Pulmonary Pathology Part 4 Flashcards
What are some facts about pneumonia?
- Second most cause of hospital admissions
- World’s leading cause of death in children <5 years old
- Most common cause for sepsis and septic shock
How is pneumonia classified by clinical setting?
- Community acquired (bacteria vs viral)
- Health care associated pneumonia
- Aspiration pneumonia
- Chronic pneumonia
- Pneumonia in the immunocompromised host
How is pneumonia classified by anatomic distribution?
- Bronchopneumonia
- Lobar pneumonia
How is lobar pneumonia diagnosed?
- Through characteristic radiographic appearance
What are the stages of lobar pneumonia?
- Congestion (vascular engorgement)
- Red hepatization (red cells and inflammation)
- Grey hepatization (inflammation and debris)
- Resolution (fibrosis and macrophage clean up)
What are some complications that can arise in lobar pneumonia?
- Abscess
- Empyema
- Bacteremia
What are some community acquired bacteria that cause pneumonia?
- S. pneumoniae
- H. influenzae
- S. aureus
- K. pneumoniae
- P. aeruginosa
- L. pneumoniae
- M. pneumoniae
Which bacteria is the most common cause of community acquired pneumonia?
- Streptococcus pneumoniae
What are the vaccination requirements for strepococcus pneumoniae?
- Recommended for infants and people >65
- Also in people that smoke or have respiratory disease
Where is H. influenzae caused pneumonia seen?
- Virulent pneumonia in children
- Recommended vaccination for type B for children >5
- Patients will first have flu virus and then this will superimpose in host
Where is S. aureus pneumonia seen?
- IV drug users
- Abscess formation
Where is K. pneumoniae pneumonia seen?
- Alcoholics
- Will have a currant jelly sputum due to parenchymal bleeding
Where is P. aeruginosa pneumonia seen?
- Seen often in cystic fibrosis patients
- Can also been seen as opportunistic infection
- May be hospital acquired
- Look likes copper rust (green) when plated
What is the typical bacterial pneumonia presentation?
- More abrupt onset
- Respiratory symptoms predominate
- Consolidation on CXR
- Older adults or young children
What is the atypical (walking) pneumonia presentation?
- Slower onset
- Systemic symptoms predominate
- Patchy infiltrates on CXR
- In young adults/teens/older children
What bacteria causes typical pneumonia?
- S. pneumoniae
- H. influenzae
- S. aureus
- K. pneumoniae
- P. aeruginosa
What bacteria causes atypical (walking) pneumonia?
- Mycoplasma pneumoniae
- Legionella pneumophila
- Chlamydia pneumonia
- Chlamydia psittaci
What is mycoplasma pneumoniae?
- Smallest free-living, self replicating organism
- Has no cell wall
What is Legionella pneumophila?
- Gram negative bacillis
- Grows in warm freshwater
- Airborne disease
Where can legionella pneumophila grow?
- AC units
- Misters
- Hot tubs
What are some viral causes of community acquired pneumonia?
- Influenze (H1N1)
- SARS
- COVID 19
- Respiratory syncytial virus
What is the difference in spread between viruses and bacteria in pneumonia?
- Bacteria spread in the alveolar spaces (wrecking ball)
- Viruses spread in the interstitium (through the walls)
How is the influenza virus classified?
- By two proteins:
- Hemagglutinin
- Neuraminidase
What does hemagglutinin do?
- Attaches to cells
What does neuraminidase do?
- Allows release of replicated virus from cells
What does tamiflu do to prevent the flu?
- Prevents the action of neuraminidase which causes the viron to be stuck
What is antigenic drift?
- Minor changes to proteins on the virus, allowing increased spread
- Similar enough to original virus to allow for some immunity in many individuals
- Causes epidemics
What is antigenic shift?
- Genomic alterations with major resulting changes to protein structures
- Naive immunity for almost all people
- Picked up from animal gene products?
What does COVID look like in regards to signaling molecules?
- Looks like ARDS with the cytokine storm
What is clinically seen in someone with COVID?
- Congested lungs
- Hyperemia on cut surfaces
- Pleurisy
- Lower extremity thrombus
- Pulmonary embolus
What is the cause of death in COVID?
- Superimposed bacterial pneumonia
What is elevated in COVID that could cause a serious issue?
- Elevated D dimer correlates with the thrombotic complications
What is COVID-19?
- ssRNA virus
- Spread via respiratory droplet
- Induces “cytokine” storm
- Coagulopathy
What bacterial pneumonia is seen in neonates?
- Group B strep
- Gram negative bacilli
- Listeria
What viral pneumonia is seen in children <1 month?
- Respiratory syncytial virus
- Parainfluenza virus
- Influenza A and B
- Adenovirus
- Rhinovirus
What bacterial pneumonia is seen in children >1 month?
- S. pneumoniae
- H. influenzae
- M. catarrhalis
- S. aureus
What pneumonia is seen in older children/adolescents?
- Same as younger children
- M. pneumoniae
- C. pneumoniae
What is respiratory syncytial virus?
- Paramyxovirus
What are the symptoms of respiratory syncytial virus?
- Symptoms of rhinorrhea and cough
- Wheezing and dyspnea
- Tachypnea
- Cyanosis
What are some specific paramyxoviridae viruses?
- RSV
- human Metapneumovirus
- Parainfluenza
- Measles
What are some illnesses that have had a decline in vaccinations recently?
- Measles
- Pertussis
- Diphtheria
What is the general presentation for bacterial pneumonia?
- Abrupt onset
- Not associated with epidemics
- May have associated bacteremia
- High grade fever
- Crackles on lung exam
- Lobar or consolidated appearance
- May involve pleura
- Responds quickly to antibiotics
What is the general presentation for viral pneumonia?
- Gradual onset
- Epidemics are common
- Not typically associated with viremia
- No fever or low grade fevers
- Diffuse infiltrates on CXR
- Will not typically involve pleura
- Will not responsed to antibiotics but usually self limiting
What can cause a lung abscess?
- Complications of pneumonia
- Aspiration
What bacterial pneumonia can cause a lung abscess?
- S. aureus
- K. pneumoniae
Who typically has lung abscesses due to aspiration?
- Chronic alcoholics
- Elderly patients
- Anaerobic bacteria
What side does aspirated material tend to go to? Why?
- Tends to go to the right lung due to a steeper descent of the right main bronchus
What happens in aspiration pneumonia?
- Abscess formation in acute bacterial pneumonia
- Food particle in inflammatory exudate indicating aspiration
What is the process of tuberculosis?
- Primary infection causes a localized caseation
- Localized caseation can heal or progress to primary TB or become latent
What can primary TB do?
- Turn into miliary TB (massive hematogenous dissemination)
- Reinfection, turning into secondary TB
What does secondary TB turn into?
- Turns into progressive secondary TB
- Then turns into miliary TB
- OR could cause localized caseating destructive lesions
What is specifically seen in TB?
- Ghon complex
What are some fungal sources of chronic pneumonia?
- Histoplasma
- Blastomycosis
- Coccidioidomycosis
What is histoplasma capsulatum?
- Endemic in midwest and caribbean
- Typically a subclinical infection with granulomatous response (coin lesions on CXR)
- Can run aggressive course, especially in immunocompromised patients
What is the characteristic form that is seen on morphology of histoplasma?
- Pumpkin seed
What is blastomyces dermatitides?
- Endemic in central and SE US
- In the lungs, infection yields a granulomatous response
- Characteristic yeast forms show broad-based budding
- Can also infect skin and rarely, disseminated infection
What is coccidiodes immitis?
- Endemic in southwestern US and Mexico
- In the lungs, yields a granulomatous response with eosinophils
- Often a subclinical, self-limited disease
- Can produce disseminated infection (immunocompromised patients)
What is pneumocystis jiroveci?
- Opportunistic fungal infection
- AIDS-defining illness
- Characteristic cup shaped yeast forms
- Can be diffuse or focal
What is mycobacterium avium complex (MAC)?
- Found in immunocompromised or elderly patients
- Thin mycobacteria seen as slender red forms on acid-fast staining
What is needed to discriminate from rejection?
- Biopsies which can produce infiltrates and fever
What does rejection show in lung transplantation?
- Mononuclear infiltrates around vessels
