Mycology and Parasitology Morphology

This set of flashcards focuses on the morphological characteristics of various fungi and parasites, including yeast, molds, protozoa, and helminths found in clinical specimens.

Malassezia furfur

A yeast that causes tinea versicolor, requires a lipid source (sterile olive oil), and exhibits a "spaghetti and meatballs" morphology.

Trichophyton rubrum

The most common dermatophyte worldwide causing skin and nail infections; characterized by a white/buff colony surface, a red (rubrum) colony bottom, tear-shaped microconidia described as "birds on a wire", and a negative hair shaft penetration test.

Trichophyton mentagrophytes

A dermatophyte that looks very similar to T. rubrum but is positive for hair perforation.

Microsporum canis

A dermatophyte causing skin and scalp infections usually from pets; colony surface is white with yellow edges and microscopically shows spindly, rough macroconidia with more than $6$ cells.

Microsporum gypseum

A dermatophyte common in animals causing scalp and skin infections; identified by oval, rough-walled macroconidia with fewer than $6$ cells.

Epidermophyton floccosum

A dermatophyte causing skin and nail infections with yellow, olive-gray, or khaki colonies; it features smooth club-shaped macroconidia with rounded ends (often in clusters of $2$ to $6$ cells) and no microconidia.

Histoplasma capsulatum

A fungus that appears as small, narrow yeast in tissues and as septate, hyaline hyphae with spiny macroconidia in its mold form.

Blastomyces dermatitidis

A broad based budding yeast (BBB) often with double contours.

Coccidioides immitis

A fungus that forms spherules at $37^{\circ}\text{C}$ and a mold form characterized by hyaline, septate hyphae with "Train track" arthroconidia.

Paracoccidioides brasiliensis

A yeast described as a large, round "mariner's wheel" with circumferential budding; the mold form has septate, hyaline hyphae with terminal and intercalary chlamydospores.

Sporothrix schenckii

The cause of "rose gardener's disease"; yeast are cigar-shaped (narrow based), and the mold consists of hyaline, septate hyphae with "rosettes" of microconidia.

Aspergillus fumigatus

Fungus with blue-green colonies featuring a white apron and reverse; a single row of phialides covers the top $2/3$ of its vesicle.

Aspergillus flavus

Fungus with yellow-green or olive colonies and a light reverse side; phialides are circumferential.

Aspergillus niger

Fungus with dark brown/black colonies, a light reverse side, black conidia, and two rows of phialides covering the whole vesicle surface.

Fusarium spp.

Fungus producing violet colonies and "canoe" or "banana" shaped microconidia.

Acremonium spp.

Fungus with gray, white, or pink colonies and long, narrow, unbranched phialides with clusters of microconidia.

Penicillium spp.

Common contaminant that can cause infection; characterized by blue-green powdery colonies with a white border and "skeleton hand" phialide/conidia arrangements.

Scorpulariopsis spp.

Fungus with powdery brown/tan colonies and rough "lemon drop" conidia.

Rhizopus spp.

Fungus characterized by rhizoids and unbranched sporangiophores (sac of spores).

Mucor spp.

Fungus that has no rhizoids and sporangia that fall apart easily.

Alternaria

A dematiaceous mold with brownish black colonies and chains of club-shaped conidia with transverse and longitudinal separations.

Trypanosoma brucei

A larger organism that is S- or C-shaped with a small posterior kinetoplast.

Trypanosoma cruzi

A smaller, C-shaped organism with a large posterior kinetoplast.

Plasmodium vivax

A parasite that infects reticulocytes (large RBCs); features ring forms more than $1/3$ the size of the RBC, ameboid mature trophozoites, schizonts with $12$ to $24$ merozoites, large oval gametocytes, and Schuffner's dots.

Plasmodium ovale

A parasite infecting reticulocytes (large RBCs); ring forms are more than $1/3$ the size of the RBC, mature trophozoites are compact or shaped like "comet forms", schizonts have $6$ to $14$ merozoites, and features Schuffner's dots.

Plasmodium malariae

A parasite that infects senescent (small to normal) RBCs; ring forms are $1/3$ the size of the RBC (bird's eye), mature trophs appear as band and basket forms, schizonts form rosettes with $6$ to $12$ merozoites.

Plasmodium falciparum

A parasite infecting all sizes of RBC; blood smears show only small, delicate ring forms (applique forms, multiple infections/dots) and banana-shaped gametocytes.

Entamoeba histolytica

An amoeba where the cyst has up to $4$ nuclei and smooth-ended chromatoidal bodies; trophozoites are $15$ to $20$ microns with central karyosomes and fine peripheral chromatin; erythrophagocytosis is diagnostic.

Entamoeba coli

An amoeba where the cyst has up to $8$ nuclei; trophozoites are $20$ to $25$ microns with eccentric karyosomes and clumpy peripheral chromatin.

Entamoeba hartmanni

A miniature version of E. histolytica; cysts have up to $4$ nuclei and trophozoites are $5$ to $10$ microns with no ingested RBCs.

Endolimax nana

An amoeba where the cyst has $4$ nuclei with karyosomes and no peripheral chromatin; trophozoites are $6$ to $10$ microns and hard to distinguish from Iodamoeba buetschlii.

Iodamoeba buetschlii

A parasite whose cyst has no peripheral chromatin and a prominent vacuole; trophozoites are $8$ to $20$ microns and appear vacuolated and granular.

Giardia intestinalis

A flagellate whose pear-shaped trophozoite has a central axoneme, $2$ nuclei, $2$ sucking disks, and $2$ parabasa; the cyst has $4$ nuclei.

Chilomastix mesnili

A flagellate whose cyst has a "shepherd's crook" cytostome and pear-shaped trophozoite has a rounded anterior and tapered posterior end.

Dientamoeba fragilis

A parasite with no cyst form; the trophozoite is round, binucleate, and contains an internal flagellum.

Balantidium coli

A large ciliate (up to $200$ microns) with a cytostome, cilia, and a kidney bean shaped nucleus.

Enterobius vermicularis

Pinworm characterized by thin-walled oval eggs with a flat side, usually found via scotch tape prep.

Trichuris trichiura

Whipworm identified by thick-walled eggs with bilateral polar plugs.

Ascaris lumbricoides

A parasite with thick-shelled eggs that are bile-stained and have a rough, bumpy surface.

Hookworm

Parasite whose eggs (Necatur and Ancylostoma) are indistinguishable and described as "steak on a plate".

Strongyloides stercoralis

A worm (rhabditiform larva) identified by a short buccal canal, a bulbar portion of the esophagus, and a genital primordium.

Taenia saginata

The beef tapeworm; worm has a smooth scolex with four suckers and proglottids that are longer than wide with more than $13$ uterine branches.

Taenia solium

The pork tapeworm; worm has a scolex with four suckers and an armed rostellum, with proglottids longer than wide and fewer than $13$ uterine branches.

Diphyllobothrium latum

A worm with an almond-shaped scolex with $2$ sucking grooves and proglottids wider than long; eggs are about $60$ microns and smooth with a shoulderless operculum and small knob.

Hymenolepis diminuta

A parasite with eggs (about $80$ microns) that have thin inner/outer shells, polar filaments between shells, and an embryo with hooklets.

Hymenolepis nana

A parasite with eggs (about $40$ microns) featuring two shells with polar filaments in between and an oncosphere with six hooklets.

Fasciola/Fasciolopsis

Genera with identical large eggs ($120$ microns) that have no shoulders and an abopercular knob.

Clonorchis sinensis

A parasite with small eggs (about $30$ microns) featuring a shouldered operculum and an abopercular knob.

Paragonimus westermani

A parasite whose eggs ($100$ microns) have a shouldered operculum and a thick abopercular end without a knob; found in stool or sputum.

Schistosoma mansoni

A blood fluke with eggs around $150$ microns long featuring a lateral spine.

Schistosoma haematobium

A blood fluke with eggs around $150$ microns long featuring a terminal spine; found in stool or urine.

Schistosoma japonicum

A blood fluke with eggs around $80$ microns long featuring an inconspicuous "spine".