Chapter 125: Pneumonia in Infants and Children

Pneumonia is an infection of the lung and lower respiratory tract, below the level of the larynx. Globally, pneumonia is a leading cause of morbidity and mortality, with an estimated 120 million cases annually resulting in nearly 1.3 million deaths.¹ The greatest burden of disease and mortality occurs in the developing world, and young children under the age of 2 account for 81% of pediatric deaths from pneumonia. Although survival in industrialized countries is better than in the developing world, the burden of disease remains high, with an estimated 2 to 2.6 million cases annually, resulting in nearly a million hospitalizations.² This chapter addresses the clinical and radiographic diagnosis of pneumonia, common viral and bacterial causes, evidence-based treatments, and appropriate disposition and follow-up for children seen in the ED. Wherever possible, you will see special mention of unusual microbes, changing patterns of immunization and resistance, and special considerations for children with underlying medical conditions. If you have limited pediatric experience, you may find the section on the use and interpretation of chest radiographs in children helpful.

Pneumonia occurs through invasion of the lower respiratory tract by pathogens. Anatomic and mechanical barriers to infection include the nasal hairs and turbinates, cilia, epiglottis, and cough reflex. Humoral immunity is largely mediated by secretory immunoglobulin A, whereas cellular immunity and phagocytic cells (e.g., alveolar macrophages) further protect against infection. Infectious agents may be inhaled or aspirated directly into the lungs, invade respiratory epithelium and spread contiguously, or, less commonly, reach the lungs hematogenously. Viral inoculation is typically by droplet or fomite (e.g., influenza, respiratory syncytial virus), whereas bacterial pneumonia often follows colonization of the nasopharynx. Infection can result in injury or death of the respiratory epithelium, interstitial inflammation, or alveolar injury. The air space fills with exudate and WBCs, which disrupt oxygenation and cause air space collapse, with eventual ventilation-perfusion mismatch.

In most cases, the causative agent is never known. Definitive microbiologic diagnosis requires invasive procedures such as bronchial lavage or sampling of pleural effusion for culture, which are unavailable or impractical in the ED.

Overall, viruses predominate in younger children, although bacterial, atypical, fungal, parasitic, and opportunistic organisms can also cause disease. Infection with Mycobacterium tuberculosis can occur in areas where it is endemic and among children with immunodeficiency, so one should take into account local and regional epidemiology, individual immunization status, and underlying health problems that may influence which pathogens are likely. The types and causes of pneumonia vary considerably according to the age of the child; a few general rules and specific exceptions are described below.^3,4

The cardinal symptoms of lower respiratory tract infection include cough, fever, tachypnea, and respiratory distress. However, signs and symptoms vary by age and specific causative agents. Both age-based etiology and pathogen-specific clinical patterns of disease are described below.

AGE-SPECIFIC CAUSES OF PNEUMONIA

Neonates

Neonates (0 to 30 days of age) require special consideration because they are at risk from bacterial pathogens acquired from the birth canal at or around the time of delivery. Specific organisms of concern include group B streptococci, gram-negative enteric bacteria such as Klebsiella and Escherichia coli, and Listeria monocytogenes. Late-onset neonatal pneumonia may be caused by Staphylococcus aureus, Streptococcus pneumoniae, or Streptococcus pyogenes. Pneumonia due to maternal genital Chlamydia trachomatis has been largely eliminated in developed countries through the systematic screening and treatment of pregnant women⁵ but is still a consideration if the mother has had little or no prenatal care. Any neonate with pneumonia is also at risk of sepsis, and between birth and 3 months, infants with pneumonia should be evaluated for sepsis.

Infants and Children between 30 Days and 2 Years of Age

Pneumonia in older infants and toddlers is usually viral rather than bacterial.⁶ Common causes include respiratory syncytial virus, influenza virus, parainfluenza virus, human metapneumovirus, and adenovirus. In this age group, the most common bacterial cause of community-acquired pneumonia remains S. pneumoniae. Other agents include Haemophilus influenzae type b in nonimmunized children and nontypeable H. influenzae in all children. Less common but important pathogens include S. aureus and Bordetella pertussis.

Children 2 to 5 Years Old

As children get older and attend day care or school, they come into contact with many pathogens, particularly respiratory viruses.

In children between 2 and 5 years of age, most community-acquired pneumonia is caused by respiratory viruses, followed by S. pneumoniae, H. influenzae type b, or nontypeable H. influenzae.^4,7 Mycoplasma and Chlamydophila pneumoniae are thought to be less common in children <5 years old.^4,7,8 Pneumonias due to varicella-zoster virus, measles, H. influenzae type b, B. pertussis, and some strains of Pneumococcus are increasingly rare in areas of widespread vaccination and herd immunity.

Children 5 to 13 Years Old

In children from age 5 to adolescence, Mycoplasma pneumoniae is thought to be a chief cause of community-acquired pneumonia, with C. pneumoniae and S. pneumoniae still important considerations.^7,9 Less common bacterial causes include S. aureus and Legionella.⁶ M. tuberculosis is a rare but important agent to consider. Pertussis immunity from the newer acellular vaccine appears to wane (in the 5 years after vaccination), so consider Bordetella even in the immunized child if clinical symptoms are strongly suggestive.¹⁰

Adolescents

By adolescence, most patients are assumed to have the same infectious risks as healthy adults. The prevalence of specific pathogens may vary according to region, season, and cyclical epidemics in the population. In North America, the role of atypical agents, especially mycoplasma and C. pneumoniae, is estimated to be significant, but data and guidelines from other parts of the industrialized world (e.g., Europe) suggest regional differences.¹¹

UNIQUE AND HIGH-RISK GROUPS

Tuberculosis remains a consideration for children with known exposures and those from endemic areas such as Native reserves, Alaska, northern Canada, and some inner-city settings. Consider tuberculosis in immigrants from high-prevalence areas of the world, including Africa, Asia, and parts of Eastern Europe.

Children with underlying disease are at risk for specific infections. For example, younger children with cystic fibrosis are often infected with S. aureus in the first years of life, and later with Pseudomonas. Children with sickle cell disease are particularly susceptible to infection with encapsulated bacteria (e.g., pneumococcus, Salmonella, Klebsiella), which can cause acute chest syndrome and sepsis. Children with congenital or acquired immune deficiencies such as human immunodeficiency virus infection, malignancy, and congenital immunodeficiencies are at risk for opportunistic infections with agents such as Pneumocystis jirovecii, cytomegalovirus, and fungi.¹

Unvaccinated children and those with incomplete immunization are at risk of serious morbidity and mortality from a variety of vaccine-preventable pathogens. They should be managed accordingly.

PATHOGEN-SPECIFIC PATTERNS OF DISEASE

"Typical pneumonias" classically present with high fever, chills, pleuritic chest pain, and productive cough and suggest a bacterial cause, especially S. pneumoniae. In contrast, "atypical pneumonias" are characterized by gradual onset over days to weeks, low-grade fever, nonproductive cough, and malaise, and suggest infection with agents like mycoplasma or C. pneumoniae. Unfortunately, there is significant overlap in the agents causing these symptoms, and it is not possible to pinpoint specific causative organisms by clinical findings alone.^4,12 If definitive identification of the pathogen is important, perform laboratory testing.

Despite these limitations, some patterns of disease do suggest certain etiologies (Table 125-1). Staphylococcal pneumonia, which may follow influenza, is notorious for rapidly progressing symptoms, high fever, toxicity, and presence of pulmonary abscesses. C. trachomatis infection in infants (which is rare where there is prenatal screening and treatment) often presents with a staccato cough, diffuse rales, and lack of fever, so-called afebrile pneumonitis. Scattered rales, rare wheezes, and bilateral interstitial infiltrates are all possible findings. Older children may complain of sore throat and dysphagia. B. pertussis and respiratory viruses are also implicated as possible causes.¹³ Mycoplasma infection typically produces a hacking, dry cough and may be associated with extrapulmonary manifestations including arthralgias, rash, and even CNS symptoms.¹⁴ An upper respiratory tract prodrome followed by paroxysmal cough, gasping respirations, and color change is characteristic of B. pertussis infection (whooping cough); the postinfection cough may persist for months. Consider tuberculosis with prolonged cough in the setting of identified risk factors and characteristic radiographic findings. Note that classic signs and symptoms of tuberculosis such as hemoptysis or tuberculosis-positive sputum may be absent in children, especially those with immune deficiencies.¹⁵ Tuberculosis in infants and young children tends to progress more rapidly from infection to clinical disease than it does in older children and adults, and hematogenous spread to extrapulmonary sites is also possible.^16,17

Wheezing in a young infant with respiratory infection typically points to bronchiolitis of viral origin. In older, school-age children, wheezing may suggest viral infection or Mycoplasma pneumonia.⁵ Distinguishing between viral and bacterial causes of pneumonia is often difficult, and radiographs may not provide a specific diagnostic pattern.

SEVERE DISEASE

The British Thoracic Society Guidelines for community-acquired pneumonia in children defines severe disease in infants as a fever >38.5°C, respiratory rate >70 breaths/min, nasal flaring, grunting, cyanosis, apnea, and poor feeding. Severe disease in older children is similarly defined by fever >38.5°C, signs of respiratory distress (respiratory rate >50 breaths/min, cyanosis, grunting), and signs of dehydration.³

DIFFERENTIAL DIAGNOSIS

The differential diagnosis of pneumonia includes both infectious and noninfectious conditions as well as extrapulmonary disorders that may mimic or complicate lower respiratory tract infection (Table 125-2). Formulating a differential diagnosis is especially important for infants and very young children, who may have undiagnosed congenital anomalies.

For children with respiratory distress but no fever, look for causes other than pneumonia. Congenital heart disease may present with cyanosis, quiet tachypnea, or respiratory distress related to congestive heart failure (see chapter 126, "Congenital and Acquired Pediatric Heart Disease"). Kussmaul breathing suggests diabetic ketoacidosis or other metabolic disease. Toddlers are particularly at risk for foreign body aspiration and ingestion of toxins. Adolescents may intentionally or unintentionally take drug overdoses that speed or slow breathing.

HISTORY

Relevant history depends on age of the patient and the underlying health of the child. Many complaints are nonspecific (e.g., cough and fever) and are common to both upper and lower respiratory tract disease. The predictive value of specific signs and symptoms is discussed below (see "Physical Examination" section).

Ask about the presence, timing, and duration of cough, fever, rapid breathing, and difficult breathing. Ask about specific exposures, sick contacts, travel, and pets, when relevant.

Choking or persistent or recurrent lower respiratory tract symptoms suggest foreign body aspiration. Recurrent pneumonias may signify underlying disease such as cystic fibrosis, immune disorders, or anatomic abnormalities.

In young children, abdominal pain may be a clue to lower lobe pneumonia or effusion.

Fever is a common but nonspecific sign of both upper and lower respiratory tract infections.

Birth History

Because neonates may acquire infections perinatally, be sure to ask questions about the mother's prenatal and perinatal health, including maternal infections (e.g., chlamydia, gonorrhea, group B streptococci, genital herpes, and human immunodeficiency virus status), intrapartum or postpartum fever, and any specific antibiotic or antiviral therapy received during labor and delivery. Other perinatal risk factors include prolonged rupture of membranes, prematurity, and immediate peripartum complications. Meconium aspiration may cause chemical or bacterial pneumonia in the first 24 to 72 hours of life. Neonatal stays in hospital suggest an underlying health problem and also increase the risk of nosocomial infection.

Medical History

Ask about the child's hospitalizations since birth and major illnesses, especially chronic respiratory problems (e.g., asthma, recurrent wheezing). In the young child, consider an undiagnosed respiratory, cardiac, renal, or immune dysfunction. Children with congenital respiratory problems (e.g., cystic fibrosis, neuromuscular disorders, immune compromise) are at increased risk of infection with common and rare agents, respiratory failure, and treatment failure. Adjust treatment and disposition accordingly (see Table 125-4).

Social History

Take a brief, focused social history, because it may influence both diagnosis and treatment. For example, children from the far north, Native reserves, or countries with high rates of tuberculosis may be exposed to this uncommon but serious infection. A travel history may also be relevant. Children born to human immunodeficiency virus–positive mothers are at risk of vertical transmission and immunocompromise. Social history may also influence treatment decisions. For outpatient management, make sure that caregivers understand instructions, can afford medication, and can provide the required care (see "Disposition and Follow-Up" section below).

Immunization History

Always inquire about childhood immunizations, and review records for confirmation when possible. Table 106-4 in chapter titled Emergency Care of Children provides a typical childhood immunization schedule. Ensure that enough time has elapsed to develop protective antibodies—typically 4 to 6 weeks for primary vaccination and 1 week for a booster. An unvaccinated child is at risk of serious morbidity, and even death, from vaccine-preventable illness.

Annual immunization against influenza is recommended for children ≥6 months of age and for those at high risk due to underlying health conditions. Influenza vaccine must be given annually to account for seasonal antigenic changes (see "Special Considerations" section below). Priority is given to children with asthma, cystic fibrosis, and other pulmonary diseases; those with significant cardiac, renal, and immune disorders; and those with diabetes. Caregivers and healthcare providers should also be immunized to avoid transmission to these at-risk children.¹⁸

Around the globe, immunization against polio, pertussis, measles, and H. influenzae type b infection has significantly lowered the risk of pneumonias and respiratory failure associated with these diseases. In some cases, simple herd immunity has decreased the chances that a child will come into contact with these once-feared diseases, but sporadic outbreaks exist in nonimmunized populations.

Immunization against varicella (chickenpox) should protect against the secondary pneumonias associated with this virus, although use of the vaccine is not yet universal. Similarly, the administration of the bacillus Calmette-Guérin vaccine to provide partial protection against certain forms of tuberculosis varies by state, province, and country.

The introduction of a seven-strain pneumococcal conjugate vaccine (Prevnar^®, PCV-7) in 2000 to 2001 led to dramatic decreases in invasive disease and modest but promising trends in the reduction of pneumococcal pneumonias, especially in children <2 years old.^19,20 Early reports suggested a somewhat diminished impact in human immunodeficiency virus–positive children.²¹ Vaccine-specific serotypes are being replaced globally by nonvaccine strains, although newer PCV-10 and PCV-13 vaccines are expected to counteract some of this serotype substitution. Children who received the initial PCV-7 series should receive a booster with PCV-13 to gain additional immunity.¹⁹ Vaccine coverage is universal in Canada but varies by state and private insurance provider in the United States.

The older 23-valent polysaccharide vaccine (Pneumovax^®) is effective in children ≥2 years of age, and it should be confirmed that the vaccine has been given to children with sickle cell disease, those who have undergone splenectomy, and others at high risk for pneumococcal disease. A booster may be required.

PHYSICAL EXAMINATION

In the developing world where imaging equipment and laboratory tests are limited, the World Health Organization has proposed a diagnostic algorithm based entirely on the presence or absence of tachypnea, respiratory distress, and lower chest retractions or indrawing. Although physicians in industrialized nations have many tools at their disposal, the diagnosis of pneumonia can still be made clinically.

Rapid respiratory rate is a simple, standardized screening tool for pneumonia⁴ (Table 125-3).

Children at very high altitudes may have a resting respiratory rate higher than children at sea level do, so oxygen saturation may be a more useful measure. Note that children who are severely malnourished or dehydrated or have impending respiratory failure may not be capable of generating rapid respiratory rates.

Markers of respiratory distress include nasal flaring, tracheal tug, and intercostal indrawing. Lower chest or "abdominal" indrawing or retractions and grunting suggest more severe pneumonia.²⁵ In infants, intermittent apnea, grunting, and an inability to feed are surrogate markers of dyspnea. Cough is less common in neonates or very young children, and productive cough is rarely seen before late childhood.

Document oxygen saturation, because hypoxia on room air (arterial oxygen saturation <93% at sea level) increases the risk of oral amoxicillin treatment failure in severe pneumonia,²⁶ and oxygen saturation <93% is a strong independent predictor of radiographic pneumonia.²⁷

Auscultate the chest using an appropriately sized stethoscope with the chest fully exposed, assessing all lung zones. Localized fine crackles (rales), coarse breath sounds (rhonchi), or diminished breath sounds suggest pneumonia, but sound recognition may not be consistent across observers²³; a toxic appearance and overall impression of illness as judged by the clinician show better diagnostic sensitivity than focal auscultatory findings.⁴

CLINICAL DIAGNOSIS

No single physical finding in isolation is diagnostic of pneumonia, and constellations of signs are more useful. For example, the combination of fever plus either tachypnea, decreased breath sounds, or fine crackles predicts x-ray–positive pneumonia with a sensitivity of 93% to 96%. The presence of fever plus all three of the other variables raises sensitivity to 98%, so much so that a radiograph is not required to make the diagnosis.²⁸

Conversely, a small but frequently cited study confirms that the child without tachypnea, respiratory distress, rales, and decreased breath sounds does not have pneumonia; a radiograph is not indicated.²⁹

Presumptive diagnosis of the causative organism and empiric treatment are made by considering historical and social factors (see above), immunization status (see above), and age of the child. See Table 125-4 for the most common causes of pneumonia by age as well as their treatment. Use care when assessing children with incomplete or no immunizations. Such children may be partially or fully susceptible to pneumonia associated with B. pertussis, H. influenzae type b, and all strains of pneumococcus, as well as measles, influenza, and varicella-zoster viruses.

LABORATORY EVALUATION

Because the results of most laboratory investigations are not known in the ED, tests are usually initiated to guide future treatment, except for rapid bedside tests for specific respiratory viruses. Nasopharyngeal assays for respiratory syncytial virus, influenza, and human metapneumovirus can be valuable, because they are quick and specific and results may negate the need for imaging, invasive testing, and antibiotic therapy. One may also defer imaging and antibiotic treatment for nontoxic children with clinical bronchiolitis or influenza, especially those with a positive nasopharyngeal swab finding.^3,22

Bacterial cultures of nasopharyngeal samples are generally not helpful, because results are delayed and oral flora correspond poorly with the organisms causing disease in the lung. The majority of newer serologic and polymerase chain reaction techniques to detect organisms such as H. influenzae or C. pneumoniae have not been validated in children and have produced variable results.^3,5,22

The routine collection of blood cultures is not recommended in healthy children with mild community-acquired pneumonia.²² For toxic-appearing children and those with severe disease requiring hospitalization, obtain blood for culture, CBC, electrolytes, and renal and hepatic function. Currently, the literature does not support the routine use of inflammatory markers (C-reactive protein or erythrocyte sedimentation rate), acute-phase reactants, or procalcitonin to distinguish bacterial from viral pneumonia in children.²²

When tuberculosis is suspected, obtain induced sputum samples from older children or gastric aspirates from infants for microscopy and confirmatory culture.³⁰ These tests require equipment and expertise beyond the scope of the ED.

IMAGING

Guidelines on the use of routine chest radiography are inconsistent.^3,22,31 Consider chest radiographs only when the results are likely to alter diagnosis, treatment, or outcome.

Benefits of radiography include diagnosis or confirmation of pneumonia and occasionally the discovery of a significant congenital abnormality. Risks and disadvantages include cost, delay, repeated exposure to ionizing radiation, and overdiagnosis of bacterial pneumonia.³² Several studies and major guidelines state that imaging should not be performed routinely in children with mild, uncomplicated acute lower respiratory tract infections.^3,22,33,34 Most of these studies and guidelines reference outpatient settings, in which children with prolonged cough, severe symptoms, and other "red flag" features were excluded, so these recommendations may not apply to the ED setting.

The chest radiograph is not the gold standard of diagnosis, because it is neither 100% sensitive nor 100% specific³⁵ and may be falsely negative (e.g., when clinical disease precedes radiographic changes) or falsely positive (e.g., poor inspiration or rotation; Figures 125-1 and 125-2). Chest radiographs do not reliably distinguish between bacterial and viral causes.^36,37 Young children with straightforward viral bronchiolitis may show radiographic areas of atelectasis or patchy collapse, resulting in a temptation to initiate antibiotic therapy for viral disease.

Although routine radiographs are not usually necessary, potential indications for chest radiography are listed below:^8,38,39,40

1. Infants and children with a toxic appearance and respiratory findings

2. Age of 0 to 3 months with fever, as part of a full sepsis evaluation

3. Child <5 years old, with a temperature of >39°C (102.2°F), WBC of ≥20,000/mm³, and no clear source of infection

4. Suspicion of a complication, such as pleural effusion or pneumothorax

5. Pneumonia that is prolonged or unresponsive to treatment

6. Children with biphasic illness (typical symptoms of upper respiratory tract infection followed by acute worsening of [respiratory] symptoms and high fever)

7. Suspected foreign body aspiration

8. Suspected congenital lung malformation (e.g., sequestration or congenital cystic adenomatous malformation)

9. Follow-up of "round pneumonia" (see Figure 125-5) to exclude an underlying mass

For a brief overview of important normal and abnormal radiographic findings unique to children, see the "The Pediatric Chest Radiograph" section at the end of this chapter.

Treatment is based on the presumptive pathogen using information from history, immunizations, and age group (Tables 125-4,125-5,125-6).

SUPPORTIVE AND SYMPTOMATIC TREATMENT

General supportive measures include supplemental oxygen to maintain oxygen saturation >92%; antipyretics; oral, nasogastric, or intravenous fluids to offset respiratory losses; and bronchodilators for wheezing. Because children depend on cough to clear mucus, cough suppressants are not generally indicated. Over-the-counter cough suppressants are not effective and have been withdrawn from the market in several countries for children <5 years of age. Narcotic-based cough suppressants are occasionally prescribed in older children, but data on their effectiveness and proper dosage are lacking. Codeine in particular is discouraged due to the risk of respiratory suppression in some children.⁴¹

Treat noninfectious pneumonitis (e.g., chemical inhalation, aspiration) and likely viral pneumonia (e.g., age 3 months to 5 years, audible wheezing, positive bedside test for respiratory syncytial virus, or influenza) with supportive measures as outlined above. Antibiotics are not indicated for viral pneumonia. Febrile infants (even those <3 months of age) with bronchiolitis (clinical and respiratory syncytial virus–positive) are at low risk for concurrent bacterial pneumonia, bacteremia, and meningitis and do not require radiographs, blood or cerebrospinal fluid testing, or empiric antibiotic therapy for their respiratory infection. The exception is infants less than 90 days old, who still have a small risk of concurrent urinary tract infection and should have their urine tested as part of a partial septic workup.³³

EMPIRIC ANTIBIOTIC TREATMENT

Treat all children with suspected bacterial pneumonia with prompt administration of empiric antibiotics.^4,6,8,38 Table 125-4 summarizes empiric treatment by age group, and Table 125-5 lists recommended antibiotic dosing.

Neonates

In neonates, who are at risk of sepsis, administer ampicillin to cover Listeria and group B Streptococcus in conjunction with an aminoglycoside (e.g., gentamicin) or a third-generation cephalosporin (e.g., cefotaxime) for expanded coverage of gram-negative organisms such as E. coli. Ceftriaxone is contraindicated in neonates because it can displace bound bilirubin.

Young Infants 1 to 3 Months Old

The syndrome of afebrile pneumonitis described in infants 1 to 3 months old (staccato cough, tachypnea, with or without progressive respiratory distress and diffuse pulmonary infiltrates) may be viral in origin but has also been associated with atypical bacteria, so authors have suggested empiric treatment with erythromycin or clarithromycin in this group.⁴ Note that azithromycin is not included in the treatment of patients this young, because it has not been approved by the U.S. Food and Drug Administration.

Infants and Children ≥3 Months Old

For children ≥3 months old, the choice of treatment remains largely empiric. There are notable differences between some North American and European recommendations,^3,11 but all presume the most frequent cause of bacterial pneumonia to be S. pneumoniae. For this reason, high-dose oral amoxicillin (80 to 100 milligrams/kg/d) or another β-lactam antibiotic remains the drug of choice. For children >5 years old, some North American guidelines assume that atypical agents such as Mycoplasma and C. pneumoniae play a more important role, so macrolides are often listed as first choice. This recommendation presumes that macrolides will treat both atypical pathogens and pneumococci. High rates of pneumococcal resistance to macrolides in vitro are a growing concern in many areas of the world, and several major guidelines now recommend amoxicillin with or without clavulanate as initial therapy for all children ≥3 months of age with simple community-acquired pneumonia.^3,22 In cases where resistant pathogens or multiple pathogens are suspected, all guidelines make provisions for double coverage with β-lactams or cephalosporins plus macrolides. With these considerations in mind, typical choices for primary or secondary bacterial pneumonia are listed in Tables 125-4 and 125-6.

For a child with significant underlying illness or fulminant viral pneumonia, special agents and antimicrobials may be indicated, and consultation is strongly advised. Specific cases and treatment suggestions are listed in Table 125-6.

These guidelines may need to be adapted according to formulary, familiarity, and local patterns of antibiotic resistance. Antibiotic choices for children with allergies, unusual exposures, or specific risk factors should be tailored in consultation with a specialist.

The choice of oral versus parenteral antibiotics depends on the clinical picture. Oral antibiotics provide adequate coverage for most mild-to-moderate cases of bacterial pneumonia. Parenteral therapy is usually limited to neonates and those with severe pneumonia requiring hospitalization.⁴ Even for children who are admitted, oral treatment can be sufficient within the monitored setting of the hospital.⁴³

The recommended duration of outpatient treatment is typically 7 to 10 days (5 days in cases in which azithromycin is used). This is based on historical precedent, although some literature suggests equivalent outcomes in mild pneumonia with as few as 3 to 5 days of outpatient treatment.^44,45,46 There are theoretical concerns, however, that shorter courses of treatment and poor adherence may drive bacterial resistance.

In pediatrics, the choice of antibiotic may also be influenced by important nonmicrobial factors, such as taste, cost, frequency of administration, availability of a liquid formulation, and the child's ability to swallow.

CONTROVERSIES OF TREATMENT

The use of macrolides (erythromycin, clarithromycin, azithromycin) as first-line agents in young children is an area of controversy.^5,47 Macrolides are generally effective against atypical and intracellular agents, which are more common in children after the age of 5 years, but they may be ineffective against common S. pneumoniae. Pneumococcal resistance to macrolides in Europe and North America ranges from 7.5% to >50.0%.¹¹ The indiscriminate use of azithromycin in treating upper respiratory tract infections appears to be driving streptococcal resistance in some populations.⁴⁸ The liquid suspension of azithromycin is not approved for children <6 months of age by the U.S. Food and Drug Administration. Some suggest that children who have fever of <2 days in duration and who are <3 years of age have a very low risk of community-acquired Mycoplasma infection and that macrolides can be safely excluded as first-line antibiotics.⁴⁹ If a preschool child fails to improve when taking amoxicillin or an equivalent β-lactam, consider adding a macrolide.

Pneumococcal resistance to penicillin and other β-lactams is another area of concern around the globe. To date, most antibiotic resistance in community-acquired streptococci has been documented in vitro, rather than in vivo, and clinical response is still satisfactory when clinicians use an increased dosage, as noted in Table 125-4.⁵⁰ The safety and efficacy of fluoroquinolones for respiratory infections in children is not established, and their use is generally restricted due to theoretical risks of arthropathy. Doxycycline, a much older and less expensive agent, has activity against atypical pathogens as well as streptococci but is restricted to use in adolescents and adults, because use in young children may cause permanent staining of the adult teeth. As resistance to amoxicillin, macrolides, and other antibiotics grows, the importance of prevention using pneumococcal conjugate vaccines is likely to increase.

Most viral pneumonias resolve spontaneously without specific therapy. Complications are similar to those for bronchiolitis and include dehydration, bronchiolitis obliterans, and apnea. Apnea is a potential complication of infection with respiratory syncytial virus, Chlamydia, or B. pertussis infection in very young infants. Pleural effusions can occur with viral pneumonias but are not common.

Uncomplicated bacterial pneumonia usually responds within 72 hours to antibiotic therapy. Failure to respond or worsening of disease suggests a complication. These include pleural effusion, empyema, pneumothorax, or pneumatocele. Although effusions can occur in a small number of pneumococcal and mycoplasmal pneumonias, they are more commonly associated with H. influenzae type b infections; S. aureus is associated with empyema, abscess, and pneumatoceles. Mycoplasma pneumonia may cause extrapulmonary complications such as arthritis and meningitis, whereas local and hematogenous spread of tuberculosis can result in myriad manifestations both inside and outside the lung. Systemic complications of pneumonia include dehydration, sepsis, and hemolytic-uremic syndrome.

The child with pneumonia who returns to the ED with a worsening clinical picture should always cause concern. If the initial treatment was supportive care for a presumed viral pneumonia, consider secondary bacterial pneumonia or an alternative diagnosis (e.g., cardiac disease, congenital anomaly, foreign body).⁵¹ Similarly, a child receiving antibiotics who returns with diminished breath sounds, dullness to percussion, or worsening respiratory distress should prompt you to look for complications, such as empyema, effusion, or pneumothorax. If you suspect antibiotic-resistant pneumonia, you may need to get blood or pleural fluid cultures because clinical findings cannot reliably differentiate between drug-resistant and drug-sensitive pathogens.^52,53

Recommendations for outpatient, inpatient, and intensive care treatment of pneumonia are presented in Table 125-7.³ In addition to these clinically based criteria, neonates and infants up to 90 days old require hospital admission, as do infants and children with significant comorbid disease (e.g., cystic fibrosis, sickle cell disease, underlying immunodeficiency or malignancy). Social indications for admission include the inability of parents or caregivers to afford, understand, or ensure outpatient treatment.³ If there is a risk that adults cannot bring a child back for follow-up with a healthcare provider in 24 to 48 hours, also consider admission.

Infants with suspected B. pertussis infection (whooping cough) are at risk for apnea and should be admitted under respiratory isolation. Indications for hospitalizing patients with respiratory syncytial virus pneumonia are the same as those for patients with respiratory syncytial virus bronchiolitis (see chapter 124, "Wheezing in Infants and Children"). Admit children of any age with suspected active pulmonary tuberculosis, under respiratory isolation. Patients who fail a trial of oral antibiotics and those with complications of pneumonia require admission for further diagnosis and therapy. The finding of a pleural effusion or pneumatocele or findings suggestive of a bacterial infection in a child <1 year of age suggest a pathogen other than S. pneumoniae (in particular H. influenzae type b or S. aureus); hospitalize these children.

DISCHARGE INSTRUCTIONS

Provide all children and families with specific instructions on the dosage and scheduling of medications and the signs of worsening respiratory distress. Encourage return to medical care for children who cannot take prescribed antibiotics or adequate amounts of fluid. Ensure that all children discharged with the diagnosis of pneumonia have follow-up within a day or two with a primary care provider. Younger children require closer follow-up.

Many factors predispose children to pneumonia. Quickly review the following topics with parents and caregivers:

1. Hand washing and general hygiene to prevent transmission

2. Breastfeeding of infants, which is known to be protective

3. Avoidance of smoking (by teens) and second-hand smoke

4. Vaccination, including pneumococcal conjugate vaccine (Prevnar^®, Synflorix^®), as well as polysaccharide vaccine (Pneumovax^®) for at-risk children older than 2 years

For a child with significant underlying illness or fulminant viral pneumonia, special agents and antimicrobials may be indicated, and consultation is strongly advised. Specific cases and treatment suggestions are listed in Table 125-6.

INFLUENZA

Influenza is a common cause of respiratory infections worldwide. Classic symptoms include fever, cough, runny nose, headache, and myalgias, lasting up to 7 days.

Complications of influenza include secondary bacterial pneumonia and occasionally a pneumonia from the virus itself.⁵⁴ Apnea is a rare but serious complication in young infants.

Point-of-care and other rapid testing may be helpful in pinpointing influenza as the source of fever in children and avoiding a search for additional causes. Sensitivities are moderate (40% to 70%), but specificities are high (85% to 100%), if performed within the first 4 days of symptoms.⁵⁵ If a false-negative result is suspected, you can perform confirmatory polymerase chain reaction or viral culture.

Treatment of influenza is largely supportive, with fluids, rest, and fever control. Note that acetylsalicylic acid should not be used for fever control, due to the risk of Reye's syndrome.

The role for antivirals is unclear. A 2012 Cochrane meta-analysis of the older medications amantadine and rimantadine showed a limited role in prevention and amelioration of influenza A in children. The number needed to treat was high (n = 12), and the quality of evidence was low.⁵⁶

The newer neuraminidase inhibitors oseltamivir (Tamiflu^®) and zanamivir (Relenza^®) showed initial promise, but subsequent reviews of the data have cast serious doubts on the utility of these drugs to shorten symptoms or prevent serious complications such as pneumonia.⁵⁷

With few treatments available, the best defense against influenza and its associated pneumonias remains annual vaccination, frequent hand washing, and droplet precautions.

The U.S. Centers for Disease Control and Preventions and the American Academy of Pediatrics recommend routine annual influenza vaccination for children 6 months and older. Special emphasis is placed on children 4 years and under, because they are most at risk for complications and most likely to transmit disease in the community.

Children generally require a single dose of the vaccine annually, to account for antigenic changes in the virus from year to year. Those being vaccinated for the very first time may require a second dose at least 28 days later.

A nasal form of the vaccine containing live, attenuated virus is approved for children 2 years of age and older and may improve compliance. However, there is an increased risk of wheezing when used in children with a prior history of wheeze. Those with asthma or immune suppression should use the standard, injectable vaccine, which contains no live virus.

TUBERCULOSIS

Children of all ages are susceptible to tuberculosis, and most have primary disease, rather than secondary reactivation. Both upper lobe infiltrates and hilar lymphadenopathy on chest radiograph suggest the diagnosis, but classic findings can be absent in children, especially those with immune deficiencies.¹⁵ Infants and young children tend to progress rapidly from infection to clinical disease, and hematogenous spread can lead to the radiographic "snowstorm" appearance of miliary tuberculosis.¹⁶ Secondary tuberculosis has a predilection for the upper segments of the lung, as in adults, and may yield a cavitary lesion in some cases. Mycobacterium avium lesions may be indistinguishable from those of secondary tuberculosis.

OPPORTUNISTIC INFECTIONS

Nodular findings in the lungs may alert the astute clinician to the presence of other, rare infectious agents, such as Histoplasma, Aspergillus, and Pneumocystis. Pediatric patients with human immunodeficiency virus/acquired immunodeficiency syndrome may be susceptible to all of these, as well as cytomegalovirus, lymphomas, and lymphocytic interstitial pneumonia.

CYSTIC FIBROSIS

Children with cystic fibrosis have decreased mucus clearance, which leads to small-airway obstruction. More advanced disease results in chest radiograph findings such as peribronchial thickening and mucous plugging, with subsequent cystic or bullous lung lesions, segmental atelectasis, and hilar adenopathy. Air trapping may be seen on expiratory views. Patients with cystic fibrosis are also at risk for pneumothorax.

ASPIRATION PNEUMONIA

Patchy atelectasis and air space consolidation in the dependent zones of the lung should raise suspicion of aspiration pneumonia or pneumonitis. Recurrent aspiration pneumonias may occur in children with chronic gastroesophageal reflux disease, tracheoesophageal fistula, developmental delay, immobility, or neuromuscular disorders.

NORMAL NEONATAL ANATOMY

The chest of a neonate (<1 month of age) has a more pyramidal or trapezoidal shape than the long, rectangular form of the adult. The cardiac silhouette may occupy up to 60% or 65% of the chest width on the frontal view and still be considered normal. In infants, bronchial branching may be visible beyond the level of the carina, giving the false impression of pathologic air bronchograms. The thymus appears as a large, dense, anterior mediastinal "sail," until involution occurs around age 6. A normal thymus can often be recognized by the sharp inferior edge of its silhouette and occasionally by a "wave" or "sail" sign at the lateral edge, where the adjacent ribs indent this soft, solid organ. Occasionally the thymus may be confused with a lobar pneumonia, mediastinal mass, or hilar lymphadenopathy (Figure 125-3). A lateral view can help to confirm the anterior location of the thymus (Figure 125-4). A silhouette that extends behind the heart shadow or posterior to the vertical lucency of the trachea should be investigated.

TRANSIENT TACHYPNEA OF THE NEWBORN AND MECONIUM PNEUMONITIS

Occasionally parents may bring a very young newborn to the ED because of real or perceived breathing difficulties. Noninfectious causes of tachypnea and respiratory distress in the first few days of life include transient tachypnea of the newborn, or "wet lung," and chemical pneumonitis from meconium aspiration. The former may cause increased vascular markings, linear interstitial opacities, and even pleural effusions on radiographs due to interstitial edema. Meconium aspiration can block small airways, leading to hyperinflation and bilateral air space opacities on plain radiographs. Signs of interstitial opacities or edema should prompt observation and/or consultation with a specialist.

FOREIGN BODY OR HYDROCARBON ASPIRATION

In addition to pneumonias from the infectious causes, toddlers are susceptible to choking and foreign body aspiration from objects they can reach. These may include organic materials (e.g., food) or inorganic objects (coins, buttons, batteries), as well as volatile toxins such as cleaning products, gasoline, or other hydrocarbons. Retained foreign bodies can lead to respiratory distress and febrile aspiration pneumonia. Radiopaque foreign bodies will appear on the chest radiograph; signs of radiolucent foreign bodies include asymmetric air trapping or segmental collapse past an obstructed bronchus. By contrast, inhaled hydrocarbons and irritants may yield a pneumonitis with patchy lower air space opacities and even pneumatoceles if the presentation is delayed.

PNEUMONIA IN THE OLDER CHILD

By school age, the radiographic signs of chest infection in children become more like the typical findings in adults. There may be obvious lobar consolidation or patchy, multifocal findings. Younger children can also present with "round pneumonia" (Figure 125-5), a sharply defined consolidation often found in the posterior lower lobe, classically from pneumococcal infection. Children with round pneumonias should have radiographic follow-up to confirm resolution and ensure that this finding is not actually a mass. Cavitation and pleural effusions should arouse suspicion of infection with S. aureus or S. pneumoniae, particularly penicillin-resistant pneumococcus (Figure 125-6).

Acknowledgments: The author would like to thank Dr. Gordon Culham, Department of Radiology, BC Children's Hospital, Vancouver, British Columbia, and Dr. James McCormack of the BC Therapeutics Initiative for their input.