Pneumonia Fungal and Viral Pathogens Flashcards
(71 cards)
Dimorphic fungi facts
most common cause of fungal pulmonary infections; grow as yeast in human tissues and as mold in lab; infection from inhalation of spores which in the lungs differentiate into yeasts or spherules; usually asymptomatic but all can cause pneumonia
Dimorphic fungal pathogens
Blastomyces dermatitidis, Histoplasma capsulatum, Coccidioides immitis, Paracoccidioides brasiliensis
Typical clinical manifestations of Histoplasmosis
varies from asymptotic to respiratory infection characterized by fever, chills, cough, chest pain. CXR findings vary from infiltrates, mediastinal LAD to cavitary lesions. If with AIDS, severe disseminated disease can develop with pancytopenia and mouth/GI mortality
Clinical manifestations of Paracoccidioidomycosis
mild respiratory infection which can progress with dissemination and development of oral, nasal, and facial nodular ulcerated lesions and submandibular lymphadenopathy
Clinical manifestations of Coccidioidomycosis
mild influenza like illness with fever and cough (“valley fever”) (erythema nodosum can develop), with dissemination occurring in 1%, most commonly bone, meninges, skin
Clinical manifestations of Blastomycosis
asymptomatic respiratory illness, however up to 50% of patients will have cough, chest pain, sputum production, fever which most often resolves spontaneously. CXR can show lobular consolidation, multi lobar infiltrates, multiple nodules, etc. Disseminated disease can result in ulcerated granulomatous lesion of the skin, bone, GU tract, and CNS
Diagnosis of Histoplasmosis
tissue biopsy: oval yeast cells within macrophages seen; serology (complement fixation or immunodiffusion) or urinary antigen
Treatment of Histoplasmosis
Ambisome for severe disease; Itraconazole otherwise
Diagnosis of Coccidioidomycosis
Spherules seen microscopically; serology for IgM or IgG; peripheral eosinophilia is common; skin test reactivity to diagnose exposure
Treament of Coccidioidomycosis
Ambisome for persistent lung lesions or disseminated disease; for meningitis give fluconazole
Diagnosis of Paracoccidioidomycosis
Tissue biopsy shows yeast cells with multiple buds; serology for IgM and IgG
Treatment of Paracoccidioidomycosis
Several months of Itraconazole. Ambisome can be used for severe disease
Diagnosis of Blastomycosis
tissue biopsy shoes thick walled yeast cells with single broad based bud; can use serology
Treament of Blastomycosis
Itraconazole is drug of choice, but Ambisome for severe disease
Pneumocystis jiroveci
usually asymptomatic infection; important cause of pneumonia in immunosuppressed; one of leading causes of death in pts w AIDS; cysts in alveoli produce inflammatory response, resulting in frothy exudate that blocks oxygen exchange; does not invade lung tissue
Clearance of Pneumocystis
CD4+ T cells recruit monocytes and macrophages which are responsible for clearance of the organism
How is Pneumocystis pneumonia diagnosed?
finding cysts by microscopic exam of lung tissues or fluids obtained by bronchoscopy, bronchial lavage, or lung biopsy; visualization of cysts by methenamine silver, Giemsa stain, or other stains; fluorescent antibody staining; PCR on respiratory tract specimens
Treatment for PCP (Pneumocystis Carinii Pneumonia)
Trimethoprim-sulfamethoxazole. Other secondary: clindamycin/Primaquine, Atovaquone, Pentamidine
Prophylactic PCP treatment for AIDS patients
Bactrim, Dapsone, Atovaquone
Common features of Aspergillus infection
Fungus ball formation in cavities of the lung, which can produce hemoptysis; allergic infection of the bronchi that produces asthmatic symptoms and high IgE titer; causes expectoration of brownish plugs containing hyphae; invasive pneumonia producing hemorrhage, infarction and necrosis, especially in those with heme malignancies and neutropenia
Mucormycosis risk factors
opportunistic infection caused by bread mold; risk factors - DM, neutropenia, iron overload, burns/surgical wounds, corticosteroid use
Mucormycosis Transmission and infection
Transmitted by airborne spores, invade tissues (also angioinvasive) of patients with reduced host defense; causes invasive rhino cerebral sinusitis, pneumonia, and cutaneous infections
Aspergillus on biopsy and culture
characterized by septate, acute-angle branching hyphae
Mucor on biopsy and culture
Characterized by nonseptate broad hyphae with frequent right angle branching
