Community-Acquired Acute Pneumonias.

onset is usually abrupt, with high fever, shaking chills, pleuritic chest pain, and a productive mucopurulent cough

Usually as a result of aspiration of pharyngeal flora, esp Pneumococcus

lower lobes or the right middle lobe most frequently involved

In the era before antibiotics, 4 stages used to be seen

Congestion:

the affected lobe is heavy, red, and boggy

M/E vascular congestion with proteinaceous fluid, numerous neutrophils containing the typical gram-positive, lancet-shaped diplococci

red hepatization

lobe has a liver-like consistency

alveolar spaces are packed with neutrophils, red cells, and fibrin

gray hepatization

lung is dry, gray, and firm, because the red cells are lysed, while the fibrinosuppurative exudate persists

Resolution

exudates within the alveoli are enzymatically digested to produce granular, semifluid debris that is resorbed, ingested by macrophages, coughed up, or organized by fibroblasts

pleuritis may similarly resolve or undergo organization, leaving fibrous thickening or permanent adhesions.

M/E of bronchopneumonia shows

focal suppurative exudate that fills the bronchi, bronchioles, and adjacent alveolar spaces.

Complications of pneumonia

Lung abscess

Empyema thoracic

Organisation

Bacteremia, causing meningitis, septic arthritis or infective endocarditis

bronchiectasis

Bronchopneumonia :

Abscess formation

Lobar Pneumonia:

Lobar Pneumonia Gray hep..

Other common organisms causing CAP:

Haemophilus influenzae

in children, often following a respiratory viral infection

most common bacterial cause of acute exacerbation of COPD.

Common cause of epiglottitis and suppurative meningitis in children

In pts with cystic fibrosis, and bronchiectasis

Staphylococcus aureus

after viral respiratory illnesses (e.g., measles in children and influenza in both children and adults)

complications, such as lung abscess and empyema are very common

intravenous drug abusers

Klebsiella pneumoniae

malnourished persons, particularly chronic alcoholics

viscid capsular polysaccharide, which the individual may have difficulty coughing up

Pseudomonas aeruginosa

Neutropenic pts,eg chemotherapy

in victims of extensive burns

those requiring mechanical ventilation

Pseudomonas bacteremia is a fulminant condition

Pseudomonas vasculitis of the pulmonary vessels is common.