Pneumonia

Community acquired Pneumonia (CAP) Symptoms: cough, purulent sputum which may be blood-stained or rust-coloured (hemoptysis), breathlessness, fever, malaise. Elderly may present with mainly systemic complaints of malaise, fatigue, anorexia and myalgia. Young children may present with nonspecific symptoms or abdominal pain. Signs: tachypnoea, bronchial breathing, crepitations, pleural rub, dullness with percussion.

CURB 65 score: (severe CAP if 3 or more) Confusion of new onset (defined as an AMTS of 8 or less) Blood Urea nitrogen > 7 mmol/l (19 mg/dL) Respiratory rate >30 Blood pressure (90/60) age 65 or older

Common organisms: S. pneumoniae,  S. aureus,  Haemophilus influenzae, 

Hospital acquired PneumoniaOrganisms: S. pneumoniae,  H. influenzae   Moraxella catarrhalis. Legionella pneumophila S. aureus (MRSA) Klebsiella E.coli Proteus Enterococcus Commonly in pts:-severe debilitated-immunocompromised-mechanical ventilation

Risk factors: Age: especially infants, young children and the elderly. Lifestyle: smoking, alcohol. Preceding viral infections Respiratory: asthma, chronic obstructive pulmonary disease (COPD), malignancy, bronchiectasis, cystic fibrosis. Immunosuppression Intravenous drug abuse (Staphylococcus aureus ) Hospitalisation (Gram-negative organisms) Aspiration pneumonia: patients with impaired consciousness, neurological disease such as cerebrovascular or Parkinson's disease, or patients with oesophageal obstruction a Underlying predisposing disease: diabetes mellitus, cardiovascular disease.

Atypical pathogens: Mycoplasma pneumoniae Chlamydophila pneumoniae Legionella pneumophila

Lobar PneumoniaLobar pneumonia is an acute exudative inflammation of an entire pulmonary lobe, produced in 95 % of cases by Streptococcus pneumoniae (pneumococci).Pathology: In the first stage, congestion (day 1 - 2), partially consolidated, and red-purple, partially aerated. (serous exudate, bacteria and rare leucocytes.) In the second stage, red hepatization (day 3 - 4),  consolidate, red-brown, dry, firm, with a liver-like consistency. The cut surface is dry, rough. (exudate rich in fibrin (mainly), with bacteria, leucocytes, and erythrocytes in alveolar lumen. Alveolar walls are thickened due to capillary congestion and oedema.) The third stage, gray hepatization (day 5 - 7), the affected lobe has a liver-like consistency, with uniform gray colour, with grayish purulent liquid drains. Alveolar lumens are filled with leukocytic exudate (neutrophils and macrophages)  Capillary congestion and edema are still present, therefore alveolar walls are thick.  The resolution stage (day 8 and continues for 3 weeks in uncomplicated cases), while the exudate within the alveolar spaces will be drained through lymphatics and airways ("productive" cough) with gradually aeration of the affected segment.

BronchopneumoniaAcute exudative suppurative inflammation of the lungs characterized by foci of consolidation surrounded by normal parenchyma.Causes: staphylococcus, streptococcus, Haemophilus influenzae, proteus, Escherichia coli.Pathology: Bronchopneumonia affects one or more lobes, being frequently bilateral and basal.  multiple foci of condensation (1 - 3 cm diameter), white-yellowish, imprecisely circumscribed, centered by bronchiole, separated by normal lung parenchyma.  In children, it has a tendency to confluence, resulting in large condensation area (pseudolobar pneumonia) foci of inflammatory condensation centered by a bronchiole with acute bronchiolitis (suppurative exudate rich in neutrophils in the lumen, foci of ulceration of the epithelium and parietal inflammation).  The alveolar lumens surrounding the bronchia are filled with neutrophils ("leukocytic alveolitis"). Capillaries in the alveolar walls show congestion. Inflammatory foci are separated by normal, aerated parenchyma. 

Investigations: FBC with differential white cell count. CRP (to aid diagnosis and as a baseline measure). Renal function and electrolytes. (UREA) LFTs. Blood cultures. CXR. (A follow-up CXR six weeks after recovery from pneumonia is recommended. Sputum examination and culture. Pulse oximetry or blood gases. Aspiration of pleural fluid (for biochemistry and culture).

Complications: Pleural effusion that is usually sterile. Empyema Lung abscess: can occur in disease due to S. pneumoniae and is classically seen in patients with klebsiella or staphylococcal pneumonia. Pneumatocele. Pneumothorax. Pyopneumothorax - eg following rupture of a staphylococcal lung abscess in the pleural cavity. Deep vein thrombosis. Septicaemia, pericarditis, endocarditis, osteomyelitis, septic arthritis, cerebral abscess, meningitis (particularly in pneumococcal pneumonia). Postinfective bronchiectasis. Acute renal failure.

Management: Oxygen for hypoxia; ventilation if there is severe hypoxia. Fluids for dehydration. Analgesics: non-steroidal anti-inflammatory drugs (NSAIDs) and paracetamol - for mild pleuritic pain; more severe pain may require opiate analgesia but care is needed not to aggravate CO2 retention. Nebulised saline may help expectoration. Physiotherapy Antibiotics

Uncomplicated CAP: Amoxicillin or tetracycline if the patient has a previously healthy chest (or erythromycin/clarithromycin if there is a known allergy). Add flucloxacillin if staphylococcal infection is suspected, eg in influenza or measles (or vancomycin if meticillin-resistant S. aureus (MRSA) is suspected). Initial empirical treatment of adults with CAP treated in hospital: Non-severe disease: oral amoxicillin plus erythromycin or clarithromycin; alternatively, oral moxifloxacin or levofloxacin. Severe disease: intravenous co-amoxiclav or cefuroxime or cefotaxime plus erythromycin/clarithromycin; alternatively, intravenous levofloxacin plus benzylpenicillin.

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