Mycology – Microbiology Test Answers – Flashcards

Blastomycosis - B. dermatitidis:

Suppurative or granulomatous inflammation. Fungi usually demonstrable at the edge of abcess.

Direct examination of prostate fluid, sputum or tissue (10-15% KOH)

Single blastoconidium attached by a broad base to the parent cell. Small single conidia, short conidiophores.

Inoculate IMA, BHI with 10% sheep blood,  Incubate at 30 C.  Keep for 4 weeks before discarding as negative.

Laboratory confirmation:

Yeast conversion.

Exoantigen tests.

DNA probes.

Blastomycosis - B. dermatitidis:

Suppurative or granulomatous inflammation. Fungi usually demonstrable at the edge of abcess.

Direct examination of prostate fluid, sputum or tissue (10-15% KOH)

Single blastoconidium attached by a broad base to the parent cell. Small single conidia, short conidiophores.

Inoculate IMA, BHI with 10% sheep blood,  Incubate at 30 C.  Keep for 4 weeks before discarding as negative.

Laboratory confirmation:

Yeast conversion.

Exoantigen tests.

DNA probes.

Blastomycosis - B. dermatitidis:

Suppurative or granulomatous inflammation. Fungi usually demonstrable at the edge of abcess.

Direct examination of prostate fluid, sputum or tissue (10-15% KOH)

Single blastoconidium attached by a broad base to the parent cell. Small single conidia, short conidiophores.

Inoculate IMA, BHI with 10% sheep blood,  Incubate at 30 C.  Keep for 4 weeks before discarding as negative.

Laboratory confirmation:

Yeast conversion.

Exoantigen tests.

DNA probes.

Blastomycosis - B. dermatitidis:

Suppurative or granulomatous inflammation. Fungi usually demonstrable at the edge of abcess.

Direct examination of prostate fluid, sputum or tissue (10-15% KOH)

Single blastoconidium attached by a broad base to the parent cell. Small single conidia, short conidiophores.

Inoculate IMA, BHI with 10% sheep blood,  Incubate at 30 C.  Keep for 4 weeks before discarding as negative.

Laboratory confirmation:

Yeast conversion.

Exoantigen tests.

DNA probes.

Blastomycosis - B. dermatitidis:

Suppurative or granulomatous inflammation. Fungi usually demonstrable at the edge of abcess.

Direct examination of prostate fluid, sputum or tissue (10-15% KOH)

Single blastoconidium attached by a broad base to the parent cell. Small single conidia, short conidiophores.

Inoculate IMA, BHI with 10% sheep blood,  Incubate at 30 C.  Keep for 4 weeks before discarding as negative.

Laboratory confirmation:

Yeast conversion.

Exoantigen tests.

DNA probes.

Blastomycosis - B. dermatitidis:

Suppurative or granulomatous inflammation. Fungi usually demonstrable at the edge of abcess.

Direct examination of prostate fluid, sputum or tissue (10-15% KOH)

Single blastoconidium attached by a broad base to the parent cell. Small single conidia, short conidiophores.

Inoculate IMA, BHI with 10% sheep blood,  Incubate at 30 C.  Keep for 4 weeks before discarding as negative.

Laboratory confirmation:

Yeast conversion.

Exoantigen tests.

DNA probes.

Coccidioidomycosis - C. immitis:

Suppurative and granulomatous inflammation.

Suppurative response seen around arthroconidia and when spherules rupture.

Granulomatous response seen around developing sherules.

Hyphae may be present in pulmonary cavity without arthroconidia.

Direct examination of fluids, sputum or tissue. Spherules 30-60 um in diameter with a thick wall. Endospores 2-5 um in diameter.

Inoculate IMA or BHI with 10% sheep blood. Incubate at 30 C. Keep for 4 weeks before discarding as negative. Fast growing; rapidly produces barrel-shaped arthroconidia with intervening dissjunctor cells.

Handled at all times with respect to Class II or III biological safety cabinet. Classified as BSL-3 agent. Seal all plates, use screw-capped tubes.

Laboratory confirmation:

Exoantigen tests.

DNA probes.

Coccidioidomycosis - C. immitis:

Suppurative and granulomatous inflammation.

Suppurative response seen around arthroconidia and when spherules rupture.

Granulomatous response seen around developing sherules.

Hyphae may be present in pulmonary cavity without arthroconidia.

Direct examination of fluids, sputum or tissue. Spherules 30-60 um in diameter with a thick wall. Endospores 2-5 um in diameter.

Inoculate IMA or BHI with 10% sheep blood. Incubate at 30 C. Keep for 4 weeks before discarding as negative. Fast growing; rapidly produces barrel-shaped arthroconidia with intervening dissjunctor cells.

Handled at all times with respect to Class II or III biological safety cabinet. Classified as BSL-3 agent. Seal all plates, use screw-capped tubes.

Laboratory confirmation:

Exoantigen tests.

DNA probes.

Coccidioidomycosis - C. immitis:

Suppurative and granulomatous inflammation.

Suppurative response seen around arthroconidia and when spherules rupture.

Granulomatous response seen around developing sherules.

Hyphae may be present in pulmonary cavity without arthroconidia.

Direct examination of fluids, sputum or tissue. Spherules 30-60 um in diameter with a thick wall. Endospores 2-5 um in diameter.

Inoculate IMA or BHI with 10% sheep blood. Incubate at 30 C. Keep for 4 weeks before discarding as negative. Fast growing; rapidly produces barrel-shaped arthroconidia with intervening dissjunctor cells.

Handled at all times with respect to Class II or III biological safety cabinet. Classified as BSL-3 agent. Seal all plates, use screw-capped tubes.

Laboratory confirmation:

Exoantigen tests.

DNA probes.

Histoplasmosis - Histoplasma capsulatum:

Intracellular budding yeast cells (localized in histiocytes and reticuloendothelial cells)

Little to no inflammatory response.

H. capsulatum predominates at the central portion of the lesions and leads to caseating lesions.

Direct examination of sputum or tissue usually yields little.

Blood specimen: direct observation of buffy coat, culture.

Inoculate IMA, BHI with 10% sheep blood. Incubate at 30 C.

Keep for 12 weeks before discarding as negative.

Slow growing. Produces large, spiked macroconidia.

May be difficult to convert to yeast form.

Serology: Antigen dectection, CF tests.

Laboratory confirmation:

Exoantigen tests.

DNA probes.

Handled at all times with respect to class II or III biological safety cabinet.

Histoplasmosis - Histoplasma capsulatum:

Intracellular budding yeast cells (localized in histiocytes and reticuloendothelial cells)

Little to no inflammatory response.

H. capsulatum predominates at the central portion of the lesions and leads to caseating lesions.

Direct examination of sputum or tissue usually yields little.

Blood specimen: direct observation of buffy coat, culture.

Inoculate IMA, BHI with 10% sheep blood. Incubate at 30 C.

Keep for 12 weeks before discarding as negative.

Slow growing. Produces large, spiked macroconidia.

May be difficult to convert to yeast form.

Serology: Antigen dectection, CF tests.

Laboratory confirmation:

Exoantigen tests.

DNA probes.

Handled at all times with respect to class II or III biological safety cabinet.

Histoplasmosis - Histoplasma capsulatum:

Intracellular budding yeast cells (localized in histiocytes and reticuloendothelial cells)

Little to no inflammatory response.

H. capsulatum predominates at the central portion of the lesions and leads to caseating lesions.

Direct examination of sputum or tissue usually yields little.

Blood specimen: direct observation of buffy coat, culture.

Inoculate IMA, BHI with 10% sheep blood. Incubate at 30 C.

Keep for 12 weeks before discarding as negative.

Slow growing. Produces large, spiked macroconidia.

May be difficult to convert to yeast form.

Serology: Antigen dectection, CF tests.

Laboratory confirmation:

Exoantigen tests.

DNA probes.

Handled at all times with respect to class II or III biological safety cabinet.

Histoplasmosis - Histoplasma capsulatum:

Intracellular budding yeast cells (localized in histiocytes and reticuloendothelial cells)

Little to no inflammatory response.

H. capsulatum predominates at the central portion of the lesions and leads to caseating lesions.

Direct examination of sputum or tissue usually yields little.

Blood specimen: direct observation of buffy coat, culture.

Inoculate IMA, BHI with 10% sheep blood. Incubate at 30 C.

Keep for 12 weeks before discarding as negative.

Slow growing. Produces large, spiked macroconidia.

May be difficult to convert to yeast form.

Serology: Antigen dectection, CF tests.

Laboratory confirmation:

Exoantigen tests.

DNA probes.

Handled at all times with respect to class II or III biological safety cabinet.

Histoplasmosis - Histoplasma capsulatum:

Intracellular budding yeast cells (localized in histiocytes and reticuloendothelial cells)

Little to no inflammatory response.

H. capsulatum predominates at the central portion of the lesions and leads to caseating lesions.

Direct examination of sputum or tissue usually yields little.

Blood specimen: direct observation of buffy coat, culture.

Inoculate IMA, BHI with 10% sheep blood. Incubate at 30 C.

Keep for 12 weeks before discarding as negative.

Slow growing. Produces large, spiked macroconidia.

May be difficult to convert to yeast form.

Serology: Antigen dectection, CF tests.

Laboratory confirmation:

Exoantigen tests.

DNA probes.

Handled at all times with respect to class II or III biological safety cabinet.

Malbranchea species are soil fungi of world-wide distribution which microscopically resemble Coccidioides immitis. Exoantigen tests are now the method of choice for culture identification of C. immitis.

Malbranchea species are soil fungi of world-wide distribution which microscopically resemble Coccidioides immitis. Exoantigen tests are now the method of choice for culture identification of C. immitis.

Microscopic view of Malbranchea sp.

Sepedonium sp.

Sepedonium species are common soil fungi and parasites of fleshy fungi however they closely resemble Histoplasma capsulatum. Therefore, positive identification of the latter, requires conversion of the mould form to the yeast phase by growth at 37C on enriched media or by exoantigen test.

Sepedonium sp.

Sepedonium species are common soil fungi and parasites of fleshy fungi however they closely resemble Histoplasma capsulatum. Therefore, positive identification of the latter, requires conversion of the mould form to the yeast phase by growth at 37C on enriched media or by exoantigen test.

The degree to which a test is able to detect true negatives.

true (-)

false (+) + true (-)

A sensitive test finds most true positive results.

true (+)

true (+) + false (-)

The amount of true positives and negative results found out of all of the results found.

true(+) + true(-)

true(+) + false(+) + true(-) + false(-)

Proportion of patients with positive results who were correctly diagnosed.

true(+)

true(+) + false(+)

Proportion of patients with negative results who were correctly diagnosed.

true(-)

false(-) + true(-)