INTRODUCTION TO MYCOLOGY

• Mycology is the study of fungi
• Causes why laboratories prevent offering mycology services?  

  • Economic constraints
  • Lack of experience
  • Training and continuing education
• Diagnostic clinical laboratory is performed by Reference laboratory
• Fungi are saprophytic (livd on dead organic matter)
• Yeasts are moist
• Molds are filamentous
• Dimorphic: organisms that display both yeast and mold forms
• Fungi are thermally dimorphic when dependent on temperature
• Fungi that have more than one form or stage are polymorphic
• Chitin is present in the cell wall of fungi
• Ergosterol is present in the cell membrane of fungi
• Fungi are sexual and asexual
• Fungi lack chlorophyll
• Fungi lack of susceptibility to antibacterial antibiotics
• Fungi are saprophytic in nature
• Phyla


  • Zygomycota
  • Ascomycota
  • Basidiomycota
  • Deutromycota
• Zygomycota

  • Sporangiospores - asexual reproduction
  • Zygospores - sexual reproduction
• Ascomycota

  • Conidia - asexual reproduction
  • Ascospores - sexual reproduction
• Basidiomycota


  Basidiospores (on basidia) - sexual reproduction
• Deuteromycota


  Conidia - asexual reproduction
• Reproductive forms

  • Teleomorph
  • Anamorph
  • Synanomorph
• Teleomorph


  Sexual form
• Anamorph


  Asexual form
• Synanomorph


  Different asexual forms in the same fungus
• Clinical Classification of the Fungi

  • Superficial cutaneous mycoses
  • Subcutaneous mycoses
  • Systemic mycoses
  • Opportunistic mycoses
• Superficial cutaneous mycoses 


  Infections involved in hair, skin, or nails without direct invasion of deep tissue
• Subcutaneous mycoses


  Infections are confined to subcutaneous tissue without dissemination
• Systemic mycoses 


  Infections often involve the lungs but can disseminate to any organ
• Opportunistic mycoses


  Infections can become systemic and occur in patients who are immunocompromised
• Mycology is the field in biology concerned with the study of fungi
• Early to mid-twentieth century: Fungi began to be recognized as a pathogen
• Factors that increase the number of fungal infections include alterations in the hosts, complex surgical procedures, and antibacterial therapy
• 100 to 1500 new species of fungi are identified annually
• Characteristics of fungi:

  • Saprophytic: living on dead or decayed organisms
  • Does not undergo person-to-person transmission
  • Transmission of fungi occurs through inhalation of spores and introduction of fungal elements into tissue by trauma
• General features of fungi based on appearance of colonies:

  Yeasts:

  • Moist, creamy
  • Fluffy, cottony or wooly
  • Pasty, powdery

  Molds:

  • Cottony or wooly
  • Powdery
• Dimorphic fungi are fungal pathogens that are either yeast or yeastlike phase and filamentous forms
• Thermally dimorphic fungi:

  • Mold phase at 25°C to 30°C
  • Yeast phase at 35°C to 37°C
• Polymorphic fungi have more than one independent form or spore stage in their life cycle
• Most fungi share characteristics such as chitin in the cell wall, ergosterol in the cell membrane, reproduction by means of spores produced asexually or sexually, lack of chlorophyll, lack of susceptibility to antibacterial antibiotics, and saprophytic nature
• Phyla of fungi:

  Zygomycota:

  • Very diverse group of organisms divided into phylum Glomeromycota, subphyla Mucoromycotin, and Entomophthoracortina

  Ascomycota:

  • Fungi that reproduce asexually by the formation of conidia and sexually by the production of ascospores, may exhibit teleomorph, anamorph, and synanomorphs

  Basidiomycota:

  • Fungi that reproduce sexually through the formation of basidiospores on a basidia, plant pathogens or environmental organisms that rarely cause disease in humans