Transcript 슬라이드 1 - Korea University

Candida albicans biofilm development,
modeling a host–pathogen interaction
Jeniel Nett and David Andes
University of Wisconsin, Department of Medicine and Medical
Microbiology and Immunology, 600 Highland Ave, Room H4/572,
Madison, WI 53792, USA
Current Opinion in Microbiology 2006, 9:340–345
Introduction
Medical device-associated infection involve the
attachment of cells to a surface.
Many Candida albicans disease states involve
biofilm growth.
Candida albicans infections have great impact
on public health.
Introduction
In vitro biofim model systems have been
successfully used to examine biofilm.
Resent studies have begun to explore
C. albicans biofolms using animal biofilm
infection models.
What is the Candida albicans?
Candida albicans is a major human fungal
pathogen.
Candida albicans is associated with surfaces in
many of its disease states.
What is the Candida albicans?
Morphology of Candida albicans
Yeast
Pseudohyphal
Hyphal
(nonvirulent)
(virulent)
(virulent)
TRENDS in Microbiology (in press)
What is the biofilm?
 These
attached microbes are member of
complex, slime-encased communities called
biofilms.
 Biofilms
are ubiquitous in nature.
 The
formation of biofimes on medical devices
often cause serious illness.
 Biofilm
can form on any surface.
Biofilm formation
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Candida biofilm on the catheter
Figure 1
Scanning electron micrographs of a C. albicans biofilm on the inside
lumen of a vascular catheter from a rat central venous catheter model.
(a) Cross section of a biofilm. Yeast and filamentous cells are seen
encased in matrix material. The depth of the biofilm in this image is
greater than 200 um. Magnified 1000 times. (b) Image of section of
venous catheter. Majority of catheter lumen is coated with biofilm.
Magnified 50 times
methods to investigate the biofilm
Determination of dry weights
Incorporation of [3H] leucine
Reduction of the tetrazolium salt, MTT
Biofilm architecture was examined using scanning
electron and confocal microscopy.
Candida biofilm models in vitro
Flow conditions
Conditions of high flow are
encountered within the
circulatory system
surrounding venous
catheters and heart valves.
Candida biofilm models in vitro
Host conditioning
Biofilm activity of three isolates of
Candida spp. on mucin (mucin;
2500 mg ml−1), fibronectin (FN;
200 mg ml−1) and saliva
supplemented with FN solution
(sal+FN)-coated acrylic specimens.
As a control pellicle, saliva diluted
with PBS (pH 6.8) (sal) was used.
The assays were carried out in
quadruplicate on two separate
occasions.
Candida biofilm models in vitro
Substrate and nutrient composition
Biofilm formation by C.
albicans GDH 2346 on discs
prepared from a range of
different catheter materials
was examined.
Candida biofilm models in vivo
Conditions encountered in vivo are quite distinct from standard in
vitro biofilm culture conditions.
 Continuous exposure to all of the potential host
proteins has not been accomplished using current
in vitro models.
 Variable that is difficult to accurately incorporate in
vitro is the nutrient environment in which these
processes occur in patients.
Candida biofilm models in vivo
Heparinized catheter was
placed from the insertion
in the internal jugular vein
to above the right atrium.
And proximal end of the
catheter was then
tunneled to the
midscapular space and
externalized through the
skin via a button, which
was tightly sutures.
Antimicrob Agents Chemother 2004, 48:1727-1732.
Candida biofilm models in vivo
 In vivo biofilms are structurally similar to in vitro
biofilm.
 The general trends in biofilm drug resistance
described in detail using in vitro systems have
been similarly observed in vivo.
(ex triazoles, amphotericin B, echinocandins, lipidassociated amphotericin B)
Candida biofilm models in vivo
mRNA abundances of selected genes
(ERG11, CDR1,CDR2, and MDR1)
from biofilm-associated C. albicans
cells (after 24 h of development)
compared to planktonically grown cells
(optical density at 600 nm of 0.6).
The height of the bars represents the
ratio or fold change in expression of
biofilm versus planktonic cells. Bars
represent data from two RT-PCR
replicates. Error bars represent
standard deviations.
Conclusion
In vitro
Fungal biofilm studies in vitro have shown that
development involves a coordinated response
of the adherence to the device surface,
morphogenic transition, matrix production and
induction of drug-resistance.
In vivo
Biofilm models should be used to confirm the
role of specific gene and regulatory pathway.