V. OPPORTUNISTIC FUNGI

• Most opportunistic fungi form colonies within ______.

• Humans generally acquire infections through _____ of the conidia.

• Most opportunistic fungi live on _____ found in the soil.

• several days (rapid growers)

• inhalation

• organic matter (saprophytic fungi)

• Identification is based on _____

• The hyphae are ____ (lightly pigmented).

• microscopic morphology.

• hyaline

• Can affect the skin, heart, lungs, and central nervous system.

• It pulmonary form affects the bronchi, lungs, or sinuses.

Aspergillus spp

The most common cause of aspergillosis

Aspergillus fumigatus

An important cause of otomycosis, a superficial mycotic infection of the outer ear canal characterized by inflammation, pruritus, and scaling

Aspergillus niger

Identifying characteristics

• Colony morphology: Form granular/fluffy or powdery growth within 2 days on SABHI. Pigmentation varies according to species.

• Microscopic appearance: Hyphae are septate; conidiophores terminate in a large, spherical vesicle bearing phialides.

Aspergillus spp.

• Aspergillus spp. form granular/fluffy or powdery growth within ___  on  ___

• Pigmentation varies according to species

2 days on SABHI.

Where:

• Have septate hyaline hyphae.

• Conidiophoresarise from a foot cell and support a single vesicle at their tip.

• Flask-shaped phialides, in a single or double row, produce chains of phialoconidia.

Aspergillus spp.

Aspergillus spp.

1. A. niger colonies are 

2. Aspergillus flavus colonies are

3. Aspergillus terreus colonies are

4. Aspergillus clavatus colonies are

5. A. fumigatus colonies are

1. A. niger colonies are yellow to black with a yellow reverse.

2. Aspergillus flavus colonies are green to brown with red-brown reverse.

3. Aspergillus terreus colonies are green to yellow with yellow reverse.

4. Aspergillus clavatus colonies are blue to green with white reverse.

5. A. fumigatus colonies are green to gray with tan reverse.

Members of the class Zygomycetes include the genera?

Absidia, Mucor, Rhizomucor, Rhizopus, and Syncephalastrum

Zygomycetes causes infection known as _____ and ____

zygomycoses and mucormycoses

Produce allergic reactions in susceptible individuals

Zygomycetes

• Are uncommon in otherwise healthy individuals.

• Infections of the paranasal sinuses that can extend to the central nervous system (rhinocerebral) are probably the most common.

• Infections can rapidly progress to a fatal outcome in patients who are immunocompromised or in diabetics with ketoacidosis.

Zygomycetes: Mucormycoses

• Some zygomycetes produce toxins that can cause _______.

• ______ can lead to central nervous system disorders.

• Gastrointestinal disturbances

• Blood infections (fungemia)

Identifying characteristics

• Colony morphology: Growth after several days is dense; colonies show a cotton candy texture, and pigmentation ranges from white, to gray, to brown.

• Microscopic appearance: Hyaline hyphae are sparsely septate and are ribbonlike with thin walls.

Zygomycetes

Zygomycetes typically form _____, which resemble tree roots and function in attachment and nutrient absorption.

Rhizoids

Species identification: Zygomycetes

1. _____ exhibit branching sporangiophores between the rhizoid (rootlike hyphae). A slight swelling below the columella at the base of the sporangia is present.

2. _____ Single or branching sporangiophores are present, but rhizoids are absent. No swelling is noted below the columella.

3. ______ produce unbranched sporangiophores that arise opposite rhizoids. No swelling is noted below the columella.

1. Absidia spp.

2. Mucor spp.

3. Rhizopus spp

Are opportunistic fungi associated with a variety of clinical presentations, including mycetomas, keratitis, and systemic infections.

Fusarium spp.

Identifying characteristics

• Colony morphology: Initially produces white, cottony colonies that quickly develop pink or violet centers.

• Microscopic appearance: They form septate hyphae and two forms of conidiation: (1) conidiophores, with phialides producing large, sickleshaped macroconidia with three to five septa; and (2) simple conidiophores, with small, oval conidia singularly or in clusters.

Fusarium spp.