pathoma - pulm infections Flashcards
pneumonia
infection of lung parenchyma
occurs when normal defenses are impared (coughing, mucocilliary elevator
features: fever and chills, cough with yellow green or rusty sputum, tachypnea with pleuritic chest pain (when you breath in you streach pleura and pleura is infected so it hurts), decreased breath sounds with dullness to percussion (replaced air with exudate from infalamation), elevated WBC count
three patterns of pneumonia on CXR
- lobar pneumonia - usually bacterial
- bronchopneumonia - usually bacterial
- runs along small airways - patchy pattern
- interstitial pneumonia - viral normally
- no consolidation but inflamation of interstitum of lung - increase in lung markings (the lines are more vissable)
lobar pneumonia
takes over entire lobe
most common cuase = strep pneumonia and Klebsiella (old person or a drunk) pneumoniae
four classic phases
- congestion
- red hepatization - develop exudate in lung - fills alveolar airsacs and gives spoungy look - red from RBCs
- grey hepatization - RBCs are broken down
- resolution - resolve exudate and regeneration of the lung tissue in airsacs (type 2 cells are the stem cells for this)
Bronchopneumonia
- scattered patchy consolidation centered around bronchioles
- often multifocal - can see multiple parts in CXR and is often bilateral
- caused by a variety of bacteria
- staphylococcus aureus
- Haemophilus infuenzae
- pseudomonas aeruginosa
- moraxella catarrhalis
- legionella pneumophilia
legionella pneumophilia
legionella pneumophilia - community aquired pneumonia, superimposed on COPD or pneumonia in immunocomped states
can also cause upper resp infection
transmitted by water sources
best visuallized by silver stain - if you suspect you have to tell the lab to use the stain
- big in airconditioner workers
moraxella catarrhalis
moraxella catarrhalis - community acquired (bacterial) pneumonia and pneumonia superimposed by COPD
pseudomonas aeruginosa
pseudomonas aeruginosa - commonly seen in CF patients
most common cuase of hospital acquired infections
Haemophilus infuenzae
Haemophilus infuenzae - common cuase of secondary pneumonia and pneumonia superimposed by COPD
staphylococcus aureus
staphylococcus aureus - most common cuase of secondary pneumonia (superimposed by viral infection that knocks out the mucocilliary elevator and leads to further bacterial infections) - often complecated by abscesses or empyema (pus in alveolar space)
Interstitial (atypical) pneumonia
- diffuse interstitial infiltrates (interstitum = connective tissue of the alveolar airsacs)
- Atypical in that it doestn present how you would expect a pneumonia to present - relatively mild upper resp symptoms (min sputum, cough and low fever)
- histologically = airsacs are empty (no exudate) but inflam cells in the interstitum
- Caused by
- Mycoplasma pneumoniae
- chlamydia pneumoniae
- respiratory syncytial virus (RSV)
- cytomegalovirus (CMV)
- influenza virus
- coxiella burnetii
mycoplasma pneumoniae
most common cuase of atypical pneumonia
usually affects young adults (classically millitary recruits or college students living in dorm)
complications: autoimmune hemolytic anemia (IgM against I antigen on RBCs cuases cold hemolytic anemia) and erythema multiforme
not visible on gram stain due to lack of cell wall
Chlamydia pneumoniae
second most common cuase of atypical pneumonia in young adults
respiratory syncytial virus (RSV)
most common cuase of atypical pneumonia in infants
cytomegalovirus (CMV)
most common cuase of atypical pneumonia in posttransplant immunosuppressive therapy
influenza virus
atypical pneumonia in the elderly, immunocompromised, and those with preexisting lung disease
also increases risk for superimposed S aureusor H influenzae bacterial pneumonia (in flu patients the flu doesnt kill them it just weakens the defenses and a bacterial infection kills them)
coxiela burnetii
atypical pneumonia with high fever (Q fever) -> abnormal because atypical pneu usually have a low fever
seen in farmers and vets (the spores are deposited on cattle by ticks or present in cattel placentas)
it is a rickettsial organism but has unique characteristics
- causes pneumonia (not normal for rickettsial)
- doesnt require an arthropod vector (survives as a heat resistant spore)
- doesnt produce a rash
aspiration pneumonia
seen in patients at risk for aspiration (eg alcoholics and comatose patients)
due to anaerobic bacteria in the oropharynx (bacteroides, fusobacterium and peptococcus)
classically results in right lower lobe abscess - anatomically makes sense because things are more likely to go down the right bronchi
tuberculosis
inhilation of aerosolized mycobacterium tuburculosis
- when patient gets exposed they get primary TB
- resulsts in focal caseating necrosis in the lower lobe of the lung and hilar lymph nodes
- foci undergo fibrosis and calcification forming Ghon complex (shows that the person has been exposed to primary TB)
- primary TB is generally asymptomatic but leads to positive PPD
- secondary TB - reactivaton of the ghon complex
- commonly seen with AIDS but may also be seen with aging
- occurs at the apex of the lung
- forms cavitary foci of caseaous necrosis; may also lead to miliary pulm TP or tuberculos bronchopneumonia
- clinical features: fevers and night sweats, cough with hemoptysis, weight loss, biopsy reveals caseating granulomas, AFB stain reveals red acid fast bacilli
- can spread to other places
- can involve any tissue
- meninges (meningitis) - granulomas at base of the brain
- cervical lymph nodes
- kidney (sterile pyuria) - most commonly found
- lumbar vetebrae (pott disease)
Lobar pneumonia: cause
-congestion: Active hyperemia, few Nphil-Red hep: nphils present and fibrin, lung feels liver like-grey hep: fibrin cell death-resolution
Lobar pneumonia: Strep Pneumonia
-Strep pneumonia: most often the cause, especially in AA, penicillin treats it-gram positive lancet shaped rods-pneumovax and prevnar (for kids) are vaccines- fibrin pyrulent exudate
Lobar pneumonia: Klebsiella
-most frequent cuase of gram neg-aspired in old people and drunks / malnourished-forms an abcess- thick blood tinged sputum
Lobar: staph aureus
-microabscess/ empyema-IV drug user-Most common secondary infection- plays role in hospital acquired pneu
Lobar: Haemophilus influenezae
-gram negative-common in kids, -Exacerbates COPD (second is Moraxells Catarrhalis)
Lobar: Pseudomonas aerguinosa
gram -common in CF patients
TB: histo
Ghon complex granuloma (complex of M*)-caseating granulomaPrimary progressive: in kidsSecondary: reactivated (miliary)
Atypical pneumonia: cause
-Mycoplasm infection of alveolar-Moderate sputum, no consolidation-especially in college or in military-ground glass
P. jirovecci
Replicated in human lung-goblet shaped cell-GMS stain for chain structures-Attacks immunocomp-Treat with bactrim
Aspergillus
Allergic aspergillos: allergy in asthmaticsAaspergilloma: non invasive fungus ball occupies the sinusInvasive aspergillosis: wedge Infarcted lung. (Or PE)Can cause hemoptysis
Legionella pneumophilia
- found in aquatic envionrments (water cooling towers…) either aerosolized or inhaled while drinking- common in predisposed individuals (cardiac, renal, immunologic, hematologic diseas)- organ transplants are susceptable
mycoplasma pneumoniae
- common in children and young adults- occur in closed communities (schools, military camps, prisons)
