Page 418 - Review of Medical Microbiology and Immunology ( PDFDrive )

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49
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Systemic Mycoses

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CHAPTER C ONTENT S

Introduction
Self-Assessment Questions
Coccidioides
Summaries of Organisms
Histoplasma
Blastomyces
Practice Questions: USMLE & Course Examinations
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INTRODUCTION
tain geographic areas.
These infections result from inhalation of the spores of
dimorphic fungi that have their mold forms in the soil.
Within the lungs, the spores differentiate into yeasts or
COCCIDIOIDES
other specialized forms, such as spherules.
Most lung infections are asymptomatic and self-limited.
Disease
However, in some persons, disseminated disease develops
in which the organisms grow in other organs, cause
destructive lesions, and may result in death. Infected per-
Properties
sons do not communicate these diseases to others. Coccidioides immitis causes coccidioidomycosis.
Coccodioides immitis is a dimorphic fungus that exists as a
Important features of the systemic fungal diseases are
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mold in soil and as a spherule in tissue (Figure 49–1).
described in Table 49–1. Systemic fungi are also called
TABLE 49–1 Important Features of Systemic Fungal Diseases
Form in Tissue Seen
Genus
Geographic Location
by Microscopy
Southwestern United
Spherule
Culture at 20°C grows mold with
Coccidioides
Valley fever in immunocompetent;
arthrospores; serologic test for
dissemination to bone and menin-
States and Latin America
ges in immunocompromised,
IgM and IgG
pregnant women, African Ameri-
cans, and Filipinos
Histoplasma Yeasts within Ohio and Mississippi River Cavitary lung lesions; granulomas in Culture at 20°C grows mold with
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macrophages
valleys; worldwide; asso-
liver and spleen; pancytopenia
tuberculate macroconidia;
serologic test for IgM and IgG;
and tongue ulcer in
ciated with bird and bat
guano
urinary antigen
immunocompromised
Yeasts with single
Blastomyces
United States; Africa
Latin America, especially
Yeasts with multiple
Ulcerated lesions of the face and
Culture at 20°C grows mold;
Paracoccidioides
mouth
serologic test for IgM and IgG
Brazil
buds
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