Pneumonia: Types and Classifications

Pneumonia

• Pneumonia is defined as the inflammation of the lung parenchyma, which encompasses the bronchioles, alveolar ducts, alveolar sacs, and alveoli.
• This inflammation is associated with consolidation of the alveolar spaces.
• Globally, pneumonia is the leading cause of death for children under 5 years old
• Pneumonia is also the main cause of respiratory distress requiring hospital admissions.
• Pneumonia incidence is lower in older children and adults.

Anatomical Classifications of Pneumonia

• These classifications are based on the location and distribution of the inflammation in the lungs.

Lobar Pneumonia

• Consolidation is localized to one or more lobes of the lung.
• Almost always caused by a bacterial infection such as pneumococcal pneumonia.
• Lobar Pneumonia is generally unilateral.

Bronchopneumonia

• Inflammation occurs in the lung parenchyma.
• Presents as small patches of consolidation along the bronchial tree distribution.
• Bronchopneumonia is usually bilateral, often affecting the lower lobes.
• It can be caused by either bacterial or viral infections.

Interstitial Pneumonia

• The interstitium, the alveolar walls, alveolar sacs, alveolar ducts, and bronchioles become inflamed.
• Generally bilateral and mainly caused by viral infections.

Etiological Classifications of Pneumonia

• These define pneumonia based on the causative agent behind the inflammation.

Infectious Pneumonia

• Represents 90% of cases and can be caused by various pathogens.
  • Bacterial Infections: TB is a specific infection type classified under Bacterial Infections.
  • Non-specific bacterial infections mostly caused by different strains:
    • 80% caused by Streptococcus pneumoniae
    • 20% caused by Hemophilus influenzae, Streptococcus, Staphylococcus, Klebsiella, E. coli, Proteus, and Pseudomonas.
  • Viral pneumonia: More than 50% is caused by respiratory syncytial virus.
    • Others: adenoviruses, parainfluenza, influenza and herpes viruses.
  • Mycoplasma pneumoniae
  • Protozoal infections: An example is Toxoplasma gondii.
  • Mycotic infections: Candida albicans is an example.

Non-Infectious Pneumonia

- Allergic pneumonia: Loffler's syndrome and parasitic pneumonia such as Ascaris are examples.
    - Chemical pneumonia: Lipoid pneumonia is an example.
    - Aspiration pneumonia: Aspiration of mucus, amniotic fluid, blood, gastric fluid, foreign body, hydrocarbons and kerosene.
    - Hypostatic pneumonia
    - Pneumonia with collagen diseases

Bacterial Pneumonia

• Most serious type, especially in developing countries.
  • Neonatal pneumonia: Predominantly caused by group B Streptococci, Coliform bacteria, and occasionally Staphylococci or Hemophilus influenzae.
  • After the neonatal period and up to five years of age: Streptococcus pneumoniae and Hemophilus influenzae type b predominate.
    • Streptococcus pneumoniae is four times more frequent than H. influenzae.
  • After 5 years of age: Streptococcus pneumoniae predominates.
    • Group A beta-hemolytic streptococci, Staphylococci, and Klebsiella pneumoniae (in debilitated patients) are less frequent.
  • Mycobacterium tuberculosis is also a major cause of bacterial pneumonia.

Pneumococcal Pneumonia

• Streptococcus pneumoniae (pneumococcus) is the most common bacterial pathogen, accounting for over 90% of childhood bacterial pneumonia.
• It is most common in winter and early spring.
• Incidence is high between 3-8 years.

Clinical Picture of Lobar Pneumonia in Children

• Following a brief, mild upper respiratory infection, symptoms onset:
  • Shaking chills are followed by fever as high as 40.5°C.
• Respiratory distress manifestation, a dry hacking unproductive cough, anxiety and occasionally delirium.
• Children prefer to lie on the affected side to minimize pleuritic pain and improve ventilation.
• Right lower lobar pneumonia may be associated with abdominal pain in the lower right quadrant, simulating acute appendicitis.
• Neck stiffness: can accompany the involvement of the upper lobe.
• Early signs: Diminished breath sounds, scattered crepitations and rhonchi over the affected lung field.
• Later signs: Signs of consolidation, like dullness over the affected lobe, bronchial breathing and increased vocal resonance, become evident.
• During resolution: Crepitations become prominent while other signs gradually fade.
• In infants and very young children: -The pathology is usually lobular. -It results in a bronchopneumonic pattern with scattered patches of consolidation in the affected part.

Clinical Picture of Bronchopneumonia

• Following an initial upper respiratory disease:
  • There is a sudden rise in temperature with restlessness and respiratory distress.
  • Signs of consolidation are not apparent because lesions are patchy in distribution.
  • Dullness: May indicate a complication such as empyema.
• Chest examination:
  • Decreased breath sounds
  • Consonating crepitations on the affected side
  • Bronchial breathing may be head

Diagnosis

• Chest X-ray will confirm the diagnosis by demonstrating:
  • Homogenous opacity: Lobar pneumonia
  • Patchy diffuse lesions: Bronchopneumonia
• Consolidation may be demonstrated by x-ray before physical examination findings are detected.
• Resolution of the infiltrate may not be complete until several weeks after the child is clinically free.
• Laboratory findings:
  • The white blood cell count is usually elevated (15,000-40,000/mm³)
  • Preponderance of polymorphonuclear leukocytes
  • WBC count < 5000/mm³ linked to a poor prognosis (overwhelming disease).
  • Isolation of organisms from secretions collected via deep coughing or gentle tracheal aspiration.
  • Blood culture results in about 30% of patients with pneumococcal pneumonia present bacteremia.
  • Lung biopsy is only done in non-resolving pneumonia and in severe debilitating cases.

Differential Diagnosis of Pneumonia

• Acute Bronchiolitis: Hyperinflation is not present in bronchopneumonia.
• Bronchial Asthma: wheezing predominates with a history of recurrence, familial tendency, and rapid response to bronchodilators.
• Pleural Effusion
• Other Acute Lower Respiratory Infections: those without respiratory distress such as acute bronchitis.
• Heart Failure

Pulmonary Complications of Pneumonia

• Collapse: segmental or lobar.
• Lung Abscess, bronchiectasis, pleural effusion, pyopneumothorax.
• Emphysema, pneumothorax.
• Exacerbation of a tuberculous focus.
• Respiratory Failure: especially with severe bacterial bronchopneumonia in infants.
• Non-Resolution (Unresolved Pneumonia): pneumonia does not resolve in 2 weeks.

Causes of Non-Resolving Pneumonia

• Inadequate treatment: inappropriate antibiotic type, dose, or course.
• Specific organism such as TB.
• Underlying Lung Pathology: neoplasia, bronchiectasis, FB or congenital lung anomalies.
• Occurrence of Complications: emphysema.
• Lowered Resistance: AIDS, diabetes mellitus, hypogammaglobulinemia especially IgA.
• Increased Pulmonary Blood Flow: as in large left to right shunt.

Extrapulmonary Complications of Pneumonia

• Septicemia, otitis media, meningitis, arthritis, peritonitis, and osteomyelitis.
• Congestive Heart Failure, shock and arrhythmia.
• Paralytic Ileus: vomiting, abdominal distension, and decreased intestinal sounds.
• Meningismus: Especially with upper lobar pneumonia.

Treatment of Pneumonia

• Hospitalization is indicated in: -Pneumonia: with severe respiratory distress or complicated cases -Young age or infants -Failure to respond to antibiotics -Need for IV fluid therapy -Poor compliance
• Oxygen Therapy: for cases with restlessness, severe chest indrawing, grunting and cyanosis.
• Antibiotics:
  • For mildly ill children: amoxicillin 100 mg/kg/d or amoxicillin/clavulanate is recommended.
  • Parenteral cefuroxime (75-100 mg/kg/d): mainstay of therapy when bacterial pneumonia is suspected.
  • Third-generation cephalosporin: cefotaxime, 150 mg/kg/d or ceftriaxone, 75 mg/kg/d.
  • Azithromycin: appropriate choice.
  • Vancomycin: (40 mg/kg/d every 6 hr) if the isolate is resistant to both penicillin and cephalosporin.
• Symptomatic Measures:
  • Antipyretics for high-grade fever and pleuritic pain.
  • Good Nutrition: high caloric, soft diet with low sodium content and liberal oral fluids.
• Oral Zinc: reduces mortality among children with severe pneumonia
• Treat any complications

Staphylococcal Pneumonia

• Staphylococcal pneumonia is caused by coagulase-positive Staphylococcus aureus.
• A rapidly progressive bronchopneumonia.
• Associated with prolonged morbidity and high mortality (up to 30%).
• Occurs less frequently than pneumococcal or viral pneumonia but is more common in infants.
• Frequently preceded by a viral upper respiratory tract infection.

Clinical Picture: Symptoms of Staphylococcal Pneumonia

• Rapid progression: symptoms with a history of staphylococcal skin lesions and an upper or lower respiratory tract infection.
• High Fever, cough, evidence of respiratory distress, irritability, toxicity, severe dyspnea and a shock-like state.
• Vomiting, anorexia, diarrhea, and abdominal distension secondary to paralytic ileus may occur.
• Signs: diminished breath sounds, scattered crepitations and wheezes are commonly heard over the affected lung early in the course.
• Staphylococcus aureus causes confluent bronchopneumonia with marked tendency for breakdown and forms thin-walled abscesses.
  • These abscesses (pneumatoceles) are liable to rupture into the pleura, causing empyema or pyopneumothorax and bronchopleural fistula.

Diagnosis of Staphylococcal Pneumonia

• Polymorphonuclear leucocytosis.
• A count < 5,000 cells/mm3 indicates a poor prognosis.
• Blood culture may be positive in 30% of cases.
• X-Ray: Diagnostic, but progression occurs over a few days from patchy or homogenous opacities to effusion or pyopneumothorax with or without pneumatoceles, which is highly suggestive.

Treatment of Staphylococcal Pneumonia

• Hospitalization
• Oxygen, hydration, blood transfusion and assisted ventilation.
• IV antibiotics: cephalosporin (e.g. ceftriaxone, (75-100 mg/kg/d), ampicillin in combination with sulbactam or amoxicillin in combination with clavulanic acid.
• Vancomycin or clindamycin: drug of choice.
• Tube drainage is recommended to reduce the risk of bronchopleural fistula and the necessity for repeated pleural taps.
• Tubes should not remain in the chest more than 5-7 days.

Viral Pneumonia

• Commones cause in pre-school children, with a peak at 2-3 years.
• Caused by RSV, adenovirus, influenza and parainfluenza virus.
• Clinically:
  • Preceding upper respiratory tract infection.
  • Fever and respiratory distress but milder than bacterial pneumonia.
  • May be widespread wheezes and crepitations.

Diagnosis of Viral Pneumonia

• Chest X-ray: hyperinflation and scattered bilateral infiltrate (bronchopneumonia or interstitial pneumonia)
• CBC: normal or mildly elevated WBCs with predominant lymphocytes
• Detection of viral antigens by immuno-fluorescence.

Mycoplasma Pneumonia

• Common in school-age children (5-15 years)
• Clinically:
  • Severe non-productive cough without significant respiratory distress.
  • Headache, low-grade fever, earache, and sore throat.
  • Minimal physical signs.
  • May be wheezes and inspiratory crepitations.
• Diagnosis: Mainly clinical.

1. Chest X-ray:
   • Scattered bilarteral perihilar pulmonary infiltrate.
     • Rarely: lobar pneumonia ± effusion.
2. CBC is usually normal.
3. Cold agglutinins may be detected.
   • Atypical pneumonia syndrome is caused by Mycoplasma pneumoniae, Chlamydia pneumoniae, Chlamydia psittaci, Legionella and Coxiella.

Pneumothorax

• Pneumothorax is the accumulation of extrapulmonary air within the pleural sac.
• May be associated with a serous effusion (i.e. hydropneumothorax) or a purulent effusion (i.e, pyopneumothorax).
• Causes:
  • Trauma or iatrogenic causes.
  • Severe pneumonia usually w/ empyema(staphylococcal), severe pertussis, or severe bronchiolitis
  • Secondary to pulmonary abscess, rupture of a cyst or an emphysematous bleb, or foreign bodies in the lung.
• Clinical Manifestations:
  • Respiratory distress
  • Marked decrease in breath sounds over the involved lung.
  • Hyperresonance on percussion of the affected area.
  • Trachea and heart are shifted to the opposite side.
• Differentials:
  • Localized or generalized emphysema
  • Large pulmonary cavities or cysts
  • Diaphragmatic hernia
• Diagnosis:
  • Plain X-ray chest: hypertranslucence of affected side, absent bronchovascular markings.
    • the mediastinal structures are shifted away from the side of the air leak.
• Treatment:
  • Underwater seal drainage of trapped air: chest tube is inserted through the 2nd intercostal space.
    • Open thoracotomy with a limited incision. Plication of blebs, closure of fistula: for recurrent pneumothorax.

Pleurisy And Pleural Effusion

• Pleurisy may be:
  • Dry (plastic)
  • Serofibrinous
  • Purulent
• Dry and serofibrinous pleurisy are almost always secondary to underlying lung disease such as: -Pneumonia -Lung Abscess -TB -Collagen disease
• Dry or plastic pleurisy
  • Clinical manifestations: include signs and symptoms of the primary disease, in addition to pain.
    • The pain is exaggerated by deep breathing, coughing and straining.
• Early in the illness:
  • Leathery rough inspiratory and expiratory friction rub may be audible, but it usually disappears rapidly.
    • Treatment is primarily to treat the underlying disease.
  • Serofibrinous Pleurisy
  • As fluid accumulates, pleuritic pain may disappear and large fluid collection may produce tachypnea, dyspnea, orthopnea and cyanosis.
    • There is mediastinal shift to the opposite side, stony dull percussion note, diminished breath sounds and diminished tactile vocal fremitus.
• Roentgenographic examination shows homogeneous opacity, obliterating the costophrenic angle, with shift of the mediastinum to the other side.
• Thoracocentesis: should be done to identify the type and nature of fluid.
  • Also to perform culture and sensitivity.
• Treatment:
  • Therapy must be directed to the underlying disease. Repeated thoracocentesis or chest tube drainage under water seal is indicated when the fluid is rapidly accumulating

Purulent Pleurisy (Empyema)

• An accumulation of pus in the pleural spaces, the spaces are most often associated with pneumonia.
  • Caused by staphylococci, less frequently with streptococci, H. Influenzae.
    • Can be caused by gram -ve organisms.
• Clinical Manifestations: The initial signs and symptoms may be primarily related to bacterial pneumonia.
  • Inadequately treated patients or treated with inappropriate antibiotic agents few days before the evidence of empyema.
    • Physical and roentgenographic findings are similar to serofibrinous pleurisy.
    • Treatment includes thoracocentesis

Types And Causes of Pleural Effusion

• Transudate: Sp. gravity: <1.015, Protein: <3 gm/dl, Cells: Few mesothelial cells., Causes: Nephrotic syndrome Congestive heart failure
• Exudate: Sp. gravity>1.015, Protein >3 gm/dl, Cells: Leukocytes, Causes: Bacterial infections of the lung and plura, TB, polyserositis, neoplasm of the lung, plura or mediastinum

Suppurative Lung Disease

• They are localized areas of thick-walled purulent material formed secondarily to lung infection.
• This:
  • Destruction of lung parenchyma, cavitation, and central necrosis
• It includes lung abscess, empyema, and bronchiectasis.
• Etiology:
  • In children, aspiration of infected materials, such as a foreign body, is the predominant source of the organisms causing a lung abscess.
• Abscesses can also occur as a result of pneumonia and hematogenous seeding from other sites.
• Both anaerobic and aerobic organisms can cause lung abscess. Fungi also cause lung abscess in immune compromised patients
• Clinical manifestation: -The clinical features are those of persisting and worsening pneumonia.
• Production of large quantities of sputum (often foul-smelling)
  • Swinging fever, malaise and weight loss. Chest signs are that of pneumonia with dullness detected over the affected side
• Diagnosis:
  • X-ray chest shows a parenchymal inflammation with a cavity containing an air-fluid level.
  • A chest C.T scan provides a better anatomic location and site of abscess.
    • Bacteriological investigations can reveal specimens that are obtained by: transbronchial aspiration, or percutaneous transthoracic aspiration with ultrasound or C.T guide.
• Treatment: Prolonged course of antibiotics (4-6 weeks according to: culture and sensitivity, and covering both aerobic and anaerobic organisms. Surgery may be needed for drainage.

Bronchiectasis

• This:
  • Irreversible
  • Abnormal dilatation of the bronchial tree
• Causes may be congenital or acquired:
  • Congenital: absence of annular bronchial cartilage
    • Acquired: can follow infection such as pertussis, measles, and tuberculosis.
  • Ciliary dyskinesia or immotile cilia syndrome
  • Resulting from epithelial surfaces leading to obstruction by viscid secretions and infection of airways can be caused by cystic fibrosis. The disease is an inherited multisystem disorder Immune deficiency syndromes Foreign body inhalation Pathogenesis: Retained secretions and recurrent infection Bronchial obstruction can be caused by a tumor, impacted mucus a foreign body. Can be caused by external damage and dilatation. Infection can be caused by various:
  • It can cause chronic inflammation and progressive bronchial wall damage and dilatation

Clinical Picture

• Anorexia, weight loss, purulent sputum with cough, coughing up blood, fever upon infection, finger nail clubbing.
• Diagnosis:
  • Chest -ray shows loss of definition of bronchovasular markings and will decrease lung volume.
  • Honeycomb appearance to lung may be seen on x-ray. A CT scan can confirm diagnosis and will show severity distribution. and grade. Treatment:
• Physiotherapy: postural
• Antibiotics: bronchodilators decrease airway obstruction and control infection. Treatment to underlying cause of disease, is possible.
• Surgical removal reserved only for localized cases refractory to all medical treatment.

Acute Bronchiolitis

• It is an inflammatory obstruction of the small airways which occurs during the first 2 yr of life with a peak incidence at 6 months of age. Occurs in winter and spring.
• Etiology:Caused by respiratory syncytial virus (RSV), human metapneumovirus, Rhinovirus, influenza and Parainfluenza viruses

Pathophysiology

• Acute bronchiolitis is characterized by bronchiolar obstruction due to edema, mucus and cellular debris.
• Resistance in the small air passages is increased during both inspiration and expiration.
• This is because the radius of an airway is smaller during expiration and resultant respiratory obstruction leads to expiratory wheezing, air trapping, and lung hyperinflation. If obstruction becomes complete: trapped distal air will be resorbed, child will develop atelectasis
• Symptoms: runny nose, sneezing, and coughing. Followed by rapid breathing, wheezes, chest indrawing, working alae nasi
• Physical Exam: -History of exposure within one week earlier to minor diseases others. -Few days of rhinitus, sneezing and coughing . Signs of marked and rapid:
• Respiratory distress, chest indrawing, and working alae nasi
• Hyperressonance on percussion. Prolonged diminished breathe sounds. expiratory wheezes are all signs
• There are few crepitations at the end of inspiration occurring in early expiration. The virus from nasal secretions demonstrates the ability.

Diagnosis

• Manifestations of respiratory distress are much more prominent than auscultatory findings
• The WBCs/differential counts are within normal limits.
• X-ray chest displays hyperinflation with patchy atelectasis and there helpful if you in bronchiolitits

Differential Diagnosis

• Bronchial asthma
• A family history of asthma where the infant exhibits repeating episode. Of wheezing and rapid response to asthma medicine provides support of asthma.
• High grade fever from pneumonia, in addition to infiltrates from what is visualized on x ray.
• Tachycardia signs in congestion. History of rapid inspiration from asthma with choking and wheezes. -Non specific respiratory from pertussis with lack if immunization will present in patients

Prognosis

• The critical duration of illness, 2-3 days and recovery is a quick process Prognosis : 1% chance of mortality.

Complications

• Bacterial and or media
• Severe breathing and decline in health.
• Pneumothorax. -Increased presence of respiratory complications or failure.
• Symptoms from heart failure. -Is mainly supportive . Infants Support: The patients with breathing trouble and respiratory difficulty are placed under medical observations. Breathing and congestion can be improved by using:
  • High frequency congestion relief to improve breath ability and increase and regulate feed.
• Normal hydration provides relief.
• Steroids not suggested for use.

Treatment

• Cold environment.
• Oxygen to improve hypoxemia.
• Elevate Head.