Transcript CHAP 7 Fungi and other organism (human)

MYCOLOGY
(MIC 206)
FUNGI AND OTHER
ORGANISMS (HUMAN)
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):
1) Systemic or deep mycoses, often fatal.
2) Cutaneous mycoses or dermatomycoses.
3) Subcutaneous mycoses.
4) Superficial mycoses.
5) Dimorphic systemic mycoses.
SYSTEMIC
MYCOSES
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
Resembles tuberculosis.
immites):
Systemic Mycosis: Histoplasmosis
Disseminated Histoplasma capsulatum, lung infection.
Source: Microbiology Perspectives, 1999.
CUTANEOUS
MYCOSES
Cutaneous mycoses
Cutaneous mycoses:
hair, and nails.
 Secrete
keratin.
keratinase,
Fungal infections of the skin,
an
enzyme
that
degrades
 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)
Athlete’s foot (Tinea pedis)
Jock itch (Tinea cruris)
Tinea pedis (feet)
Cutaneous Mycosis
Ringworm skin infection: Tinea
corporis
Source: Microbiology
Perspectives, 1999
Candida albicans infection of
the nails.
Source: Microbiology
Perspectives, 1999.
SUBCUTANEOUS
MYCOSES
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.
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)
Tinea capitis (scalp)
Epidermophyton floccosum
Bifurcated hyphae with
multiple,
smooth,
club
shaped macroconidia (2-4
cells)
Dermatophyte Culture
OPPORTUNISTIC
MYCOSES
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.
DIMORPHIC
SYSTEMIC
MYCOSES
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.