candida Flashcards
a commensal organism that lives in
50% of individuals mouth and GI tracts
20% of women have it within
genital tract
three main types of Candida
albicans
tropicalis
glabrata
superficial infections caused by candida
vagina, mouth, penis, skins and nails
predisposing factors
normal individuals, antibiotics, diabetes, pregnancy
75%
of women have at least one vaginal infection
5-8% have
4 episodes a year
deep seated disseminated infections occur
single organs or widespread
predisposing factors of deep seated infections
immunocompromised hosts,neutropenia, organ and bone marrow transplants, major urns, abdominal surgetr, catheters
33% of
bone marrow transplant cases will get the infection, with a mortality of 30-50%.
what is virulence
ability to cause disease- a continuous variable defining strains within a species
violence is significant impacted by
host response
damage from candidias results form
a range of host pathogen interactions e.g. if the host response to not significant enough, then damage is due to microbial factors, however if the host immune system over reacts, then the damage is caused by the host
how can virulence factors be identified
reverse genetics- candidate gene approach
forward genetics- genome wide approach
confirmation of virulence using Koch postualtes
- disrupts target gene to create mutant strain
- demonstrates attenuated virulence of mutant
- reintrodurciton of gene restores virulence
in a candida albicans infection what is importnant
the host- in immunocompirimes host
C.albicans virulence is
multi-factorial and pdiases occurs due to host-pathogen interaction
stages of candida infection
1) adhesion and colonisation
2) epithelia penetration
3) vascular dissemination
4) endothelial colonisation and penetration
virulence factors of candida
- adhesion to host surface
- invasion and penetration epithelial
- obtaining nutrients
- opposing host defences
host defences to candida
- flushing mechanism
- phagocytosis and killing
candida albicans
diploid organism, largely asexual, polymorphic, primary cause candidosis
quorum sensing of candida
high cell densities- promote yeast growth
hyphal growth promoted
at less than 35 degrees and low oxygen levels
hyphae
tissue penetration - causes invasion an tissue damage and allows escape fro,
yeas
vascular dissemination
which cell surface protein plays a key role in adhesion
mannoproteins- enriched in cell surface (outer layer)
C.albicans ALS family
Agglutinin like sequence family of cell wall proteins. 8 members in .albicans (ALS1-7,9) share a common structure
ALS3 is especially important for
adhesion
two main routes of invasion and penetration
induced endocytosis and active penetration
C.albicans bioflms
form on a variety of ionic and abiotic surfaces. Structured assemblies encased one extracellular matrix- display inherent resistance to antigun gals and host defences
biofilms allows for
quorum sentence and polymicrobial interactions which impact formation
c. albicans
exploit iron from the host to use as a food and growth resource
