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Antimicrobial Agents and Chemotherapy, December 2003, p. 3976-3978, Vol. 47, No. 12
0066-4804/03/$08.00+0 DOI: 10.1128/AAC.47.12.3976-3978.2003
Copyright © 2003, American
Society for
Microbiology. All Rights Reserved.
Efficacy of Voriconazole in Treatment of Systemic Scedosporiosis in Neutropenic Mice
Javier Capilla, Carolina Serena, F. Javier Pastor, Montserrat Ortoneda, and Josep Guarro*
Unitat
de Microbiologia, Facultat de Medicina, Universitat Rovira i Virgili,
Reus, Spain
Received 23 April 2003/
Returned for modification 21 May 2003/
Accepted 30 August 2003

ABSTRACT
We
have evaluated the efficacy of voriconazole (VRC) in a murine
model of
systemic infection by
Scedosporium apiospermum. The
survival
of mice treated with VRC at 5, 20, or 40 mg/kg/day
was greater than
that of the control group (
P 
0.0009). VRC
reduced
the tissue burden in the spleen and brain (
P < 0.001
in
both organs) in comparison with that of the control
group.

TEXT
Scedosporium apiospermum is an opportunistic filamentous fungus
that
causes severe infections, not only in immunodepressed patients
but
also in the immunocompetent. These infections are generally
treated
with amphotericin B (AMB) alone or in combination with
other antifungal
drugs, but outcomes are often unsuccessful.
In vitro studies have
revealed that this fungus is resistant
to the available antifungal
drugs, and voriconazole (VRC) is
one of the few drugs that have shown
some in vitro activity
against this fungus
(
3,
4,
11). Further studies in
appropriate
animal models are needed to confirm its in vivo activity.
However,
concentrations of VRC in the serum of mice are very low, at
times
undetectable because of the rapid clearance of the drug. Some
authors
have demonstrated the inhibitory effect of grapefruit juice
on
the cytochrome P450 enzymes that are involved in the metabolism
of VRC
(
5), which can be useful
for increasing the concentrations
of such drugs in murine serum
(
15). In the present
study, we
have evaluated the efficacy of VRC in a systemic
S.
apiospermum infection of immunodepressed mice drinking grapefruit
juice
instead of water.
The clinical strain S.
apiospermum FMR 6694 was used in this study. The fungus was stored
in slant cultures covered with sterile paraffin oil and subcultured on
potato dextrose agar plates at 35°C for 7 days. In a previous
in vitro study, the MIC of VRC against this strain was 1 µg/ml
(data not shown). Preparation of the inoculum was done as previously
described (14). Male OF-1
mice weighing 30 g (Charles River, Barcelona, Spain) were
used in this study. Groups of 10 animals were housed under standard
conditions, with drink and feed supplied ad libitum. Conditions were
approved by the Animal Welfare Committee of the Rovira i Virgili
University. Animals were immunodepressed by intraperitoneal (i.p.)
administration of a single dose of 200 mg of cyclophosphamide (Genoxal,
Laboratorios Funk, Barcelona, Spain) per kg plus intravenous (i.v.)
administration of 150 mg of 5-fluorouracil (Productos Roche, Madrid,
Spain) per kg 1 day prior to infection. VRC was provided by Pfizer
(Madrid, Spain). Stock solutions of this drug were prepared in
polyethylene glycol 200 (PEG 200). AMB was purchased from Squibb
Industria Farmacéutica and reconstituted in accordance with the
manufacturer's instructions.
Groups of 10 animals were
infected with an inoculum of 104 CFU given i.v. via the
lateral tail vein. Mice treated with VRC received the drug at 5, 20, or
40 mg/kg/day perorally (p.o.) by gavage; these doses were tested twice.
AMB deoxycholate was administered at 0.8 mg/kg of body weight per day
i.v. or at 1.5 mg/kg of body weight per day i.p. The control group
received PEG 200 p.o. All treatments were begun 1 day after
challenge and administered daily for 10 days. Animals were checked
daily for 14 days. Three days prior to infection, the mice that
received VRC or PEG 200 were given grapefruit juice (Hero España,
Murcia, Spain) in place of water.
In the fungal-burden study,
groups of 10 animals were infected with an inoculum of 3.4 x
103 CFU i.v. The control group received PEG 200, and the
treatment groups received AMB i.v. at 0.8 mg/kg/day and VRC p.o. at 5,
20, and 40 mg/kg/day, respectively. All treatments were administered
daily for 10 days, and approximately 24 h after
administration of the last dose, the surviving animals were sacrificed
by inhalation of halothane. The brain, kidneys, and spleen were removed
aseptically, weighed, and homogenized in 2 ml of 0.9% saline.
Serial 10-fold dilutions of these homogenates were placed on potato
dextrose agar plates and incubated at 35°C. After 72 to
96 h, the number of CFU was determined. Survival rates were
evaluated by the Kaplan-Meyer test, and organ burdens were compared by
the Mann-Whitney U test with GraphPad Prism software.
Figure
1 shows the survival curves of the different groups of mice included in
the survival study. Untreated animals began to die on day 5
postinfection, and on day 10, no animals were alive. The mean survival
time (MST) of the control group was 6.90 days. Similar mortality rates
were found in animals treated with AMB i.p. at 1.5 mg/kg (MST =
6.50 days) and with AMB i.v. at 0.8 mg/kg (MST = 6.40
days).
The treatments with VRC at 5, 20, and 40 mg/kg/day were
tested
twice. Data from the two experiments were not statistically
significantly
different and are grouped in a single curve (Fig.
1). Survival
of animals
treated with VRC increased significantly, with MSTs
of 9.2, 9.45, and
11.9 days with doses of 5, 20, and 40 mg/kg/day,
respectively (VRC at 5
mg/kg/day versus the control,
P <
0.0001; VRC at 5
mg/kg/day versus both AMB treatments,
P 
0.0187;
VRC
at 20 mg/kg/day versus the control and AMB treatments,
P
0.0009; VRC at 40 mg/kg/day compared to the control and to
both
AMB treatments,
P < 0.0001). VRC at 40 mg/kg was
more effective
at prolonging survival than both VRC at 5 mg/kg/day
(
P = 0.018)
and VRC at 20 mg/kg/day (
P
= 0.009). No significant differences
were found between the
group that received VRC at 5 mg/kg and
that which received VRC at 20
mg/kg (
P = 0.95). The most-affected
organs in
untreated animals were the brain and kidneys. In the
spleen, CFU counts
were a bit lower. AMB did not reduce the
tissue burden in any of the
organs studied (Table
1). VRC at
5, 20, or 40 mg/kg/day significantly reduced tissue burden in
the
brain in comparison to both the control mice (
P <
0.02 in
all cases) and the AMB-treated mice (
P < 0.009
in all cases).
The tissue burden in the kidneys was reduced somewhat in
animals
treated with VRC at any dose, but the differences from the
control
group were only significant in the animals receiving VRC at
20
mg/kg. In the spleens of animals treated with VRC at any
dose,
CFU counts were significantly lower than in those untreated
or
treated with AMB (
P < 0.05).
View this table:
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|
TABLE 1. Semiquantitative
results of organ cultures of mice treated with antifungal therapy begun
24 h after challenge and sacrificed 24 h after
completion of therapy
|
In this study, we
have used a murine model of systemic
S. apiospermum infection
previously developed by us but with a different lethal
dose
(
2,
14) to test the efficacy
of VRC. González et
al.
(
7) recently described a
similar model, although they used
a less virulent strain because, even
though the inoculum was
the same, only 25% of the mice died
after 25 days. The differences
in mortality could be due to the
different immunosuppression
regimens used in the two studies. We used
cyclophosphamide plus
5-fluorouracil, and González et al.
(
7) used cyclophosphamide
alone.
In previous studies, we demonstrated some variability in the
virulence
of different
S. apiospermum strains
(
14), which could be
another
reason for the mentioned differences between the models. The
ability
of grapefruit juice to improve the pharmacological availability
of
different drugs in mice has been extensively documented
(
5,
15).
Some authors
(
10) have reported that
the effect of grapefruit
juice is merely due to an increase in the
intestinal absorption
of VRC. Although the effect of grapefruit juice
remains controversial,
this pharmacokinetic interaction proved to be
useful in our
case and previously in resolving experimental
blastomycosis
in mice
(
16). In a previous
study, we demonstrated that grapefruit
juice did not exert any in vitro
or in vivo inhibitory effect
against this fungus (data not shown). The
increase in survival
was markedly evident in animals that received VRC
at 40 mg/kg,
half of which survived after 14 days. VRC administered at
lower
doses had a moderate but significant effect in increasing
survival.
In experimental fusariosis in mice receiving grapefruit juice
by
gavage, other authors
(
8) have previously
observed a partial
response due to VRC at doses lower than 40
mg/kg/day. In immunocompromised
patients,
S. apiospermum
usually presents tropism for the central
nervous system (CNS), causing
primary brain abscesses that are
usually fatal
(
9,
13). In approximately
half of the reported
cases, no site of
S. apiospermum
infection other than the CNS
was found
(
1). Although correlations
between results obtained
with animal models and the course of
infections in humans is
not always good, this study and others
(
2,
7,
14) confirm this
CNS
tropism. In the present model, only animals receiving VRC
were able to
reduce the fungal load in the brain. Although few
data still exist,
clinical findings on the role of VRC in human
scedosporiosis are very
positive and seem to confirm experimental
studies. In recent years,
several human cases of disseminated
infection by this fungus have been
treated with VRC with very
favorable outcomes
(
6,
12,
13,
17).
On the basis
of our results and those obtained by other authors, VRC seems to be an
option for the treatment of severe scedosporiosis.

ACKNOWLEDGMENTS
This work was supported by a grant from the Fondo
de Investigaciones
Sanitarias from the Ministerio de Sanidad y Consumo
of Spain
(PI
020114).

FOOTNOTES
* Corresponding
author. Mailing address: Unitat de Microbiologia, Facultat de Medicina
i Ciències de la Salut, Universitat Rovira i Virgili, 21 Sant
Llorenç St., 43201 Reus, Spain. Phone: 977 759 359. Fax: 977 759
322. E-mail:
umb{at}fmcs.urv.es.


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Antimicrobial Agents and Chemotherapy, December 2003, p. 3976-3978, Vol. 47, No. 12
0066-4804/03/$08.00+0 DOI: 10.1128/AAC.47.12.3976-3978.2003
Copyright © 2003, American
Society for
Microbiology. All Rights Reserved.
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