Differential Diagnosis for Community-Acquired Pneumonia (CAP) in a 3-year-old
- Single most likely diagnosis
- Streptococcus pneumoniae: This bacterium is the most common cause of CAP in children, especially in those under the age of 5. It is a significant pathogen due to its virulence and potential for severe disease.
- Other Likely diagnoses
- Haemophilus influenzae type b (Hib): Although vaccination has reduced its incidence, Hib remains a consideration, especially if vaccination status is unclear or incomplete.
- Respiratory Syncytial Virus (RSV): Common in young children, RSV is a leading cause of lower respiratory tract infections, including pneumonia, especially during seasonal outbreaks.
- Influenza: Seasonal influenza can cause pneumonia in children and is particularly concerning due to its potential for severe illness and secondary bacterial infections.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Staphylococcus aureus: Including methicillin-resistant S. aureus (MRSA), this bacterium can cause severe pneumonia with significant morbidity and mortality if not promptly treated.
- Mycoplasma pneumoniae: Typically seen in older children, but can occur in younger ones, especially those with atypical presentations or severe disease.
- Pneumocystis jirovecii: In immunocompromised children, this opportunistic infection can cause severe pneumonia.
- Rare diagnoses
- Mycoplasma pneumoniae in very young children: While more common in school-aged children, it can rarely cause CAP in younger children.
- Chlamydophila pneumoniae: Another atypical bacterium that can cause pneumonia, more commonly seen in older children but possible in younger ones.
- Legionella: Rare in young children but can cause severe pneumonia, often requiring specific treatment.