Fungi

• Increased (but not due to epidemic like virus & bacteria)

• incr. use of immunosuppressive drugs -> ISP -> more prone to get fungal disease

• Eukaryotic

  • Cell membrane: Ergosterol instead of Cholesterol

  • Cell wall: Mammalian no, fungi chitin, mannan & glucan

  • Haploid DNA (not diploid)

  • 80S Ribosome

• stain like Gram + bacteria (purple) but are 5x bigger

• Extracellular digestion via exoenzymes -> glycogen stored

• Ergostrol in cell membrane -> amphotericin B, azole group (intracellular kations leak)

• Chitin, mannan & glucan in cell wall

Structure: polysaccharide

Functions: antiphagocytic -> virulence factor

Cryptococcus neoformans

• oxygen (aerobe)

• Room or human body temperature

• Nitrogen & carbon

• Sabouraud-dextrose-agar (SDA) medium

• takes longer than bacteria

Yeast 1-2 days

Mold up to 4 weeks

1. Yeasts

2. Yeast like fungi

3. Molds

4. Dimorphic fungi

1. Yeasts

• reproduce by budding at 37°C

• smooth, creamy colonies

2. Yeast like fungi

• called pseudo hyphae bc grow partly as yeasts and partly as elongated cells

3. Molds

• reproduce by spores at 26°C

• mycelia/hyphae (branching, tubular, multicellular)

4. Dimorphic fungi

• exist as yeast & mold depending on environment (mold in cold, yeast in heat)

• reproduce by spores

  • asexual form pathogenic for humans (lab)

  • sexual

    • Ascospores from Ascomycetes -> formed in a sac called “ascus”

    • Basidiospores from Basidiomycetes -> formed in a pin-shaped structure called basidium -> ejected from the ends of mycelia

    • Zygospores from Zygomycetes -> occur by fusion of morphologically identical cells of same hyphae (homotality)

• cause systemic infections

• molds 26°C (soil); yeast 37°C (host tissue)

1. Yeasts

• Candida

• Cryptococcus

2. Yeast like fungi

• Candida albicans

3. Molds

• Dermatophyts

• Aspergillus spp

• Pneumocytis jirovecii

• Rhizopus

• Mucor

4. Dimorphic fungi

• Histoplasma capsulatum

• Blastomyces dermatidis

• Paracoccidioides brasiliensis

• Coccidioides immitis

• Penicillium marneffei

• Sporothrix schenkii

• Phylum Glomeromycota

• Phylum Ascomycota

• Phylum Basidiomycetes

• Phylum Microspora

• Superficial

• Cutaneous

• Subcutaneous

• Systemic opportunistic

• Systemic deep

• Superficial

  • Tinea versicolor & negra

  • White & black piedra

• Cutaneous

  • Dermatophytosis

• Subcutaneous (not important)

• Systemic opportunistic

  • Yeasts: Candida and Cryptococcus

  • Molds: Aspergillus and Mucorales

• Systemic deep

  • Dimorphic = Diphasic mycosis

• Primary: more in ISP but also in immunocompetent patients

• Opportunistic: in ISP

• decreased hosts immunity

• high amount of fungi ingested

• adherence

• Capsules (resistance to phagocytosis)

• Cytokines (suppr. complement prod. in C.albicans)

• block the cell-mediated immune defences of the host

• acquire iron from RBC

• secr. enzymes damaging host (keratinase, elastase, collagenase)

• secrete mycotoxins

• thermal dimorphism

• Surface hydrophobicity

• Aspergillus species, H. capsulatum, C. neoformans adhere in lungs -> avoid clearance -> resp. tr. inf.

• C. albicans -> adheres to niches -> not washed out -> spread & hematogenous infections

Candida

C.albicans: Phospholipase

A.fumigatus: Proteinase

makes mo resistant to leukocyte attack

C. neoformans

A.fumigatus & molds

• T-cell/lymphocyte-mediated immunity

• Delayed-type hypersensitivity -> granulomas (can become chronic granulomatous reactions)

• Hypersensitivity (Type I; III) -> I allergic pulmonary diseases due to inhalation, III Antigen-Antibody complex

• ID reaction in Candida -> fungus-free skin leasons elsewhere in body

• strong immune reaction to dermatophyte -> lesion on scalp (Kerion)

• Granuloma due to intracellular fungi-delayed hypersensitivitiew

• allergic pulmonary diseases when inhaled (f.e. aspergillosis)

• Type I (degranulation)

• Type II Antibodies help clearing out Candida and Cryptococcus (opsonization & complement activation)

  
  

• site of infection: superficial, cutaneous, subcutaneous, systemic opportunistic or systemic deep

• route of acquisition: endo- orexogenous

• virulence:primary or opportunistic