Myocology

• Mycoses


  Fungal infection
• Kingdom of Fungi;

  • Domain: Eukarya
  • Either unicellular or multicellular
  • Heterotrophic
  • Need oxygen to survive
  • Stain gram positive
  • Has cell walls made of chitin.
• Fungus cell wall:

  Key features

  •Chitin layer

  •Glucan polysaccharides

  •Ergosterol within the membrane
• Chytridiomycota:

  • Live in aquatic habitats
  • Causes disease in aquatic life.
  • Asexually reproduces by zoospores.
  • Zoospores, zoosporangium, hyphae rhizoid
• Zygomycota;

  • Found on decaying vegetables and breads.
  • Reproduce asexually by spores
  • 3 types of hyphae: Rhizoids, Sporangiophores, Stolon
• Basidiomycota

  • Includes jelly fungus, mushrooms and stinkhorns.
  • Has basidium which release spores.
  • Sexual reproduction.
• Ascomycota:

  • Includes edible truffles, common yeasts, several fungal infections.
  • Some yeasts bud by mitosis asexually.
  • Some other Ascomycota produces sexual spores called ascospores from its ascus.
  • Can produce asexual spores called conidia.
• Ascomycota:

  • Called ‘sac’ fungi due to the presence of the ascus.
  • Contains 3 phylum subdivisions.
  • Ascocarp structures can include:
  • Stalked stoma – Aspergillus fumigatus
  • Cleistothecium – Truffles
  • Apothecium – Lichens
  • Perithecium – Grows on bark of trees
• ChytridiomycotaL:

  • Aquatic habitats
  • Asexual reproduction by Zoospores
  • Has one hyphae (rhizoidal)
• Zygomycota:

  • Found on decaying matter.
  • Asexual reproduction through spores.
  • Has three hyphae (sporangiophore, stolon, rhizoids)
• Basidiomycota:

  • Includes mushrooms and jelly fungus
  • Sexual reproduction through spores in Basidium.
  • Club like body is made from hyphae
• Ascomycota

  • Includes truffles and common yeasts
  • Both sexual and asexual reproduction
  • Sac like structure made form hyphae
• Contains 3 major subdivisions:

  •Saccharomycotina – Includes unicellular yeasts, which reproduce by asexual budding.

  •Taphrinomycotina – Multicellular hyphae, reproduce by sexual spores.

  •Pezizomycotina – Multicellular hyphae, reproduce by sexual fission or asexual spores. 
• Saccharomycotina: Cell structure:

  • Unicellular
  • Has cell walls made of chitin.
  • Ability to bud.
• Saccharomycotina: Reproduction

  • Most reproduce through asexual budding.
  • Parent nucleus is split and migrates into the daughter cell.
  • Cytoplasm divides to create a new yeast cell.
  • Sometimes the yeast can form chains called Pseudo-hyphae.
• Saccharomycotina: Infections

  • Most common infection is caused by the opportunistic pathogen Candida albicans.
  • C.albicans colonise in our bodies and don’t do any harm.
  • Lives in moist and warm conditions.
  • Infections are called Candidiasis.
  • Individuals at risk: Immunocompromised individuals, Antibiotic therapy, Pregnant individuals
• Candida albicans infections:

  Oral thrush:

  •Overgrowth of C.albicans on the tongue.

  •White spots seen down the throat.

  Common in individuals with dentures

  Vaginal thrush

  • Overgrowth of C.albicans in the vaginal tract.
  • Thick, cottage cheese like discharge.
  • Painful urination.
  • Common in individuals with IUDs.
• Invasive Candida albicans infections:

  • Candidaemia is the presence of Candida in the blood.
  • C.albicans is one of the ten most common pathogens isolated from blood cultures.
  • Symptoms may include:

  fever and chills

  skin rash

  generalized weakness or fatigue

  low blood pressure

  muscle aches

  vision changes or signs of an eye infection

  headaches and neurological deficits

  abdominal pain
• Candida albicans: Diagnostic tests

  • Culture onto agar
  • Sabouraud agar is used for fungal infections.
  • 37o C for 48 hours.
  • Should be tapped up
• Candida albicans: Diagnostic tests

  • Germ tube test (GTT)
  • Used to differentiate Candida albicans from other yeasts.
  • Put 0.5 ml of sheep or human serum into a small tube.
  • Add a colony of yeast to the serum.
  • Incubated the tube at 37°C for 2 to 4 hours.
  • Transfer a drop of the serum to a slide for examination.
  • Coverslip and examine microscopically.
• Saccharomycotina: Industrial uses

  • Most commonly used yeast is saccharomyces cerevisiae.
  • Commonly called brewers or bakers yeast.
• Pezizomycotina: Reproduction

  • Asexual reproduction (Mitosis):
  • Conidiophore releases spores
  • Germination occurs
  • Sexual reproduction (Meiosis and mitosis): Ascogonium (Male), Antheridium (Female)
  • Nuclei in the asci form a diploid zygote
  • Meiosis occurs and four haploid ascospores form.
  • Mitosis occurs to give eight haploid ascospores.
• Pezizomycotina: Illness

  -Aspergillosis

  Normally a lung infection caused by any aspergillus species, most commonly aspergillus niger.

  • Dermatophytosis

  Skin, hair or nail infection caused by Dermatophytes. These include ringworm and athletes foot.
• Athletes Foot:

  • Symptoms: White cracked painful skin in-between toes.
  • Cause: Commonly caused by T. rubrum.
  • Laboratory testing: Lactophenol cotton blue staining and SAB agar.
  • Treatment: Foot creams available over the counter.
• Aspergillosis: Aspergillus fumigatus

  • Risk factors: Immunocompromised patients.
  • Symptoms: Shortness of breath, coughing up mucus.
  • Causes: Most common cause is Aspergillus fumigatus.
  • Laboratory testing: Culture of sputum onto SAB agar.
  • Treatment: Antifungal tablets, unless a aspergilloma has grown in which case surgery is the best option.
• Pezizomycotina: Industrial use

  • Penicillium moulds are used as common antibacterial medications.
  • Originally discovered by Alexander Fleming.
• 1. Cryptococcal meningitis is caused by Cryptococcus neoformans, a type of fungus.
• 1. Cryptococcus neoformans belongs to the Phylum Basidiomycota.
• It primarily infects the central nervous system, particularly the meninges surrounding the brain and spinal cord.
• The fungus spreads through inhalation of airborne spores present in the environment, especially from bird droppings (such as pigeon droppings).
• The fungus can be detected in the laboratory through various methods, including microscopic examination of cerebrospinal fluid (CSF) for yeast cells, culture of CSF or other clinical specimens on fungal growth media, and detection of cryptococcal antigen in serum or CSF using immunoassays such as latex agglutination or enzyme immunoassay.