Max is a 4-year-old boy who presents with a 2-day history of cough, fever, and chills. He tells you that his tummy hurts. On examination, he appears moderately ill and his breathing is rapid (about 55 breaths per minute); his oxygen saturation on room air is 94 percent. You hear decreased breath sounds and crackles on the left side of his chest and possibly on the right. You obtain a chest x-ray which is concerning for bacterial pneumonia. (Figures 50-1 and 50-2). You admit him to the hospital with a diagnosis of probable bacterial pneumonia and prescribe intravenous antibiotics. He improves considerably over 48 hours and is discharged home on oral antibiotics.

Pneumonia refers to an infection in the lower respiratory tract (distal airways, alveoli, and interstitium of the lung). Community-acquired pneumonia (CAP) has traditionally referred to pneumonia occurring outside of the hospital setting. A subgroup of CAP that is associated with health care risk factors (e.g., prior hospitalization, dialysis, immunocompromised state) has been classified as health care-associated pneumonia.

CAP can be caused by a wide variety of viral, bacterial, and “atypical” pathogens. The age and immune status of the host are important in considering the potential causes and management of pneumonia in the pediatric population.

• 
  

  The incidence rate of CAP among children in the first 5 years of life is 10 to 40 cases/1000,¹ with an incidence rate of 6 to 12 cases/1000 in children older than 9 years in North America.²

  
  
• 
  

  In the National Hospital Discharge Survey (2006) of 1,232 first-listed pneumonia discharges from short-stay hospitals, 172 (14%) were children aged <15 years.³

  
  
• 
  

  The distribution of the pneumococcal vaccine in 2000 has resulted in an approximately 35 percent decrease in all-cause pneumonia hospitalizations in US children since 1997–1999, with incident rates in 2005 and 2006 for children aged <2 years of 9.1/1,000 and 8.1/1,000, respectively.⁴ For pneumococcal pneumonia, rates of hospitalizations between 1997–1999 and 2004 in an employer-based population study of children <AGE p="" decline).

  
  
• 
  

  CAP is the most frequent cause of death due to infectious disease in the US and the eighth leading cause of death overall (2007).^5,6

  
  
• 
  

  Deaths in 2009 from influenza and pneumonia occurred in 5.9/50,000 children <AGE 0.9="" and="" children="" to="" 0.6="" years="" years.⁷

• 
  

  Streptococcus (S) pneumoniae is the most important pathogen at all ages.⁸ Age, however, is an important consideration: in the first 20 days of life, most cases of pneumonia are secondary to Group B Streptococci or gram negative enteric bacteria while among young children with CAP, respiratory syncytial virus (RSV), influenza, and rhinovirus are common.⁹ Mycoplasma pneumoniae and Chlamydophila pneumoniae are common in school-aged children and adolescents.⁸⁹ Mycoplasma pneumoniae is the single most common cause of CAP is school-aged children. Newly identified microbes in childhood pneumonia include human metapneumovirus, human bocavirus, and Simkania negevensis (an intracellular bacterium).⁸

  
  
• 
  

  For children who are immunocompromised, other pathogens such as Pneumocystis jiroveci and Mycobacterium tuberculosis should be considered.⁹

  
  
• 
  

  In a study of children hospitalized with CAP (N = 254), the cause of the disease (identified in 85% of cases) was most often viral (62%, with 30% having evidence of both viral and bacterial pathogens).¹⁰ The most common identified pathogens were S. pneumoniae (37%), RSV (29%), and rhinovirus (24%). Dual bacterial infections were found in 19 patients; only one patient of 125 tested had a positive blood culture.

  
  
• 
  

  In a retrospective study of children with unresponsive or recurrent CAP undergoing flexible bronchoscopy with bronchoalveolar lavage, an infectious agent was detected in the majority (76%) of cases with aerobic bacteria identified in about half including nontypeable Haemophilus influenzae (75%), Moraxella catarrhalis (28.9%), and S. pneumoniae (13.3%).¹¹

  
  
• 
  

  The most common route of infection is microaspiration of oropharyngeal secretions colonized by pathogens.¹² In this setting, S. pneumoniae and Haemophilus influenza are the most common pathogens.

  
  
• 
  

  Pneumonia can also occur secondary to gross aspiration (postoperatively or in those with central nervous system disorders) where anaerobes and gram-negative bacilli are common pathogens.¹²

  
  
• 
  

  Hematogenous spread, most often from the urinary tract, can result in Escherichia coli pneumonia and hematogenous spread from intravenous catheters or in the setting of endocarditis may cause Staphylococcus aureus pneumonia.¹²

  
  
• 
  

  Mycobacterium tuberculosis (TB), fungi, legionella, and many respiratory viruses are spread by aerosolization.

  
  
• 
  

  Etiology is unknown in up to 70 percent of cases of CAP.

Among children <5 years of age, risk factors include:

• 
  

  History of recurrent respiratory infections during the past year (odds ratio [OR] 5.5) or previous chest infections (2.31; 95% confidence intervals [CI], 1.55–3.43).

  
  
• 
  

  History of wheezing episodes (OR 5.3).

  
  
• 
  

  History of otitis media and tympanocentesis before the age of 2 years (OR 3.6).

  
  
• 
  

  Lower weight for height (OR 1.28; 95% CI, 1.10–1.51).

  
  
• 
  

  Spending less time outside (1.96; 95% CI, 1.11–3.47).

  
  
• 
  

  Mold in the child’s bedroom (1.93, 95% CI, 1.24–3.02).

Among older children, risk factors include:

• 
  

  History of recurrent respiratory infections during the previous year (OR 3.0).

  
  
• 
  

  History of wheezing periods at any age (OR 2.1).

Clinical Features

• 
  

  Constellation of symptoms includes fever (88% to 96%), cough (76% to 88%), dyspnea (37% to 40%), chills, pleuritic chest pain, and sputum production.⁸ Children may also complain of fatigue, myalgia, and headache.⁹

  
  
• 
  

  Patients with viral or atypical pathogens (e.g., mycoplasma or chlamydia) often present with low-grade fever, nonproductive cough, and constitutional symptoms developing over several days.⁹

  
  
• 
  

  About half of children report nonspecific signs like vomiting and abdominal pain.⁸

  
  
• 
  

  Wheezing is most frequently associated with viral or atypical pathogens and bacterial infection is less likely when true wheezing is present.⁹

  
  
• 
  

  Signs of pneumonia include increased respiratory rate, dullness to percussion, bronchial breathing, egophony, crackles, wheezes, and pleural-friction rub. Nonspecific crackles were reported in two recent Italian studies in 1/3 to half of children with CAP.^15,16 Lung findings in atypical pneumonia may be more diffuse. Pleural effusion is common and appears to increase the risk of a bacterial etiology.⁹

  
  
• 
  

  In one emergency department case series of children >12 months of age with suspected pneumonia, respiratory rates >50 breaths per minute and oxygen saturation below 96 percent had a high specificity (97%) for predicting radiographic evidence of pneumonia.¹⁷ In another study, tachypnea was present in 50 percent to 80 percent of pediatric radiologically-confirmed CAP cases.¹⁸

  
  
• 
  

  Signs of respiratory distress in children include tachypnea (defined as age 0 to 2 months: >60 breaths per minute, age 2 to 12 months: >50 breaths per minute, age 1–5 years: >40 breaths per minute, and age >5 years: >20 breaths per minute), apnea, altered mental status, dyspnea, grunting, nasal flaring, pulse oximetry <90 percent on room air or retractions.¹⁹

Laboratory Studies¹²

• 
  

  Routine complete blood count (CBC) and acute phase reactants (e.g., erythrocyte sedimentation rate, C-reactive protein, procalcitonin) are not necessary for children with suspected CAP managed as outpatients but should be considered for children with more serious disease, if deemed useful.¹⁹ SOR C

  
  
• 
  

  In one RCT of hospitalized children with CAP, use of procalcitonin (admission level <0.25 ng/mL) reduced antibiotic prescriptions (85.8% versus 100%).²⁰

  
  
• 
  

  Acute phase reactants should not be used as the sole determinant for distinguishing between viral and bacterial CAP.¹⁹ SOR A

  
  
• 
  

  CBC should be obtained in children hospitalized for severe pneumonia (interpreted in the context of other tests).¹⁹ SOR C

  
  
• 
  

  Sputum culture and gram stain should be obtained in hospitalized children who can produce sputum.¹⁹ SOR C Tracheal aspirates for gram stain, culture, and viral pathogens (as appropriate) should be obtained at the time of initial endotracheal tube placement in children requiring mechanical ventilation.¹⁹ SOR C

  
  
• 
  

  Blood cultures are not recommended routinely for nontoxic, fully immunized children with CAP managed in the outpatient setting.¹⁹ SOR B In developing the microbial testing strategy for the Pneumonia Etiology Research for Child Health (PERCH) study, investigators found that only 1 percent to 5 percent of children with CAP have documented bloodstream infections; prevalence is higher among children with severe infection. ²¹

  
  
• 
  

  Blood cultures should be obtained in children who fail to demonstrate clinical improvement and in those who have progressive symptoms or clinical deterioration after initiation of antibiotics.¹⁹ SOR B

  
  
• 
  

  Blood cultures are recommended for children requiring hospitalization for presumed bacterial CAP that is moderate to severe, particularly those with complicated pneumonia.¹⁹ SOR C

  
  
• 
  

  Sensitive and specific tests for the rapid diagnosis of influenza virus and other respiratory viruses should be used in the evaluation of children with CAP.¹⁹ A positive influenza test may decrease both the need for additional diagnostic studies and antibiotic use, while guiding appropriate use of antiviral agents in both outpatient and inpatient settings.¹⁹ SOR A Serology (fourfold rise in IgM titer) may also be useful in diagnosing Mycoplasma pneumoniae, Chlamydophilaia pneumoniae, legionnaires, and other viral pneumonia.¹⁹ SOR C

  
  
• 
  

  Urinary antigen detection tests are not recommended for the diagnosis of pneumococcal pneumonia in children, as false-positive tests are common.¹⁹ SOR A

  
  
• 
  

  Pulse oximetry should be performed in patients with pneumonia and suspected hypoxemia. The presence of hypoxemia should guide decisions regarding site of care and further diagnostic testing.¹⁹ SOR B

Imaging

• 
  

  Routine chest x-ray (CXR) is not necessary for the confirmation of suspected CAP in children treated in the outpatient setting.¹⁹ SOR A

  
  
• 
  

  CXR, posteroanterior and lateral, should be obtained in patients with suspected or documented hypoxemia, significant respiratory distress, those who failed initial antibiotic therapy, and hospitalized patients.¹⁹ SOR B

  
  
• 
  

  In one RCT in Pakistan of treatment of CAP in young children (2 to 59 months), CXRs were normal in most children (82%) with a clinical diagnosis of pneumonia.²²

  
  
• 
  

  There are four general patterns of pneumonia seen on CXR;¹² however, they do not differentiate causative agents in CAP¹⁹:

  
  
  
  
  • 
    

    Lobar—Consolidation involves the entire lobe (Figures 50-1 to 50-5). Early, especially with pneumococcal pneumonia in children, infiltrates can appear as round and can be mistaken for a pulmonary or mediastinal mass (Figures 50-6 and 50-7).²³ In young children, the thymic shadow can be mistaken as a pneumonic infiltrate (Figure 50-8).

    
    
  • 
    

    Bronchopneumonia—Patchy involvement of one or several lobes that may be extensive, usually in the dependent lower and posterior lungs. Although bilateral patchy infiltrate with hilar lymphadenopathy are commonly associated with atypical pneumonia, lobar consolidation is not uncommon (Figures 50-9 to 50-11).

    
    
  • 
    

    Interstitial pneumonia—Inflammatory process involves the interstitium and is usually patchy and diffuse (Figure 50-12). Viral pneumonia in children often appears radiographically as parihilar peribronchial infiltration in a diffuse reticular pattern; the heart’s borders may appear shaggy due to adjacent peribronchial inflammation.²³ Pneumocystis pneumonia can be represented by any type of radiographic pattern, but a diffuse interstitial pattern has classically been described (Figure 50-13).

    
    
  • 
    

    Miliary pneumonia—Numerous discrete lesions from hematogenous spread (see Chapter 186, Tuberculosis).

  
  
  
  
• 
  

  Parapneumonic effusions and empyema, as well as necrotizing pneumonia, can often be appreciated on CXR (Figure 50-14).

  
  
• 
  

  Ultrasound may be useful for evaluation of pleural effusion.²⁴

  
  
• 
  

  Computed tomography (CT) may be useful in the evaluation of complications of pneumonia, such as parapneumonic effusions, empyema, and necrotizing pneumonia (Figures 50-15 and 50-16).