection.

BY MR. NICHOLAS:

Q Now as I understand it, Dr. Walker, prior to testing the organism to
determine the micro-organism ‑‑ in this case campylobacter ‑‑ to
determine whether it\'s resistant or susceptible to a particular
antimicrobial, the organism has to be isolated, the organism has to be
speciated so that there are other standards that are available to deal
with the isolation culture of the organism ‑‑ and your testimony does
not primarily address those issues.

A That\'s correct. There is not ‑‑ that\'s correct.

Q And when you test organisms for ‑‑ against various antimicrobials, you
want to be sure that you\'re testing a pure culture. Is that correct?

A It depends on what you\'re defining as a pure culture.

Q Well, I\'ll turn it around. Could you please define pure culture?

A A pure culture may mean that there is a single species involved. And
that\'s what you always want to do is test a pure species or a single
species.

But within a single species there may be different bio-types; and if you
look at the NCCLS document, the NCCLS documents say that you pick four
to five well-isolated colonies, put those into a broth suspension
incubator for a short period of time, make the dilution, and do the
testing.

Now of those four to five well-isolated colonies with the same cloning
morphology, are they exactly the same bio-type? Is that the question?

Q But you\'re looking for the same species?

A The same species.

Q Okay. Thank you. So at least for the purposes of your testimony,
you\'re not dealing with the isolation of organisms in order to test
them; you\'re dealing with the test ‑‑ starting from the testing of the
organisms; and your testimony doesn\'t deal with the source of
resistance, does it?

You can\'t determine from your work what the, what the ‑‑ from your
testimony where the organism came from, how it developed its resistance
to the extent it was resistant. You are just testing ‑‑ you\'re
receiving a sample basically to test for antimicrobial susceptibility?

A That\'s correct.

Q And your testimony doesn\'t deal principally with whether one uses the
Ciprofloxacin, or Amacrolyte (phonetic), or other antibiotics to treat
human cases of campylobacteriosis, does it?

A It does not deal with the clinical aspect.

JUDGE DAVIDSON: I\'m sorry, I didn\'t hear that.

THE WITNESS: It does not deal with the clinical aspect.

JUDGE DAVIDSON: Thank you.

BY MR. NICHOLAS:

Q Now I\'d like to turn to your testimony directly in a minute, but
before I do that, I\'d like to ask you the definitions of several terms
that are used in your testimony and ones that I think I want to make
sure I understand accurately.

An antimicrobial susceptibility test, it\'s a laboratory method?

A It is a laboratory method.

Q So it doesn\'t involve studies of how people respond in clinical
settings, it\'s a laboratory method?

A Susceptibility testing efforts are not ‑‑

Q And could you define for us minimum inhibitory concentration, or MIC?

A Minimum inhibitory concentration is the minimum concentration of an
antimicrobial agent required to inhibit the growth of an organ
susceptible for an organism.

Q And with respect to what you term ASTs, or Antimicrobial
Susceptibility Tests, the MIC is recorded how?

A In terms ‑‑ quantitative ‑‑

Q Quantitative ‑‑

A Right.

Q And the quantitative number that you get from conducting one of these
tests will tell you, if I understand correctly, that the organism has a
certain response in that test system. It won\'t tell you anything
without interpretative criteria as to whether that organism will be
clinically resistant or not ‑‑ is that correct?

A It will give you an indication as to how much drug is required to
inhibit the growth of that organism under those testing conditions.

Q Could you define for us, please, breakpoint?

A In regards to susceptibility testing?

Q That\'s correct.

A Okay. Breakpoint in regards to susceptibility testing is that point at
which an organism is determined to be susceptible for the susceptible
breakpoint, intermediate for the intermediate breakpoint, or resistant
for the resistant breakpoint. Q Now when I asked you to define
breakpoint, you asked me to clarify with respect to antimicrobial
susceptibility testing. Is there another breakpoint known as the
clinical breakpoint?

A Generally speaking, these breakpoints are clinical breakpoints.

Q Is there ‑‑ I thought you testified earlier that there was no
NCCLS-established clinical breakpoint for campylobacter and
Ciprofloxacin.

A I did not.

Q So similarly, there is no established breakpoint for antimicrobial
susceptibility tests that define something as susceptible, intermediate,
or resistant with respect to clinical outcome, is that correct?

A It is not correct.

Q Let me come back to that. Let\'s ‑‑ the ‑‑ let\'s talk about
campylobacter from there. Would you agree that campylobacter, which
principally causes gastral enteritis and infection of the
gastro-intestinal tract, frequently is self-limited?

A I would agree.

Q And is what\'s known as a fastidious organism? A I would agree.

Q And why is it characterized as a fastidious organism?

A Because it requires unique growth requirements and it also is not an
organism that is capable of surviving for a prolonged time outside a
well-defined environment.

Q That would be one of the reasons that it would be important to
standardize testing of campylobacter isolates, is that correct?

A Any time you have an organism that has unique growth characteristics,
it is important that you develop standardized testing methods for that
organism and its unique growth characteristics.

Q Now I\'d like to direct you to page 3 of your testimony, Exhibit 1481.
And on that page, at line 15 to 17, you describe the standardized
susceptibility testing methods used ‑‑ one of three methods. Is that
correct?

JUDGE DAVIDSON: It\'s self-explanatory. That\'s what it says.

BY MR. NICHOLAS:

Q And would you describe ‑‑ you described those tests as agar dilution,
the gold standard of susceptibility testing; broth dilution; and agar
diffusion.

Would you tell us briefly please what agar dilution is? What an agar
dilution antimicrobial susceptibility test is.

A An agar dilution antimicrobial susceptibility testing method is where
the antimicrobial agent is incorporated into the agar, and the
organisms ‑‑ the test organisms are then placed on the surface of that
agar.

And it generally ‑‑ the drugs are incorporated into the agar at two-fold
dilution ‑‑ using a two-fold dilution scheme and the ‑‑ test ‑‑

Q And what\'s broth dilution? Would you describe that, broth dilution?

A Broth dilution can be macro or micro and it\'s where the antimicrobial
agent is incorporated into a broth medium ‑‑ again, using the two-fold
dilution ‑‑ generally, using the two-fold dilution scheme.

Q And disk diffusion?

A Disk diffusion is where an antimicrobial agent is incorporated into
some carrier device, like a paper disk, and placed on the surface of a
medium that\'s already been seeded with a micro-organism and allowed to
diffuse into the medium, radiating out from the point of contact.

Q And you listed agar dilution as the gold standard. What makes it the
gold standard?

A It\'s ‑‑ in many circles, it is referenced as the gold standard
because it\'s what everything ‑‑ all the other testing methods are
referred back to. In other words, if you test by a broth-dilution
testing method, you want to compare the broth-dilution testing method
back to the agar-dilution testing method for comparability because the
agar dilution would be the more accurate of the testing methods.

Q And did you list these in sort of order of accuracy, from most
accurate in descending order?

A No.

Q Now as you describe these tests, they basically have somewhat
different characteristics. Tell me how a laboratory, the FDA for
instance, would choose which test method it would use generally, and
then I want to ask you to be specific ‑‑

A In our laboratory, the first ‑‑ it depends on the ‑‑ what you are
trying to accomplish, what your end point is. In our laboratory, because
of our end point, the first thing we would look at is using standardized
testing methods. The second thing we would look at is volume.

And, of course, this is all being with the understanding that their
accuracy is equal.

Q Would you look at cost?

A We\'re a government lab, we don\'t have to.

Q Well, I think that Congress might think otherwise, but I don\'t
presume to speak for the Congress.

A No ‑‑

Q We all operate within budgets.

A \-- because of what we do, we\'re more concerned with accuracy; but
cost is a consideration.

Q How about ease of use, practicality?

A In our laboratory we cannot sacrifice accuracy for ease of use.

Q So you would use the gold standard?

A We do use the gold standard.

Q Would you use it most of the time?

A Are you ‑‑ in reference to?

Q Well, you were describing your laboratory and your mission, so I want
to talk generally and then I\'ll ask you specific ‑‑

A For all organisms, no, we would not, because there are other testing
methods that have been shown to be as accurate, or equally, in terms of
accuracy and have a greater throughput.

Q Now a throughput is a question of speed of ‑‑

A Volume.

Q Volume.

A Volume of what you get ‑‑

Q Now let\'s talk about campylobacter in your laboratory. Do you use the
agar-dilution testing?

A Yes, we do.

Q And when you describe your mission, could you tell me what your
mission is? Meaning CVM\'s mission in your laboratory.

MS. STEINBERG: Objection, Your Honor, that is an awfully vague question.
Could Mr. Nicholas narrow the scope to that question?

JUDGE DAVIDSON: You can answer the question, but only to the extent that
it is not already covered in your testimony.

THE WITNESS: We have in our division a mission statement. I am not ‑‑ I
cannot recall exactly what that mission statement says at this point in
time. BY MR. NICHOLAS:

Q I wasn\'t trying to put you on the spot from that perspective. I was
trying to understand what it is you were talking about when you said
that you would use a particular standard given our mission ‑‑ accuracy
is important to me ‑‑ sometimes there are screening tests, sometimes
there are enforcement methods. So FDA has many different missions and
many different standards. I was trying to understand your context.

A In this respect, our mission is to provide accurate antimicrobial data
to support CVM\'s mission for the approval of safe and effective drugs
for use in humans.

Q So for the screening of campylobacter to various antimicrobials, your
center routinely uses agar dilution?

A Yes, sir.

Q Now the NCCLS committee that you served on that finalized the
performance standards identified as G-1796, that standard did not adopt
disk diffusion, did it, as the standardized method?

A When you said that I served on, am I offered it?

Q I\'m sorry?

A That I served on. Am I offered it?

Q You\'d be in a better position to know than I would, sir.

A Okay. What do you mean it does not?

Q Well, being adopted as the reference standard, I believe ‑‑
standardized agar dilution as the antimicrobial susceptibility standard
for campylobacter, did it not?

A Yes.

Q All right. And it did not adopt any of the other kinds of tests as the
standardized test for campylobacter, did it?

A At this point in time, it has not.

Q So at least at this point in time, meaning May of 2002, when the
standard was published ‑‑ is that correct ‑‑ the committee did not adopt
as a consensus standard disk diffusion, or any other method. It adopted
agar dilution, is that correct?

A As the reference method, yes.

Q Now if I understood your testimony correctly earlier, your oral
testimony, you were describing reasons for standardizing tests and test
methodologies, and essentially you testified that, if I have this
correctly, that it was important to standardize tests so that one could
have confidence in the accuracy of the data coming out of different
laboratories so that one could rely on it, compare it, use it in
whatever fashion that would be appropriate; but that basically
standardization was important to be able to use the data. Is that
correct?

A Standardization ‑‑ if parties are going to compare
intra/inter-laboratory data, there needs to be a common basis by which
they do their testing method. And that is ‑‑ that common method has been
defined by NCCLS as standardized testing.

Q So prior to May of 2002, because there was no standardized NCCLS
method, it would be difficult to rely on data coming from different
laboratories if they did not use the standardized method as standardized
by NCCLS?

MS. STEINBERG: Your Honor, is that a question? I want to object to the
form.

MR. NICHOLAS: I thought it was. My voice went up at the end.

JUDGE DAVIDSON: You can answer.

THE WITNESS: That\'s an interesting question. BY MR. NICHOLAS:

Q Well, let\'s ‑‑ could we start off with a yes or no and then I
could ‑‑ I\'d like to hear more.

A Okay, would you repeat the question?

Q That\'s an interesting question.

Well, I\'m basically saying that you testified earlier that standards
were important so you could have the ability to compare ‑‑ you would
have the ability to rely upon data from other laboratories that was
developed in the same way ‑‑ the results were comparable, if you
would ‑‑ and that before there was a standard, an NCCLS standard, it
would be difficult to do that laboratory to laboratory ‑‑ that different
laboratories, in the absence of standards by NCCLS, would perhaps be
doing tests differently ‑‑ even the same test.

A That\'s true.

Q And this would have been true prior to 2002, May, for disk diffusion,
or micro-growth dilution, and growth dilution as well. Is that correct?

A Sure.

Q Now could you tell us about the E-test? You referenced an E-test in
your testimony. I\'m sure you remember ‑‑

A Yes, sir.

Q \-- and you\'ve used the E-test frequently ‑‑ did frequently?

A We use it frequently.

Q Okay. And when you say we use it frequently, now you\'re talking about
in your laboratory ‑‑

A My laboratory ‑‑

Q \-- in the FDA, performing your functions and ‑‑ is that correct?

A For ‑‑ to a limited extent, yes.

JUDGE DAVIDSON: I\'m sorry?

THE WITNESS: To a limited extent, yes.

JUDGE DAVIDSON: Thank you.

BY MR. NICHOLAS:

Q And you ‑‑ did you use the E-test previously, when you were at
Michigan State?

A Yes, I did.

Q Now when did the E-test become available?

A I\'m not sure when it was first marketed. I think probably back in the
early \'90s.

Q And the E-test ‑‑ when you use the E-test, do you also use the
campylobacter ‑‑ testing campylobacter susceptibilities to various
antimicrobics?

A Yes, we do.

Q Okay. And you do that as a routine part of your mission and work for
CVM?

A No.

Q Could you tell me the difference?

A For the vast majority of the organisms that we do susceptibility
testing on, we use broth micro-dilution. Because we are involved in an
inter-laboratory collaboration, we use the E-test for campylobacter
isolates that pertain to those inter-laboratory collaborations, but we
also do the agar dilution on those same isolates.

Q And who are the laboratories that collaborate with you on this effort?

A ARS and CVC.

Q And do ARS and CVC use ‑‑ if you know ‑‑ use the E-test?

A Yes, they do.

Q And they also do agar dilution?

A I don\'t know.

Q Now could you tell me ‑‑ the E-test has the scale for reading the MICs
of various antimicrobials that it\'s formatted for ‑‑ and what\'s the
upper end of that scale for Ciprofloxacin?

A Jeez, I\'m just guessing. I\'d probably say 256, but I couldn\'t tell
you for sure.

Q This is the E-test?

A Yes.

Q And how about agar dilution?

A Agar dilution can be ‑‑ the upper end of that scale can be determined
within the laboratory on any particular testing day. In our laboratory
we frequently or routinely use 8 micro-grams per ‑‑

Q But is it ‑‑ could it be used for higher?

A If we chose to we could go higher.

Q Now the E-test is not validated as the gold standard, is it, by NCCLS?

A No, it is not.

Q Now there was a study done in your laboratory, I believe. And let
me ‑‑ it\'s Exhibit Number 763, G-763, by NCCLS. Is that correct?

A Yes.

Q And you\'re listed as an author on that?

A Yes, sir.

Q And when was that study commenced, do you know?

A Probably in the year 2000, late 2000/early 2001.

Q And was that study done as a result of the NOOH published by FDA?

A No.

Q And what was the purpose of the test ‑‑ I\'m sorry, the study?

A We had gone to the NCCLS with a standardized testing method for
campylobacter using the agar dilution. We had gotten ‑‑ received
tentative approval of the testing method and QC organism; and I knew
that a lot of labs were doing the E-test and I wanted to know how well
the E-test compared to the agar dilution.

Q Is the E-test difficult to use? Does it have some features that make
it difficult to use?

A Susceptibility testing in general, when properly performed, is not
necessarily an easy testing procedure.

Q And it\'s more difficult with fastidious organisms such as
campylobacter, is that correct?

A Not necessarily once you define the conditions.

Q Well, I thought campylobacter were difficult to grow, for instance.

A They are.

Q And indeed, in this study that I\'ve handed you, there were some
difficulties in growing campylobacter, were there not?

If you\'ll turn to page 10. Let me read to you. It says: \"Certain
fastidious bacteria and campylobacter present difficulties in
antimicrobial susceptibility testing due to both unique requirements and
test conditions. The methodology has proved relatively accurate methods
to test antimicrobial susceptibility of fastidious organisms.\"

And on page 11, at line 7, it says, \"A technical problem that arose
during this study was the poor growth of some campylobacter isolates on
E plates, causing difficulty in interpreting the results.\"

So there are difficulties in using the E-test, would you acknowledge
that?

A For testing campylobacter, once you define the testing conditions,
then you have a fastidious organism that will not grow under normal
testing conditions, in which case the results would be not appropriate;
but once you define those testing conditions, those are testing
conditions under which the organism performs very well.

So under those conditions, the E-test should work basically the same for
campylobacter as it would for E-coli, but there are some, as indicted
here ‑‑ there are always some isolates that may not be as easy to
cultivate in the laboratory as other isolates.

Q Thank you. But in the absence of standardization, you would expect to
see, or likely would see, variability lab to lab in the use of the
E-test?

A The purpose of standardization is to demonstrate that you do
have experience ‑‑

Q I would think the purpose of standardization would be to eliminate the
variability so that you set standards and you eliminate the
variability ‑‑ not to ‑‑ not to establish variability. So is that my
misunderstanding, sir?

A You define a standardized testing method. Then, because you have those
standards, if you have ‑‑ if you\'re doing a test and you\'re testing
and you do not meet those standards, that tells you that there\'s a
problem within your testing environment.

Q And in the absence of those standards, you really can\'t tell, can
you?

A It\'s difficult. It\'s difficult.

Q Now on page 4 of Exhibit G-763 ‑‑ the reference is page 3, I\'m
sorry ‑‑ at line 18, it says, the study indicated \"The E-tests were not
in complete agreement with the agar dilution tests. Although the E-test
has proven to be a satisfactory testing method, its use for
campylobacter susceptibility testing requires further standardization.\"

Now it says it\'s not in complete agreement and it says it\'s a
satisfactory ‑‑ and in order for it to be proven to be satisfactory, it
requires further standardization.

Would you disagree with that?

MS. STEINBERG: I\'m sorry. Can you clarify where you are on the
document?

MR. NICHOLAS: Page 2, line 18 to 20. I\'m sorry.

MS. STEINBERG: And I\'m sorry. Now that we have the right page, could
you repeat your question?

BY MR. NICHOLAS:

Q Dr. Walker, on page 2, line 18 to 20, it says the study indicated the
E-tests were not in complete agreement with the agar dilution test.
\"Although E-test has proven to be a satisfactory testing method, its
use for campylobacter susceptibility testing requires further
standardization.\"

Do you disagree with that statement?

MS. STEINBERG: Your Honor, I object. It\'s ‑‑ this ‑‑ I withdraw the
objection.

THE WITNESS: I agree with that statement.

BY MR. NICHOLAS:

Q I\'d also like to direct your attention to page 8. On Page 8, lines 14
to 15, it states, \"On the other hand the E-test tended to yield much
higher resistant MICs than those measured by agar dilution at the
resistant end of the ranges.\"

Is that correct?

A (No audible response.)

Q And it further goes on to say \"The Ciprofloxacin-MIC agreement
between the two methods was 85.2 percent.\"

MS. STEINBERG: Objection, form of question, Your Honor.

JUDGE DAVIDSON: Yes, I mean, Mr. Nicholas, you\'re reading material
that\'s already in the record again into the record. And then I want a
question. And if you have a question ‑‑ if you just want the witness to
agree with all this, why don\'t you ask him if he has any problems with
the study?

I mean, this is ‑‑ I know you like to see it again and again and again
and again if it proves a point you\'d like to get across, but once is
enough for me.

MR. NICHOLAS: Thank you, Your Honor. Appreciate that.

BY MR. NICHOLAS:

Q Dr. Walker, if in this study one was looking at the performance of ‑‑
the performance of two different tests, you would ‑‑ well, let me
rephrase the question.

MR. NICHOLAS: Excuse me a minute, Your Honor.

JUDGE DAVIDSON: Certainly.

BY MR. NICHOLAS:

Q Let\'s turn to interpretive criteria, if we may.

JUDGE DAVIDSON: Are we talking about his testimony now?

MR. NICHOLAS: Yes, Your Honor.

JUDGE DAVIDSON: Thank you. Do you have a page and line number for us?

MR. NICHOLAS: Beginning on line 23 on page 4, and going on to page 5.

BY MR. NICHOLAS:

Q Now as I understand it, there are no interpretive criteria for
interpreting the antimicrobial susceptibility results from a test
testing campylobacter to Ciprofloxacin. Is that correct?

A There are no NCCLS-approved interpretive criteria.

Q Are there other criteria approved that have been established in the
same fashion as an NCCLS criteria?

A Not that I\'m aware of.

Q So the British standard that you mentioned on page 6, line 39, and ‑‑
the British report, I\'m sorry, that you mentioned on that page; and the
French proposal, or tentative standard that you mentioned on line ‑‑
beginning on line 44 on page 6 and going over onto page 7 ‑‑ neither of
these proposals, or tentative criteria, were promulgated in the same
fashion as NCCLS would have been on the standardized criteria for
interpreting antimicrobial susceptibility of campylobacter. Is that
correct?

A I\'m not sure how they determined that.

Q Well, would it surprise you to know that the British standard is based
on disk diffusion?

MS. STEINBERG: Objection.

JUDGE DAVIDSON: Sustained.

BY MR. NICHOLAS:

Q Do you know whether the British standard was based on disk diffusion?

A No, I do not.

JUDGE DAVIDSON: Do you need some time?

MR. NICHOLAS: No.

JUDGE DAVIDSON: Okay.

BY MR. NICHOLAS:

Q When you were mentioning the British standards, is that the document
you make reference to?

A Yes.

Q And would you take a moment to look at it and tell me whether it is
based on the standard of agar dilution testing?

JUDGE DAVIDSON: While he\'s doing that, do you want to give it a number?

MR. NICHOLAS: I\'m sorry? Yes.

JUDGE DAVIDSON: It\'s going to be in the record. You\'re referring to
it. It has to have a number, as petty as that may seem.

MR. NICHOLAS: B-1939.

JUDGE DAVIDSON: Okay. Thank you.

MS. STEINBERG: Your Honor, excuse me, I think that\'s also Government
Exhibit G-776, that Mr. Nicholas ‑‑

JUDGE DAVIDSON: Well, if it is we can strike 1930 and just call it ‑‑
it\'s the same document.

MS. STEINBERG: It does look to be the same document. It has the same
citation.

JUDGE DAVIDSON: Well, unless someone can show me otherwise, it\'s
Exhibit G what?

MS. STEINBERG: 776.

JUDGE DAVIDSON: 776. And the next number for Bayer will be 1930.

MR. NICHOLAS: Thank you, Your Honor.

(Government Exhibit 776 was marked for identification.)

BY MR. NICHOLAS:

Q Mr. Walker, Have you previously read this document?

A I have looked at it; I have not read it in detail.

Q On page 79, it speaks about campylobacter.

A Yes, sir.

Q And if you read the ‑‑ well, it says here, does it not, that
susceptibility tests for campylobacter species are not standardized and
therefore there is some variability. I\'m reading now in paragraph 1,
where it talks about campylobacter in this document.

A Mm-hmm.

Q \"Susceptibility tests for campylobacter species are not standardized
and therefore there is some variability in the susceptibility data
reported in the literature.\" And then they go on to discuss disk
diffusion, do they not?

A They do.

Q Is there any discussion of clinical data or any of the other extensive
requirements that NCCLS would use in setting a standard?

A No, there\'s not.

Q Okay. Thank you. Are you familiar with the French standard that\'s
cited in ‑‑

A No, I\'m not.

Q So if I told you that that standard ‑‑ you said you\'re not familiar
with it, so let me find it and ‑‑ it is cited in your testimony, is it
not?

A Right.

Q If you are not familiar with this document, Dr. Walker, could you tell
us why you cited it in your testimony?

A I was familiar with other ‑‑ with breakpoints being set. And you can
be familiar with breakpoints being set without reviewing all the
literature that pertains to them.

Q Let me give you this document. Let\'s see, it looks like we may have
B-1930, Your Honor.

This was pulled off the Web site and cited in the testimony. And I
believe campylobacter is discussed in the back of that document. If you
turn to the table of contents, it lists campylobacter on page 44.

JUDGE DAVIDSON: Do you have a copy for the reporter?

MR. NICHOLAS: Yes, Your Honor.

(Respondent Exhibit 1930 was marked for identification.)

BY MR. NICHOLAS:

Q And on page 44, where it discusses campylobacter, is there any
discussion of clinical data or the other types of data that NCCLS would
use to establish a standard?

A No, there\'s not.

Q And I think you said earlier in response to a question by Ms.
Steinberg that your reference with respect to the Danish surveillance
system was incorrect.

And that\'s on page 7, line 3 to 6, where you state that it was lowered,
but in fact it was raised.

A Yes, sir.

Q Now in paragraph 17, on page 7 of your testimony, you discuss the
NCCLS interpretive criteria for enterobacteriosis, is that correct?

A Yes, sir.

Q And this is a standard established by and adopted by NCCLS; and it is
Exhibit 1794. Is that correct? I think I gave you that, but if I
didn\'t, please let me know.

Now this is an NCCLS-approved interpretive criterion, is that correct?
Adopted?

A This 1794?

Q Right. Yes.

A Yes, sir.

Q And would you tell us whether this standard, by its terms, covers
campylobacter?

A In this particular document, it does not. It does not.

Q Now would you describe how one would go about setting a standard for
campylobacter, a breakpoint for campylobacter resistance to
Ciprofloxacin?

A The NCCLS protocol for establishing interpretive criteria for an
organism is, number one, develop or identify a testing method, including
the appropriate QC organisms and QC testing ranges.

Number two, to determine the susceptibility of ‑‑ type organisms to that
drug, using the approved testing method, and in conjunction with the QC
organisms that have been developed.

The next would be looking at the pharmaco-kinetic/pharmaco-dynamic
parameters associated with that drug in the target animal species.

And the fourth would be looking at the clinical response of the patient
when treated with the approved dosing regime against organisms, against
the target organisms.

Q And, as I understand from what you\'ve said, this is both
organism-specific and antimicrobial-specific. So that if one wanted to
develop an interpretive criteria for ‑‑ and a breakpoint for
campylobacter resistance to Ciprofloxacin, you would basically have to
go through all of these steps for NCCLS approval. Is that correct?

A Generally speaking. There are some exceptions.

Q Now if you are looking at, in the NCCLS process, developing such
interpretive criteria ‑‑ you mentioned clinical response. This is
essentially data from clinical studies or from patients participating in
the studies ‑‑ and if you are looking for a clinical response, you would
be looking at infections ‑‑ you would be looking at response to
different kinds of infections. Is that correct?

Or would you just, for instance, look at responses to respiratory
infections, or would you look at gastro-enteritis, for instance?

A If a drug were being marketed for treating respiratory tract
infections caused by a specific organism, that would be the target of
the study. It would not address other organisms associated with ‑‑

Q Let\'s go back to pharmaco-kinetic ‑‑ okay. Now you\'ve worked in this
area. You\'ve done these kinds of studies with respect to various
antimicrobials, have you not?

A I\'ve done some PK-PD studies, yes.

Q And in your testimony, I believe, you go through a calculation with
respect to how you might set a resistance breakpoint for the clinical
response of campylobacter to Ciprofloxacin.

I\'m looking now on page 7, paragraph 17.

A Could you repeat your question?

Q Well, looking at paragraph 17, on page 7 in your testimony, you
describe a calculation based on, I believe, MIC ‑‑ I\'m sorry, based on
PK data and PD data that would result, in your estimation, when someone
is dosed with 500 milligrams of Ciprofloxacin and they have a
campylobacter infection ‑‑ you describe an MIC ratio of 8 to 12 would be
necessary in order to have a clinical response to the ‑‑

MS. STEINBERG: Objection, Your Honor.

JUDGE DAVIDSON: Is that a question?

MR. NICHOLAS: Is that correct?

JUDGE DAVIDSON: The exhibit speaks for itself.

BY MR. NICHOLAS:

Q Is this ‑‑ the question was is this how you would go about
establishing a resistance breakpoint for campylobacter ‑‑ Ciprofloxacin?

A Yes, it is one part of the equation.

Q Right. But it\'s not the complete part of the equation?

A No.

Q And you have not done the complete part of the equation, have you?

A By myself ‑‑

Q That\'s correct.

A \-- have I done all aspects of it?

Q Yes, sir.

A No, I have not.

Q Has NCCLS reviewed all of these criteria? They haven\'t have they?
They have not published a standard?

A For?

Q For interpretive criteria for Ciprofloxacin resistance to
campylobacter.

A NCCLS cannot initiate establishing interpretive criteria on their own.

Q A pharmaceutical company is required to initiate those efforts?

A If, in human medicine, a pharmaceutical company is desirous of having
an NCCLS interpretive criteria, it is their responsibility to put
together a package, following the M-23 guidelines, and present that
information to the NCCLS for their review for establishment of NCCLS
interpretive criteria.

Q So would you tell me how you derived ‑‑ how you reached your
conclusion that, based on these values, one would expect that a
resistant breakpoint ‑‑ I\'m reading on page 7, line 25 to 26 ‑‑ \"that
one would expect that a resistant breakpoint for bacterium should be no
higher than one microgram per milliliter.\" And this is for
campylobacter specifically.

A This is my opinion, based on using PK-PD analysis: It does not
incorporate clinical trials. And, while this is my opinion, if we were
to do clinical trials and demonstrate that I am right or wrong ‑‑
whichever it may be ‑‑ those are the values that we would accept because
that is the method the NCCLS has defined for generating that
information.

Q All right, but clinical studies have not been done?

A The sponsor of Ciprofloxacin has not provided the clinical studies.

Q Does FDA require, if you know, in the drug-approval process, the human
drug-approval process, require such standard?

A If a drug, as far as I know ‑‑ if a drug is ‑‑ has FDA approval for a
specific disease entity, there must be clinical data to support that
claim.

Q And Ciprofloxacin is an approved drug, is that correct?

A Is what?

Q Is an approved drug?

A It is an approved drug for treating a number of disease entities, but
I don\'t know if it has specific FDA approval for treating
campylobacteriosis.

Q But if it did have approval for treating campylobacteriosis, then
it ‑‑ according to your testimony ‑‑ you would expect to find those data
in the NDA?

A I would have expected that the sponsor would have provided FDA with
appropriate clinical trials to support that claim.

Q Now let\'s talk about how you arrived at your calculation using PK and
PD data. You measured ‑‑ you looked at certain concentrations, is that
correct?

A That\'s correct.

Q Now you stated earlier that gastro-enteritis ‑‑ will you agree with my
statement that gastro-enteritis is primarily a disease of the
gastrointestinal tract?

Is that correct?

MS. STEINBERG: Your Honor ‑‑

JUDGE DAVIDSON: Preliminary ‑‑

MS. STEINBERG: Thank you, Your Honor.

JUDGE DAVIDSON: Let him answer.

BY MR. NICHOLAS:

Q I\'m sorry, campylobacteriosis ‑‑

A It is an inflammation of the epithelial cells lining the
gastrointestinal tract.

Q And when you look at the activity of the drug in order to determine ‑‑
antimicrobial ‑‑ in order to determine whether that antimicrobial is
likely to be effective, you typically tend to look at the site of the
infection, don\'t you? The concentration of the drug at the site of the
infection?

A That\'s part of the PD package.

Q Now in your calculation you use serum concentrations, is that correct,
and not blood-level concentrations?

A In my calculations, I did use a ratio associated with serum
concentrations.

MR. NICHOLAS: I have no further questions, Your Honor.

JUDGE DAVIDSON: Okay. We\'ll take a brief, brief, brief ‑‑ unless, does
anybody need a pit stop or break? If not, we can get to the redirect by
changing sides.

MS. STEINBERG: How about a five- or ten-minute break?

JUDGE DAVIDSON: All right. We\'ll take a ten-minute recess. When we come
back, we\'ll switch tables. MS. STEINBERG: Thank you very much.

(A brief recess was taken.)

MS. STEINBERG: Thank you, Your Honor.

REDIRECT EXAMINATION

BY MS. STEINBERG:

Q Dr. Walker, I want to go back to some of the issues that were raised
on cross examination. Specifically, I want to ask you a few questions
about the E-test. In your opinion, is the E-test a sufficient method for
detecting Ciprofloxacin resistance in campylobacter ‑‑

A I would say that it is an adequate method, yes.

JUDGE DAVIDSON: Sorry, I didn\'t hear.

THE WITNESS: I would say that it is an adequate method.

JUDGE DAVIDSON: Thank you.

BY MS. STEINBERG:

Q And can the E-test be used to monitor changes in the prevalence of
Ciprofloxacin resistance in campylobacter?

A I think in this day and age it can be.

Q Are there any advantages to using the E-test in a clinical test
setting?

A In a clinical situation where a lab may have a single isolate, it
would be to their advantage to use something like the E-test as opposed
to the agar dilution, mainly because of the ease of operation.

Q Turning to agar dilution, is that method a practical method for
routine clinical ‑‑

A No, it is not.

Q Why?

A In order to use the agar dilution ‑‑ to run the agar dilution, a
series of plates need to be made and on those plates you can run up to
35 isolates; and, if the lab has a single isolate, it is not worth ‑‑ it
doesn\'t make sense for them to use that much material to test a single
isolate.

Q Have there been any tests or studies that compare results obtained
through use of E-test and use of agar dilution for campylobacter,
specifically for Ciprofloxacin and tests against campylobacter?

A Have there been any tests that have compared E-test and agar dilution
results when testing campylobacter against Ciprofloxacin? Yes, there
have been.

Q And what did those tests show in terms of a correlation? What did
those studies show as ‑‑ in terms of a correlation between these two
testing methods ‑‑ antimicrobial susceptibility testing ‑‑

A The ones that I\'m familiar with there\'s any where from an 85 to
about 88 percent agreement.

Q And are you referring to an agreement with the MIC?

A I think in some of those papers they talk about an agreement and
whether it is an agreement in interpretations or actual MIC values. I\'d
have to go back and refresh my memory on that. In some of the studies
that we have done, we find that the agreement is within the
interpretation.

Q And just to clarify so that I make sure that it is clear ‑‑ in terms
of comparability, are there two ways you can compare results?

A There are two way that you can interpret ‑‑ there are two ways that
you can use the data generated by the E-test versus the agar dilution.
One is in terms of the interpretation ‑‑ susceptible versus resistant.
The other is the actual MIC value.

And I think the studies that ‑‑ where they talk about the correlation,
it is an interpretation for susceptible versus resistant.

Q And do you recall the correlation? Was there a good correlation?

A A reasonable correlation. Like I said, 85 to 88 percent, I think.
Yeah.

Q What is a bimodal population discrimination?

A A bimodal is where you have two peaks, and those two peaks could be
side by side ‑‑

MR. NICHOLAS: Your Honor, we object to this question. It\'s outside the
scope of the questions on cross-examination.

JUDGE DAVIDSON: Okay. Respond?

MS. STEINBERG: I am trying ‑‑ can we have a sidebar?

JUDGE DAVIDSON: Now the response you have to give me on the record is
whether or not you believe it is or is not within the scope of cross?

MS. STEINBERG: I\'ll withdraw the questions and ask the next question.

JUDGE DAVIDSON: Thank you.

BY MS. STEINBERG:

Q Is there anything special about campylobacter MIC results that would
help determine the usefulness of certain antimicrobial susceptibility
testing methods ‑‑ A Are there certain criteria about susceptibility
testing ‑‑ about the susceptibility testing of campylobacter ‑‑ would
you repeat the question?

Q Yes. I\'ll rephrase it. Are there certain characteristics noted about
campylobacter MIC results that would help you interpret the usefulness
of antimicrobial resistance testing methods ‑‑ certain ones that ‑‑

A One of the things that we\'ve noticed about campylobacter is that
we\'re either dealing with a very susceptible population or a very
resistant population. We don\'t seem to see a lot in the middle. And
when you have a population of organisms that exhibits that type of
susceptibility testing results, you have more degrees of freedom in the
type of testing methods that you use because you\'re not held to a
one-dilution difference in interpretation.

Q And is that observation of the MIC levels in campylobacter commonly
referred to in any way?

A What we\'re seeing with the campylobacter and what is referred to as a
bimodal distribution in terms of susceptibility profiles.

Q And with a bimodal distribution, is it ‑‑ does it ‑‑ with observation
of a bimodal distribution, does it make it easier to use in several
different antimicrobial-resistant methods when you are trying to
determine susceptible versus resistant?

A When you have an organism that displays the bimodal distribution
pattern that campylobacter displays ‑‑ and the reason I make the
distinction there is because you could have bimodal where you have two
peaks side by side. In this case, you would have two peaks that are a
great distance apart. When you have those peaks such a distance, then it
allows greater flexibility in your testing methods. It\'s not a correct
statement really. It provides you with ‑‑ I guess that\'s what you\'d
say ‑‑ it provides you with increased flexibility in your testing
methods.

MS. STEINBERG: May I have one minute, Your Honor?

JUDGE DAVIDSON: Certainly.

(A brief recess was taken.)

BY MS. STEINBERG:

Q Dr. Walker, is there any precedence in using serum concentration of an
antimicrobial agent to determine clinical applicacy of that agent
against enteric pathogens?

A In the NCCLS document there are antimicrobial agents that have been
approved for use in treating organisms belonging to the family
enterobacteracin. Some of those organisms may be associated with soft
tissue infections, but some other are associated with enteritis.

And the NCCLS document does not necessarily make a distinction between,
say, a salmonella that\'s associated with a pneumonia versus a
salmonella that\'s associated with and an enteritis. In fact, it
specifically talked about using extra-intestinal and inter-intestinal
interpretations. It specifically mentioned that you can use that.

Q Was the answer yes?

A Yes.

Q Thank you. Turning to the standards setting organizations in the UK
and in France ‑‑ and this follows up on some questions that Mr. Nicholas
asked you about your written testimony ‑‑ page 6 and 7. The bottom of
page 6, starting at line 42: \"Are the British Society for
Inter-microbial ‑‑ Therapy and the French Society\" ‑‑ if I can
pronounce this in French ‑‑ are these two societies the
standards-setting societies of organizations in their respective
countries?

A They are as far as I know. It\'s ‑‑ I think that that ‑‑ they are, but
there\'s a new organization that has come into play within the last
three years and that\'s EUCAST ‑‑ European Community ‑‑ European
Communities of Antimicrobial Susceptibility Testing, I think is what it
stands for.

And EUCAST is trying to unite the European communities into a common
organization in terms of susceptibility testing.

Q As far as you know, are there ongoing attempts to bring forward other
antimicrobial susceptibility testing methods for NCCLS approval?

A Yes, there are.

Q Turning to Exhibit G-776, page 79. The second column under
campylobacter solutions ‑‑ when, during cross examination, Mr. Nicholas
had you agree that the middle part of that first paragraph under
campylobacter species indicated what it said ‑‑ however, he stopped
before the next sentence and I would ask you to read that sentence now.

A \"However, disk diffusion methods are ‑‑ for detecting resistance to
the commonly used antimicrobials.\"

Q I have one further question. Who is the sponsor of Ciprofloxacin?

A Bayer.

Q Thank you.

MS. STEINBERG: No further questions, Your Honor.

JUDGE DAVIDSON: Mr. Nicholas?

MR. NICHOLAS: Two short questions.

RECROSS EXAMINATION

BY MR. NICHOLAS:

Q Dr. Walker, you discussed the concordance between the E-test and
several other types of antimicrobial susceptibility testing. And was
that with respect to solely antimicrobial susceptibility testing of
Ciprofloxacin ‑‑ campylobacter ‑‑ campylobacter ‑‑ Ciprofloxacin ‑‑

A What are you saying?

Q You replied to Ms. Steinberg\'s question about how comparable E-test
results were to other kinds of antimicrobial susceptibility testing.

A The E-test is a drug-dependent testing method. In other words, the
correlation of ‑‑ with the E-test and the agar dilution for
Ciprofloxacin in our laboratory is around 86 percent ‑‑ 85 - 86 percent.
But for other drugs, i.e., Gentamiacin, the correlation is about 92
percent. For other drugs, it\'s not as ‑‑ it may not be as good.

Q So your reply to Ms. Steinberg\'s question was not based solely on
Ciprofloxacin and campylobacter, but was more general with respect to
other kinds of organisms and antimicrobials, is that correct?

A No, I think I was answering her question in regards to Ciprofloxacin
and campylobacter.

Q In those studies that you were relying upon when you answered that
question, do you know whether any of those studies looked at comparing
agar dilution to the E-test at the upper end of the MIC range of 32? A
No, am not aware of whether that they did that or not.

Q And in your own ‑‑ this ‑‑ the G study, G-763, you did not look at the
upper end of the MIC range, did you?

A No, we only looked at up to 8 micrograms.

Q So, based on the G study, and the other studies, you cannot say that
there is good comparability between the upper level MIC range between
the E-test and the agar dilution or disk diffusion?

A I think the comparability was in the interpretation in terms of
susceptible and resistant. But in terms of whether or not we would, in
an agar dilution, try to test up to 256 micrograms ‑‑ I\'m not familiar
with anybody that would ‑‑ has done that or would do that.

Q Well, Table 2 of the study, which I believe you still have ‑‑ if I\'m
interpreting this correctly, the Ciprofloxacin ‑‑

JUDGE DAVIDSON: What study are you talking about?

MR. NICHOLAS: It\'s Table 2. This is Exhibit G-763.

JUDGE DAVIDSON: 763?

MR. NICHOLAS: I believe there are two numbers from this exhibit, Your
Honor. This is the study that was put into evidence by FDA before it
appeared in a published journal.

MS. STEINBERG: What page are you on?

MR. NICHOLAS: I\'m on Table 2 on page 21.

MS. STEINBERG: Thank you.

JUDGE DAVIDSON: You still haven\'t answered my question.

MR. NICHOLAS: Yes, well, I have that as Exhibit 763, Your Honor. Is
there another exhibit number?

MS. STEINBERG: I think that\'s correct.

JUDGE DAVIDSON: Okay. Thank you.

BY MR. NICHOLAS:

Q If I\'m interpreting this correctly, if you look three lines down
under antimicrobials agents, it says Ciprofloxacin and then there are ‑‑
it\'s a little hard to interpret, but it looks like with the agar
dilution test, it was run to ‑‑ by an MIC of 4. Is that correct?

A An MIC ‑‑ the dilution scheme went out to 4.

Q Four. And with the E-test, the MIC went out to 32? The dilution went
out to 32?

A I\'m not sure how far that went out. We call it greater than 32, so
one would think that it might have gone to 32.

Q Okay. So there\'s no comparison between ‑‑ you can\'t make a
comparison of what would have happened if you had run your agar dilution
test out further, can you?

A That\'s correct.

Q Thank you. Now when Ms. Steinberg asked you whether there was
precedent to use serum levels for establishing interpretative criteria
for gastro bacteria, you discussed salmonella, I believe. Do you know
whether the clinical data used in the establishment of that standard,
interpretive standard, related to cases of gastro-enteritis, or whether
it just related to respiratory disease?

A I was not there when those ‑‑ when discussions took place, so I\'m not
aware.

Q So you don\'t know that that\'s actually a precedent?

A The only thing you can do is assume.

JUDGE DAVIDSON: Is that it?

MR. NICHOLAS: No further questions, Your Honor.

MS. STEINBERG: I\'ve got a couple more.

JUDGE DAVIDSON: Well, if your couples are as long as his couple, we\'ll
never finish here.

No disrespect, Mr. Nicholas. I understand exactly what happened.

Go right ahead.

MS. STEINBERG: Thank you.

REDIRECT EXAMINATION

BY MS. STEINBERG:

Q Dr. Walker, can you explain why, in Exhibit G-763, that study, you did
not get to a higher MIC level? You did not test to a higher MIC level
with agar dilution?

A Two reasons, I would suspect, or three maybe. One is the ‑‑ like I
alluded to earlier ‑‑ the number of the amount of materials involved in
performing this test. Then two is the number of isolates that we had to
run. And number three, because we were interested in looking at
susceptibility or MICs around what were being looked at as a susceptible
breakpoint.

Q And given your testimony earlier about the fine little nature of
campylobacter, is it necessary to bring the ‑‑ to test for an MIC level
256, or ‑‑ is it necessary to bring ‑‑ to test for a high MIC level?

A I see no practically in doing that.

MS. STEINBERG: If I can have one more minute. JUDGE DAVIDSON: Sure.

MS. STEINBERG: No further questions, Your Honor.

JUDGE DAVIDSON: Okay. Is that it, or do you want more?

MR. NICHOLAS: No further questions, Your Honor.

JUDGE DAVIDSON: Okay, you\'re excused then.

Anything else you have to dig up really quick? Between housekeeping
and ‑‑ we have a number of exhibits that have been identified and some
of them are awaiting my rulings, I know; and some have not been moved
into evidence ‑‑ they\'re just identified.

Just ‑‑ not do it now, but before we quit, I want to make sure all
that\'s taken care of.

MR. NICHOLAS: Yes, Your Honor.

JUDGE DAVIDSON: So if I forget, you remind me, all right? Okay. I\'m
sure you\'ll all be very unhappy to know that we\'re going to start at
9:30 again tomorrow morning. And we\'re adjourned until 9:30 a.m.,
tomorrow in this room.

(Whereupon, the hearing was adjourned, to reconvene on Wednesday, April
30, 2003 at 9:30 a.m.)

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