Lower Respiratory Tract Infection

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Lower Respiratory Tract Infection
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Pneumonia

• Common with high morbidity and mortality rates.
• Acute respiratory infection with focal chest
  signs and radiographic changes.
• Classification
• 1. Community-acquired pneumonia.
• 2. Hospital-acquired pneumonia (nosocomial).
• 3. Pneumonia in the immunocompromised.

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Community-acquired Pneumonia

• Epidemiology Worldwide disease, common in the
  winter months.
• Clinical features
• 1. Symptoms malaise, fever, and shortness in
  breath productive cough, pleuritic chest pain,
  tachycardia.
• 2. Chest X-ray lobar, patchy consolidation, or
  diffuse shadowing.
• . Complications. Septicaemia and empyaema

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• . Laboratory diagnosis
• Sputum specimens for microscopy (Gram stain) and
  culture.
• Bronchial-alveolar lavage specimens.
• Blood cultures.
• Serology (viruses, mycoplasma, chlamydia,
  coxiella, Legionella).

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Causes of Community-acquired Pneumonia
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S. pneumonia

• 30-50 of community-acquired pneumonia.
• Occurs in all age groups.
• Risk group patients with chronic lung disease,
  splenectomized patients and immunocompromised
  patients.
• X-rays shows lobar consolidation.
• Laboratory diagnosis by sputum and blood
  cultures.
• Treatment penicillin or erythromycin.

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Mycoplasma pneumoniae

• 1-20
• Occur primarily in young adults.
• X-ray shows diffuse changes.
• Laboratory diagnosis is by serology.
• Treatment erythromycin.

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Haemophilus influenzae

• lt10 of all community acquired cases.
• Common in infants lt5 years.
• Diagnosis by sputum culture.

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Staphylococcus aureus

• Very rare
• Post-influenza pneumonia
• Laboratory diagnosis sputum culture.

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Legionella pneumophila

• L. pneumophila is transmitted via aerosols
  particularly from contaminated air-conditioning
  systems.
• lt5
• Elderly and immunocompromised are in particular
  risk.
• Specimen culture, serology, direct
  immunofluorescence.

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C. pneumoniae

• 10
• Young adults have high incidence.
• Diagnosis by serology.

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C. psittaci

• Contact with birds
• Serology

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Hospital-acquired (nosocomial) pneumonia
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• Symptoms appears gt2 days after admission.
• Common nosocomial infection
• Risk factors include assisted respiration,
  immunocompromised and pre-existed pulmonary
  disease.
• Aetiology S. pneumoniae, H. influnzae, Gram
  negative organisms like E. coli, Klebsiella.

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Pneumonia in the immunocompromised
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• Infected with classical chest pathogen like S.
  pneumoniae M. pneumoniaeetc
• Or with opportunistic pathogens
• Actinomyceteae
• Atypical mycobacteria
• Legionella pneumophila.

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Whooping cough (pertussis)
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Tuberculosis