Pathology of Pulmonary Infections Flashcards
(41 cards)
What bacteria is the most common bacterial cause of acute exacerbation in COPD? What type of this bacteria is it?
Haemophilus influenzae
Typically the non-encapsulated, non-typable forms (people are vaccinated against b capsule)
What is the second most common cause of bacterial exacerbation of COPD? What is it morphology?
Moraxella catarrhalis
-> gram negative diplococci
What are the features of pneumonia with Klebsiella and Pseudomonas?
Klebsiella - severe, necrotizing with thick, mucoid sputum
Pseudomonas - severe, necrotizing inflammation with vasculitis leading to thrombosis and hemorrhage
What bacterias are commonly nosocomial?
Gram negatives are more commonly to be involved in nosocomials: I.e. pseudomonas or E. coli, other enteric gram negatives
S. aureus and S. pneumoniae are still feared (latter is most common in every population)
What type of infection does aspiration pneumonia / what lung damage and why?
Necrotizing, fulminant infection with pulmonary abscess due to a mix of gastric acid, and aerobic / anaerobic bacteria
What is the most frequent cause of lobar pneumonia?
S. pneumoniae
& other community acquired pneumonias
What is meant by bronchopneumonia and in what type of pneumonia (broadly) does this typically occur?
Patchhy distribution around airways and in MULTIPLE lung lobes
Most frequent in nosocomial pneumonia
What are the classical stages of acute bacterial pneumonia in order?
Congestion (hyperemia) -> red hepatization -> gray hepatization -> resolution
What is happening in the congestion stage of pneumonia?
Dilated blood vessels with pulmonary edema, numerous bacteria -> not many immune cells have leaked in yet
What is the difference between gray and red hepatization?
Red hepatization (firm like liver) -> happens earlier, with numerous erythrocytes, neutrophils, and fibrinous exudate
Gray -> more macrophages now as well, and RBCs have become lysed and eatin by neutrophils / MACs
How does acute bacterial pneumonia finally resolve?
Enzymatic digestion of intra-alveolar exudate, with clearance by expectoration, resorption, or ingestion by dust cells
What are some of the complications that can happen secondary to acute bacterial pneumonia?
- Pleuritis
- Pulmonary abscess - (in necrotizing infections, like S. aureus / K. pneumoniae)
- Foci of pulmonary fibrosis
- Bacteremia / sepsis
What are the complications of pleuritis?
Exudative effusions or empyema (pus in pleural space) -> can lead to fibrous scarring with adhesions
What are the clinical manifestations of acute bacterial pneumonia?
Acute onset of fever and chills
Productive cough with dyspnea and tachypnea
Left shift of WBC
Pleuritic chest pain / friction rub
What is the most common cause of lung abscess and where does it most commonly occur?
Aspiration of oropharyngeal contents
-> occurs in right lower lobe (due to right broncus branching at a less acute angle)
What patients are particularly susceptible to aspiration of oropharyngeal contents? What makes this more likely to become an abscess?
Impaired cough reflex -> anesthesia, unconscious, alcoholics
Abscess -> with periodontal disease, growing more anaerobes in mouth
What condition is most likely to cause multiple pulmonary abscesses? With what bacteria?
Septic embolism due to IV drug user tricuspid valve endocarditis
-> most frequently S. aureus
How can a neoplasm cause a lung abscess?
By obstructing a bronchial, bacteria cannot be cleared, and they form an abscess distal to the obstruction
What type of inflammation occurs to cause lung abscess and how can this manifest on chest X-ray?
Suppurative inflammation -> liquefactive necrosis
Can become surrounded by fibrous connective tissue with chronicity
Chest X-ray, after airway destruction -> seen as air-fluid level (fluid sitting perfectly level in a cavity)
What are the patient symptoms of lung abscess?
Fever, productive cough with foul-smelling and bloody sputum (trying to clear airway), weight loss (TNF from inflammation)
->** digital clubbing, due to growth factors released from abscess reaching systemic circulation
What are the three major causes of atypical pneumonias?
Aka walking pneumonias
- Mycoplasma pneumoniae
- Chlamydia pneumoniae
- Viruses (hehe i got u good)
How do viruses predispose to bacterial pneumonia?
They attach to and are endocytosed by mucosal epithelial cells, and lead to cellular injury
What viruses are known for causing bronchiolitis +/- pneumonia especially in young children?
RSV
human metapneumovirus
Give two viruses which can cause atypical pneumonias, inducing cell fusion and forming inclusion bodies?
Rubeola virus -> measles
Varicella virus -> VZV
