Fungal infection Flashcards
is Fungi prokaryote or Eukaryote
Eukaryote
what does a fungi cell wall contain
Chitin
reproduction on fungi is
sexual or asexual
most fungi are
saprophytes
saprophytes=
live on dead organisms
are any fungi primary pathogens to humans
no
why is human fungi infection rare (4)
- Not well adapted to growth at 37 degrees
- poorly adapted to using human nutrients
- host defence mechanisms are efficient at dealing with inhaled/ ingested fungi
- Slow growing
In whom are fungal infections more likely to occur
Immunocompromised
who are immunocompromised (6)
HIV Diabetes mellitus Pregnancy Lymphoma/ Leukemia Chemotherapy steroids
3 fungi type
Moulds
yeasts
dimorphic
how do moulds grow
Hyphae
Hyphae=
growth by formation of filaments
what does an entangled mass of hyphae form
A mycelium
how does asexual reproduction happen
Through production of conidia (asexual spores)
sexual reproduction happens by
sexual spores mixing of DNA
or Hyphae breaking off
what is the only type of fungi spread/ reproduction in humans
hyphae
what are yeasts
single cell round or ovoid organisms
how do yeasts reproduce
by budding
2 important pathogenic yeasts
candida cryptococcus neoformans (causes menigitis)
what can some yeasts form under stress in the human body
elongated buds (pseudohyphae)
what can candida form versions off in the human body (2)
Hyphae and pseudohyphae
least common type of fungi
dimorphic
what do dimorphic fungi grow as
yeasts or moulds
which type of dimorphic fungi causes infection
yeast form
what form of dimorphic fungi lives in the environment
Mould form
are dimorphic fungi found in the Uk
No
2 non-infections that fungi can cause
Mycotoxins
Hypersensitivity
Mycotoxins=
some fungi produce mycotoxins often renal or neurological
2 hypersensitivity affects of fungus
Asthma
farmers lung
2 types of superficial mycoses=
no tissue invaded and no cellular response from host
no tissue invaded but host response elicited
e.g of superficial mysoses
Dermatophytoses (ringworm or tinea)
what is tinea caused by
yeast (malasezzia)
what does tinea feed on
keratin and superficial parts of the stratum corneum
three groups of transfer for fungi
Geophillic (contact with soil)
Zoophillic (contact with animals)
Anthropophillic (contact with humans)
anthropophillic =
contact with humans, the only fungi which require humans for survival
what can superficial mycoses look like
eczema but can be anywhere on body, more round and isn’t itchy
what type of mycoses is probably a tropical infection
Subcutaneous mycoses
commonest IMPORTANT systemic/ deep mycoses
Aspergillus fumigatus
what is Aspergillus fumigatus
deep infection that follows inhalation of spores resulting in invasive pulmonary aspergillosis
what may happen to aspergillus fumigatus infection in the immunocompromised
- hyphae may break off into the blood system
- Angiotropic invasion of blood vessels causes pulmonary haemorrhage or infarction
- can disseminate from lung
why are fungal infections never infections person to person
Because they don’t spore only hyphae
where does candida live normally
in our bowel and mucus membranes
what does candida often cause
mouth infections and in IC patients can run down into oesophagus
most common yeast candida=
candida albicans
where does candida albicans live normally
normal mouth flora and lower female genital tract
what can candida albicans cause
superficial candidosis of skin and mucosa (thrush) or nails
hepatosplenic candidasis causes=
white patches on liver and spleen can cause liver failure in end stages
Symptoms of hepatosplenic candidasis
weight loss
low grade fever
hard to diagnose
what can happen when candida is in the larger arterioles
can easily jam bc they are large and cause haemorrhage and bleeding
what is the first sign of systemic candidosis
haemorrhage and bleeding
deep mycoses caused by
dimorphic fungi
deep mycoses usually acquired by
inhalation of spores (found in soil)
geographic associations
3 antifungal drugs
Amphotericin
Azoles
Echinocandins
Amphotericin resistance=
rare
toxicity of amphotericin=
renal damage if given long enough will get major kidney damage
how can amphotericin be less toxic
lipid associated forms are less toxic
most common antifungal drug type=
Azoles
suffix of azoles=
-azole
MOA of azoles
inhibit lanosterol demethylase
2 types of azoles
Fluconazole
voriconazole
resistance of azoles=
Becoming common especially in candida
e.g of echinocandins
Caspofungin
MOA of echinocandins
Inhibits glucan synthase (cell wall sythesis inhibitor)