Gregory L. Williams, as Successor Personal Representative of the Estate of Addilyn Leeann Shirer v. Leesburg Regional Medical Center, Inc., d/b/a Central Florida Health n/k/a UF Health Leesburg Hospital, Paragon Emergency Services, LLC, Mariano De La Mata, Tina Best, and Lorraine Chmielewski

FIFTH DISTRICT COURT OF APPEAL
STATE OF FLORIDA
_____________________________
Case No. 5D2024-1910
LT Case No. 2021-CA-000450
_____________________________
GREGORY L. WILLIAMS, as
Successor Personal
Representative of the Estate of
Addilyn Leeann Shirer,
Appellant,
v.
LEESBURG REGIONAL MEDICAL
CENTER, INC. d/b/a CENTRAL
FLORIDA HEALTH n/k/a UF
HEALTH LEESBURG HOSPITAL,
PARAGON EMERGENCY SERVICES,
LLC, MARIANO DE LA MATA,
TINA BEST, and LORRAINE
CHMIELEWSKI,
Appellees.
_____________________________
On appeal from the Circuit Court for Lake County.
Danny Ray Mosley, Judge.
Wesley T. Straw, Matthew D. Emerson, and Nicole M. Ziegler, of
Emerson Straw, PL, St. Petersburg, and Adam Richardson, of
Burlington & Rockenbach, P.A., West Palm Beach, for Appellant.
Christina R. Davis, of Davis Appeals, PLLC., St. Petersburg, for
Appellee, Leesburg Regional Medical Center, Inc.

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Jennifer L. Phillips, Thomas E. Dukes, III, and Wilbert R.
Vancol, of McEwan, Martinez, Dukes, Hall, & Vancol, P.A.,
Orlando, for Appellees, Paragon Emergency Services, LLC, and
Mariano De La Mata.
No Appearance for Remaining Appellees.
January 30, 2026
BLOCKER, ASSOCIATE J.
Appellant Gregory Williams, as successor personal
representative to the Estate of Addilyn Leeann Shirer, seeks
review of the trial court’s exclusion of his causation experts under
Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579 (1993),
in a medical malpractice action. Appellant contends the trial
court’s reliance on deposition transcripts gives this Court de novo
review, and that the trial court erroneously oversimplified the
experts’ opinions in excluding them. Because both contentions are
incorrect, we affirm.
I.
Late morning on March 31, 2019, Christopher Shirer and
Tabitha Ryan brought their two-month-old baby, A.S., to Appellee
Leesburg Regional Medical Center (“Hospital”). She was pale and
lethargic, having had a cough for several days. Her medical notes
from Appellee Nurse Tina Best and a nurse practitioner not a
party to this action indicated she was not in acute distress, was
alert (although Nurse Best noted initially that she was difficult to
arouse) and responsive, and had a regular respiratory pattern.
Appellee Mariano de la Mata (“Doctor”) found her lungs clear and
ordered albuterol treatment. In administering the albuterol,
Appellee Respiratory Therapist Lorraine Chmielewski noted that
A.S. had normal breathing other than passing grunting and
tachypnea (rapid breathing). Another nurse saw A.S. and noted
the presence of “rhonchi”—a coarse breath sound and pertussis
indicator. She was discharged that afternoon and directed to
follow up with her primary care provider and return to the
emergency room if symptoms worsened.

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The next day, A.S. saw her primary care doctor with a
worsened cough and decreased oxygen saturation, warranting an
emergency transfer back to Hospital. She arrived at 12:04 pm and
was in significant distress, with oxygen saturation at 78 percent
and a respiratory rate of 62. Doctor found her tachypneic with
mild tachycardia and called Hospital’s pediatrician, who
recommended that she be transferred to another hospital. Prior to
her transfer, blood testing was performed, finding A.S. had an
extremely elevated white blood cell count of 58,200. A.S. had not
yet been vaccinated against pertussis (commonly known was
whooping cough) because of her age.
Arriving at the second hospital—not named in this lawsuit—
at approximately 6:12 p.m., A.S. was having coughing fits lasting
several minutes and causing her to turn red. Her white blood cell
count continued to increase, and rapid testing not available at
Hospital resulted in a diagnosis of pertussis and rhino enterovirus.
At that time, close to midnight, she was administered the
antibiotic azithromycin without any improvement. Her white
blood cell count rose to 81,000, she was intubated and put on a
ventilator on April 4, 2019, and tragically passed away on April 6,
2019.
II.
Appellant filed a complaint against Appellees for failing to
timely diagnose and treat A.S., thereby causing her death. A
plaintiff seeking to recover in a medical malpractice case such as
this one must prove the standard of care each defendant owed the
plaintiff, each defendant breached that standard, and the breach
proximately caused the damages. Gooding v. Univ. Hosp. Bldg.,
Inc., 445 So. 2d 1015, 1018 (Fla. 1984). To establish causation,
“[t]he plaintiff must show that the injury more likely than not
resulted from the defendant’s negligence.” Id. at 1020. Put
differently, “the plaintiff must show that what was done or failed
to be done probably would have affected the outcome.” Id.; accord
Chaskes v. Gutierrez, 116 So. 3d 479, 488 (Fla. 3d DCA 2013)
(collecting cases following Gooding standard and finding no
proximate causation where plaintiff had “no better than even
chance” of surviving absent breach of standard of care).

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At issue in this appeal are only the expert opinions related to
causation, not the appropriate standard of care.1 Appellant offered
the expert testimony of Patricia Penkoske, M.D., and Harry Hull,
M.D., which the trial court struck under Daubert and section
90.702, Florida Statutes (2023). The trial court found these
experts did not meet the reliability threshold for admissibility
because they did not rely on testing, peer review, potential error
rate, or general acceptance. Appellant then offered a second set of
experts, Jennifer Snow, M.D., and Ramzy Rimawi, M.D. In
excluding these experts, the trial court provided the following
explanation:
The Court further find[s] Ramzy Rimawi,
M.D., and Jennifer Snow, M.D., [sic] opinions
concerning causation are inadmissible. The
experts[’] background, training and experience
coupled with the various articles they had
referenced in their deposition and reports do not
satisfy the requirements of Florida Statutes,
section 90.702, and Daubert v. Merrell Dow
Pharmaceuticals, Inc., 509 U.S. 579 (1993).
There are no concrete facts to support their
conclusions. Daubert requires scientific evidence
“fit” the plaintiff’s theory of causation. Reliance
on various publications that early
administration of antibiotics is recommended or
preferred is not sufficient to render expert
opinions as to causation in this case. To satisfy
Daubert, an expert opinion must assist the trier
of fact concerning specific facts in dispute. Here
the issue is whether the delay of 12–24 hours to
1. To clarify, in this appeal, this Court is reviewing the
opinions of the experts as to whether it is more likely than not that
administering antibiotics either on March 31, 2019, when A.S. was
first at Hospital, or on April 1, 2019, prior to her transfer to the
second hospital, would have prevented her death. It does not
consider any opinions regarding whether Appellees should have
known to administer antibiotics at either point.

5
administer antibiotics more likely than not
caused the death. The notion of early treatment
is well within common knowledge that would be
obvious to the average juror but has nothing to
do with causation. There is no record evidence
connecting the delay to the causation of the
death. The Court finds their testimony not
reliable. Therefore, their opinions as to
causation shall not be permitted.
In that same order, the trial court granted summary judgment in
favor of Appellees.
III.
This Court reviews exclusion of expert witnesses under
Daubert and its statutory counterpart for abuse of discretion.
Lewis v. Norfolk S. Ry. Co., 420 So. 3d 1099, 1104 (Fla. 5th
DCA), reh’g denied (Oct. 24, 2025); see also Baan v. Columbia
County, 180 So. 3d 1127, 1131 (Fla. 1st DCA 2015) (noting
standard of review is the same even where excluding an expert’s
testimony is “outcome determinative”). Although the inquiry is
typically more involved, it is ultimately an evidentiary ruling like
any other under Florida Statutes Chapter 90. See generally Booker
v. State, 397 So. 2d 910, 914 (Fla. 1981) (“The trial judge enjoys
wide discretion in areas concerning the admission of evidence. His
ruling on the admissibility of evidence will not be disturbed unless
an abuse of discretion is shown.”); see also Gen. Elec. Co. v. Joiner,
522 U.S. 136, 141 (1997) (“[A]buse of discretion is the proper
standard of review of a [trial] court’s evidentiary rulings.”). So long
as the trial court conducted a proper Daubert analysis, this Court
is confined to abuse of discretion review. “Such discretion is
limited by the rules of evidence, and a trial court abuses its
discretion if its ruling is based on an erroneous view of the law or
on a clearly erroneous assessment of the evidence.” Sanchez v.
Cinque, 238 So. 3d 817, 822 (Fla. 4th DCA 2018) (quoting Patrick
v. State, 104 So. 3d 1046, 1056 (Fla. 2012)). Under the deferential
abuse of discretion standard, an appellate court will not reverse
“unless the trial court makes a ruling [with] which no reasonable
judge would agree.” Miller v. State, 379 So. 3d 1109, 1128 (Fla.
2024) (quoting Wells v. State, 364 So. 3d 1005, 1013 (Fla. 2023));

6
see also Fertil v. Univ. of Miami, 388 So. 3d 174, 176 (Fla. 3d DCA
2023) (“[W]e will reverse a trial court’s striking of an expert
witness only if we can find that no other reasonable judge would
have taken the view adopted by the trial court.”).
Plaintiff suggests that because the trial court did not conduct
a “live” hearing—relying instead on deposition transcripts,
medical literature, and other documents—this Court should give
less deference. Plaintiff’s cited cases are inapposite. See Jacob v.
Henderson, 840 So. 2d 1167, 1168–69 (Fla. 2d DCA 2003) (“While
we apply the abuse of discretion standard, case law has narrowed
a trial court’s discretion in cases involving dismissal for fraud. . . .
A more stringent abuse of discretion standard is appropriate
because dismissal is an extreme remedy.” (internal citations
omitted))2; InPhyNet Contracting Servs., Inc. v. Soria, 33 So. 3d
766 (Fla. 4th DCA 2010) (explaining, in class action certification,
appellate court gives trial court’s factual determinations less
deference where issues of fact were decided without an evidentiary
hearing); Littles v. State, 354 So. 3d 1169, 1171 (Fla. 5th DCA
2023) (stating appellate court gives less deference to trial court’s
factual findings based on video evidence); Morris v. Muniz, 252 So.
3d 1143, 1154–55 (Fla. 2018) (examining de novo whether an
expert’s unrefuted qualifications met the requirements of section
766.102, Florida Statutes). This appeal does not rest on a factual
dispute of statements, qualifications of the experts, or the
underlying facts of the case. It rests on the trial court’s application
of the Daubert standard to the expert opinions presented in
relation to the central of the case: causation. The appropriate
standard of review is abuse of discretion.
2. In Jacob, the court also cited Hervey v. Alfonso, 650 So. 2d
644 (Fla. 2d DCA 1995), for the proposition that less deference
applies when the trial court reviewed the same materials the
appellate court is reviewing. Id. at 1170. But the Hervey court
was reviewing a summary judgment entered under the old
summary judgment rule, which, in any event, was subject to de
novo review.

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IV.
Upon a proper challenge to expert testimony, its proponent
bears the burden of establishing admissibility. Lewis, 420 So. 3d
at 1104. Section 90.702, Florida Statutes, codifying Daubert,
provides:
If scientific, technical, or other specialized
knowledge will assist the trier of fact in
understanding the evidence or in determining a
fact in issue, a witness qualified as an expert by
knowledge, skill, experience, training, or
education may testify about it in the form of an
opinion or otherwise, if:
(1) The testimony is based upon sufficient
facts or data;
(2) The testimony is the product of reliable
principles and methods; and
(3) The witness has applied the principles
and methods reliably to the facts of the case.
In assessing a challenge under the statute, the trial court
must first determine whether an individual qualifies as an expert
for the purposes of giving opinion testimony. By its plain
language, an expert may be qualified based on “knowledge, skill,
experience, training, or education.” Id. While “‘an expert may be
qualified by experience,’ it does not follow ‘that experience,
standing alone, is a sufficient foundation rendering reliable any
conceivable opinion the expert may express.” Baan, 180 So. 3d at
1133 (quoting United States v. Frazier, 387 F.3d 1244, 1266 (11th
Cir. 2004)). The expert “must explain the logic and relevance of
the expert opinion.” Id.
An expert opinion that is both reliable and relevant is
admissible. Lewis, 420 So. 3d at 1104. Reliability is determined
by examining the expert’s underlying methodology rather than his
or her ultimate opinion; the analysis is a flexible one based on non-
exhaustive factors like whether the methodology has the potential
for or has been subjected to testing, has been subject to peer review

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and publication, has a potential rate of error, or is generally
accepted. Id. at 1105. Testimony is relevant if it assists the trier
of fact in understanding evidence or determining a fact at issue.
Id. In other words, “testimony must be ‘tied to the facts of the case
[so] that it will aid the jury in resolving a factual dispute.’” Id.
(alteration in original) (quoting Vitiello v. State, 281 So. 3d 554,
560 (Fla. 5th DCA 2019)).
In conducting this significant analysis, a trial court’s
gatekeeping role requires a careful balance. On one hand, it must
ensure expert testimony “employs in the court room the same level
of intellectual rigor that characterizes the practice of an expert in
the relevant field.” Id. at 1104 (quoting Cristin v. Everglades Corr.
Inst., 310 So. 3d 951, 955–56 (Fla. 1st DCA 2020)). On the other,
it must allow the adversarial system to address any shakiness in
otherwise admissible testimony. See id. at 1104–05. Exclusion of
the testimony is the exception rather than the rule. Id. at 1105.
Nothing prevents a trial court, however, from excluding expert
testimony when “there is simply too great an analytical gap
between the data and the opinion proffered.” Kemp v. State, 280
So. 3d 81, 89 (Fla. 4th DCA 2019) (quoting Joiner, 522 U.S. at 146).
V.
Understanding the progression of pertussis is critical to an
evaluation of the admissibility of the medical testimony proffered
in this case:
Whooping cough, or pertussis, is caused by
the Bordetella pertussis bacteria. It is one of the
most contagious diseases known to man, with
virtually 100% of susceptible children who are
exposed to the disease becoming infected. The
risk of disease is significant for children less
than five years, with death rates highest in
infants. The disease occurs year round, and
females are more susceptible than males.
Pertussis occurs in three stages. The
catarrhal stage is like an upper respiratory
infection and lasts one to two weeks. The

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paroxysmal stage starts when the child begins
to have spells of coughing. During this stage,
which lasts two to four weeks or longer, the
coughing spells become longer and the coughs
themselves stronger. The spells consist of five to
ten strong coughs during one expiration,
followed by an enormous inspiration during
which a “whoop” sound is heard. The episodes,
which are extremely tiring, are the body’s
attempts to remove mucous plugs blocking an
airway. They may also be associated with
bulging of the eyes and neck veins and crying,
all of which reflect the forcefulness of the
coughs. The patients look comfortable between
episodes. During the convalescent stage, the
coughing spells begin to decrease, although the
cough itself often stays.
Pertussis is easily diagnosed clinically
during the paroxysmal stage. The diagnosis can
also be confirmed by antibody titers. If the
disease is suspected during the catarrhal stage
and the throat culture, the Bordetella pertussis
bacteria may be isolated. During the later
stages, the bacteria is no longer present. The
symptoms presented at these stages are due to
damage to the respiratory tract caused by the
infection.
§ 54:44. Whooping cough (pertussis)—Generally, 6 Attorney’s
Medical Advisor § 54:44 (footnotes omitted).
As noted above, Appellant finds error in the trial court’s
exclusion of four experts sought to be introduced to establish that
a delay in administering antibiotics of up to a possible 36 hours
caused A.S.’s death. His first expert, Dr. Penkoske, treated for
pertussis—at most—one or two infants who were less than three
months old, as she is primarily a heart surgeon and pediatric
critical care doctor. Her opinion was that A.S. was in the second
or paroxysmal stage of pertussis on both March 31 and April 1,
2019, because of her coughing symptom. She indicated that

10
although a white blood cell count was not determined, it would
have been elevated. Dr. Penkoske testified A.S. died because she
was already in the full-blown disease, and she felt strongly that if
she had gotten the antibiotics 24 hours earlier, she would not have
died. She testified, “At what time does the door close? All I know
is that it was closed when she got the antibiotics and that before
that, you know, when you look statistically at the number of babies
that get pertussis, the majority of them don’t die.” Dr. Penkoske
later repeated that all she can say is A.S. would not have died if
she had gotten the antibiotics earlier—but how much earlier—she
could not determine. Dr. Penkoske’s opinion is not based on
sufficient facts or data or produced using a reliable methodology.
Thus, it was not error for the trial court to exclude it.
Next was Dr. Hull, who has worked as an epidemiologist
consultant since 2007. He practiced pediatric medicine for about
a year in 1990, and was board certified in pediatrics in 1979. Dr.
Hull had not practiced medicine clinically since 2007. He believed
that A.S. was in the first or catarrhal state of pertussis on March
31, 2019, although he explained the stages can overlap in younger
children. He based his opinion on what stage A.S. was in when she
had a cough and stuffy nose but no fever. In his opinion, once
pertussis is established in the paroxysmal stage, antibiotic
treatment will not affect the course of the disease. This is because
antibiotics kill the bacteria but not the toxins they produce. Dr.
Hull echoed Dr. Penkoske’s opinion that A.S.’s white blood cell
count would have been extremely elevated on the first day she
presented at Hospital, and higher white blood cell counts are
associated with infant deaths from pertussis. In Dr. Hull’s
opinion, A.S. would have survived if she had been given antibiotics
on the afternoon of March 31, 2019. Similar to Dr. Penkoske, when
asked if antibiotics would more likely than not have made a
difference the next day, Dr. Hull explained that the antibiotics did
not make a difference at the time they were given and, as with any
infectious disease, the longer treatment is delayed, the more likely
there will be severe complications. Dr. Hull could only say that
A.S. was in full paroxysmal stage when she arrived at the second
hospital because she had posttussive emesis (vomiting after
coughing), and her cough got much more severe. He could not say
when the transition to the second phase occurred. It was not error
for the trial court to exclude Dr. Hull’s opinion for the same reason

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as Dr. Penkoske—he could not provide a scientifically reliable
basis for his opinion that A.S. would probably have survived if she
had received antibiotics during her first visit to Hospital on March
31 as opposed to when the medicine was administered on April 1.
Third was Dr. Snow. She is board certified in pediatric critical
care medicine and general pediatrics and has treated eight to ten
infants suffering with pertussis in her eighteen years as a
physician, four of whom were under three months old, and only one
who died. She cited medical literature that concluded antibiotics
only limit the severity of pertussis if given in the catarrhal stage.
She did not have any medical literature determining the
significance of a 24-hour delay in antibiotic administration on the
last day of the catarrhal phase. Dr. Snow found literature
indicating the majority of infants with a white blood cell count
above 46,000 died, as well as 90 percent of those with counts above
70,000. She testified that administration of antibiotics will
eliminate the pertussis bacteria in the airways of vaccinated
adults within 48 hours. Because death is tied to the presence of
toxins released by the pertussis bacteria, the earlier the antibiotics
are administered, the more likely they are to kill the bacteria
before they can produce enough toxins and have an impact on the
outcome. Dr. Snow’s opinion echoed Dr. Hull as to what stage A.S.
was in—the first on March 31, 2019, and the second on April 1,
2019. While Dr. Snow perhaps could have been cross-examined on
the applicability of the cited studies on vaccinated adults to that of
unvaccinated infants, the greater deficiency is that her opinion
would not assist the jury in determining whether A.S. more likely
than not would have survived if she had been given antibiotics on
what Dr. Snow opined was the last day of the catarrhal stage of
pertussis. She explained there were no studies on the impact of
the antibiotics on the toxins that ultimately cause death. The trial
court did not err in finding that Dr. Snow failed to reliably apply
her principles and methods to the facts of the case in a manner
that would assist the jury. See § 90.702(3), Fla. Stat.
The final expert presented was Dr. Rimawi. He is board
certified in infectious disease and critical care medicine. He has
treated roughly thirty pediatric patients with pertussis on an
outpatient basis, with three to four fewer than six months old
(although he admitted that he did not know when he was treating

12
them that they had pertussis). Dr. Rimawi also believed A.S. was
in the last day of the catarrhal stage of pertussis on March 31,
2019. He has published articles related to sepsis, treated patients
for sepsis, and primarily based his opinion on medical literature
related to sepsis. Dr. Rimawi believed A.S. had sepsis as of around
1:00 p.m. on March 31, 2019, because of her elevated heart and
respiratory rates. He opined that if she had been given antibiotics,
it would have increased her chances of survival, but the window to
do so after sepsis was three hours. Dr. Rimawi explained that,
while he did not know the efficacy of antibiotics based on a
particular day in the progression of the disease, he echoed the
testimony of the other experts that “in general earlier is better.” If
given any earlier on April 1, 2019, Dr. Rimawi could only say
survival was possible. The trial court did not err in excluding his
opinion either.
VI.
Overall, Appellant argues that the trial court improperly
conflated the number of hours that passed without treatment
(which he contends is not relevant) with the stage of progression
A.S. was in (which he contends is). The two concepts, however, are
intertwined. Depending on each expert’s opinion about what stage
A.S. was in at Hospital, and at what stage antibiotics would no
longer affect the disease, the factfinder would have to apply the
stage to the time frame to determine whether, more likely than
not, if A.S. had received antibiotics at that time and in that stage
of pertussis, she would have survived. While Appellant is correct
that an expert does not have to establish causation conclusively to
be admissible, a reasonable judge could conclude, as this one did,
that the expert testimony proffered was not sufficiently reliable
(Drs. Penkoske and Hull) and/or would not assist the jury (Drs.
Snow and Rimawi) in determining whether a delay in antibiotics
more likely than not caused A.S.’s untimely death. Accordingly,
the trial court did not abuse its discretion in excluding any of
Appellant’s experts.
AFFIRMED.
HARRIS and SOUD, JJ., concur.

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_____________________________
Not final until disposition of any timely and
authorized motion under Fla. R. App. P. 9.330 or
9.331.
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