• Pneumonia

    by  • 13/06/2013 • Respiratory

    Pneumonia

    Definition

    1. is an inflammatory condition of the lung
    2. It is often characterized as including inflammation of the parenchyma of the lung (alveoli) and abnormal alveolar filling with fluid (consolidation and exudation)

     

    Can be acute / chronic

    Acute pneumonias

    1. Classic pneumococcal bronchopneumonias (such as Streptococcus pneumoniae)
    2. Atypical pneumonias (such as the interstitial pneumonitis of Mycoplasma pneumoniae or Chlamydia pneumoniae)
    3. Aspiration pneumonia syndromes

     

    Chronic pneumonias, on the other hand, mainly include those of Nocardia, Actinomyces and Blastomyces dermatitidis, as well as the granulomatous pneumonias (Mycobacterium tuberculosis and atypical mycobacteria, Histoplasma capsulatum and Coccidioides immitis)

    Community-acquired pneumonia

    1. Community-acquired pneumonia (CAP) is infectious pneumonia in a person who has not recently been hospitalized.
    2. CAP is the most common type of pneumonia.
    3. The most common causes of CAP vary depending on a person’s age, but they include Streptococcus pneumoniae, viruses, the atypical bacteria, and Haemophilus influenzae. Overall, Streptococcus pneumoniae is the most common cause of community-acquired pneumonia worldwide.
    4. CAP is the fourth most common cause of death in the United Kingdom and the sixth in the United States.

     

    CURB-65, also known as the CURB criteria, is a clinical prediction rule that has been validated for predicting mortality in community-acquired pneumonia and infection of any site.

    1. Confusion of new onset (defined as an AMT of 8 or less)
    2. Urea greater than 7 mmol/l (Blood Urea Nitrogen > 19)
    3. Respiratory rate of 30 breaths per minute or greater
    4. Blood pressure less than 90 mmHg systolic or diastolic blood pressure 60 mmHg or less
    5. age 65 or older

     

    Hospital-acquired

    1. Hospital-acquired pneumonia (HAP) also called nosocomial pneumonia, is pneumonia acquired during or after hospitalization for another illness or procedure with onset at least 72 hrs after admission.
    2. The causes, microbiology, treatment and prognosis are different from those of community-acquired pneumonia.
    3. HAP is more deadly than CAP!
    4. Up to 5% of patients admitted to a hospital for other causes subsequently develop pneumonia.
    5. Hospitalized patients may have many risk factors for pneumonia, including mechanical ventilation (VAP), prolonged malnutrition, underlying heart and lung diseases, decreased amounts of stomach acid, and immune disturbances.
    6. Additionally, the microorganisms a person is exposed to in a hospital are often different from those at home .
    7. Hospital-acquired microorganisms may include resistant bacteria such as MRSA, Pseudomonas, Enterobacter, and Serratia.
    8. It tends to be more deadly than community-acquired pneumonia. Ventilator-associated pneumonia (VAP) is a subset of hospital-acquired pneumonia. VAP is pneumonia which occurs after at least 48 hours of intubation and mechanical ventilation.

     

    Aspiration pneumonia

    1. Aspiration pneumonia is caused by aspirating foreign objects which are usually oral or gastric contents, either while eating, or after reflux or vomiting which results in bronchopneumonia

     

    1. The resulting lung inflammation is not an infection but can contribute to one, since the material aspirated may contain anaerobic bacteria or other unusual causes of pneumonia.

     

    1. Aspiration is a leading cause of death among hospital and nursing home patients, since they often cannot adequately protect their airways and may have otherwise impaired defenses

     

    1. A lobar pneumonia is an infection that only involves a single lobe, or section, of a lung. Lobar pneumonia is often due to Streptococcus pneumoniae (though Klebsiella pneumoniae is also possible.)
    2. Bronchial pneumonia affects the lungs in patches around the tubes (bronchi or bronchioles).
    3. Interstitial pneumonia involves the areas in between the alveoli, and it may be called “interstitial pneumonitis.” It is more likely to be caused by viruses or by atypical bacteria.

     

    P/c: coryza, pharyngitis, high fever, myalgias, confusion, tachypnoea, tachycardia, dull percussion note over consolidation, basal crackles, bronchial breathing (audible gap between inspiration and expiration with harsh/turbulent flow).

    Diagnostic tools/investigations

    1. CXR / ECG
    2. Chest CT
    3. Sputum = Strep pnuemoniaea = G+ve diplococcus, MTB (AAFB on ZNS),
    4. FBC – WCC, urea, serology.
    5. Blood serology
    6. LFT
    7. Urine = Legionella antigen.

     

    Aetiology

    1. Streptococcus pneumonia
    2. Staphylococcus aureus/MRSA (VAP)
    3. Streptococcus agalactiae
    4. Haemophilus influenzae (CAP)
    5. Klebsiella pneumoniae
    6. Escherichia coli (aspirate)
    7. Pseudomonas aeruginosa (HAP)
    8. Moraxella catarrhalis.

     

    “Atypical” bacteria

    1. Chlamydophila pneumoniae,
    2. Mycoplasma pneumoniae,
    3. Legionella pneumophila.

     

    Atypical p/c: not responsive to normal Abx, no lobar consolidation, no leucocytosis, extarpulmonary and neuro symptoms, no alveolar exudate. Overall few symptoms, yet patient is VERY UNWELL!

    1. Mycoplasma = young patient with cold agglutins
    2. Klebsiella = older patient
    3. Legionella = air conditioning/institutionalised/traveller.

     

    Viral pneumonia is commonly caused by viruses such as

    1. influenza virus
    2. respiratory syncytial virus (RSV)
    3. adenovirus
    4. parainfluenza.

     

    Fungal pneumonia is most often caused by

    1. Histoplasma capsulatum = histplasmosis
    2. Blastomyces
    3. Cryptococcus neoformans = cryptococcosis
    4. Pneumocystis jiroveci = PCP
    5. Coccidioides immitis.

     

    The most common parasites causing pneumonia are

    1. Toxoplasma gondii
    2. Strongyloides stercoralis
    3. Ascariasis lumbricoides = especially in asthma patients

     

    Hereditary? Infective? How does it spread?

    1. Airborne droplets

     

    Treatment and management (conservative/medical/surgical)

    1. Prevention by screening, smoking cessation
    2. When an influenza outbreak is occurring, medications such as amantadine, rimantadine, zanamivir, and oseltamivir can help prevent influenza
    1. HAP = third- and fourth-generation cephalosporins, carbapenems, fluoroquinolones, aminoglycosides, and vancomycin
    2. CAP = amoxicillin, erythromycin, or azithromycin
    3. Common options include clindamycin, a combination of a beta-lactam antibiotic and metronidazole, or an aminoglycoside 
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