Fungal Pathogens L14 Flashcards
what do eukaryotic fungi contain
nucleus
nuclear membrane
what can happen in eukaryotic fungi
mitosis
what are saprophytic fungi
live on dead / decaying material
not causing disease
what is parasitic fungi
live on another organism at its expense
what is the fungal cell wall like
Firm polysaccharide structure
what is fungal cell wall similar to
similar to higher plants / animals
what is fungi cell wall made of
cellulose
chitin
what are hyphae
long filamentous structures grow on surface of food
what may fungal cell walls exist as
single cells (yeasts) or as connecting filaments or hyphae (moulds)
which are bigger fungi or bacteria
fungi
what nucleus do fungi have
eukaryotic
what nucleus do bacteria have
prokaryotic
what is in the cytoplasm of fungi
mitrochondria
ER etc
what is in the cytoplasm of bacteria
no organelles
what is the bacteria cell wall
muramic acid
is dimorphism present in fungi
may be present
is dimorphism present in bacteria
never
how do fungal moulds grow
Grow by elongation or lateral branching
how do fungal yeasts grow
budding
how does fungal reproduce
asexual
sexual
what is asexual fungal reproduction
Dissemination of spores singly or in multitudes from specialised structures
what is sexual fungal reproduction
fungi are haploid – meiosis takes place following fusion
can we inhale spores
Form spores as a reproductive state
Spores spread in air, we can inhale these spores as they disseminate
what are the yeasts
Spherical, often budding
example of yeast
Cryptococcus neoformans
what are yeast-like fungi
yeasts but elongated, pseudomycelia may be seen
example of yeast-like
Candida albicans
what are filamentous fungi
form a carpet or layer (mould)
examples are filamentous fungi
Aspergillus fumigatus
what are dimorphic fungi
may exist as yeasts or filamentous forms
examples of dimorphic fungi
Histoplasma capsulatum
what is considered in medically important dungi
frequency
pathogenicity
therapeutics
what is frequency of medically-important fungi
extremely common infections
examples of frequent medical-important fungi
candidiasis and ringworm
what is pathogenicity of medically-important fungi
some are highly pathogenic
examples of high pathogenicity medical fungi
e.g. Histoplasma or cause significant mortality in the immunocompromised e.g. Aspergillus fumigatus
what is therapeutics in medical fungi
treatment options are limited compared to bacterial infections
can fungi cause problems
Generally fungal infections don’t cause problems, can be very serious in those that are immunosuppressed
how are superficial diseases caused by fungi
hair, nails, mucous membranes – changes in host resistance and normal flora, or physical contact
how are subcutaneous diseases caused by fungi
skin or deeper tissues, often from soil e.g. Sporothrix schenckii. Commoner in developing world
how are systemic diseases caused by fungi
inhalation e.g. spores → If in lungs can cause pneumonia then can invade bloodstream (candida)
are diseases caused by fungi transmissible
Some are transmissible from person-to-person contact – superficial ones, not too serious
how can fungal diseases be diagnosed
clinical suspicion microscopy culture histology antibody/antigen
how are fungal diseases diagnosed via clinical suspicion
e.g. fever unresponsive to antibacterials. Meningitis or pneumonia in the immunocompromised
how are fungal diseases diagnosed via microscopy
Gram’s stain, India ink, wet prep
how are fungal diseases diagnosed via culture
Sabouraud’s agar, Neutral glucose peptone agar +/- chloramphenicol
how are fungal diseases diagnosed via histology
Grocott’s stain
how are fungal diseases diagnosed via antibody/antigen
candida/aspergillus precipitins; galactomannan
what happens in superficial infection fungal diagnosis
skin scrapings for microscopy (KOH – make skin cells translucent can see if fungal cells there) and culture
what happens in systemic infections fungal diagnosis
blood cultures, grow bacteria from the blood. tissue (e.g. lung biopsy), serology or antigen detection (more invasive techniques)
what are yeast-like fungi part of
GI and respiratory flora
what are the yeast-like fungi like
Opportunistic pathogens
what are the yeast-like structures overgrowth/infection predisposed by
diabetes mellitus malignancy defects in CMI trauma drugs
what does diabetes mellitus cause
these organisms cause a problem, will grow on sugar as a nutrient and use it
what is malignancy
immunosuppressant therapy
what is CMI
cell mediated immunity
what is the effect of CMI defects
don’t have functioning phagocytic cells, so organisms can overgrown and cause problem
what can trauma cause
organisms may be pushed into different sites
what do ringworms infect
keratinous tissues of the hair, nails and skin, uses the keratin
are ringworms contagious
only contagious mycosis from humans or animals
Animals and humans get infected can infect each other vice versa
how are ringworms diagnosed
clinical, scrapings for microscopy and culture
what is the treatment of ringworms
clotrimazole, terbinafine
what do filamentous fungi have
Ubiquitous spores (all over the place) – soil, dust (building work)
what clinical illnesses do filamentous fungi cause
pulmonary
systemic
other e.g. sinusitis
what causes the pulmonary clinical illnesses - filamentous fungi
breathe in spore and can cause asthma, if starts to grow in the lung can cause fungal ball which can lead to invasive aspergillosis and into blood stream so around the body to e.g. brain
examples of pulmonary clinical illness - filamentous fungi
Asthma (Bronchopulmonary aspergillosis [ABPA])
Aspergilloma (fungal ball)
Invasive aspergillosis
examples of systemic clinical illness - filamentous fungi
Lung, renal, cerebral (immunocompromised)
with Cryptococcus neoformans where is it found
Environmental organism: soil, bird droppings
what is Cryptococcus neoformans
true yeast
opportunistic pathogen
what is the clinical problem that Cryptococcus neoformans cause
meningitis in HIV / cancer patients; pulmonary disease (pneumonia / nodules); disseminated
what does Cryptococcus neoformans cause
defects in CMI
how is Cryptococcus neoformans diagnosed
clinical suspicion
microscopy
culture
antigen detection
how is Cryptococcus neoformans clinical suspicion diagnosed
(signs + symptoms; e.g. meningitis in an HIV patient)
how is Cryptococcus neoformans microscopy diagnosed
India Ink stain on CSF
how is Cryptococcus neoformans culture diagnosed
CSF, blood
how is Cryptococcus neoformans antigen detection
CSF, blood
what do dimorphic fungi exist as
a mould in the environment; but as a yeast in tissues
how are histoplasma capsulatum detected
Xray detect in lungs
Lower temp form filamentous structures
