Lung Path 4 Pulmonary Infections and Lung Transplants (Singh) Flashcards
What are the 4 stages of the inflammatory response which have been classically described for lobar pneumonia?
1) Congestion: vascular engorgement; intra-alveolar fluid
2) Red hepatization: massive exudation of alveolar spaces w/ lots of neutrophils; red, firm, airless lobe; liver-like consistency
3) Gray hepatization: disintegration of red cells w/ fibrinosuppurative exudate
4) Resolution: fibrosis and macrophage clean-up
Congested septal capillaries due to massive confluent exudation w/ numerous intra-alveolar neutrophils is characteristic of what stage of lobar pneumonia?
Red Hepatization
Which inflammatory stage of lobar pneumonia is characterized by progressive disintegration of red cells and the persistence of a fibrinosuppurative exudate?
Grey Hepatization
Exudates within alveolar spaces converted into fibromyxoid masses rich in macrophages is characteristic of which inflammatory stage of lobar pneumonia?
Resolution/Organization
What are the gross morpholigical features of hepatization?
Noarmal vs.
Red
Gray
etc..
What is the most common cause of death in viral influenza epidemics?
Superimposed bacterial pneumonia
What are 2 acute phase markers made in the liver that are specific for bacterial infection and can be useful in pneumonia diagnosis?
- CRP
- Procalcitonin
What organisms cuase communiy acquired pneumonia (CAN)?
S. pneumoniae
H. influenzae
S. aureus
K. pneumoniae
P. aeruginosa
L. pneumophila
M. pneumoniae
Which serotype of the encapsulated H. influenzae is most virulent?
Type B
What will the sputum culture of a patient with community-acquired bacterial pneumonia caused by Streptococcus pneumoniae show morphologically?
Lancet-shaped gram (+) diplococci in pairs and chains
Which patient population is at a high risk for development of invasive infection by H. influenzae?
Neonates and children w/ comorbidities
What is the 1st and 2nd most common bacterial cause of acute exacerbation of COPD?
- Most common = H. influenzae
- 2nd = M. catarrhalis
Pneumonia caused by what bacteria is a pediatric emergency due risk of acute epiglottitis w/ high mortality rate?
H. influenzae
What is the pulmonary consolidation associated w/ H. influenzae typically like?
Lobular and Patchy
Which patient population is especially susceptible to bacterial pneumonia by Moraxella Catarrhalis?
Elderly
S. aureus pneumonia is associated with a high incidence of which 2 complications?
- Lung abscess
- Empyema (aka pus in the pleural space)
What is the most frequent cause of gram-negative bacterial pneumonia and who does it most commonly afflict?
- Klebsiella pneumoniae
- Debilitated and malnourished people, particularly chronic alcoholics
What type of sputum is characteristic of Klebsiella pneumoniae?
Thick, mucoid (blood-tinged) –> “currant jelly”
Pseudomonas aeruginosa is a common cause of pneumonia in whom and in what setting?
Hospital acquired
Cystic Fibrosis
Immunocompromised
(fun fact: aeruginosa means copper rust)
What is the gram stain, shape, and O2 dependency of Pseudomonas aeruginosa?
AEROBIC Gram NEGATIVE; bacillus
What are the characteristics of typical pneumonia?
- More abrupt onset
- Respiratory symptoms predominate
- Consolidation on CXR
- Older adults or young children
What are the characteristics of atypical (walking) pneumonia?
- Slower onset
- Systemic symptoms predominate
- Patchy infiltrates on CXR
- Young adults/teens/older children
Mycoplasma pneumoniae infections are common in which age groups and occur most often how?
Children and young adults (<30)
Sporadically or as local epidemics (i.e., schools, military camps, prisons)
Smallest free-living, self- replicating microorganisms
NO CELL WALL!
Which cause of bacterial pneumonia is classically seen in military recruits or college student i.e., those living in close quarters?
Mycoplasma pneumonia
Which bacteria cause of pneumonia flourished in warm freshwater (i.e., AC units, misters, hot tubs); what does it live inside?
Legionella pneumophila
Lives in amoebas
What are the 2 common modes of transmission for Legionella pneumophilia?
- Inhalation of aerosolized organisms
- Aspiration of contaminated drinking water
What is the gram stain and morphology of Legionella pneumophila?
Gram NEGATIVE bacillus
Pt’s with what predisposing conditions are most at risk for Legionella pneumonia?
Pt’s w/ cardiac, renal, immunologic, or hematologic diseases
Organ transplant recipients****
Elderly smokers
How is rapid diagnosis of Legionella pneumophila done and what is the gold standard?
- Legionella Ags in the urine
- (+) fluorescent Ab test on sputum samples
- CULTURE = gold standard
Which bacterial cause of pneumonia is associated with hypokalemia, elevated CPK, and lobar infiltrates?
Legionella pneumophila
Air-fluid level within cystic space seen on CXR associated with pneumonia suggests what?
Common causes?
Lung abscess
Compliction from S. aureus or K. phenumoniae
Apiration (EtOH, elderly, or anearobic bacteria) –> tends to follow gravity
What is a common cause of postobstructive pneumonia which may lead to abscess formation?
Neoplasia causing obstruction
What is a cause of lung abscess which may originate in systemic venous circulation or the right side of the heart?
Septic embolism
When all the causes have been exluded and in which there is no discernible basis for lung abscess formation, what is this referred to as?
Primary cryptogenic lung abscesses
Lung abscesses due to aspiration are more common on which side of the lung and are most often (single/mutliple)?
Right side of lung; most often single
What is the cardinal histologic change in all lung abscesses?
Suppurative destruction of the lung parenchyma within the central area of cavitation
Clinical signs/sx’s of lung abscess?
- Cough + fever + copious amounts of foul-smelling purulent or bloody sputum
- Fever + chest pain + weight loss = common
- Clubbing of digits may appear within a few weeks
If a lung abscess is discovered in an elderly pt, what must be ruled out?
Underlying carcinoma
Complications which may arise from a lung abscess?
- Extension into pleural cavity
- Hemorrhage
- Brain abscesses or meningitis from septic emboli
- Rarely, secondary amyloidosis (AA)
Tissue destruction and abscess formation as a complication of pneumonia are most common associated w/ what 3 organisms?
- Type 3 pneumococci
- Klebsiella
- S. aureus
Patchy consolidation of the lung is the dominant characteristic of what type of bacterial pneumonia?
Bronchopneumonia
Which pattern of bacterial pneumonia is often multilobular and frequently bilateral and basal?
Bronchopneumonia
Histologically, the rxn associated with bronchopneumonia shows areas of acute suppurative inflammation rich in what type of immune cell?
Neutrophilic exudate filling bronchi, bronchioles, and adjacent alveolar spaces
Bacteremic dissemination as a complication of pneumonia can spread where and cause what?
- Heart valves, pericardium, brain, kidneys, spleen, or joints
- Metastatic abscesses, endocarditis, meningitis, or suppurative arthritis
What are the major sx’s of acute bacterial pneumonia?
- Abrupt onset of high fever + shaking chills + cough
- Mucopurulent sputum and occasionally hemoptysis
What are the 2 most important components in term of virulence for Influenza virus allowing it to cause infections; function of each?
- Hemagglutinin: allows for attachment to cells; via sialic acid residues
- Neuraminidase: allows release of replicated virus from cells; cleaves sialic acid residues
What is antigenic drift in regards to Influenza virus and what changes occur; leads to what type of outbreak?
Spontaneous mutation that alter antigenic epitopes on the vial Hemagglutinin and Neuraminidase proteins
–> Result in new viral strains, leading to epidemics
What is antigenic shift in regards to Influenza virus and what changes occur; leads to what type of outbreak?
Both hemagglutinin and neuraminidase genes are replaced through recombination w/ animal influenza viruses (maybe ?).
Resulting in major changes in protein structure
–> Leads to pandemics
If influenza virus gains entry into pneumocytes what are the cytopathic changes that it can elicit which contribute to its pathogenesis?
- Inhibits Na+ channels –> electrolyte + H2O shifts = fluid accumulation in alveolar lumen
- Inhibits host cells mRNA translation and activates caspases –> cell death via apoptosis
What complications may arise with viral pneumonia as a result of activation of the nearby pulmonary endothelium causing lung injury?
For all viruses
ARDS
Fatal pulmonary disease from superimposed bacterial infection
In case of COVID
cytokine storm
Which bacteria is most commonly found as cause of superimposed bacterial infection on a viral pneumonia?
Staphylococcus aureus
Which family of viruses does SARS belong to?
Coronavirus
Why is SARS a distinct coronavirus in terms of infection?
- Many upper respiratory infections are caused by coronavirus
- SARS differs in that it can infect the lower respiratory tract and spread throughout the body
What is the molecular pathogenesis of COVID?
Explain image…
Take note of the D-dimer!
–> It correlates with a poorer outcome in COVID patients due to the thrombotic complications
What histological findings might you see in a biopsy for a COVID pt?
diffuse alveolar damage as well as a fibrin microthrombus
What uniqe cells in circulation can help you identify COVID?
Megakaryocytes
Besides, the lung and circulation, where else may you find megakaryocytes associated with COVID?
liver
heart
kideny
She said IMPORTANT slide!