Bacterial pneumonias frequently cause inflammatory fluid to collect in the adjacent pleural space, causing a parapneumonic effusion or, if grossly purulent, an empyema. Small effusions may not require any special therapy. Large effusions may restrict breathing and require drainage. Air dissection within lung tissue results in a pneumatocele. Scarring of the airways and lung tissue may leave dilated bronchi, resulting in bronchiectasis and increased risk for recurrent infection.
Pneumonia that causes necrosis of lung tissue may evolve into a lung abscess. Lung abscess is an uncommon problem in children and usually is caused by aspiration, infection behind an obstructed bronchus, or certain virulent organisms. Anaerobic bacteria usually predominate, along with various streptococci, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Staphylococcus aureus. Chest radiograph or CT scan reveals a cavitary lesion, often with an air-fluid level, surrounded by parenchymal inflammation. If the cavity communicates with the bronchi, organisms may be isolated from sputum. Diagnostic bronchoscopy may be indicated to exclude a foreign body and obtain microbiologic specimens. Lung abscesses usually respond to appropriate antimicrobial therapy with clindamycin, penicillin G, or ampicillin-sulbactam.
Most children recover from pneumonia rapidly and completely, although radiographic abnormalities may take 6 to 8 weeks to return to normal. In a few children, pneumonia may persist longer than 1 month or may be recurrent. In such cases, the possibility of underlying disease must be investigated further, such as with tuberculin skin test, sweat chloride determination for cystic fibrosis, serum immunoglobulin and IgG subclass determinations, bronchoscopy to identify anatomic abnormalities or foreign body, and barium swallow for gastroesophageal reflux.
Severe adenovirus pneumonia may result in bronchiolitis obliterans, a subacute inflammatory process in which the small airways are replaced by scar tissue, resulting in a reduction in lung volume and lung compliance. Unilateral hyper-lucent lung, or Swyer-James syndrome, is a focal sequela of severe necrotizing pneumonia in which all or part of a lung has increased translucency radiographically; it has been linked to adenovirus type 21.
Annual influenza vaccine is recommended for all children over 6 months of age (see Chapter 94). Trivalent, inactivated influenza vaccine is licensed for use beginning at 6 months of age; live, attenuated vaccine can be used for persons 2 to 49 years of age. Universal childhood vaccination with conjugate vaccines for H. influenzae type b and S. pneumoniae has greatly diminished the incidence of these pneumonias. The severity of RSV infections can be reduced by use of palivizumab in high-risk patients (see Chapter 109).
Reducing the duration of mechanical ventilation and administering antibiotics judiciously reduces the incidence of ventilator-associated pneumonias. The head of the bed should be raised to 30 to 45 degrees for intubated patients to minimize risk of aspiration, and all suctioning equipment and saline should be sterile. Hand washing before and after every patient contact and use of gloves for invasive procedures are important measures to prevent nosocomial transmission of infections. Hospital staff with respiratory illnesses or who are carriers of certain organisms, such as methicillin-resistant
S. aureus, should comply with infection control policies to prevent transfer of organisms to patients. Treating sources of aerosols, such as air coolers, can prevent Legionella pneumonia.