This document discusses four true fungal pathogens - Histoplasma capsulatum, Blastomyces dermatitidis, Coccidioides immitis, and Paracoccidioides brasiliensis. It describes their distribution, how infection occurs through inhalation of spores, resulting disease manifestations including primary pulmonary infection and potential dissemination to other organs, diagnostic tests, and treatments.

1. True Pathogens
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Mohamed Abdullatif Abdurahman
B.Pharm, MMM

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Systemic Infections by True Pathogens
• Histoplasmosis
• Blastomycosis
• Coccidioidis
• Paracoccidioidis

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Histoplasmosis
• Histoplasma capsulatum
– most common true
pathogen; causes
histoplasmosis
• Typically dimorphic
• Distributed worldwide
• Grows in moist soil high
in nitrogen content

5. Inhaled conidia produce:
Primary pulmonary Histoplasmosis
• Flu-like illness in symptomatic patients,
resolves without treatment.
• Common symptoms include fever, chills,
headache, myalgia, loss of appetite, cough and
chest pain.
Chronic pulmonary Histoplasmosis
• Occurs most often in men and is usually a
reactivation process which is precipitated by
pulmonary damage.
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6. Disseminated Histoplasmosis
• Develop in infants, elderly & immunocompromised
and involve enlarged spleen and liver, fever,
anemia and Mucocutaneous ulceration.
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7. Diagnosis:
• Microscopy: stained smears show small oval
budding cells within macrophages.
• Culture: definitive diagnosis although in vitro
conversion to yeast and exoantigen testing are
important.
• Serology: Immunodiffusion (ID) and
complement fixation (CF)
Treatment: Itraconazole and Amphotericin B
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8. • African histoplasmosis: is other variant caused
by H capsulatum var duboisii, which differ by
causing less pulmonary involvement and more
skin and bone lesions.
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Blastomycosis
• Causes by Blastomyces
dermatitidis
• Dimorphic
• Free-living species, Soil is
natural habitat.
• Midwestern and southeastern
regions of North America; it
also occurs in Central and South
America and parts of Africa.

10. • Inhaled conidia convert to
yeasts and multiply in
lungs causes:
• Pulmonary
blastomycosis: rang from
mild and self limited cases
to chronic pneumonia
• When disseminated
lesions of skin, bones,
genitalia and CNS also
occur.
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11. Diagnosis:
• Microscopic examination show broad buds
attached to thick walled yeast.
• Culture is the definitive test.
Treatment : Amphotericin B
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Coccidioidomycosis: Valley Fever
• Coccidioides immitis – causes
coccidioidomycosis
• Found in semiarid soil as
mycelium which fragment into
arthrospore
• Most cases occur in the
southwestern USA, and in parts
of Central and South America.

13. • Arthrospores inhaled from dust, creates
spherules ( containing endospores) and
nodules in the lungs.
• Infection is usually self limited, and
dissemination is rare but serious
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14. • Primary infection is asymptomatic in 60% of
individuals.
• The other 40% develop valley fever (desert
rheumatism) which is self-limited influenza-
like illness.
• Some individuals develop a chronic but
progressive pulmonary disease with
multiplying or enlarging nodules or cavities.
• Dissemination involve the skin, bones and
joints, and the meninges.
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16. Diagnosis :
• Large, thick-walled endospore
containing spherules can be seen
on direct microscopy
• Culture,
• Skin tests
• Detection of IgM and IgG
Treatment:
• Primary infection require
supportive treatment
• Amphotericine B, Itraconazole
and Fluconazole
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Paracoccidioidomycosis
• A benign and transient
pulmonary infection caused by
thermally dimorphic
Paracoccidioides brasiliensis.
• Large oval cells with
characteristic multiple buds
encircling the mother cell in
tissue.
• Distributed in Central and South
America

18. • Lung infection occurs through inhalation or
inoculation of spores.
• Later reactivation results in chronic infection
of the lungs or other organs, in particular the
skin and oral mucous membranes.
Diagnosis:
• Microscopic examination, culture, serologic
tests and skin test.
Treatment: Ketoconazole, amphotericin B,
sulfa drugs
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19. Thank you
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