Community-acquired pneumonia (CAP) is a lung infection contracted outside of the hospital. Lower respiratory tract infection includes pneumonia, bronchitis, bronchiolitis, or any combination of the three. In the United States, pneumonia is the most common cause of hospitalization in children.¹

Etiology

• In a U.S. population of 2,638 patients younger than 18 years hospitalized with CAP, a viral pathogen was more likely than a bacterial pathogen (66% compared with 8%, respectively; 7% of patients had both viral and bacterial pathogens; no pathogen was identified in 19%).²

• Respiratory syncytial virus is the most common pathogen overall, particularly in children younger than two years.²

• Other common respiratory viruses include influenza virus, coronavirus (including SARS-CoV-2, which causes COVID-19), human rhinovirus, human metapneumovirus, and adenovirus.²

• Due to routine childhood vaccinations, the prevalence of Streptococcus pneumoniae and Haemophilus influenzae has decreased significantly. In the United States, the introduction of the pneumococcal conjugate vaccine resulted in a reduction in hospitalizations for pneumococcal pneumonia from 53.6 to 23.3 per 100,000 admissions from 2006 to 2014.³

• Table 1 shows the specific etiology in hospitalized children with pneumonia based on the Centers for Disease Control and Prevention's Etiology of Pneumonia in the Community study, a multicenter, population-based, prospective study conducted from 2010 to 2012.²

Diagnosis

SIGNS AND SYMPTOMS

• Typical presenting signs and symptoms include tachypnea, cough, fever, anorexia, dyspnea, retractions, and lethargy.^2,4,5

• In a series of 570 children one to 17 years of age with clinically suspected pneumonia, findings most strongly associated with an infiltrate on chest radiography were grunting (odds ratio [OR] = 7.3), history of fever (OR = 3.1), retractions (OR = 2.8), and crackles (OR = 2.0).⁶ Other findings associated with infiltrate included measured fever, tachypnea, tachycardia, and decreased breath sounds. Although grunting and retractions are uncommon, when present they have a high positive predictive value for pneumonia.⁶

• Based on a systematic review of three studies, the overall clinical impression is moderately accurate for diagnosing CAP in children (positive likelihood ratio = 2.7; negative likelihood ratio = 0.63).⁷

• Wheezing, retractions, and respiratory rate are the examination findings with the highest interrater reliability in children with CAP.⁸

CLINICAL PREDICTION RULES

• Clinical prediction rules have been studied but have not been prospectively validated, particularly in primary care settings.^6,9,10

• The Bilkis Simpler Prediction Model has high sensitivity (93.8%) for the diagnosis of pneumonia in children presenting with any combination of fever, localized rales, decreased breath sounds, and tachypnea.⁹ A similar model also had excellent sensitivity (93% to 98%) but poor specificity (6% to 19%), making it unhelpful in clinical practice.⁶

• The Pediatric Acute Febrile Respiratory Illness rule assigns points for duration of fever, chills, absence of nasal symptoms, tachypnea, and abnormal chest examination. Once prospectively validated in a new population, it may help clinicians to decide which children should have chest radiography.¹⁰

DIAGNOSTIC TESTING

• Chest radiography is not necessary to confirm suspected pneumonia in children in the outpatient setting. It should be obtained for patients with hypoxemia (oxygen saturation less than 90%) or significant respiratory distress or for those without clinical improvement within 48 to 72 hours after initiation of antibiotic therapy.¹¹ Figure 1 shows a chest radiograph demonstrating a left upper-lobe opacity consistent with pneumonia.

• Chest ultrasonography is more often used to evaluate local complications such as parapneumonic effusion or empyema, but it may also detect lung consolidation and save time and cost.^12,13 Novice and expert physician-sonologists have achieved a reduction of chest radiography use in emergency department settings without missed cases of pneumonia or an increase in adverse events.¹⁴

• Procalcitonin may be used in conjunction with other clinical findings to guide the management of pneumonia in children. Values less than 0.25 ng per mL can accurately identify children at lower risk of bacterial CAP for whom antibiotics are unlikely to be helpful.^15,16

• Complete blood count and levels of acute-phase reactants such as erythrocyte sedimentation rate and C-reactive protein are not typically obtained in the outpatient setting. However, they may be beneficial for management decisions in more severely ill children in the hospital setting, according to Infectious Diseases Society of America (IDSA) guidelines.¹¹ Measurement of C-reactive protein in general practice settings for children with nonsevere acute infections has not been shown to reduce antibiotic prescribing and is not recommended.¹⁷

• Blood cultures should not be performed routinely in nontoxic, fully immunized children in the outpatient setting.¹¹ Blood cultures should be obtained in hospitalized patients, but even in this setting, a pathogen is identified in only 2% to 7% of children with CAP.^11,18

• Sputum cultures are difficult to obtain in children and have low diagnostic yield.¹¹

• Physicians should have appropriate suspicion and consider testing for COVID-19, influenza, respiratory syncytial virus, or Mycoplasma pneumoniae as indicated.^11,19,20