Overview
Epidemiology
- Incidence in resource-rich countries: 1.5–3.3 per 1000 children
- Incidence in resource-limited countries: 231 per 1000 children
- Increased prevalence during colder months
- Present in all ages; more common at < 5 years of age (leading cause of death globally in this age group)
- Introduction of routine pneumococcal vaccination in 2000 dramatically decreased incidence in United States
- Risk factors:
- Environmental:
- Crowded conditions
- School-age siblings
- Airway irritant exposures, including secondhand smoke
- Anatomic abnormalities of airway or lungs
- Impaired airway protection
- Neuromuscular disorders
- Dysphagia
- Altered mental status
- Environmental:
- Underlying cardiopulmonary disease:
- Asthma
- Bronchopulmonary dysplasia
- Congenital heart disease
- Cystic fibrosis
- Immunodeficiency:
- Sickle cell (functional asplenia)
- Organ transplantation
Classification
- By clinical course:
- Typical:
- Abrupt onset
- More severe symptomatic presentation
- Atypical:
- More insidious onset
- Usually less severe symptoms
- Typical:
- By location acquired:
- Community-acquired pneumonia (CAP)
- Nosocomial/hospital-acquired (onset > 48 hours after admission)
- By pattern of anatomical involvement:
- Lobar or multilobar
- Bronchopneumonia
- Interstitial
- Necrotizing
- Caseating granuloma
- By patient’s immune status:
- Immunocompetent
- Immunocompromised
- By patient’s age:
- Newborn
- 4 weeks to 5 years
- > 5 years
Etiology and Pathophysiology
Etiology
- Community-acquired pneumonia:
- Viral: accounts for approximately 50% of cases in children < 5 years:
- Respiratory syncytial virus (RSV; most common)
- Influenza virus
- Adenovirus
- Metapneumovirus
- Parainfluenza virus
- Enterovirus
- Coronavirus
- Rhinovirus
- Bacterial in age < 4 weeks:
- Group B streptococcus
- Escherichia coli
- Klebsiella spp.
- Chlamydia trachomatis
- Listeria
- Bacterial in age > 4 weeks:
- Streptococcus pneumoniae: most common cause of typical clinical course
- Haemophilus influenzae
- Staphylococcus aureus (MSSA and MRSA)
- Mycoplasma pneumoniae: common cause of atypical clinical course
- Moraxella catarrhalis
- Strep. pyogenes
- Chlamydia pneumoniae: common cause of atypical clinical course
- Mycobacterial
- Fungal:
- Coccidioides immitis
- Blastomyces dermatitidis
- Histoplasma capsulatum
- Viral: accounts for approximately 50% of cases in children < 5 years:
- Nosocomial/hospital-acquired:
- Gram-negative bacilli
- Staph. aureus
- Special populations:
- Immunocompromised:
- Gram-negative bacilli
- Fungal
- Pneumocystis jirovecii
- Varicella zoster virus
- Cytomegalovirus
- Cystic fibrosis:
- Pseudomonas aeruginosa
- Aspergillus
- Immunocompromised:
- Noninfectious:
- Aspiration pneumonia (caused by gastric contents)
- Foreign body
Pathophysiology
- 2 possible mechanisms of infectious inoculation:
- Respiratory tract invasion
- Hematogenous dissemination: less common
- Bacterial colonization of nasopharynx → aspiration or inhalation of organisms
- Viral invasion of nasopharyngeal mucosa → contiguous spread to lower respiratory tract
- Lower respiratory tract infected by pathogens → release of inflammatory mediators and recruitment of WBCs → air spaces fill with WBCs, fluid, and cellular debris → reduced lung compliance, small airway obstruction, and atelectasis → impaired ventilation
Causal pathogens in community-acquired pneumonia according to age group and special circumstances
Image by Lecturio. License: CC BY-NC-SA 4.0Clinical Presentation
Clinical presentation
Clinical presentation varies by age of patient and by course of the illness.
By age:
- Neonates:
- Apnea
- Lethargy
- Poor feeding
- Irritability
- Fever
- Infants and children:
- Fever
- Tachypnea
- Cough
- Chest pain
- Abdominal pain
By clinical course:
- Typical course:
- History:
- Fever/chills
- Malaise
- Productive cough
- Chest pain
- Dyspnea
- Exam:
- Tachypnea and tachycardia
- Hypoxia
- Reproducible, fixed-point rales/crackles audible on lung exam
- Decreased breath sounds
- Tactile fremitus
- Dullness to percussion
- Retractions/use of accessory muscles of breathing
- History:
- Atypical course:
- History:
- Nonproductive cough
- Fatigue
- Headache
- Sore throat
- Myalgias
- Exam:
- Common to be unremarkable
- Possible wheezing (also viral)
- History:
Criteria for respiratory distress in children with pneumonia
- Tachypnea:
- Ages 0–2 months: > 60 breaths/min
- Ages 2–12 months: > 50 breaths/min
- Ages 1–5 years: > 40 breaths/min
- Ages > 5 years: > 20 breaths/min
- Dyspnea
- Apnea
- Retractions (use of suprasternal, intercostal, or subcostal muscles)
- Grunting
- Nasal flaring
- Altered mental status
- Pulse oximetry < 90%
Diagnosis
Diagnosis made based on history and exam and can be confirmed or refined with imaging.
Imaging
- Indicated for:
- Severe disease
- Hospitalization
- Recurrent pneumonia
- Exclusion of other causes of respiratory distress
- Assessment for complications
- Chest radiography findings:
- Lobar pattern:
- Opacity +/– air bronchograms
- More likely bacterial etiology
- Bronchial pattern:
- Patchy infiltrates
- More likely atypical or viral etiology
- Interstitial pattern:
- Diffuse reticular opacities
- More likely viral etiology
- Effusion or empyema
- Lobar pattern:
- Chest CT: if infection refractory to inpatient treatment or recurrent
- Bronchoscopy: to evaluate anatomy or masses if infection recurrent
Round pneumonia:
Case 1: 5-year-old boy with evidence of round pneumonia by chest X-ray in middle region of the left lung (A) detected by lung ultrasound (B)
Case 2: 8-year-old boy with round pneumonia in middle/upper region of right lung by chest X-ray (C) and corresponding ultrasound image (D)
Laboratory evaluation
- Supportive, but not used to diagnose
- CBC showing leukocytosis
- ↑ CRP
- Arterial blood gas (ABG): low partial pressure of oxygen (PaO2)
- Blood culture
- Viral respiratory panel: high false positive rate
- Gram stain and culture of sputum
- Thoracentesis: evaluate effusion or empyema fluid
Management
General supportive care
- Oxygen
- Fluid resuscitation
- Incentive spirometry
- Antipyretics
Antimicrobials
- CAP outpatient:
- Viral:
- Supportive care
- Flu antiviral medication as appropriate
- Typical course:
- Amoxicillin
- 2nd- or 3rd-generation cephalosporin
- Fluoroquinolones (discouraged owing to side effect profile)
- Atypical course: azithromycin
- Response:
- Anticipate improvement in < 72 hours
- If no response, then need to consider alternative diagnosis, complication, ineffective coverage
- Cough may last weeks after resolution of all other symptoms.
- Viral:
- CAP inpatient:
- Hospital admission for:
- Infants
- Hypoxia
- Dehydration
- Respiratory distress
- Complication
- Failed outpatient management
- Choice of antimicrobials:
- Ampicillin: 1st-line
- 3rd-generation cephalosporin: for patients < 12 months or underimmunized
- 3rd-generation cephalosporin + vancomycin if MRSA suspected
- 3rd-generation cephalosporin + macrolide if atypical infection suspected
- Hospital admission for:
- Special cases:
- < 6 months:
- Birth to 1 month: ampicillin and gentamicin
- 1–6 months: macrolides
- Cystic fibrosis : antipseudomonal coverage
- Aspiration: ampicillin–sulbactam or clindamycin
- < 6 months:
- Nosocomial: gentamicin + aminoglycoside
Criteria for hospitalization in children with community-acquired pneumonia
- Infants:
- Apnea or grunting
- Oxygen saturation ≤ 92%
- Poor feeding
- Respiratory rate > 70 breaths/min
- Older children:
- Grunting
- Inability to tolerate oral intake
- Oxygen saturation ≤ 92%
- Respiratory rate > 50 breaths/min
- All age groups:
- Comorbidities (e.g., chronic lung disease, asthma, unrepaired or incompletely repaired congenital heart disease, diabetes mellitus, neuromuscular disease)
- Family not able to provide appropriate observation
Prognosis and Prevention
Most children with pneumonia recover without long-term sequelae; however, some complications can occur.
- Complications:
- Prolonged cough
- Pleural effusion
- Empyema
- Lung abscess
- Pneumatocele
- Bacteremia/sepsis
- ARDS
- Respiratory failure
- Death
- Vaccination is the most important means of prevention:
- Pneumococcal vaccination
- Haemophilus influenzae type B vaccination
- Influenza vaccination
- Varicella vaccination
- Diphtheria–tetanus–acellular pertussis (DTaP) vaccination
Other complications of pneumonia in children include:
- Pulmonary:
- Lung abscess
- Pneumothorax
- Bronchopleural fistula
- Necrotizing pneumonia
- Acute respiratory failure
- Metastatic:
- Meningitis
- CNS abscess
- Pericarditis
- Endocarditis
- Osteomyelitis
- Septic arthritis
- Systemic:
- Sepsis
- Hemolytic uremic syndrome
Differential Diagnosis
- Asthma: inflammatory airway disease that leads to bronchial luminal narrowing due to smooth muscle narrowing and mucus overproduction in response to an irritant stimulus (cold air, infection, or allergies) and thus obstruction of airflow. Asthma is characterized by cough, wheezes, and dyspnea and is usually diagnosed after the age of 2. Asthma has known triggers, with reversibility of symptoms with bronchodilator use in all cases.
- Bronchiolitis: respiratory condition caused by inflammation of the medium and small airways (bronchioles), with the majority of cases in children caused by RSV. Patients usually first present with upper respiratory symptoms, such as cough and congestion, and may progress to dyspnea, wheezing, and hypoxia. Diagnosis is clinical, and treatment is directed at improving oxygenation and hydration. The condition is self-limited and has a good prognosis.
- Pertussis: potentially life-threatening bacterial infection, also called “whooping cough.” Pertussis presents with an intense paroxysmal cough followed by an inspiratory “whooping” sound. The condition can be severe for infants < 1 year of age. If pertussis is suspected, immediate antibiotic therapy with macrolides should be initiated, even if laboratory confirmation is pending. Pertussis is preventable with immunization.
- Foreign-body aspiration: common finding in the pediatric population. Aspirated foreign bodies may become lodged in the bronchi, affecting breathing, and can lead to infection or erosion of the bronchial walls. Children may present acutely with coughing or wheezing, but symptoms may also be more indolent, with persistent recurring pneumonia symptoms associated with the infection caused by the aspiration. Diagnosis is made on imaging, and treatment is to promptly remove the foreign body.
- Heart failure: life-threatening condition with multiple etiologies. Heart failure is due to the inability of the heart to output enough blood to supply the body’s metabolic needs. Presentation includes chest pain, dyspnea on exertion, cough made worse with reclining, fatigue, pitting edema, and crackles on lung exam. Echocardiography and cardiac stress testing will show reduced cardiac function, and a chest x-ray will show pulmonary edema. Management involves multiple pharmaceutical agents, such as diuretics, and lifestyle modifications.
References
- Ranganathan, S.C., Sonnappa, S. (2009). Pneumonia and other respiratory infections. Pediatric Clinics of North America 56:135–156. https://doi.org/10.1016/j.pcl.2008.10.005
- American Academy of Pediatrics. (2011). Management of community-acquired pneumonia (CAP) in infants and children older than 3 months of age. Pediatrics 128:e1677. https://doi.org/10.1542/peds.2011-2385
- Kelly, M.S., Sandora, T.J. (2020). Community-acquired pneumonia. In Kliegman, R.M., et al. (Eds.), Nelson textbook of pediatrics. pp. 226–2274.e1. https://www.clinicalkey.com/#!/content/3-s2.0-B9780323529501004284
- Copeland, J.E. (2016). Pneumonia in infants and children. In Tintinalli, J.E., et al. (Eds.), Tintinalli’s Emergency Medicine: A comprehensive study guide, 8th ed. New York: McGraw-Hill Education. https://accessmedicine.mhmedical.com/Content.aspx?bookid=1658§ionid=109407264
- Jokinen, C., et al. (1993). Incidence of community-acquired pneumonia in the population of four municipalities in eastern Finland. American Journal of Epidemiology 137:977–988. https://doi.org/10.1093/oxfordjournals.aje.a116770
- Kemp, W.L., Burns, D.K., Brown, T.G. (2008). Pulmonary pathology. Chapter 13 of Pathology: The Big Picture. New York: McGraw-Hill. https://accessmedicine.mhmedical.com/content.aspx?aid=57053485
- Mandell, L.A., Wunderink, R. (2018). Pneumonia. In Jameson, J., et al. (Eds.), Harrison’s Principles of Internal Medicine, 20th ed. New York: McGraw-Hill Education. https://accessmedicine.mhmedical.com/content.aspx?aid=1155964517
- Leung, A.K.C., et al. (2018). Community-acquired pneumonia in children. Recent Patents on Inflammation & Allergy Drug Discovery 12(2):136–144. https://doi.org/10.2174/1872213X12666180621163821
