Atypical Lung Infections TEST ONLY.pdf

Atypical Lung Infections Atypical Pneumonias • “Atypical” differentiates from more common or ‘typical’ bacterial pneumonia • Causes: o Viral o Fungus o Nontuberculous mycoplasma o Protozoa • Signs/Symptoms: “walking pneumonia” Viral Pneumonia • Causative agents: o Influenza A, B o Resp Syncytial Vir...

Atypical Lung Infections Atypical Pneumonias • “Atypical” differentiates from more common or ‘typical’ bacterial pneumonia • Causes: o Viral o Fungus o Nontuberculous mycoplasma o Protozoa • Signs/Symptoms: “walking pneumonia” Viral Pneumonia • Causative agents: o Influenza A, B o Resp Syncytial Virus (RSV) o Coronavirus o Rhinoviruses • Symptoms: o Less severe o Slow onset than bacterial pneumonia o Dry cough o Fever/chills • Labs o CBC: No diagnostic findings for viral o Chemistry: No specific finding for viral o C Reactive Protein: elevated o ELISA Rapid Antigen § HSV § RSV § Flu A, B § Cytomegalovirus o PCR: § CMV § RSV § Coronavirus Bacterial v Viral Pneumonia typical CXR findings (in radiographs): Bacterial Pneumonia Viral Pneumonia Rarely normal Often normal Confluent, alveolar infiltrates Non-confluent, reticular infiltrates Often in lobar distribution Central, non-lobar Unilateral Bilateral Fungal Pneumonia • Pathogenic o Histoplasma o Coccidioides immitis o Blastomycosis dermatitis • Opportunistic cause disease in the immunocompromised hosts Histoplasmosis • Inhaled as a microconida • Within macrophage it converts to yeast, macrophages then lysed • Helper T cells recognized fungal cell wall o secretes gamma -IFN to activate macrophages to kill yeast o Secretes TNF recruits and stimulates other macrophages to kill histoplasma • Associated with Erythema Nodosum o Delayed hypersensitivity rxn o Common on anterior legs below knees • Diagnosis: o Fungal Cultures § Definitive § May need 6 wks to grow o Histology: Granulomas o Histoplasma Antigen Detection Enzyme Immunoassay (EIA)o Immunodiffusion (H or M antibodies) Coccidiomycosis • Inhaled as arthroconidia (barrel shaped) • Spore ingested by macrophages and converts to spherules • Diagnosis: o Histopathologic Findings: Methenamine silver or periodic acid-schiff (PASS) o Immunologic: Enzyme linked immunoassays (EIA) for IgG and IgM Blastomycosis • Dimorphic fungus • Inhaled mold that changes to yeast in lungs • Immunity: o Neutrophils o T cells and Macrophages • Diagnosis by culture: May require bronchoscopy for adequate sputum sample Aspergillosis • Inhaled conidia in alveolae • Alveolar macrophages recognize aspergillus by TLR2 and lectin dectin-1 • In immunocompromised pts, Inflammatory mediators and neutrophils are triggered • Invasive aspergillosis = neutropenia • Allergic alveolitis often in asthmatic pts • Clinical course: o Allergic (2 types) § Allergic aspergillus sinusitis § Extrinsic allergic alveolitis o Invasive (has severe forms): Bronchopneumonia Spreads as yeast Spreads as endospore Atypical Mycobacterial Pneumonias Non-TB Mycobacteria • Most common: o M avium complex (MAC) o M kansasii o M abcessus • Risk factors: o HIV w low CD4 o Immunosuppression for transplant rejection o TNF inhibitors o Cystic fibrosis • Diagnosis: o Culture: Growth takes 6 wks o Histology: § Noncaseating granulomas § Hallmark in pts with MAC infections and HIV Organism Histoplasmosis Pathogenesis Inhaled as micronidia, converts to yeast. Helper T cell secretes IFN to hide in Coccidioidomycosis Inhaled as arthroconid Spherule conversion, rupture, spread Blocks fusion of phagosome and lysosome Branching hyphae Spreads thru blood, neutrophils/T meditated macrophages Dichotomous acute angle hyphae Assc with neutropenia Blastomycosis Aspergillosis Mycoplasma HIV pts, abundant AFB w macrophages Pulmonary Asymptomatic Acute and chronic pulmonary Mediastinal fibrosis granuloma Asymptomatic, low grade, severe dz Extra Pulmonary Erythema nodosum Pericarditis Arthritis disseminated Diagnosis Histo – PAS, culture, Ag, AB Radiology Infiltrates Hilar nodes Arthralgias Erythema nodosum disseminated Culture, Histo w meth silver, PAS Infiltrates Hilar nodes Asymptomatic Acute pneumonia subacute/chronic Primary cutaneous disseminated Culture from tissues and fluids, meth silver, PAS, urine test No hilar adenopathy Invasive: Bronchopneumonia, necrotizing tracheobronch, aspergilloma Allergic alveolitis Appears like TB Cavitary lesions Allergic sinusitis, invasive sinusitis, disseminated Histo, culture, assay Crescent sign Halo sign Night sweats Cervical lymphadenopathy Histo – noncaseating granuloma, AFB in macrophages, culture Upper lobe fibrosis Pneumoconiosis: Lung dz from dust inhalation (environmental) • Silicosis o Inhalant - silica dust o Associated with fibrosis of the lungs. • Asbestosis o Inhalant - asbestos fibers o Consequences: § (a) Mesothelioma (malignant mesothelial tumor) § (b) Lung cancer • Anthracosis o Inhalant - carbon dust o Macrophages contain carbon Other Lung Diseases • Cystic Fibrosis o Transmission due to genetic mutation (autosomal recessive) o Chromosome7 (7q31.2) Know inhalants!