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| Identifier |
000400061 |
| Title |
Η δραστικότητα της πενταμιδίνης έναντι του υφομύκητα fusarium in vitro και in vivo σε πειραματικό μοντέλο ποντικού με διηθητική πνευμονική φουσαρίωση |
| Alternative Title |
Pentamidine is active against fusarium species in vitro and in vivo in a murine model of invasive pulmonary fusariosis |
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Author
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Λιονάκης, Μιχαήλ Σ.
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Thesis advisor
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Σαμώνης, Γεώργιος
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Reviewer
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Γεωργούλιας, Βασίλειος
Καλμαντή, Μαρία
Μπούμπας, Δημήτριος
Παπαδάκη, Ελένη
Γκίκας, Αχιλλέας
Μαυρουδής, Δημήτριος
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| Abstract |
Background
Fusariosis is an opportunistic mycosis that has emerged as a significant cause of morbidity
and mortality in immunosuppressed patients with hematological malignancies and
recipients of bone marrow transplantation. Currently used antifungal agents have limited
activity against Fusarium species accounting for the exceedingly high mortality of this
mycosis.
Methods
In the present work, we first investigated the in vitro activities of pentamidine (PNT) against
10 clinical isolates of Fusarium species (five Fusarium solani isolates and five non-Fusarium
solani isolates) by using the NCCLS microdilution method in three different media (RPMI,
RPMI-2, YNB), disk diffusion susceptibility testing, and viability dye staining. We also
tested the in vitro interaction of PNT and amphotericin B (AMB), the current mainstay of
treatment of fusariosis in clinical practice. We then investigated the in vivo activity of PNT,
as prophylaxis or early treatment in a murine model of acute invasive pulmonary fusariosis.
Balb-c mice were rendered neutropenic by intraperitoneal (IP) cyclophosphamide and 96
hours later were infected intranasally with conidia of a Fusarium oxysporum isolate, followed
by IP cyclophosphamide 24 hours post-infection. Groups of 10 mice each were given: (1)
PNT prophylaxis (8.5 mg/kg/day intravenously [IV] starting 24 hours prior to infection), or
(2) PNT treatment (8.5 mg/kg/day IV starting 6 hours post-infection), or (3) AMB
prophylaxis (1.5 mg/kg/day IP starting 24 hours prior to infection), or (4) IV saline (control).
Survival was assessed until 96 hours post-infection when surviving mice were euthanized.
Lungs from euthanized mice were harvested for quantification of tissue fungal burden by
qPCR and histopathology analysis.
Results
PNT had significant in vitro activities against all 10 Fusarium isolates. Non-Fusarium solani
isolates were more susceptible than Fusarium solani isolates (P < 0.05). Additionally, PNT
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was fungicidal against all non-Fusarium solani isolates, whereas it had fungistatic effects
against four of the five Fusarium solani isolates. PNT also exhibited greater activity against
conidial than against hyphal developmental program of growth of the fungus. This
fungicidal activity against non-Fusarium solani isolates was confirmed microscopically after
staining of PNT-treated Fusarium oxysporum hyphae with the fluorescent viability dyes
5,(6)-carboxyfluorescein diacetate (CFDA) and bis-(1,3-dibutylbarbituric acid) trimethine
oxonol (DiBAC). The MICs at which 50% of the isolates were inhibited (MIC50: 2 μg/ml for
non-F. solani isolates and 4 μg/ml for Fusarium solani isolates) and the minimum fungicidal
concentration at which 50% of the isolates were killed (MFC50: 8 μg/ml for non-Fusarium
solani isolates) were much lower than the PNT tissue concentrations previously reported in
humans using conventional daily intravenous PNT dosing (4 mg/Kg/day). In addition, PNT
was more active against Fusarium isolates in a hypoxic environment of in vitro growth (P <
0.05). This finding may be clinically significant, because Fusarium, an angiotropic mold,
causes tissue infarcts with resultant low tissue perfusion. Also, PNT and AMB were
synergistic against the majority of tested Fusarium isolates, mainly by using the
checkerboard method but also, to a lesser extent by using the disk diffusion susceptibility
testing method. In the in vivo part of this work, it was found that intranasal inoculation of
mice with ~ 70 x 105 conidia of a Fusarium oxysporum clinical isolate (35 l from a 2 x 108
conidia/ml solution) resulted in an acute necrotizing pneumonia with reproducible
mortality of 90 – 100% 96 hours post-infection. Mice given PNT prophylaxis had significant
better survival 96 hours post-infection (77%) compared to control mice (10%; P = 0.003) or
mice given AMB prophylaxis (33%; P = 0.01). PNT-treated mice had better survival (30%)
than untreated controls (10%; P = 0.01). The tissue fungal burden of mice given PNT
prophylaxis was significantly lower compared to control mice or mice given AMB
prophylaxis by both histopathology and qPCR analysis.
Conclusions
PNT had significant in vitro activity against all tested Fusarium clinical isolates and had
synergistic effects with AMB against the majority of the tested isolates. In addition, PNT
given as prophylaxis or early treatment had substantial in vivo activity in a neutropenic
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murine model of acute invasive pulmonary fusariosis. These findings suggest that clinical
studies are warranted to explore the potential of PNT in the management of human
invasive fusariosis.
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| Language |
Greek |
| Subject |
Fungal infection |
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Μυκητίαση |
| Issue date |
2008-01-25 |
| Collection
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School/Department--School of Medicine--Department of Medicine--Doctoral theses
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Type of Work--Doctoral theses
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| Permanent Link |
https://elocus.lib.uoc.gr//dlib/1/0/a/metadata-dlib-1459329341-471907-27853.tkl
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| Views |
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