The parents of a 14-month-old female infant bring her to the emergency department in mid-w… — USMLE Step 2 CK

The parents of a $14$ -month-old female infant bring her to the emergency department in mid-winter because of a worsening cough and rapid breathing. The infant had a $3$ -day history of mild nasal congestion and clear rhinorrhea, but over the past $24$ hours, she developed a high fever and became increasingly lethargic. She was born at full term and is up-to-date on all routine childhood immunizations, including the Haemophilus influenzae type b and pneumococcal conjugate vaccines. Her temperature is $39.4^\circ\text{C}$ ( $102.9^\circ\text{F}$ ), heart rate is $155/\text{min}$ , respiratory rate is $58/\text{min}$ , and oxygen saturation is $91\%$ on room air. On physical examination, the infant is lethargic but arousable. Nasal flaring and moderate intercostal retractions are present. Auscultation of the lungs reveals decreased breath sounds and fine crackles localized over the right lower lobe. The left lung fields are clear, and no wheezing is appreciated. Chest radiography shows a dense consolidation in the right lower lobe with no pleural effusion. She is admitted to the pediatric ward and placed on supplemental oxygen via nasal cannula. Which of the following is the most appropriate initial pharmacotherapy for this patient?

Intravenous ampicillinAnswer
B
Intravenous ceftriaxone and azithromycin
C
Inhaled albuterol and hypertonic saline
D
Oral azithromycin
E
Intravenous vancomycin and ceftriaxone

Answer

Intravenous ampicillin is the most appropriate targeted pharmacotherapy for this fully immunized child with uncomplicated community-acquired pneumonia.

This patient's presentation of high fever, tachypnea, hypoxia, focal crackles, and lobar consolidation is diagnostic of typical community-acquired pneumonia (CAP). Because she is hypoxemic (

91\%

on room air) and showing significant respiratory distress, inpatient admission is required. The most common bacterial cause of typical CAP in preschool-aged children is Streptococcus pneumoniae. According to pediatric infectious disease guidelines, fully immunized children hospitalized with uncomplicated CAP should be treated with narrow-spectrum intravenous antibiotics, specifically ampicillin or penicillin G. This provides excellent coverage for susceptible pneumococcal strains while preventing unnecessary broad-spectrum antibiotic exposure.

Step-by-Step Solution

Analyze the clinical presentation to establish a diagnosis.

The patient has high fever, tachypnea, focal crackles, and lobar consolidation on chest x-ray, which confirms a diagnosis of typical community-acquired pneumonia (CAP).

Differentiating between viral bronchiolitis and bacterial pneumonia is critical. Focal findings and high fever point to a bacterial etiology rather than a viral process.

Determine the required setting of care (disposition).

The infant has an oxygen saturation of 91% and moderate respiratory distress (retractions, nasal flaring), necessitating inpatient admission and intravenous therapy.

Hypoxemia and increased work of breathing are absolute indications for hospitalization in pediatric CAP.

Select the appropriate antibiotic based on immunization status and severity.

The patient is fully immunized against H. influenzae type b and Streptococcus pneumoniae. For non-life-threatening inpatient CAP in fully immunized children, narrow-spectrum coverage with IV ampicillin or penicillin G is recommended.

Streptococcus pneumoniae remains the most common typical bacterial pathogen. Narrow-spectrum penicillins provide excellent coverage while adhering to antibiotic stewardship principles.

Key Concept

Management of Pediatric Community-Acquired Pneumonia

Estimated Time:1m 30s

Question

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Topics

More questions from this topic