Resp Fungal

Question 1

Rhizopus & Mucor (General)

Answer 1

• Fungi-Mucorales of phylum zygomycota
• Monomorphic, non-septate hyphae w/broad irregular walls/branches (Right angles)
• Root structures=Nodal Rhizoids
  
  • Short, non-branched brown
  • Grow off hyphae
• Asexual spore=Sporangium
• Resevoir: abdunant in nature WORLDwide, rotting fruit, Bread, air/water/soil
• Transmission: Inhalation of sporangiospores
• High risk: Immunocomprimised
• ketoacidosis=diabetics
• Neutropenia=corticosteroid treatment

Question 2

Rhizopus & Mucor (Pathogenesis)

Answer 2

• Acute inflammation of soft tissue
• Fungal invasion of blood vessel (arteries)
  
  • Paranasal
  • Lungs
  • GI
  • Oral mucosa
• Produce hydrolytic enzyme (saprophytes)
• Tissue destruction leads to thrombosis-infarction-ischemia-**NECROSIS **
• Disease spreads rapidly
• Zygomycosis/Mucormycosis
• Rhino/facial/cranial area
• Lungs & GI tract
• Rhinocerebral mucormycosis=Fatal
• Begins in nasal mucosa-Orbits-palate-brain
• Orbital cellulitis,bulging of affected eye (proptosis), Destruction of palate, facial bones, septum
• Seizures, partial paralysis-COMA
• Thoracic Muco=Pulmonary-Infarct of lung tissue, local hemo, CAVITATION w/fungal ball

Question 3

Rhizopus & Mucor (Diagnosis)

Answer 3

• Microscopically: Nasal discharge, sputum, BAL, paranasal, aspirate
• Use of KOH (K+ hydroxide)
• ID by non-septate, ribbon-like hyphae BRANCH @ right angles (sporangium)
• Culture: Sabouraud’s dextrose (SDA)-Cotton candy appaerance
• Treatment: Early diagnosis CRUCIAL
• Surgical removal of damaged tissue
• Anti-fungal w/Amphotericin B

Question 4

Aspergillus Spp (general)

Answer 4

• Monomorphic (mold) w/Septate hyphae branching @ 45 angles (V-shaped)
• Spore: Condia=Extending chains ^(flower)
• Reservoir: Found everywhere ex. decaying vegetation
• Transmission: Air borne-inhalation
• High risk: Severe in immunocompromised-Neutopenic pts & rare in healthy pts
• Diagnosis-Sputum treat w/KOH & stain
• Septate branching hyphae & conidia
• _Culture: _SDA w/Antibio (gentamicin or chlorampenicol w/o cycloheximide allow for mold formation)
• Serology: allergy detection of **specific IgE=RAST Early detection **
• Invasive infection: Detection of galactomannan Ag serum-ELISA (rapid)
• Treatment: Amphotericin B, Voriconazole, Surgical removal

Question 5

Aspergillus Spp (Pathogenesis)

Answer 5

• Allergic use RAST
• Obstructive asper: Sinusitis & bronchitis=Colonization forming plugs made of hyphal mass/mucus (in CF pts)
• ABPA (allergic broncho pulm asper)=colonization + allergy w/bloody sputum-Asthmatic symptoms w/HIGH IgE
• Pulm asper: Colonization of pre-existing cavity (pts w/lung conditions)- ^{(rhizopus,TB, CF, etc)} Appear as Fungal balls
• Sinuses ^{(resemble TB lesions)}
• Invasive asper (immunocompromised):
• Vascular invasion-Pulm Necrotizing asperg
• possible disseminating to other organs
• Detection can take up to 1 month
• Mycotoxicosis: mold in grains/nuts make aflatoxin=Carcinogenic

Question 6

Pneumocystis Jiroveci-PCP (general)

Answer 6

• Fungus based on nucleic acid & biochem analysis
• Lack ergosterol = No growth in fungal media NOT sensitive to anti-fungal drugs
• Have protozoa properties-Trophozoites & cysts ex. Malaria
• Reservoir: worldwide in humans/animals-Normally found in alveoli asymptomatic until pt becomes immunocomprimised
• High risk: Common in AIDS pts
• Other-Steroid treatment, organ transplant, cancer
• Specimen: Secretions stained with Giemsa, sliver, DFA
• Cyst thick walled round/cup w/crescent shape-Spores are released
• NO culture media or serology
• Treat: Trimeth-sulfa=anti bacterial NOT antifungal

Question 7

Pneumocystis Jiroveci-PCP (Pathogenesis)

Answer 7

• Interstitial Pneumonia or atypical
• Inflammatory response w/damage to alveoli
• Frothy exidate creates blockage of gas exchange
• Honeycomb appearance exudate
• Reduced CD4 = High risk for pneumonia
• Pulmonary: Fever & dyspnea
• Xray=Bilateral infiltrate (ground glass or ping-pong balls)
• Extapulm: Lesions occur in minor of pts involving-Lymph nodes, spleen, liver & bone marrow

Question 8

Histoplasma Capsulatum (general)

Answer 8

• “Cave disease”
• Dimorphic-Mold @ 25C & yeast @ 37C
• 2 asexual spores:
• Tuberculate macroconida-Thick walled w/finger like projections
• Microconidia-Smaller thin smooth walled
• Resevoir: Soil in caves w/bird or bat droppings ALSO alkaline soils
• High risk: Regional travel to Great river basins of North America-
• Ohio
• Missouri
• Mississippi river valley
• Ex. Excavation of soil during construction or exploration of bat infested caves

Question 9

Histoplasma Capsulatum (Pathogenesis)

Answer 9

• Faciltative intracellular
• Inhaled spores engulfed by macrophages
• Develop into yeast form-divide by budding
• Survive inside phagolysosomes by making Bicarb/Ammonia = pH alkaline = prevents killing process
• Carried to regional lymph POSSIBLE dissemination to liver, spleen, etc
• Disease-Histoplasmosis:
• Most cases are asymptomatic
• Pulm=Acute flu like, fever, cough, mediastinal lymphadenopathy, patchy infiltrates (form cavity)
• Heptosplenomegaly can be present
• Extra-pulm=Immunocomprimised w/reduced cell mediated immunity-Disseminates systemic ^{(Ulcers in mouth/skin)}

Question 10

Histoplasma Capsulatum (Diagnosis)

Answer 10

• Tissue biop, bone marrow, Broncheoalveolar lavage
• Microscopy: Intracellular yeast form w/in macrophage/neutrophils
• Culture: Sabouruad’s agar (37C yeast) @ 25C=Hyphal growth w/conidia
  
  • ^{Tuberculate macro & micro}
• Detection of Ag: urine or sera, ELISA, BETTER for disseminated disease

Question 11

Blastomycyes Dermatitidis (general)

Answer 11

• Dimorphic=Mold @ 25C & yeast @ 37C
• EXTRAcellular
• Yeast is heavy/double walled w/broad based bud w/cap
• Mold=Septate hypha w/microconida
• Reservoir: Moist soil RICH in decomposing organic debris
• Endemic=US (SE & Midwest), Central & south america
• Can cause serious disease in dogs
• High risk: Exposure to wooded sites
• Farmers
• Forest workers
• Hunters
• Campers

Question 12

Blastomycyes Dermatitidis (Pathogenesis)

Answer 12

• Inhalation of conidia=infection as yeast develops
• Incubation time=weeks
• Pulmonary & extra pulm manifestation
• Pulm can present as mild flu like
• Severe pulm=Bacterial pneumonia-Typical
• Acute onset, fever, cough w/lobular infiltrates
  
  • Resp failure can occur
• Chronic pneumonia-Resemble TB or Lung cancer
• Extrapulm-Spread to skin&bone
• Chronic cutaneous lesions-Painless nodules CAN ulcerate exposed skin
  
  • Appearance wart-like

Question 13

Blastomycyes Dermatitidis (diagnosis)

Answer 13

• Specimen: Sputum, lung biopsy, or biopsy of nodules/drainage-Treat w/KOH
• Micro: Wet or stained-Shows broad base budding yeast
• Culture @ 25-37C on standard media
• Takes a month to grow
• Serology & Ag detection in urine
• Treat w/Amphotericin B or Azoles

Question 14

Coccidioides Immitis (general)

Answer 14

• Dimorphic fungus=Septate hypha @ **25C w/athroconida **
• In Tissues=Spherules (endospore containing)-Thick walled
• Reservoir: Soil in hot semi-arid of US, southern Cali, Central/south America
• Transmission: Inhalation of single spore **(arthroconidia) **
• High risk: Travel, people of Asian descent (Filipino), African-Americans, Pregers or Immuno-comprimised
• Specimen sputum treat w/KOH
• Microscopy: Show Spherules
• Culture: not preferred-Grow @ 25C w/athroconidia-ID confirm w/nucleic acid probe _{^{<strong>(spherules do NOT grow)</strong>}}
• Serology: IgM/IgG
• Treat: Amphotericin B, Azoles

Question 15

Coccidioides Immitis (pathogenesis)

Answer 15

• Valley fever or Desert Rheumatism
• Inhaled arthrospores convert to spherules in LUNGS-Make endospores
• Endospores release to make more spherules-Rupture release endospores
• Formation of granuloma in diff tissues
• Lungs W/in 1-3 weeks flu-like symptoms
  
  • _{^{Pulm lesions may calcify in healing}}
• Erythema Nodosum (desert bumps) & arthralgias
• Tender lesions ant surface of lower body
• Inflammation of fat cells under skin-T-cell response (Type 4) leading to granuloma formation
• RARE cases you have disseminated disease involvin multi-system