What empiric antibiotic should be prioritized for a 3-year-old boy with CF showing symptoms of severe pneumonia?

In a 3-year-old boy with cystic fibrosis (CF) presenting with severe pneumonia, prioritizing intravenous vancomycin is appropriate due to the potential for serious bacterial infections commonly associated with this condition. Patients with CF are at a higher risk of developing infections from specific pathogens, especially Staphylococcus aureus, including methicillin-resistant Staphylococcus aureus (MRSA). Vancomycin is effective against MRSA and is commonly used as part of empiric therapy in severe cases of pneumonia where MRSA is a concern.

In the context of CF, the lung microbiome is altered, which makes patients susceptible to both typical pathogens such as Streptococcus pneumoniae and atypical pathogens, including Pseudomonas aeruginosa. While ceftriaxone can cover certain infections, it does not provide effective coverage against MRSA, which is a critical consideration in severe pneumonia scenarios.

Oral antibiotics like amoxicillin or azithromycin do not provide adequate coverage for severe infections, particularly in a hospital setting, as systemic administration of antibiotics is often necessary for optimal treatment outcomes in severe cases. Azithromycin may be used in maintenance therapy for chronic infections in CF but is not sufficient as monotherapy for acute severe pneumonia. Thus,