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2 Several Candidaspecies grow as normal resident

commensalson the mucosal membranes of healthy

individuals, but can become invasive in appropriate

conditions. The diploid yeast Candida albicans is the

prime example of this. It is found commonly on

the mucosa of the gut, the mouth, and the vulvo-

vaginal tract. But in response to environmental

triggers the yeast cells can produce hyphal out-

growths that invade the mucosa, leading to clinical

or subclinical conditions. For example, “thrush” is

a white, invasive speckling of the throat, which is

common in neonates and immunocompromised

individuals, including AIDS and cancer patients, and

people in the advanced stages of diabetes. Candida

can also cause intense irritation of the vulvo-uterine

tract of women during stages of menstruation or dur-

ing pregnancy, and it commonly causes stomatitis

in people who wear dentures.

3 A diverse group of fungi that normally grow as

saprotrophs in soil or on plant or animal remains

can establish infections in the lungs from inhaled

spores. These infections invariably stem from an

environmental source of spores rather than from

direct patient-to-patient transmission. Almost any

fungus that produces spores small enough (c. 3– 4μm)

to reach the alveoli, that can grow at 37°C, and

THE MOULDS OF MAN 323

Table 16.1The major types of fungus that cause mycoses of humans.

Primary route

of entry

Skin

Mucosa

Lungs

Wounds/

lesions

Lungs

Fungus

Trichophyton(22 species)

Microsporum(19 species)

but only 9 are involved

in infections

Epidermophyton

(2 species)

Candida albicans

Some other Candidaspp.

Aspergillus fumigatus

Blastomyces dermatitidis

Coccidioides immitis

Cryptococcus neoformans

Histoplasma capsulatum

Paracoccidioides

brasiliensis

Phialophora Cladosporium

Sporothrix, etc.

Rhizopus, Absidia, etc.

Pneumocystisspecies

Sexual stage

Arthroderma

(Ascomycota)

Recently reported

(see text)

None

Ajellomyces

(Ascomycota)

None

Filobasidiella

(Basidiomycota)

Ajellomyces

(Ascomycota)

None

Often none

Zygomycota

None

Disease

Dermatomycosis:

ringworm, tinea,

athlete’s foot, etc.

Candidosis: thrush,

vulvovaginitis, stomatitis

Aspergillosis: invasive

(systemic) or

aspergillomas of lungs

Blastomycosis: lungs,

skin lesions, bones, brain

Coccidioidomycosis:

lungs, systemic

Cryptococcosis: lungs,

brain, meninges

Histoplasmosis: lungs,

rarely systemic

Paracoccidioidomycosis:

lungs, cutaneous, lymph

nodes

Subcutaneous mycoses:

chromomycosis,

sporotrichosis, etc.

Zygomycosis

Virulent pneumonia

Natural distribution

Keratinized tissues,

humans and wild or

domesticated animals

Commensal on mucosa

Saprotrophic in soil or

organic matter (composts)

Saprotrophic

Saprotrophic in soil

Bird excreta, vegetation

(eucalypt trees)

Bird and bat droppings

Soil?

Saprotrophic in soil, dead

plant material

Saprotrophic

Humans, other mammals

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