Fungal ball infection of the lung
Distinctive funnel-like expansion of the terminal conidiophore
4 day growth
Acremonium have long slender phialides that produce oval, unicellular microconidia that cluster at the tip of the phialide.
The clusters of microconidia are easily disrupted from the tip of the phialide.
Fungal conidia type
Aleurioconidia are formed from a newly formed hyphal branch which then separates from the main hypha by formation of a cross wall.
The porocondia of Alternaria are formed in chains and have a club-like shape.
Alternaria produces dematiaceous (dark), poroconidia with transverse and longitudinal septa (muriform).
Characterized by chains or groups of large dematiaceous (dark-colored), club shaped conidia. Many of the conidia show both transverse and longitudial segmenation.
Antifungal with ability to form pore in cell wall
Inhibition of cytochrome P-450 to block synthesis of ergosterol
Nucleic acid synthesis inhibitor used for cryptococcus meningitis
Bone marrow toxicity and resistance can develop in days so always use in combination
Target of echinocandins
Block B-1,3-glucan synthase inhibitors
Echinocandins do not work on...
Fungal conidia type
Arthrocondia are formed by structural changes in the cell walls and septa of preformed hyphae. They are produced along the entire length of the hypha.
Product of diploid yeast that undergo meiosis
On routine Kinyoun acid-fast stain, ascospores stain red and vegetative cells stain blue.
Aspergillis in a lung specimen (Ag stain)
In tissue, Aspergillis produces hyphal filaments only. Note the cross walls and regular 45o angle branching of the hyphae. Compare this to Candida albicans (produces yeast and hyphae) and Rhizopus (produces large, aseptate hyphae with irregular branching).
Chains of conidia on phialides arising from a swollen vesicle. Compare this with Penicillium and Scopulariopsis. Aspergillus is an opportunistic fungus.
Antigen used to detect Aspergillus
This species is most likely to produce a cleistothecium, indicated by the yellow arrow
3.5 day old brown/black smooth yeast colony
Usually considered a contaminant but visceral infections reported
What is the identifying characteristic of Aureobasidium pullulans?
Black yeast-like colony
The production of polar germ tubes is a characteristic that is associated with which dematiaceous fungi?
Candida albicans is a yeast that produces white and creamy colonies.
May see starring of colonies, particularly on CHOC agar
Candida albicans can be differentiated from other yeasts by its positive germ tube test.
Candida albicans in sputum (Gram stain)
Note the budding forms and pseudohyphae. Yeast usually stain purple with a Gram stain, but this slide has been overdecolorized so some look pink.
Appearance of Candida albicans on chromagar
Candida albicans in tissue (Ag stain)
Budding yeast (Blastoconidia), pseudohyphae and true hyphal forms all in the same tissue are characteristic of Candida albicans infection. The only other fungus that has yeast and hyphae in the same specimen is Malassezia furfur but it is usually only found in the superficial skin infection called tinea versicolor.