Neumonia

Community-Acquired Pneumonia in Infants and Children
MICHAEL OSTAPCHUK, M.D., DONNA M. ROBERTS, M.D., and RICHARD HADDY, M.D.

University of Louisville School of Medicine, Louisville, Kentucky Community-acquired pneumonia is one of the most common serious infections in children, with an annual incidence of 34 to 40 cases per 1,000 children in Europe and North America. When diagnosingcommunity-acquired pneumonia, physicians should rely mainly on the patient’s history and physical examination, supplemented by judicious use of chest radiographs and laboratory tests as needed. The child’s age is important in making the diagnosis. Pneumonia in neonates younger than three weeks of age most often is caused by an infection obtained from the mother at birth. Streptococcus pneumoniae andviruses are the most common causes in infants three weeks to three months of age. Viruses are the most frequent cause of pneumonia in preschool-aged children; Streptococcus pneumoniae is the most common bacterial pathogen. Mycoplasma pneumoniae and Chlamydia pneumoniae often are the etiologic agents in children older than five years and in adolescents. In very young children who appear toxic,hospitalization and intravenous antibiotics are needed. The symptoms in outpatients who present with community-acquired pneumonia can help determine the treatment. Knowing the age-specific causes of bacterial pneumonia will help guide antibiotic therapy. Childhood immunization has helped decrease the incidence of invasive Haemophilus influenzae type B infection, and the newly introduced heptavalentpneumococcal vaccine may do the same for Streptococcus pneumoniae infections. (Am Fam Physician 2004;70:899-908. Copyright© 2004 American Academy of Family Physicians.)

See page 801 for definitions of strength-ofrecommendation labels.

he term “community-acquired pneumonia” (CAP) refers to a pneumonia in a previously healthy person who acquired the infection outside a hospital. CAP is one of the mostcommon serious infections in children, with an incidence of 34 to 40 cases per 1,000 children in Europe and North America.1-3 Although death from CAP is rare in industrialized countries, lower respiratory tract infection is one of the leading causes of childhood mortality in developing countries.4,5 Etiology Determining the cause of pneumonia in a child is often difficult, but the patient’s agecan help narrow the list of likely etiologies. Table 16-9 lists common and less common causes of CAP by age group. Group B streptococcus and gram-negative enteric bacteria are the most common pathogens in neonates (i.e., birth to 20 days) and are obtained via vertical transmission

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from the mother during birth. Anaerobic organisms may be acquired from chorioamnionitis. Pneumonia in infantsaged three weeks to three months is most often bacterial; Streptococcus pneumoniae is the most common pathogen. In infants older than four months and in preschool-aged children, viruses are the most frequent cause of CAP; respiratory syncytial virus (RSV) is the most common. Viral pneumonia occurs more often in the fall and winter than in the spring and summer. Bacterial infections can occur at anytime of the year in preschool- and schoolaged children and in adolescents. S. pneumoniae is the most common bacterial cause of CAP after the neonatal period. Less common bacterial etiologies include Haemophilus influenzae type B, Moraxella catarrhalis, and Staphylococcus aureus. Mycoplasma pneumoniae and Chlamydia pneumoniae frequently are associated with CAP in preschool-aged children and arecommon causes

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TABLE 1

Causes of Community-Acquired Pneumonia by Age Group...