FUNGI AND OTHER ORGANISMS (HUMAN)

1
MYCOLOGY (MIC 206)

• FUNGI AND OTHER ORGANISMS (HUMAN)

2
PARASITIC FUNGI AND HUMAN

• Mycoses Any fungal disease. Tend to be chronic
  because fungi grow slowly.
• Mycoses are classified into the following
  categories (based on the level of penetration
  into the body tissues)
• Systemic or deep mycoses, often fatal.
• Cutaneous mycoses or dermatomycoses.
• Subcutaneous mycoses.
• Superficial mycoses.
• Dimorphic systemic mycoses.

3
SYSTEMIC MYCOSES
4
Systemic mycoses

• Fungal infections deep within the body. Can
  affect a number if tissues and organs.
• Usually caused by fungi that live in the soil and
  are inhaled.
• Examples
• Histoplasmosis (Histoplasma capsulatum) Initial
  infection in lungs. Later spreads through blood
  to most organs.
• Coccidiomycosis (Coccidioides immites)
  Resembles tuberculosis.

5
Systemic Mycosis Histoplasmosis
Disseminated Histoplasma capsulatum, lung
infection. Source Microbiology Perspectives,
1999.
6
CUTANEOUS MYCOSES
7
Cutaneous mycoses

• Cutaneous mycoses Fungal infections of the
  skin, hair, and nails.
• Secrete keratinase, an enzyme that degrades
  keratin.
• Infection is transmitted by direct contact or
  contact with infected hair (hair salon) or cells
  (nail files, shower floors).
• Examples
• Ringworm (Tinea capitis and T. corporis)
• Athletes foot (Tinea pedis)
• Jock itch (Tinea cruris)

8
Tinea pedis (feet)
9
Cutaneous Mycosis
Candida albicans infection of the nails. Source
Microbiology Perspectives, 1999.
Ringworm skin infection Tinea corporis Source
Microbiology Perspectives, 1999
10
SUBCUTANEOUS MYCOSES
11
Subcutaneous mycoses

• Subcutaneous mycoses Fungal infections beneath
  the skin.
• Caused by saprophytic fungi that live in soil or
  on vegetation.
• Infection occurs by implantation of spores or
  mycelial fragments into a skin wound.
• Can spread to lymph vessels.

12
Superficial mycoses

• Superficial mycoses Infections of hair shafts
  and superficial epidermal cells. Prevalent in
  tropical climates.
• 3 Genera of dermatophytes
• Trichophyton (Hair, Skin, Nails)
• Microsporum (Skin, Hair)
• Epidermophyton (Skin, Nails)

13
Tinea capitis (scalp)
14
Epidermophyton floccosum
Bifurcated hyphae with multiple, smooth, club
shaped macroconidia (2-4 cells)
15
Dermatophyte Culture
16
OPPORTUNISTIC MYCOSES
17
Opportunistic mycoses

• Caused by organisms that are generally harmless
  unless individual has weakened defenses
• AIDS and cancer patients
• Individuals treated with broad spectrum
  antibiotics
• Very old or very young individuals (newborns).
• Examples
• Aspergillosis Inhalation of Aspergillus spores.
• Yeast Infections or Candidiasis Caused mainly
  by Candida albicans. Part of normal mouth,
  esophagus, and vaginal flora.

18
DIMORPHIC SYSTEMIC MYCOSES
19
Dimorphic Systemic Mycoses

• Caused by dimorphic fungal pathogens (by changing
  their morphological form.
• Geographically restricted and the primary sites
  of infection is usually pulmonary, inhalation of
  conidia.
• Histoplasmosis
• World-wide, espceially USA, sporadic cases do
  occur in Australia.
• Agent Histoplasma capsulatum.
• Coccidioidomycosis
• Respiratory infections Endemic in south-western
  USA, nothern mexico and various centres in South
  America.
• Agent Coccidioides immitis.