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Community Acquired Pneumonia

Community Acquired Pneumonia



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    Pneumonia Pneumonia Presentation Transcript

    • Pneumonia • Acute inflammation of lung parenchyma • Inflammatory infiltrate in alveoli ( = consolidation)
    • CLASSIFICATION: Aetiology. Morpological class. - Bronchopneumonia vs. lobar pneumonia. Community acquired vs hospital acquired (nosocomial) infection. The patient's immune status.
    • AETIOLOGY • Bacteria, viruses, fungi, mycoplasma, chlamydia. • Microbiological identification of organism often not possible.
    • • Previously healthy individual: → S. pneumoniae • Pre-existing viral infection → Staph. aureus or S. pneumoniae • Chronic bronchitis → Haemophilus influenzae or S. pneumoniae • AIDS → Pneumocystis carinii, cytomegalovirus, TB
    • Morphological classification - Bronchopneumonia - Lobar pneumonia
    • Bronchopneumonia: • Infants + young children and the elderly. • Usually secondary to other conditions associated with local and general defence mechanisms: - viral infections (influenza, measles) - aspiration of food or vomitus - obstruction of a bronchus (foreign body or neoplasm) - inhalation of irritant gases - major surgery - chronic debilitating diseases, malnutrition
    • Lobar pneumonia: S. pneumoniae. Previously healthy individuals. Abrupt onset. Unilateral stabbing chest pain on inspiration (due to fibrinous pleurisy).
    • Pathology of lobar pneumonia: 4 phases: Congestion Lasts < 24 hours: Alveoli filled with oedema fluid and bacteria.
    • Red hepatization • Firm, 'meaty' and airless appearance of lung. • Alveolar capillary dilatation. • Strands of fibrin extending from one alveolus to another via inter-alveolar pores of Kohn. • Also neutrophils in alveoli. • Pleura: Fibrinous exudate.
    • Grey hepatization Less hyperaemia. Macrophages, neutrophils + fibrin
    • Resolution - Lysis and removal of fibrin via sputum + lymphatics. - Begins after 8-9 days (without antibiotics). - Sudden improvement of patient's condition.
    • Complications of lobar pneumonia 1. Abscess formation 2. Empyema 3. Failure of resolution ⇒ intra-alveolar scarring ('carnification') ⇒ permanent loss of ventilatory function of affected parts of lung. 4. Bacteraemia: - Infective endocarditis - Cerebral abscess / meningitis - Septic arthritis
    • Klebsiella pneumoniae • Common inhabitant of oral cavity (poor oral hygiene). • Lobar pneumonia in the elderly, diabetics, alcoholics (aspiration of saliva).
    • Community acquired vs. nosocomial infection Nosocomial infection: - Often patients in ICU - ↓ Local resistance to infection in lungs - Intubation of respiratory tract - Altered normal flora due to antibiotics - E.coli, Klebsiella, Proteus, Pseudomonas, Staph. aureus.
    • Immune status Infection by usually non-pathogenic organisms ('opportunistic infection') - Pneumocystis carinii - Other fungi - Cytomegalovirus (CMV)
    • Fig. A viral pneumonia with interstitial lymphocytic infiltrates. Note that there is no alveolar exudate. Thus, the patient with this type of pneumonia will probably not have a productive cough.
    • The most common causes for viral pneumonia are: • Influenza • Parainfluenza • Adenovirus • Respiratory syncytial virus (RSV) - appears mostly in children • Cytomegalovirus - in immunocompromised hosts.
    • Fig. RSV accounts for many cases of pneumonia in children under 2 years, and can be a cause for death in infants 1 to 6 months of age or older.
    • Lung abscess DEFINITION: Localised area of suppuration and tissue necrosis.
    • Fig. Chest X-ray. Abscess. Note air-fluid level
    • Aetiopathogenesis • Aspiration of infected oropharyngeal contents / vomitus. NB: Poor oral hygiene and sepsis. Risk of aspiration: - Loss of consciousness (alcoholic stupor, anaesthesia, epilepsy). - Oesophageal pathology (carcinoma, congenital atresia / fistula).
    • • Obstruction of bronchus - carcinoma, foreign body. • Complication of pneumonia - virulent organisms esp. Klebsiella, Staph. • Bronchiectasis. • Septic embolism (infective endocarditis on right-sided heart valves) or septisaemia. • Penetrating trauma e.g. stab wound. • Direct spread of sepsis from other organs (e.g. amoebic liver abscess).
    • Complications • Rupture into pleural space ⇒ empyema or broncho-pleural fistula (⇒ pyopneumothorax). • Rupture into pericardium ⇒ pericarditis. • Septisaemia ⇒ sepsis in other organs e.g. osteomyelitis, brain abscess. • Erosion of blood vessels ⇒ haemoptysis. • Organisation ⇒ fibrosis.