Respiratory Tract Infections

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Respiratory Tract Infections

Aetiology

Classification gives idea of organism

  • Pneumonias

    • Community acquired

    • Hospital-acquired

      • Gram -ve - e.g  pseudomonas

      • Staph. aureus

    • Immunosuppressed

    • Aspiration (anaerobes)

  • Exacerbation of COPD / asthma (no consolidation)

  • TB

  • Bronchiectasis

Organisms

  • Strep pneumoniae

  • H. influenzae

  • Chlamydia (6 yr cycle)

  • Mycoplasma (4 year cycle)

  • Legionella

  • Viral

  • None identified (50%)

Clinical Features

Symptoms

  • Cough + sputum
  • Rigors
  • Weakness / Malaise
  • Extra-pulmonary
  • Elderly

    • confusion

    • hypothermia

Signs

  • Fever

  • Tachycardia

  • Tachypnoea

  • Consolidation

  • Effusion

    • could become empyema so tap

Bronchopneumonia

  • Terminal Bronchi
  • Segmental
  • Widespread
  • Patchy
  • Organisms
    • Strep. pneumoniae
    • H. Influenzae
    • Influenza virus
      • primary
      • secondary - Staph. aureus
    • TB

Viral Pneumonia

  • Primary
    • Influenza
    • Adenovirus
    • RSV
      • infants
      • bronchiolitis
    • CMV
      • immunosuppressed

Lobar pneumonia

  • Association with proximal obstructing tumour

Organisms

  • Strep. pneumoniae
    • symptoms
      • sudden onset
      • fever
      • pleuritic pain
      • rusty sputum
      • rigors
      • herpes labialis
    • Investigation
      • CXR
      • Sputum
        • Gram stain
        • culture
      • leucocytosis
    • Therapy
      • amoxicillin
      • erythromycin
  • Viruses
  • Mycoplasma
  • Associated with cavitation
    • Staph. aureus
    • TB
    • Klebsiella

Anaerobic Infection

  • segmental pneumonia
  • aspiration
  • dependent parts of lung

Association

  • existing respiratory disease
    • bullae
    • pneumoconiosis
    • bronchiectasis
  • Oropharynx infection
  • Gum infection
  • Epilepsy
  • Loss of consciousness
    • coma
    • drug overdose
    • general anaesthetic
  • bulbar palsy
  • dysphagia
  • alcoholism

Clinical features

  • foul sputum
  • foul breath

Therapy

  • amoxycillin
  • metronidazole

Complications

  • necrotising pneumonia
  • abscess
  • empyema

Risks for hospital-acquired pneumonia

  • age
  • chronic lung / heart disease
  • reduced consciousness
  • intubation
  • H2-receptor antagonists

Investigations

  • Confirm diagnosis / cause
    • serology
    • urinalysis
    • pleural aspiration
  • Pulse ox / Arterial blood gases (ABG)
  • End organ damage
    • FBC
    • U&E
    • LFTs

Management

  • Antibiotics
    • Community acquired
      • Broad spectrum antibiotics
        • Benzyl penicillin
        • amoxycillin + clarithromycin
        • cephalosporin
        • +/- macrolide
      • Sick enough for ITU
        • cephalosporin + macrolide
      • Legionella
        • quinolone
        • rifampicin
    • Hospital acquired
      • specific if possible
      • augmentin
      • Quinolones
      • IV cephalosporin + aminoglycoside +/- flucloxacillin
  • Hydration
  • Oxygenation

Management of immunocompromised patients

Think of diagnosis early and call senior staff / specialists

Differential diagnosis

  • drug / radiation injury
  • bleeding
  • cancer
  • infection elsewhere

Organism dependent on immunological defect

Mortality increased when

  • Respiratory rate > 30
  • Diastolic BP <60 mmHg
  • Urea > 7 mmol/l +confusion

2 out of 3 leads to 21x increase in death

Pneumonia in children

Bronchopneumonia

  • commonest in young children

  • older children with chronic condition

  • commonly follows

    • bronchiolitis

    • viral infections

    • whooping cough

Clinical features

  • rapid breathing

  • dry cough

  • fever

  • fretfulness

  • generalised crepitations

  • rhonchi

  • cyanosis in severe cases

  • cardiac failure (infants)

Investigations

  • CXR

    • small patches of consolidation

Treatment

  • hospitalisation
  • oxygen
  • broad-spectrum antibiotics
  • gentle physiotherapy to mobilise secretions
  • tube-feeding (infants)

Lobar pneumonia

Clinical features

  • sick child
  • sudden illness
  • high fever
  • looks flushed
  • breathes fast
  • respiratory distress
  • may NOT be cough
  • pleuritic pain
    • causes child to lean to affected side
    • referred to abdomen or neck
  • consolidation may not be present at first
  • transient pleural rub
  • usually Strep pneumoniae
    • penicillin achieves dramatic improvement within 24 hours

Causative agents

Treatment

  • penicillin if Strep. pneumoniae suspected
  • if ill child start with broad spectrum antibiotic parenterally
  • ensure adequate fluid intake
  • consider mycoplasma in older child

 

 

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