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• Lower respiratory tract infections

  Pneumonia & Bronchiolitis
• Lower respiratory tract infections (Pneumonia & Bronchiolitis) Dr. Dereje wakgari 2023
• Course outline

  • Definition
  • Epidemiology
  • Etiology
  • Pathogenesis
  • C/manifestations & Diagnosis
  • Management and complications
  • Prognosis & Prevention
• Pneumonia


  Acute inflammation of the parenchyma of the lungs
• Pneumonia is a substantial cause of morbidity and mortality in childhood throughout the world.
• Pneumonia is estimated to cause ≈ 3 million deaths, or an estimated 29% of all deaths, among children younger than 5 yr worldwide. The incidence of pneumonia is more than 10-fold higher, and the number of childhood-related deaths due to pneumonia ≈2000-fold higher, in developing than in developed countries
• Causes of pneumonia


  • Infectious - bacterial, viral, fungal, mycobacterial, parasitic
  • Non-infectious - aspiration of food or gastric acid, foreign bodies, hydrocarbons, and lipoid substances, hypersensitivity reactions, and drug- or radiation-induced pneumonitis
• Etiologic agents of pneumonia grouped by age of the patient

  • Neonates (<3 wk): Group B streptococcus, Escherichia coli, other gram-negative bacilli, Streptococcus pneumoniae, Haemophilus influenzae (type b, nontypable)
  • 3 wk-3 mo: Respiratory syncytial virus, other respiratory viruses (parainfluenza viruses, influenza viruses, adenovirus), S. pneumoniae, H. influenzae (type b, nontypable); if patient is afebrile, consider Chlamydia trachomatis
  • 4 mo-4 yr: Respiratory syncytial virus, other respiratory viruses (parainfluenza viruses, influenza viruses, adenovirus), S. pneumoniae, H. influenzae (type b, nontypable), Mycoplasma pneumoniae, group A streptococcus
  • ≥5 yr: M. pneumoniae, S. pneumoniae, Chlamydophila pneumoniae, H. influenzae (type b, nontypable), influenza viruses, adenovirus, other respiratory viruses, Legionella pneumophila
• Pathogenesis of viral pneumonia

  Spread of infection along the airways, accompanied by direct injury of the respiratory epithelium, which results in airway obstruction from swelling, abnormal secretions, and cellular debris
• Pathogenesis of bacterial pneumonia

  Respiratory tract organisms colonize the trachea and subsequently gain access to the lungs
• Recurrent pneumonia


  2 or more episodes in a single year or 3 or more episodes ever, with radiographic clearing between occurrences
• Clinical manifestations of pneumonia

  • Viral and bacterial pneumonias are often preceded by several days of symptoms of an upper respiratory tract infection, typically rhinitis and cough
  • Tachypnea, grunting, intercostal, subcostal, and suprasternal retractions, nasal flaring, and use of accessory muscles, cyanosis and respiratory fatigue
  • Auscultation of the chest may reveal crackles and wheezing
• Diagnosis of pneumonia


  Mainly clinical, with an infiltrate on chest radiograph supporting the diagnosis
• Radiographic findings in pneumonia

  • Viral pneumonia - hyperinflation with bilateral interstitial infiltrates and peribronchial cuffing
  • Confluent lobar consolidation is typically seen with pneumococcal pneumonia
• Laboratory findings in pneumonia

  • In viral pneumonia, the WBC count can be normal or elevated but is usually not higher than 20,000/mm3, with a lymphocyte predominance
  • Bacterial pneumonia is often associated with an elevated WBC count, in the range of 15,000-40,000/mm3, and a predominance of granulocytes
• Definitive diagnosis of viral infection

  Isolation of a virus or detection of the viral genome or antigen in respiratory tract secretions
• Definitive diagnosis of bacterial infection

  Isolation of an organism from the blood, pleural fluid, or lung
• Blood culture results are positive in only 10% of children with pneumococcal pneumonia
• Indications for inpatient admission for pneumonia

  • Age <6 mo
  • Sickle cell anemia with acute chest syndrome
  • Multiple lobe involvement
  • Immunocompromised state
  • Toxic appearance
  • Moderate to severe respiratory distress
  • Requirement for supplemental oxygen
  • Dehydration
  • Vomiting or inability to tolerate oral fluids or medications
  • No response to appropriate oral antibiotic therapy
  • Social factors (e.g., inability of caregivers to administer medications at home or follow up appropriately)
• Antibiotic treatment for pneumonia

  • For mildly ill children who do not require hospitalization - amoxicillin, alternatives include cefuroxime axetil and amoxicillin/clavulanate
  • For suspected bacterial pneumonia in a hospitalized child - Parenteral cefotaxime or ceftriaxone
  • If viral pneumonia is suspected, it is reasonable to withhold antibiotic therapy
• Prognosis of uncomplicated community-acquired bacterial pneumonia

  • Patients show response to therapy, with improvement in clinical symptoms (fever, cough, tachypnea, chest pain) within 48-96 hr of initiation of antibiotics
  • Mortality from community-acquired pneumonia in developed nations is rare, and most children with pneumonia do not experience long-term pulmonary sequelae
• Causes of no improvement in pneumonia


  • Complications, such as empyema
  • Bacterial resistance
  • Nonbacterial etiologies such as viruses and aspiration of foreign bodies or food
  • Bronchial obstruction from endobronchial lesions, foreign body, or mucous plugs
  • Pre-existing diseases such as immunodeficiencies, ciliary dyskinesia, cystic fibrosis, pulmonary sequestration, or cystic adenomatoid malformation
  • Other noninfectious causes (including bronchiolitis obliterans, hypersensitivity pneumonitis, eosinophilic pneumonia, aspiration, and Wegener's granulomatosis)
• Complications of pneumonia


  • Intra-thoracic - pleural effusion, empyema, mediastinitis, pericarditis
  • Extra-thoracic - Meningitis, suppurative arthritis, and osteomyelitis
  • S. aureus, S. pneumoniae, and S. pyogenes are the most common causes of parapneumonic effusions and of empyema
• Prevention of pneumonia


  • Vaccination - pneumococcal, influenza
  • Adequate Sunlight exposure
  • Avoid overcrowding, smoking
  • Proper nutrition
  • Avoid aspiration
• Bronchiolitis


  Inflammation of the bronchioles, mainly due to viral cause
• Approximately 50,000–80,000 of hospitalizations annually among children <1 yr old due to bronchiolitis. Peak age: 3-6 months, more common in males, in those who have not been breast-fed, and in those who live in crowded conditions
• Causes of bronchiolitis


  • Respiratory syncytial virus (RSV) is responsible for >50% of cases
  • parainfluenza, adenovirus, Mycoplasma, and occasionally, other viruses
  • Human metapneumovirus is an important primary cause of viral respiratory infection or it can occur as a co-infection with RSV
  • There is no evidence of a bacterial cause for bronchiolitis, although bacterial pneumonia is sometimes confused clinically with bronchiolitis and bronchiolitis is rarely followed by bacterial superinfection
• Pathogenesis of bronchiolitis


  1. Bronchiolar obstruction with edema, mucus, and cellular debris

  2. Even minor bronchiolar wall thickening significantly affects airflow

  3. If obstruction becomes complete, there will be resorption of trapped distal air, and the child will develop atelectasis

  4. Resistance in the small air passages is increased during both inspiration and exhalation, but because the radius of an airway is smaller during expiration, the resultant respiratory obstruction leads to early air trapping and overinflation

  5. Hypoxemia is a consequence of ventilation-perfusion mismatch early in the course
• Clinical manifestations of bronchiolitis

  • Initially mild upper respiratory tract infection with sneezing and clear rhinorrhea, may be accompanied by diminished appetite and fever of 38.5–39°C, although the temperature may range from subnormal to markedly elevated
  • Gradually, respiratory distress ensues, with paroxysmal wheezy, cough, dyspnea, and irritability
  • Apnea may be more prominent than wheezing early in the course of the disease, particularly with very young infants (<2 mo old) or former premature infants
  • The physical examination is characterized most prominently by wheezing, the degree of tachypnea does not always correlate with the degree hypoxemia or hypercarbia
  • Auscultation may reveal fine crackles or overt wheezes, with prolongation of the expiratory phase of breathing, barely audible breath sounds suggest very severe disease with nearly complete bronchiolar obstruction
  • Hyperinflation of the lungs may permit palpation of the liver and spleen
• Diagnosis of bronchiolitis


  • Chest radiography reveals hyperinflated lungs with patchy atelectasis
  • The white blood cell and differential counts are usually normal
  • Viral testing (usually rapid immunofluorescence, polymerase chain reaction, or viral culture) is helpful if the diagnosis is uncertain or for epidemiologic purposes
  • The diagnosis is clinical, particularly in a previously healthy infant presenting with a first-time wheezing episode during a community outbreak
  • Confirmation of viral bronchiolitis may obviate the need for a sepsis evaluation in a febrile infant and assist with respiratory precautions and isolation if the patient requires hospitalization
• Management of bronchiolitis


  1. The mainstay of treatment is supportive, with cool humidified oxygen if hypoxemic

  2. The infant is sometimes more comfortable if sitting with head and chest elevated at a 30-degree angle with neck extended

  3. Use of bronhodilators, nebulized epinephtine or corticosteroids is controversial

  4. Ribavirin, an antiviral agent administered by aerosol, has been used for infants with congenital heart disease or chronic lung disease

  5. Antibiotics have no value unless there is secondary bacterial pneumonia
• Prognosis of bronchiolitis


  • Highest risk for further respiratory compromise in the 1st 48–72 hr after onset of cough and dyspnea
  • Case fatality rate is <1%, with death attributable to apnea, uncompensated respiratory acidosis, or severe dehydration
  • The median duration of symptoms in ambulatory patients is ≈12 days
  • Infants with conditions such as congenital heart disease, bronchopulmonary dysplasia, and immunodeficiency often have more severe disease, with higher morbidity and mortality
• Prevention of bronchiolitis


  • Reduction in the severity and incidence of acute bronchiolitis due to RSV is possible through the administration of pooled hyperimmune RSV intravenous immunoglobulin (RSV-IVIG, RespiGam) and palivizumab (Synagis), an intramuscular monoclonal antibody to the RSV F protein, before and during RSV season
  • Palivizumab is recommended for infants <2 yr of age with chronic lung disease (bronchopulmonary dysplasia) or prematurity
• THANK YOU!