Star Team

Introduction
Fungi are eukaryotic cells that lack chlorophyll. They have cell walls and filamentous structures and produce spores, or conidia. These organisms grow as saprophytes that obtain nutrients from dead organic matter. Most of the fungi that cause systemic infections may infect incidental hosts (i.e. humans and other animals) who are exposed to fungal elements or spores.

Systemic mycoses

Histoplasma capsulatum

Epidemiology
Dimorphic fungus (exists as mold in soil and yeast in tissue) that is found worldwide and in temperate, subtropical and tropical climates. Grows in soil and material contaminated with bat or bird droppings.

Causes
Histoplasmosis. Infection occurs resulting from inhalation of spores.

Transmission
Infection resulting from inhalation of spores of the fungi in their mold forms in soil. Within the lungs, the spores differentiate into yeasts.

Signs & symptoms
Fever
Headache
Malaise
Myalgia (muscle pain)
Abdominal pain
Chills

Mode of control
No means of prevention except avoiding exposure in areas of endemic infection.


Dermaphytes

Trichophyton species
Trichophyton ajelloi (geophilic)
Trichophyton concentricum (anthrophilic)
Trichophyton flavescens (geophilic)
Trichophyton gloriae (geophilic)
Trichophyton interdigitale (anthrophilic)
Trichophyton megnini (anthrophilic)
Trichophyton mentagrophytes (zoophilic, anthrophilic) (rodents)
Trichophyton phaseoliforme (geophilic)
Trichophyton rubrum (anthrophilic) (most common)
Trichophyton schoenleinii (anthrophilic)
Trichophyton simii (zoophilic) (monkey, chicken)
Trichophyton soudanese (anthrophilic)
Trichophyton terrestre (geophilic)
Trichophyton tonsurans (anthrophilic)
Trichophyton vanbreuseghemii (geophilic)
Trichophyton violaceum (anthrophilic)
Trichophyton yaoundei (anthrophilic)

Epidermophyton floccosum

Epidemiology
Found worldwide, more common in countries with hot and humid climates with crowding or debilitation

Cause
Dermatophytosis
Tinea corporis (ringworm)
Tinea cruris (jock itch)
Tinea pedis (athlete’s foot)
Tinea manuum (hand)
Tinea favosa (scalp)
Folliculitis (inflammation of hair follicles)
Tinea capitis (hair infection)
Onychomycosis (nail infection)
Invasive infection for immunocompromised host

Transmission
Direct or indirect contact with infected host (human or animal)
Direct or indirect contact with skin or hair
Geophilic species are acquired via contact with spores in the soil
Skin trauma (burns, cuts), high temperature and humidity and increase susceptibility to infection

Signs & symptoms
Itching, stinging and burning between the toes, on the soles
Excessive dryness of the skin on the bottom of the feet
Thick, crumbly, discoloured, brittle and ragged nails
Blisters
Hair loss
Scabs
Tinea of the nails

Mode of control
No means of prevention except avoiding exposure in areas of infection

Microsporum species
Microsporum audouinii (anthrophilic)
Microsporum canis (zoophilic) (cats and dogs)
Microsporum cooeki (geophilic, zoophilic) (fur from cats, dogs and rodents)
Microsporum ferrugineum (anthrophilic)
Microsporum gallinae (zoophilic) (chicken)
Microsporum gypseum (geophilic)
Microsporum nanum (geophilic, zoophilic) (pig)
Microsporum persicolor (zoophilic) (rodents)

Epidemiology
Found worldwide, more common in countries with hot and humid climates with crowding or debilitation

Cause
Dermatophytosis
Tinea corporis (ringworm)
Tinea cruris (jock itch)
Tinea pedis (athlete’s foot)
Tinea manuum (hand)
Tinea favosa (scalp)
Tinea capitis (scalp)
onychomycosis (rare)
Invasive infection for immunocompromised host
Note: Microsporum persicolor does not infect hair

Transmission
Direct or indirect contact with infected host (human or animal)
Direct or indirect contact with skin or hair
Geophilic species are acquired via contact with spores in the soil
Skin trauma (burns, cuts), high temperature and humidity and increase susceptibility to infection

Signs & symptoms
Itching, stinging and burning between the toes, on the soles
Excessive dryness of the skin on the bottom of the feet
Thick, crumbly, discoloured, brittle and ragged nails
Blisters
Hair loss
Scabs
Tinea of the nails

Mode of Control
No means of prevention except avoiding exposure in areas of infection

Malassezia furfur

Epidemiology
Worldwide, part of normal skin flora, infections likely to occur in hot and humid conditions

Cause
Pityriasis versicolor (skin rash)
Seborrheic dermatitis (flaky scalp, face, trunk)
Folliculitis (inflammation of hair follicles)
Blepharitis (inflammation of the eyelids)
Tinea Blanca (hair)
Severe systemic infections in immunocompromised host

Transmission
Normal skin flora, that causes infection when it becomes an opportunistic infection

Signs and Symptoms
Itching
Scaling
However sometimes the infection is asymptomatic


Sporothrix schenckii

Epidemiology
Worldwide, isolated from soil, living and decomposing plants, wood and moss

Cause
Sporotrichosis (Rose handler’s disease)
Invasive sinusitis
Meningitis
Osteoarticular infection
Bursal infection

Transmission
Infection by entry of infecting fungus through the skin via minor trauma (eg. cuts)

Signs & symptoms
Large ulcerations
Small painless skin bump on the arms, fingers or hand
Boil-like lesions
Firm skin nodules
Suppurative nodules


EXCLUSION OF FUNGI

1. Opportunistic mycoses
These fungi cause infections only in immunocompromised people.

Candida species
Candida albicans
Candida guilliermondii
Candida parapsilosis
Candida tropicalis

Epidemiology
This fungus is found worldwide. For some of the fungi, they are part of the normal microbial flora of the mucous membranes of the mouth and intestinal tract.

Cryptococcus species
Cryptococcus neoformans
Cryptococcus gattii

Epidemiology
Cryptococcus neoformans is found in soil, especially those enriched by pigeon droppings
Cryptococcus gattii can be found in eucalyptus trees and decaying wood forming hollows in living trees

Aspergillus species
Aspergillus fumigatus
Aspergillus niger
Aspergillus flavus
Aspergillus terreus
Aspergillus nidulans

Epidemiology
Fungus is ubiquitous in the environment, growing in soil and decaying vegetation. The transmission of fungus is by airborne conidia.

2. Coccidioides immitis

Epidemiology
This fungus is found in arid regions of USA and South America

3. Blastomyces dermatitidis

Epidemiology
This fungus is endemic in North & South America, Africa and in the Middle East.


References
Martin
http://www.emedicine.com > search > Cryptococcosis
http://www.emedicine.com > search > Histoplasmosis
http://www.doctorfungus.org > search > Cryptococcus
http://www.mycology.adelaide.edu.au > search > Candida
Levinson, W. (2006). Review of Medical Microbiology & Immunology. San Francisco, California: Lange Medical Books/McGraw-Hill publishing company.
Murray, P.R. (2002). Medical Microbiology. St. Louis, Missouri: Mosby Inc.
Virella, G. (1997). Microbiology and Infectious Diseases. Pennsylvania, USA: Williams & Wilkins.

Randall
http://www.doctorfungus.org > search > Trichophyton
http://www.wrongdiagnosis.com > T > tinea
http://www.mayoclinic.com/ > health > search > athlete’s foot
http://www.emedicine.com/aaem/topic277.htm
http://www.doctorfungus.org > search > Epidermophyton
http://www.doctorfungus.org > search> Microsporum
http://www.doctorfungus.org > search > Malassezia furfur
http://www.doctorfungus.org > search > Sporothrix schenckii
http://www.wrongdiagnosis.com > S > sporotrichosis
Walker, T.S. (1998). Microbiology. Philadelphia, Pennsylvannia: W.B Saunders Company
Levinson, W. (2006). Review of Medical Microbiology & Immunology. San Francisco, California: Lange Medical Books/McGraw-Hill publishing company.

Done by: Martin Ng & Randall Chua (TG02)

# posted by Star team @ 10:32 AM