Mycology Flashcards
(29 cards)
What are fungi?
Eukaryotic
Chitinous cell wall
Heterotrophic
“Move” by means of growth or generation of spored (conidia).
How is conidia carried?
Through air or water.
Define yeast
Small single celled organisms - divide by budding.
Account for <1% of fungal species but include several highly medically relevant ones.
Define mould
Form multicellular hyphae and spores.
Why only a limited number of fungi cause human infection?
Unable to grow at 37 degrees.
The innate and adaptive immune response fights it.
What genera of mycoses cause human disease?
Ascomycota: Aspergillus, Pneumocystis, Candida, Fusarium, Scedosporium.
Basidiomycota: Cryptococcus, trichosporon.
Mucormycot: zygomycetes.
What are the similarities between human cells and fungi?
DNA/RNA synthesis and protein synthesis.
What are some of the differences between eukaryotic cells and fungi?
Fungi has cell wall made up from mannoproteins, B1,3 glucan and B1,6 glucan, chitin.
Plasma membrane contains ergosterol.
Flucytosine and Griseofulvin act on
DNA/RNA synthesis, protein synthesis
Echinocandins act on
Cell wall
Polyenes (amphotericin)
Azoles
Allylamines (terbinafine) act on
Plasma membrane.
Mucosal candidiasis
Common and recurrent disease with significant morbidity.
Normal commensal - RF for immunosuppressant, diabetic, ABX therapy, mucosal disruption.
What is the treatment for mucosal candidiasis?
Topical or oral azoles.
If resistant - swab.
Dermatophytes ( transmission and causative agents)
Human-human, animal-human.
Caused by: Trichophyton spp, Micrsporum spp, Epidermophyton floccosum.
Treatment for dermatophytes
Topical or oral azoles/terbinafine.
What are some example of ringworm infections?
Tinea capitis, tinea corporis, tinea cruris, tinea unguium, tinea pedis.
Dimorphic fungi infection
Mould at ambient temperature (25-30).
Infection via inhalation of conidia from soil or implantation.
Convert to yeast at 37 (due to heat related stress).
True pathogens.
Examples of severe fungal infections:
- Histoplasma capsulatum
- Blastomyces dermatitidis
- Coccidioides immitis and posadasii
- Paracoccidioides brasiliensis
- Sporothrix schenkii
- Talaromyces marneffei
Coccidioides
2 species:
C. immitis and C. posadasii
Geography - warm, arid conditions in SW USA.
Disease
Asymptomatic/subclinical infection common (2/3)
Most of rest – community acquired pneumonia 1-3 weeks post-exposure (1/3 of CAP in Ariziona)
Severe disease= respiratory failure or septic shock in context of high inoculum or cell-mediated immune defect – e.g. HIV
Late disease – does not correlate with the severity of initial symptoms
Late manifestations of Coccidioides
Cavitatory lung disease
may result in pleuritic pain or cough or become colonised by Aspergillus
Orthopaedic
Asymetrical chronic arthritis with effusion or vertebral osteomyelitis
Cutaneous ulcers and abscesses
Cervical lymphadenopathy
Intracranial – chronic meningitis- BAD
Invasive candidiasis is mostly due to what?
Infection of prosthetic devices or intra-abdominal disease.
Cryptococcus causes what?
Acute or chronic meningitis in patients with reduced cell mediated immunity.
What are the differential diagnosis of sub-acute/chronic meningitis?
Infective
Tuberculosis
Cryptococcus
Dimorphic fungi – Histoplasma, Coccidioides, Blastomyces
Lyme
Brucella
Syphilis
Non-infective
Sarcoidosis
Behçets’s
SLE
Malignant
Drug induced
Invasive aspergillosis is associated with what?
Profound immunocompromise but is increasingly recognised in patients with severe viral infection.
