Pediatric Pneumonia & Pertussis
Age picks the bug, the bug picks the drug, and pertussis spares no contact
Community-acquired pneumonia by age
Age predicts the organism. Pneumonia in a child presents with fever, cough, tachypnea, retractions, and focal crackles or decreased breath sounds. The likely pathogen, and therefore the empiric antibiotic, shifts with age.
| Age | Usual pathogens | Empiric treatment |
|---|---|---|
| 0–28 days | Group B strep, E. coli and other gram-negative enterics, Listeria | IV ampicillin plus gentamicin with a sepsis evaluation |
| 1–3 months, afebrile | Chlamydia trachomatis | Oral azithromycin |
| Infants and preschoolers | Mostly viral (RSV, human metapneumovirus, parainfluenza, influenza, rhinovirus); S. pneumoniae the leading bacterial cause | Viral: no antibiotic; bacterial: high-dose amoxicillin |
| School age and adolescents | Mycoplasma pneumoniae; S. pneumoniae still common | Azithromycin if atypical; amoxicillin if typical |
Neonates. Pneumonia in the first month is acquired around delivery and behaves like sepsis, so obtain blood cultures, consider a lumbar puncture, and give IV ampicillin (group B strep, Listeria) plus gentamicin (gram-negatives). Ceftriaxone is generally avoided in neonates because it displaces bilirubin.
Typical bacterial pneumonia. S. pneumoniae causes high fever, tachypnea, focal crackles, and lobar consolidation. Outpatients receive high-dose amoxicillin (90 mg/kg/day in 2 doses), which overcomes intermediate pneumococcal resistance. Admitted, fully immunized children receive IV ampicillin; ceftriaxone is used if immunization is incomplete or illness is severe. Add vancomycin or clindamycin when MRSA is suspected, and a macrolide only when an atypical organism is likely. Well-appearing outpatients need no routine chest X-ray or blood tests.
After influenza, S. aureus (including MRSA) can cause a rapidly progressive necrotizing pneumonia with empyema and pneumatoceles; cover it with vancomycin or clindamycin.
Atypical pneumonia
Mycoplasma pneumoniae. The classic pneumonia of school-age children and adolescents. Onset is gradual, with days of low-grade fever, headache, sore throat, malaise, and a persistent dry cough; the child often looks better than the patchy interstitial infiltrates on X-ray. Extrapulmonary clues include bullous myringitis, erythema multiforme or mucositis, and hemolysis from cold agglutinins (IgM antibodies against the I antigen on red cells). Because Mycoplasma has no cell wall, β-lactams fail; treat with azithromycin, with doxycycline or levofloxacin as alternatives.
| Feature | Chlamydia trachomatis pneumonia | Pertussis |
|---|---|---|
| Age | 1–3 months | Any age; most dangerous under 6 months |
| Fever | Absent | Absent or low-grade |
| Cough | Repetitive staccato cough with tachypnea | Paroxysms; young infants gag, turn blue, or become apneic |
| Key history | Neonatal conjunctivitis | Coughing adolescent or adult contact |
| Blood count | Eosinophilia | Marked lymphocytosis |
| Chest X-ray | Hyperinflation, interstitial infiltrates | Often clear between paroxysms |
| Diagnosis | Nasopharyngeal NAAT | Nasopharyngeal PCR |
| Treatment | Oral azithromycin; treat the mother and her partner | Azithromycin; prophylaxis for all close contacts |
Admission and parapneumonic effusion
Admission criteria:
- Hypoxemia, SpO2 below about 90–92% on room air
- Age under 3–6 months with suspected bacterial pneumonia
- Toxic appearance or moderate–severe distress (grunting, retractions, nasal flaring, apnea)
- Dehydration or inability to take oral medication
- A virulent pathogen such as MRSA, failure of outpatient therapy, or unreliable follow-up
Effusion and empyema. Fever that persists 48–72 hours into appropriate therapy, with dullness and decreased breath sounds, suggests a parapneumonic effusion, most often from S. pneumoniae, S. aureus, or S. pyogenes. Ultrasound confirms the fluid and shows loculations. Small effusions resolve with antibiotics alone. Moderate to large, loculated, or purulent collections need drainage: a chest tube with intrapleural fibrinolytics or video-assisted thoracoscopic surgery (VATS), which give similar outcomes.
Pertussis
Organism and toxin. Bordetella pertussis, a gram-negative coccobacillus, spreads by respiratory droplets. Pertussis toxin keeps lymphocytes from leaving the blood, producing a marked leukocytosis with lymphocytosis; the child is typically afebrile with clear lungs between spells.
- Catarrhal (1–2 weeks)runny nose and mild cough; the most contagious phase
- Paroxysmal (2–6 weeks)bursts of coughing ending in an inspiratory whoop, post-tussive vomiting, and cyanosis; the child looks well between spells
- Convalescent (weeks to months)the cough gradually fades: the 100-day cough
Age changes the picture. Infants under about 6 months often never whoop; they gag, become cyanotic or apneic, or develop bradycardia after coughing. They have the highest mortality and should be admitted. Complications include pneumonia (the leading cause of pertussis deaths), seizures, encephalopathy, and pulmonary hypertension with extreme leukocytosis. Adolescents and adults, whose vaccine immunity has waned, often have only a prolonged cough and are the usual source of infant infection.
Diagnosis. Nasopharyngeal PCR, most sensitive in the first 3–4 weeks of cough; culture is specific but slow.
Treatment and contacts. Azithromycin is used at every age and is preferred under 1 month, because erythromycin causes infantile hypertrophic pyloric stenosis. TMP-SMX is an alternative after 2 months; before then, sulfonamides displace bilirubin and risk kernicterus. All household and close contacts receive the same prophylaxis regardless of vaccination status. Keep the patient on droplet precautions until 5 days of therapy are complete.
Give Tdap during every pregnancy, ideally early in the 27–36-week window, so maternal antibodies cross the placenta and protect the infant until DTaP begins at 2 months (then 4, 6, and 15–18 months and 4–6 years, with Tdap at 11–12 years).