12/2 Chronic Pneumonia - Nagella Flashcards
chronic pneumonia
prolonged illness caused by slow-growing pathogens (6 weeks approx)
- fungi
- mycobacteria
can have persistent acute aspect, recurrent aspect
who gets it?
- can occur in immune-competent pts
- immune-compromised pts or pts taking immunosuppressants (TNFalpha inhibitors, IL inhibitors, rituximab, methotrexate, steroids)
Histoplasmosis
more common in Caribbean, MS River Valley
inf via inhalation of dust particles from soil contaminated with bird/bat droppings that contain infectious spores
pathogenesis
- target macrophages: enter thru opsonization, then multiply and lyse
- also induces macrophage secretion of TNF → recruits and stimulates other macrophages to kill pathogen
- helper T cells usually recog fungal cell wall antigens
- IFNgamma secreted → activates macrophages → kills intracellular yeasts
- if T cell suppression is impaired, cant form granulomas → see disseminated form
clinical sx:
- self ltd or latent pulmo involvement (“coin lesions”)
- chronic progressive secondary lung disease (lung apices, cough, fever, night sweats)
- spread to extrapulm sites
- wide dissemination (esp in immunocomp)
granulomas cause compression
broncholithiasis (LN erodes into trachea)
fibrosing mediastinitus (extensive fibrosis of mediastinum from large antigen release → SVC blockage, airway constriction)
cavitary histoplasmosis (in pt with abnormal lungs)
Blastomycosis
soil-inhabiting dimorphic fungus found in Central and SE United States
forms:
- pulmonary lastomycosis
- usually abrupt onset illness
- variable radiographic presentation (lobar, diffuse)
- usually resolves spontaneously
- disseminated blastomycosis
- primary cutaneous form (rare)
dx via antigen in urine or serum
“broad based budding yeast”
Coccidiomycosis
Southwestern United States
very pathogenic
inhalation → infection (via blocade of lysosome phagosome fusion)
delayed type hypersensitivity rxn
commonly see peripheral eosinophilia
usually asymptomatic
- 10% progress to lung lesions, cough, pleuritic pain and erythema nodosum or erythema multiforme (San Joaquin Valley fever complex)
- 1% progress to disseminated disease
opportunistic mycoses: Aspergillus
usually hits immunosuppressed
- chronic cavitary lesions
- prolonged neutropenia
- hallmark sign: 45 degree branching
Cryptococcus
Mucormycosis
Cryptococcus
- budding encapsulated yeast (ubiquitous in soil)
- HIV association
- India ink stain to visualize
Mucormycosis
- tx for Aspergillus can be a risk factor
- infects sinuses first
- more nodular, leads to necrotic cavitation
- hallmark: 90 degree branching
Pneumocystis pneumonia
esp seen in HIV and immunosuppressed pts
- more neutrophils on bronchoscopy, fewer cysts on metheneamine silver stain
- prophylaxis? reduced incidence
- can be spreak airborne, person-to-person
- normal immune individs can be colonized
- presentaiton: fulminant or subacute w/ dry cough, fever
- HIV pt: more subacute (bronchoscopy fluid has more lymphocytes and CD8 cells, not many neutrophils, more cysts)
- HIV candidiasis can predispose
- tendency to see destauration on exertion
Cytomegalovirus
immunosuppressed pts from unique pop at risk: TRANSPLANT PTS
- organ/blood pdt received from CMV+ donor
CMV disease signs and sx
- fever, malaise (viral syndrome)
- tissue invasive disease (pneumonitis)
HIV assoc pulmo disease
lung abscess
infection that causes necrotic lung tissue to cavitate
- not all cavitation is infectious
- small zones of necrosis in consolidated regions of pneumonia form single or multiple abscesses that erode into bronchi →→→ fibrosis
bacteria are more assoc with cavitation/abscess
- Actinomyces (Gram+): alcoholic, poor dental hygiene post dental procedure, more immune competent
- Nocardia (Gram+): soil, immune compromised
empyema
infected pleural space (pus or purulent material on pleural fluid drainage)
radiologic clue: obtuse angle with posterior wall → empyema
causes?
- usual causes of bacterial pneumonia
- could be major complication of pulmo inf
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