Pneumonia

Introduction

Pneumonia is an inflammation of the lung parenchyma caused by pathogenic microorganism. Various bacterial species, fungi and viruses may cause it.
The setting in which infection is acquired
could be a predictor of the infecting pathogen.
Bacterial Pneumonia: is defined as bacterial infection of the lung parenchyma associated with recently developed radiological shadowing which may be segmental, lobar or multi lobar.

Types

  1. Community Acquired Pneumonia (CAP)
  2. Hospital Acquired pneumonia (HAP)
  3. Ventilator Associated pneumonia (VAP)
  4. Health care Pneumonia (HCAP)
    associated
  5. Pneumonia in the immunocompromised
  6. Aspiration pneumonia

Streptococcus pneumoniae is the most common pathogen in community-acquired pneumonia
Common bacteria causing CAP:

  • Streptococcus pneumoniae
  • Mycoplasma pneumonia
  • Legionella pneumophilia
  • Chlamydia pneumonia
  • Haemophilus influenza
  • Staphylococcus aureus
  • Chlamydia psittaci
  • Coxiella burnetti
  • Klebsiella pneumonia
  • Actinomyces israelli

Other causative organisms:

  • Pseudomonas aeruginosa (usually implicated in nosocomial pneumonia)

Clinical features

Typical pneumonia:

  • Sudden onset fever, chills and rigors
  • Cough with purulent sputum production
  • Pleuritic chest pain
  • Breathlessness with short inspiratory efforts

Signs:

  • Fever
  • Herpes labialis
  • Tachypnoeal
  • Signs of lung consolidation.
  • Pleural friction rubs.
  • Chest signs are very helpful depending on the phase of the inflammatory response

When consolidated

  • Dull percusision
  • Increased Tactile and vocal fremitus
  • Bronchial breath sounds
  • Whispering pectoriloquy
  • Crepitations

Signs of severity

  • Confusion
  • Urea> 7mmol/L
  • Respiratory rate > 30/min
  • Systolic BP<90
  • Age 65years

Score 1 point for any of the above features present

  • 0 or 1 – home treatment
  • 2 – Hospital-supervised treatment
  • 3 or more – manage in Hospital as severe pneumonia
  • 4 or 5 – ICU Admission

Atypical pneumonia:

  • Gradual onset
  • Dry cough
  • Prominent extra-pulmonary symptoms
  • Headache
  • Sore throat
  • Fatigue
  • Myalgia
  • Chest crackles or rales

Differential diagnosis

  • Acute bronchitis
  • COPD Exacerbation.
  • Pulmonary embolism/infarction
  • TB
  • Pulmonary eosinophilia

Complications

  • Empyema Thoracis
  • Pleural effusion.
  • Lung abscess
  • Lobar collapse
  • Deep vein thrombosis and pulmonary embolism
  • Pneumothorax
  • ARDS
  • Multi organ failure
  • Hepatitis, pericarditis, myocarditis,
    meningoencephalitis
  • Pyrexia from drug hypersensitivity

Relevant Investigations

  • FBC+ESR+CRP
  • Serum E/U/Cr
  • LFT
  • Blood Culture
  • Serology
  • Cold agglutinins
  • Arterial blood gases/ SPO₂
  • Sputum gram stain,M/C/S
  • Urine pneumococcal and legionella antigen
  • Chest X-ray
  • Pleural fluid M/C/S

Treatment objectives

  • Eliminate the infection
  • Return to normal lung function

Treatment

General

  • Oxygen to maintain Pao, at or above 8kPa
  • IV fluids especially in severe cases

Antipyretics
Antibiotics

1. Uncomplicated CAP + No modifying factor, + no antibiotics use in the last 3 months:

Amoxicillin Clavulanic acid

  • Adult: 1g 12hourly for 5-7 days
  • Child:
    • Neonate and premature infants, 25mg/kg 12 hourly;
    • Infants up to 3 months, 25 mg/kg 8 hourly;
    • 3 months – 12years, 25mg/kg 8hourly increased to 6hourly in more severe infections.

OR

Benzyl penicillin

  • Adult: initially 2million units 6 hourly.
  • Child:
    • preterm and neonate under 7 days, 25mg/kg by IM injection Or by slow IV injection or infusion every 12 hours; double dose in severe infections.
    • Neonate 7-28 days: 25mg/kg 8hourly; double dose in severe infections.
    • 1 month – 18years: 25mg/kg 4 – 6hourly. Double dose in severe infections.
  • Commence oral therapy as soon as possible.

OR

  • Macrolide (azithromycin 500mg stat,then 250mg daily,

OR

  • Clarithromycin 500mg twice
    daily for up to 14days)

OR

Cefuroxime axetil

Adult: 500mg orally 8 hourly for 5-7 days

Child:

    • 3 months 2years: 10mg/kg (maximum 125mg) orally 12 hourly
    • 2-12 years: 15mg/kg orally 12 hourly
    • 12-18 years: 12 hourly. May double doses in severe infections.

2. Patients with history of recent use of Antibiotics

Respiratory quinolone (levofloxacin).

  • Quinolones are generally better
    avoided in TB endemic areas because of their potential use as part of 2nd line regimen in the treatment of MDR-TB.
  • Advanced macrolide+ amoxicillin

Advanced
macrolide + amoxicillin + clavulanic acid

3. Complicated CAP

  1. IV β lactam + advanced macrolide
  2. Iv respiratory quinolones + advanced macrolide
  3. Penicillin G+advanced macrolide

Adverse reaction

Amoxicillin Clavulanic acid:

  • Nausea, diarrhoea, skin rashes,
  • contraindicated in penicillin hypersensitive individuals.

Cefuroxime:

  • Nausea, vomiting, abdominal
    discomfort, headaches, rarely antibiotic associated colitis.

Macrolides:

  • Similar to those mentioned above
    but usually milder.
  • Hepatoxicity and antibiotic associated colitis are quite rare.

Prevention

  • Pneumococcal vaccine
  • Haemophilus influenzae vaccine