Respiratory Infections
Core concepts
Bronchiolitis is a viral lower respiratory infection, most often respiratory syncytial virus, in children under 2 years. It presents with coryza, tachypnea, wheeze or crackles, and feeding difficulty. Management is supportive: hydration, oxygen if hypoxemic, and suctioning. Routine bronchodilators, corticosteroids, antibiotics, and chest radiographs are not recommended. Community-acquired pneumonia is commonly bacterial due to Streptococcus pneumoniae; Mycoplasma is a common atypical pathogen in school-age children, and viruses predominate in young infants. Amoxicillin is first-line for typical outpatient pneumonia. Pertussis causes paroxysmal cough, a whoop, post-tussive emesis, and lymphocytosis; treat with a macrolide. Croup causes a barking cough, hoarseness, and inspiratory stridor; dexamethasone is standard, with nebulized epinephrine for moderate or severe disease. Epiglottitis causes drooling, tripod positioning, and a muffled voice; do not examine the throat, and secure the airway. Tuberculosis in children is best evaluated with gastric aspirates.
Traps
Do not diagnose bacterial pneumonia from a radiograph alone. Avoid antibiotics for bronchiolitis. Atypical pneumonia may have gradual onset and a normal white count. A normal white count does not exclude pertussis. Distinguish croup from epiglottitis by onset and toxic appearance.
Worked example and rule of thumb
A 4-month-old with 2 days of coryza, tachypnea, wheeze, and oxygen saturation 88% has bronchiolitis; give oxygen and supportive care, not albuterol or antibiotics. Rule of thumb: bronchiolitis is a clinical diagnosis, and supportive care is the default.