Systemic mycoses Notes

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Osmosis High-Yield Notes

This Osmosis High-Yield Note provides an overview of Systemic mycoses essentials. All Osmosis Notes are clearly laid-out and contain striking images, tables, and diagrams to help visual learners understand complex topics quickly and efficiently. Find more information about Systemic mycoses by visiting the associated Learn Page.
NOTES NOTES SYSTEMIC MYCOSES GENERALLY, WHAT ARE THEY? PATHOLOGY & CAUSES DIAGNOSIS ▪ Fungal infections in internal organs (esp. lungs) DIAGNOSTIC IMAGING CAUSES LAB RESULTS ▪ Dimorphic species of fungi ▪ Transmitted by spore inhalation; lymphohematogenous dissemination SIGNS & SYMPTOMS ▪ X-ray, CT scan, MRI ▪ Culture-based observation, direct microscopy, serologic tests, lab tests (e.g. abnormal blood exams) TREATMENT MEDICATIONS ▪ Cough, chest pain, fever ▪ Antifungal agents BLASTOMYCES SPP. osms.it/blastomyces PATHOLOGY & CAUSES ▪ Blastomycosis ▫ Systemic fungal infection caused by Blastomyces dermatitidis, B. gilchristii; usually manifests as chronic pneumonia ▪ Incubation period: 3–6 weeks ▪ Spore inhalation → conversion to yeast in lungs → phagocytosis by macrophages → acute suppurative inflammation ▪ Immune response: mainly cellular, mediated by T-lymphocytes, macrophages ▪ Common sites of infection: primarily lungs (90%); skin, bones, genitourinary tract, central nervous system (CNS) 558 OSMOSIS.ORG Blastomyces spp. ▪ Size: 8–15μm ▪ Broad-based budding (wide connection between two cells before splitting apart during reproduction) ▪ Thermal dimorphism ▫ Mold form (< 37°C/98.6°F): produces spores ▫ Yeast form (37°C/98.6°F): multinucleate; antiphagocytic (e.g. thick cell wall) ▪ Virulence ▫ Thick cell wall: resistance to phagocytosis ▫ BAD-1: cell surface glycoprotein; adhesin ▫ Binds yeast to extracellular matrix, macrophages
Chapter 100 Systemic Mycoses ▫ Blocks production of tumor necrosis factor (TNF) alpha (proinflammatory cytokine) Clinical syndromes ▪ Pulmonary blastomycosis ▫ Pneumonia, mostly chronic ▫ Frequently affects upper lobes ▪ Primary cutaneous blastomycosis ▫ Ulcerative/verrucous skin lesions ▪ Disseminated blastomycosis ▫ Osteomyelitis; prostatitis, epididymoorchitis (inflammation of epididymis/ testicles); meningitis; intracranial abscesses RISK FACTORS Outdoor occupations (e.g. farming) Recreational exposure to soil Immunosuppression High prevalence in North America Recent travel to endemic areas (e.g. Ohio, Mississippi river valleys) ▪ Comorbid conditions ▪ ▪ ▪ ▪ ▪ COMPLICATIONS LAB RESULTS Culture-based observation ▪ tissue, sputum, body fluids ▫ Sabouraud dextrose agar without cycloheximide ▫ Confirmation requires conversion (mold → yeast) at 37°C/98.6°F Direct microscopic examination ▪ Periodic acid–Schiff stain ▪ Differentiation: size, yeast morphology Lab tests ▪ Anemia, leukocytosis, ↑ erythrocyte sedimentation rate Tissue biopsy ▪ Pyogranulomatous response ▪ Skin ▫ Epithelial hyperplasia, intraepidermal abscesses, multinucleated cells ▪ Fungus observation Serologic tests ▪ Polymerase chain reaction (PCR) ▫ Antigen detection assays ▪ Acute respiratory distress, multiorgan disease, chronicity SIGNS & SYMPTOMS ▪ Cough, fever, weight loss, sputum production, dyspnea, night sweats, chills, hemoptysis, arthralgia, soft tissue swelling ▪ Verrucous skin lesions with irregular borders, ulcerative skin lesions DIAGNOSIS TREATMENT MEDICATIONS ▪ Antifungal treatment ▪ Amphotericin B; followed by azole ▫ Liposomal amphotericin B: CNS infections SURGERY ▪ Resection of abscesses, devitalized bone, empyemas, pericardial effusion DIAGNOSTIC IMAGING X-ray ▪ Pneumonia ▫ Lobar consolidation, alveolar infiltrates, fibronodular infiltrates, cavitation, nodules, pleural effusion ▪ Osteomyelitis ▫ Well-defined, osteolytic bone lesions OSMOSIS.ORG 559
COCCIDIOIDES SPP. osms.it/coccidioides ▫ Metalloproteinase: inhibits phagocytosis ▫ Alteration of pulmonary surfactant proteins PATHOLOGY & CAUSES ▪ Coccidioidomycosis ▫ Systemic fungal infection caused by Coccidioides immitis, C. posadasii; usually manifests as acute pneumonia ▪ AKA San Joaquin Valley Fever/“desert rheumatism” (associated with arthralgia) ▪ Arthroconidium inhalation → conversion to spherules → activation of T-lymphocytes → production of cytokines → inflammation → acute pneumonia ▫ In infected tissue, spherules grow, septate → release endospores → infection spreads ▪ Immune response ▫ Mainly mediated by Th1 cells ▫ Interleukin 17, TNF alpha, interferongamma ▪ Incubation period: 1–4 weeks ▪ Common sites of infection: lungs, skin, bones, CNS ▪ High prevalence areas: arid, dry regions in U.S. (e.g. California, Southwest), Mexico, Central America, South America Coccidioides spp. ▪ Size: 20–70μm ▪ Dimorphism ▫ Mold form: found in soil ▫ Yeast form: parasitic ▪ Produces arthroconidia (barrel-shaped, multinucleated spores) ▫ Production stimulated by human sex hormones ▫ Arthroconidia convert to spherules (2–5μm; in infected tissues) ▪ Infectious particles: arthroconidia ▪ Virulence ▫ Enzyme with elastase activity: ↑ infection, inflammation ▫ Cell surface glycoprotein with adhesin activity 560 OSMOSIS.ORG Clinical syndromes ▪ Acute pneumonia ▪ Dermatologic lesions ▫ Wart-like lesions on face ▫ Erythema nodosum/multiforme ▪ Osteomyelitis ▪ Meningitis RISK FACTORS ▪ Outdoor occupations; recreational exposure to soil (e.g. gardening, camping); immunosuppression; recent travel to endemic areas; comorbid conditions COMPLICATIONS ▪ Adult respiratory distress syndrome; fatal multilobar pneumonia; pyopneumothorax; meningitis; chronicity SIGNS & SYMPTOMS ▪ ▪ ▪ ▪ ▪ Mostly mild/asymptomatic Non-specific: fever, malaise Cough, pleuritic pain, hemoptysis, arthralgia Erythema nodosum/multiforme Wart-like lesions on face (e.g. nasolabial folds) DIAGNOSIS DIAGNOSTIC IMAGING X-ray ▪ Pneumonia ▫ Parenchymal infiltrates, thin-walled cavities ▪ Osteomyelitis ▫ Osteolytic bone lesions
Chapter 100 Systemic Mycoses LAB RESULTS TREATMENT ▪ Culture-based observation Serologic tests ▪ IgM, IgG antibody detection (e.g. enzyme immunoassays) ▪ Antigen detection Direct microscopic observation ▪ Spherules in sputum, blood, body fluid samples Lab tests ▪ ↑ erythrocyte sedimentation rate ▪ Eosinophilia (mostly with dissemination) MEDICATIONS High risk of dissemination ▪ E.g. immunosuppression, pregnancy ▫ azoles Severe ▪ Amphotericin B SURGERY ▪ Debridement of abscesses, devitalized bone, pyopneumothorax Extrathoracic tissue biopsy ▪ Essential for diagnosis of Coccidioides dissemination ▪ Pyogranulomatous inflammation ▪ Presence of spherules Spherulin skin test ▪ Positive after resolution; not available in U.S. Figure 100.1 Numerous spores in the lungs of an individual with coccidioidomycosis. OSMOSIS.ORG 561
HISTOPLASMA CAPSULATUM osms.it/histoplasma-capsulatum PATHOLOGY & CAUSES ▪ Histoplasmosis ▫ Systemic fungal infection caused by Histoplasma capsulatum; usually manifests as acute pneumonia ▪ Most frequent systemic mycoses in U.S. ▪ Microconidia inhalation → conversion to yeast form → macrophage phagocytosis → inflammation → pneumonia ▪ Immune response: mainly cellular, mediated by T-lymphocytes, macrophages, TNF alpha, interferon-gamma ▪ Infection sites: primarily lungs; may disseminate to other organs Histoplasma capsulatum ▪ Size: 2–3μm x 3–4μm ▪ Thermal dimorphism ▫ Mold form (< 35°C/95°F); produces microconidia (spores, 2–5μm) ▫ Yeast form (37°C/98.6°F) ▪ Infectious particles: microconidia ▪ Bird, bat fecal material promotes growth Pulmonary histoplasmosis clinical syndromes ▪ Pneumonia: acute (diffuse/localized); chronic ▪ Broncholithiasis Disseminated histoplasmosis clinical syndromes ▪ Progressive disseminated histoplasmosis: excessive reticuloendothelial infection ▪ Adrenal perivasculitis (common) ▪ Endocarditis ▪ Mediastinal granuloma ▪ Mediastinitis ▪ Meningitis ▪ Ocular histoplasmosis (e.g. retinal lesions) ▪ Lesions: intestinal (e.g. ulcers, polyps), skin (e.g. dermatitis, papules) 562 OSMOSIS.ORG RISK FACTORS ▪ Outdoor occupations (e.g. construction, excavation) ▪ Outdoor activities (e.g. camping) ▪ Immunosuppression ▪ High prevalence regions: U.S. (Ohio, Mississippi river valleys), Mexico, Central America, South America ▪ Recent travel to endemic areas ▪ Comorbid conditions ▪ Extremes of age COMPLICATIONS ▪ Fatal acute diffuse pneumonia, mediastinal granuloma, mediastinitis, chylothorax, pleural effusion SIGNS & SYMPTOMS ▪ Mostly asymptomatic Acute pulmonary histoplasmosis ▪ Systemic ▫ Fever, headaches, fatigue ▪ Chest pain (pleuritic/substernal), dry cough, myalgia, arthralgia, erythema nodosum/ multiforme Chronic pulmonary histoplasmosis ▪ Systemic ▫ Fever, fatigue, night sweats, weight loss ▪ Productive cough, hemoptysis, dyspnea ▪ Consolidation: dullness to percussion, crackles DIAGNOSIS DIAGNOSTIC IMAGING Chest X-ray ▪ Hilar/mediastinal lymphadenopathy, patchy/ nodular pulmonary infiltrates, occasional cavitation
Chapter 100 Systemic Mycoses LAB RESULTS ▪ Culture-based observation ▪ Direct microscopic observation Serologic tests ▪ Antibody detection (e.g. immunodiffusion, complement fixation assays) ▪ Antigen detection in urine, sputum, body fluids (e.g. enzyme immunoassays) Lab tests ▪ Anemia, ↑ erythrocyte sedimentation rate, progressive disseminated histoplasmosis (e.g. pancytopenia) Tissue biopsy ▪ Granulomas, lymphohistiocytic aggregates, mononuclear cell infiltrates, fungi visualization TREATMENT Figure 100.2 Grocott methenamine silver stain highlights spores in the lung tissue of an immunocompromised individual with histoplasmosis. MEDICATIONS ▪ Progressive disseminated/prolonged/severe pulmonary histoplasmosis ▫ Corticosteroids: ↓ inflammation ▫ Antifungal treatment: amphotericin B, azoles PARACOCCIDIOIDES BRASILIENSIS osms.it/paracoccidioides-brasilienses PATHOLOGY & CAUSES ▪ Paracoccidioidomycosis ▫ Systemic fungal infection caused by Paracoccidioides brasiliensis, P. lutzii; usually manifests as chronic lung disease ▪ AKA South American blastomycosis ▪ Spore inhalation → conversion to yeast form in lungs → phagocytosis by macrophages → inflammation → pneumonia ▪ Immune response: mostly cell-mediated ▪ Common sites of infection: mainly lungs; oral mucosa, skin, adrenal glands, CNS Paracoccidioides spp. ▪ Size: 4–40μm ▪ Thermal dimorphism ▫ Mold form (22–26°C/71.6–78.8°F): present in soil ▫ Yeast form (37°C/98.6°F): “pilot’s wheel” appearance ▪ Stimulated by sex hormones Clinical syndromes ▪ Acute/subacute paracoccidioidomycosis ( juvenile) ▫ Hepatosplenomegaly, OSMOSIS.ORG 563
lymphadenopathy, skin lesions, pulmonary manifestations (rare) ▪ Chronic paracoccidioidomycosis (adult) ▫ Progressive pulmonary fibrosis (esp. lower lobes), ulcers (mouth, larynx); adrenal involvement RISK FACTORS ▪ High prevalence regions: Central, South America (80% in Brazil) ▪ Outdoor occupations ▪ Outdoor activities: contact with soil ▪ More common in individuals who are biologically male ▪ Immunosuppression COMPLICATIONS ▪ Bone marrow, adrenal dysfunction; chronic respiratory failure SIGNS & SYMPTOMS ▪ Generally asymptomatic (95%) ▪ Non-specific symptoms: fever, weight loss ▪ Cough, dyspnea, hepatosplenomegaly, lymphadenopathies, odynophagia, sialorrhea, skin lesions (ulcers, nodules) ▪ Compressive manifestations: jaundice (bile duct obstruction) DIAGNOSIS DIAGNOSTIC IMAGING X-ray/CT scan ▪ Acute/subacute paracoccidioidomycosis ▫ Lymph node enlargement ▪ Chronic paracoccidioidomycosis ▫ Pulmonary disease: alveolar/interstitial infiltrates, consolidation, masses/ nodules, cavitation ▫ CNS disease: ring enhancing lesions ▫ Articular disease: effusion, erosions, space narrowing LAB RESULTS ▪ Direct microscopic observation ▪ Culture-based observation 564 OSMOSIS.ORG Figure 100.3 A child with numerous lesions on the face caused by Coccidioidomycosis brasiliensis. Serologic tests ▪ Detection of antibodies through immunodiffusion TREATMENT MEDICATIONS ▪ Antifungal treatment: azoles ▪ Trimethoprim-sulfamethoxazole

Osmosis High-Yield Notes

This Osmosis High-Yield Note provides an overview of Systemic mycoses essentials. All Osmosis Notes are clearly laid-out and contain striking images, tables, and diagrams to help visual learners understand complex topics quickly and efficiently. Find more information about Systemic mycoses by visiting the associated Learn Page.