Mycology Opportunistic Molds

MycologyOpportunistic Molds

Division of Medical Technology

Carol Larson MSEd, MT(ASCP)

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Basic Characteristics

• Rapid growers (4-5 days)

• Found in soil (saprobic)

• Conidia are airborne

• Opportunistic pathogens

• Treatment

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Opportunistic Mold Classification

• Aseptate (sparsely septate) / hyaline

• Septate / dematiaceous

• Septate / hyaline


Zygomycetes

• Lid lifters

• Sporangiospores

• Rhizoids

Aseptate (sparsely septate) hyaline hyphaeClick icon for audio

Clinical Significance

• Causes Zygomycosis (Mucormycosis, Phycomycosis)

• Predisposition– Diabetics– Malnutrition– Immunosuppressed– Prolonged antibiotic therapy

• Pathogenesis– Nasal sinuses– Migrate to brain and meninges


Absidia species

• Internodal rhizoids


Mucor species

• No rhizoids


Rhizopus species

• Nodal rhizoids


In Review …

• Aseptate (sparsely septate) hyaline hyphae

• Zygomycetes– Lid lifters, sporangiospores– Absidia – internodal rhizoids– Mucor – no rhizoids– Rhizopus – nodal rhizoids

• Zygomycosis


Alternaria species

• Colony morphology:

• Microscopic morphology:

Septate / dematiaceous hyphaeClick icon for audio

Cladosporium species




In Review …

• Septate, dematiaceous hyphae

• Alternaria species

• Cladosporium species

• Generally nonpathogenic


Aspergillus species

• Causes Aspergillosis

• Predisposed– Debilitated & immunocompromised

• Pathogenesis– Inhale conidia– Pulmonary disease– Systemic

Septate / hyaline hyphaeClick icon for audio

Aspergillus fumigatus




Aspergillus niger




Aspergillus flavus




Aspergillus species

• Colony morphology:– Velvety, white, green

yellow, cinnamon brown, reverse varies

• Microscopic morphology:– Single or double row of

phialides covering entire vesicle


In Review …

• Aspergillus species– A. fumigatus– A. niger– A. flavus– Many others

• Aspergillosis


Other Opportunistic Molds

• Penicillium species

• Paecilomyces species

• Fusarium species

• Sepedonium species


Penicillium species




Paecilomyces species




Fusarium species




Sepedonium species




In Review …

• Septate hyaline hyphae

• Opportunistic pathogens– Aspergillus– Fusarium

• Lab contaminants– Penicillium– Paecilomyces– Sepedonium


In Summary …

• Key characteristics

• Identification methods– Colony morphology– Microscopic morphology

• Clinically significant opportunistic molds– Zygomycetes– Aspergillus fumigatus, A. niger, A. flavus– Fusarium species

Opportunistic MoldsClick icon for audio

Who am I?

Aspergillus fumigatus

Potato Dextrose Agar LPCB Stain of Slide Culture

Who am I?


Rhizopus species

Who am I?

Fusarium species


Who am I?

Penicillium species


Mycology Opportunistic Molds

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